2640 lines
80 KiB
C
2640 lines
80 KiB
C
/* Early (pre-RA) rematerialization
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Copyright (C) 2017-2020 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "backend.h"
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#include "rtl.h"
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#include "df.h"
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#include "tree-pass.h"
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#include "memmodel.h"
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#include "emit-rtl.h"
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#include "insn-config.h"
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#include "recog.h"
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/* FIXME: The next two are only needed for gen_move_insn. */
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#include "tree.h"
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#include "expr.h"
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#include "target.h"
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#include "inchash.h"
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#include "rtlhash.h"
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#include "print-rtl.h"
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#include "rtl-iter.h"
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#include "regs.h"
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#include "function-abi.h"
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/* This pass runs before register allocation and implements an aggressive
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form of rematerialization. It looks for pseudo registers R of mode M
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for which:
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(a) there are no call-preserved registers of mode M; and
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(b) spilling R to the stack is expensive.
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The assumption is that it's better to recompute R after each call instead
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of spilling it, even if this extends the live ranges of other registers.
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The motivating example for which these conditions hold are AArch64 SVE
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vectors and predicates. Spilling them to the stack makes the frame
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variable-sized, which we'd like to avoid if possible. It's also very
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rare for SVE values to be "naturally" live across a call: usually this
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happens as a result of CSE or other code motion.
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The pass is split into the following phases:
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Collection phase
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================
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First we go through all pseudo registers looking for any that meet
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the conditions above. For each such register R, we go through each
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instruction that defines R to see whether any of them are suitable
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rematerialization candidates. If at least one is, we treat all the
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instructions that define R as candidates, but record which ones are
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not in fact suitable. These unsuitable candidates exist only for the
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sake of calculating reaching definitions (see below).
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A "candidate" is a single instruction that we want to rematerialize
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and a "candidate register" is a register that is set by at least one
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candidate.
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Candidate sorting
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=================
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Next we sort the candidates based on the cfg postorder, so that if
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candidate C1 uses candidate C2, C1 has a lower index than C2.
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This is useful when iterating through candidate bitmaps.
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Reaching definition calculation
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===============================
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We then compute standard reaching-definition sets for each candidate.
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Each set specifies which candidates might provide the current definition
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of a live candidate register.
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From here on, a candidate C is "live" at a point P if the candidate
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register defined by C is live at P and if C's definition reaches P.
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An instruction I "uses" a candidate C if I takes the register defined by
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C as input and if C is one of the reaching definitions of that register.
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Candidate validation and value numbering
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========================================
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Next we simultaneously decide which candidates are valid and look
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for candidates that are equivalent to each other, assigning numbers
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to each unique candidate value. A candidate C is invalid if:
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(a) C uses an invalid candidate;
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(b) there is a cycle of candidate uses involving C; or
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(c) C takes a candidate register R as input and the reaching
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definitions of R do not have the same value number.
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We assign a "representative" candidate C to each value number and from
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here on replace references to other candidates with that value number
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with references to C. It is then only possible to rematerialize a
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register R at point P if (after this replacement) there is a single
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reaching definition of R at P.
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Local phase
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===========
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During this phase we go through each block and look for cases in which:
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(a) an instruction I comes between two call instructions CI1 and CI2;
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(b) I uses a candidate register R;
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(c) a candidate C provides the only reaching definition of R; and
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(d) C does not come between CI1 and I.
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We then emit a copy of C after CI1, as well as the transitive closure
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TC of the candidates used by C. The copies of TC might use the original
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candidate registers or new temporary registers, depending on circumstances.
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For example, if elsewhere we have:
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C3: R3 <- f3 (...)
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...
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C2: R2 <- f2 (...)
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...
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C1: R1 <- f1 (R2, R3, ...) // uses C2 and C3
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then for a block containing:
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CI1: call
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...
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I: use R1 // uses C1
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...
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CI2: call
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we would emit:
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CI1: call
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C3': R3' <- f3 (...)
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C2': R2' <- f2 (...)
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C1': R1 <- f1 (R2', R3', ...)
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...
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I: use R1
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...
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CI2: call
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where R2' and R3' might be fresh registers. If instead we had:
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CI1: call
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...
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I1: use R1 // uses C1
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...
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I2: use R3 // uses C3
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...
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CI2: call
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we would keep the original R3:
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CI1: call
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C3': R3 <- f3 (...)
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C2': R2' <- f2 (...)
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C1': R1 <- f1 (R2', R3, ...)
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...
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I1: use R1 // uses C1
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...
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I2: use R3 // uses C3
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...
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CI2: call
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We also record the last call in each block (if any) and compute:
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rd_after_call:
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The set of candidates that either (a) are defined outside the block
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and are live after the last call or (b) are defined within the block
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and reach the end of the last call. (We don't track whether the
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latter values are live or not.)
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required_after_call:
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The set of candidates that need to be rematerialized after the
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last call in order to satisfy uses in the block itself.
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required_in:
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The set of candidates that are live on entry to the block and are
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used without an intervening call.
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In addition, we compute the initial values of the sets required by
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the global phase below.
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Global phase
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============
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We next compute a maximal solution to the following availability
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problem:
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available_in:
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The set of candidates that are live on entry to a block and can
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be used at that point without rematerialization.
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available_out:
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The set of candidates that are live on exit from a block and can
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be used at that point without rematerialization.
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available_locally:
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The subset of available_out that is due to code in the block itself.
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It contains candidates that are defined or used in the block and
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not invalidated by a later call.
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We then go through each block B and look for an appropriate place
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to insert copies of required_in - available_in. Conceptually we
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start by placing the copies at the head of B, but then move the
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copy of a candidate C to predecessors if:
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(a) that seems cheaper;
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(b) there is more than one reaching definition of C's register at
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the head of B; or
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(c) copying C would clobber a hard register that is live on entry to B.
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Moving a copy of C to a predecessor block PB involves:
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(1) adding C to PB's required_after_call, if PB contains a call; or
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(2) adding C PB's required_in otherwise.
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C is then available on output from each PB and on input to B.
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Once all this is done, we emit instructions for the final required_in
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and required_after_call sets. */
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namespace {
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/* An invalid candidate index, used to indicate that there is more than
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one reaching definition. */
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const unsigned int MULTIPLE_CANDIDATES = -1U;
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/* Pass-specific information about one basic block. */
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struct remat_block_info {
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/* The last call instruction in the block. */
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rtx_insn *last_call;
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/* The set of candidates that are live on entry to the block. NULL is
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equivalent to an empty set. */
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bitmap rd_in;
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/* The set of candidates that are live on exit from the block. This might
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reuse rd_in. NULL is equivalent to an empty set. */
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bitmap rd_out;
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/* The subset of RD_OUT that comes from local definitions. NULL is
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equivalent to an empty set. */
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bitmap rd_gen;
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/* The set of candidates that the block invalidates (because it defines
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the register to something else, or because the register's value is
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no longer important). NULL is equivalent to an empty set. */
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bitmap rd_kill;
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/* The set of candidates that either (a) are defined outside the block
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and are live after LAST_CALL or (b) are defined within the block
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and reach the instruction after LAST_CALL. (We don't track whether
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the latter values are live or not.)
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Only used if LAST_CALL is nonnull. NULL is equivalent to an
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empty set. */
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bitmap rd_after_call;
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/* Candidates that are live and available without rematerialization
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on entry to the block. NULL is equivalent to an empty set. */
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bitmap available_in;
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/* Candidates that become available without rematerialization within the
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block, and remain so on exit. NULL is equivalent to an empty set. */
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bitmap available_locally;
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/* Candidates that are available without rematerialization on exit from
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the block. This might reuse available_in or available_locally. */
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bitmap available_out;
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/* Candidates that need to be rematerialized either at the start of the
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block or before entering the block. */
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bitmap required_in;
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/* Candidates that need to be rematerialized after LAST_CALL.
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Only used if LAST_CALL is nonnull. */
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bitmap required_after_call;
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/* The number of candidates in the block. */
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unsigned int num_candidates;
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/* The earliest candidate in the block (i.e. the one with the
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highest index). Only valid if NUM_CANDIDATES is nonzero. */
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unsigned int first_candidate;
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/* The best (lowest) execution frequency for rematerializing REQUIRED_IN.
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This is the execution frequency of the block if LOCAL_REMAT_CHEAPER_P,
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otherwise it is the sum of the execution frequencies of whichever
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predecessor blocks would do the rematerialization. */
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int remat_frequency;
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/* True if the block ends with an abnormal call. */
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unsigned int abnormal_call_p : 1;
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/* Used to record whether a graph traversal has visited this block. */
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unsigned int visited_p : 1;
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/* True if we have calculated REMAT_FREQUENCY. */
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unsigned int remat_frequency_valid_p : 1;
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/* True if it is cheaper to rematerialize candidates at the start of
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the block, rather than moving them to predecessor blocks. */
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unsigned int local_remat_cheaper_p : 1;
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};
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/* Information about a group of candidates with the same value number. */
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struct remat_equiv_class {
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/* The candidates that have the same value number. */
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bitmap members;
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/* The candidate that was first added to MEMBERS. */
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unsigned int earliest;
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/* The candidate that represents the others. This is always the one
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with the highest index. */
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unsigned int representative;
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};
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/* Information about an instruction that we might want to rematerialize. */
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struct remat_candidate {
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/* The pseudo register that the instruction sets. */
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unsigned int regno;
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/* A temporary register used when rematerializing uses of this candidate,
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if REGNO doesn't have the right value or isn't worth using. */
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unsigned int copy_regno;
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/* True if we intend to rematerialize this instruction by emitting
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a move of a constant into REGNO, false if we intend to emit a
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copy of the original instruction. */
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unsigned int constant_p : 1;
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/* True if we still think it's possible to rematerialize INSN. */
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unsigned int can_copy_p : 1;
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/* Used to record whether a graph traversal has visited this candidate. */
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unsigned int visited_p : 1;
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/* True if we have verified that it's possible to rematerialize INSN.
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Once this is true, both it and CAN_COPY_P remain true. */
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unsigned int validated_p : 1;
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/* True if we have "stabilized" INSN, i.e. ensured that all non-candidate
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registers read by INSN will have the same value when rematerializing INSN.
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Only ever true if CAN_COPY_P. */
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unsigned int stabilized_p : 1;
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/* Hash value used for value numbering. */
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hashval_t hash;
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/* The instruction that sets REGNO. */
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rtx_insn *insn;
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/* If CONSTANT_P, the value that should be moved into REGNO when
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rematerializing, otherwise the pattern of the instruction that
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should be used. */
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rtx remat_rtx;
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/* The set of candidates that INSN takes as input. NULL is equivalent
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to the empty set. All candidates in this set have a higher index
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than the current candidate. */
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bitmap uses;
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/* The set of hard registers that would be clobbered by rematerializing
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the candidate, including (transitively) all those that would be
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clobbered by rematerializing USES. */
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bitmap clobbers;
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/* The equivalence class to which the candidate belongs, or null if none. */
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remat_equiv_class *equiv_class;
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};
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/* Hash functions used for value numbering. */
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struct remat_candidate_hasher : nofree_ptr_hash <remat_candidate>
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{
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typedef value_type compare_type;
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static hashval_t hash (const remat_candidate *);
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static bool equal (const remat_candidate *, const remat_candidate *);
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};
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/* Main class for this pass. */
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class early_remat {
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public:
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early_remat (function *, sbitmap);
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~early_remat ();
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void run (void);
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private:
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bitmap alloc_bitmap (void);
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bitmap get_bitmap (bitmap *);
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void init_temp_bitmap (bitmap *);
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void copy_temp_bitmap (bitmap *, bitmap *);
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void dump_insn_id (rtx_insn *);
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void dump_candidate_bitmap (bitmap);
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void dump_all_candidates (void);
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void dump_edge_list (basic_block, bool);
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void dump_block_info (basic_block);
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void dump_all_blocks (void);
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bool interesting_regno_p (unsigned int);
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remat_candidate *add_candidate (rtx_insn *, unsigned int, bool);
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bool maybe_add_candidate (rtx_insn *, unsigned int);
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bool collect_candidates (void);
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void init_block_info (void);
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void sort_candidates (void);
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void finalize_candidate_indices (void);
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void record_equiv_candidates (unsigned int, unsigned int);
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static bool rd_confluence_n (edge);
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static bool rd_transfer (int);
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void compute_rd (void);
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unsigned int canon_candidate (unsigned int);
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void canon_bitmap (bitmap *);
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unsigned int resolve_reaching_def (bitmap);
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bool check_candidate_uses (unsigned int);
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void compute_clobbers (unsigned int);
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void assign_value_number (unsigned int);
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void decide_candidate_validity (void);
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void restrict_remat_for_unavail_regs (bitmap, const_bitmap);
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void restrict_remat_for_call (bitmap, rtx_insn *);
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bool stable_use_p (unsigned int);
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void emit_copy_before (unsigned int, rtx, rtx);
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void stabilize_pattern (unsigned int);
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void replace_dest_with_copy (unsigned int);
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void stabilize_candidate_uses (unsigned int, bitmap, bitmap, bitmap,
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bitmap);
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void emit_remat_insns (bitmap, bitmap, bitmap, rtx_insn *);
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bool set_available_out (remat_block_info *);
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void process_block (basic_block);
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void local_phase (void);
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static bool avail_confluence_n (edge);
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static bool avail_transfer (int);
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void compute_availability (void);
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void unshare_available_sets (remat_block_info *);
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bool can_move_across_edge_p (edge);
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bool local_remat_cheaper_p (unsigned int);
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bool need_to_move_candidate_p (unsigned int, unsigned int);
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void compute_minimum_move_set (unsigned int, bitmap);
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void move_to_predecessors (unsigned int, bitmap, bitmap);
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void choose_rematerialization_points (void);
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void emit_remat_insns_for_block (basic_block);
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void global_phase (void);
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/* The function that we're optimizing. */
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function *m_fn;
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/* The modes that we want to rematerialize. */
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sbitmap m_selected_modes;
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/* All rematerialization candidates, identified by their index into the
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vector. */
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auto_vec<remat_candidate> m_candidates;
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/* The set of candidate registers. */
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bitmap_head m_candidate_regnos;
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/* Temporary sets. */
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bitmap_head m_tmp_bitmap;
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bitmap m_available;
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bitmap m_required;
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/* Information about each basic block. */
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auto_vec<remat_block_info> m_block_info;
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/* A mapping from register numbers to the set of associated candidates.
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Only valid for registers in M_CANDIDATE_REGNOS. */
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auto_vec<bitmap> m_regno_to_candidates;
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/* An obstack used for allocating bitmaps, so that we can free them all
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in one go. */
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bitmap_obstack m_obstack;
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/* A hash table of candidates used for value numbering. If a candidate
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in the table is in an equivalence class, the candidate is marked as
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the earliest member of the class. */
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hash_table<remat_candidate_hasher> m_value_table;
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/* Used temporarily by callback functions. */
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static early_remat *er;
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};
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}
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early_remat *early_remat::er;
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/* rtx_equal_p_cb callback that treats any two SCRATCHes as equal.
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This allows us to compare two copies of a pattern, even though their
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SCRATCHes are always distinct. */
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static int
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scratch_equal (const_rtx *x, const_rtx *y, rtx *nx, rtx *ny)
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{
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if (GET_CODE (*x) == SCRATCH && GET_CODE (*y) == SCRATCH)
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{
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*nx = const0_rtx;
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*ny = const0_rtx;
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return 1;
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}
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return 0;
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}
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/* Hash callback functions for remat_candidate. */
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hashval_t
|
|
remat_candidate_hasher::hash (const remat_candidate *cand)
|
|
{
|
|
return cand->hash;
|
|
}
|
|
|
|
bool
|
|
remat_candidate_hasher::equal (const remat_candidate *cand1,
|
|
const remat_candidate *cand2)
|
|
{
|
|
return (cand1->regno == cand2->regno
|
|
&& cand1->constant_p == cand2->constant_p
|
|
&& (cand1->constant_p
|
|
? rtx_equal_p (cand1->remat_rtx, cand2->remat_rtx)
|
|
: rtx_equal_p_cb (cand1->remat_rtx, cand2->remat_rtx,
|
|
scratch_equal))
|
|
&& (!cand1->uses || bitmap_equal_p (cand1->uses, cand2->uses)));
|
|
}
|
|
|
|
/* Return true if B is null or empty. */
|
|
|
|
inline bool
|
|
empty_p (bitmap b)
|
|
{
|
|
return !b || bitmap_empty_p (b);
|
|
}
|
|
|
|
/* Allocate a new bitmap. It will be automatically freed at the end of
|
|
the pass. */
|
|
|
|
inline bitmap
|
|
early_remat::alloc_bitmap (void)
|
|
{
|
|
return bitmap_alloc (&m_obstack);
|
|
}
|
|
|
|
/* Initialize *PTR to an empty bitmap if it is currently null. */
|
|
|
|
inline bitmap
|
|
early_remat::get_bitmap (bitmap *ptr)
|
|
{
|
|
if (!*ptr)
|
|
*ptr = alloc_bitmap ();
|
|
return *ptr;
|
|
}
|
|
|
|
/* *PTR is either null or empty. If it is null, initialize it to an
|
|
empty bitmap. */
|
|
|
|
inline void
|
|
early_remat::init_temp_bitmap (bitmap *ptr)
|
|
{
|
|
if (!*ptr)
|
|
*ptr = alloc_bitmap ();
|
|
else
|
|
gcc_checking_assert (bitmap_empty_p (*ptr));
|
|
}
|
|
|
|
/* Move *SRC to *DEST and leave *SRC empty. */
|
|
|
|
inline void
|
|
early_remat::copy_temp_bitmap (bitmap *dest, bitmap *src)
|
|
{
|
|
if (!empty_p (*src))
|
|
{
|
|
*dest = *src;
|
|
*src = NULL;
|
|
}
|
|
else
|
|
*dest = NULL;
|
|
}
|
|
|
|
/* Print INSN's identifier to the dump file. */
|
|
|
|
void
|
|
early_remat::dump_insn_id (rtx_insn *insn)
|
|
{
|
|
fprintf (dump_file, "%d[bb:%d]", INSN_UID (insn),
|
|
BLOCK_FOR_INSN (insn)->index);
|
|
}
|
|
|
|
/* Print candidate set CANDIDATES to the dump file, with a leading space. */
|
|
|
|
void
|
|
early_remat::dump_candidate_bitmap (bitmap candidates)
|
|
{
|
|
if (empty_p (candidates))
|
|
{
|
|
fprintf (dump_file, " none");
|
|
return;
|
|
}
|
|
|
|
unsigned int cand_index;
|
|
bitmap_iterator bi;
|
|
EXECUTE_IF_SET_IN_BITMAP (candidates, 0, cand_index, bi)
|
|
fprintf (dump_file, " %d", cand_index);
|
|
}
|
|
|
|
/* Print information about all candidates to the dump file. */
|
|
|
|
void
|
|
early_remat::dump_all_candidates (void)
|
|
{
|
|
fprintf (dump_file, "\n;; Candidates:\n;;\n");
|
|
fprintf (dump_file, ";; %5s %5s %8s %s\n", "#", "reg", "mode", "insn");
|
|
fprintf (dump_file, ";; %5s %5s %8s %s\n", "=", "===", "====", "====");
|
|
unsigned int cand_index;
|
|
remat_candidate *cand;
|
|
FOR_EACH_VEC_ELT (m_candidates, cand_index, cand)
|
|
{
|
|
fprintf (dump_file, ";; %5d %5d %8s ", cand_index, cand->regno,
|
|
GET_MODE_NAME (GET_MODE (regno_reg_rtx[cand->regno])));
|
|
dump_insn_id (cand->insn);
|
|
if (!cand->can_copy_p)
|
|
fprintf (dump_file, " -- can't copy");
|
|
fprintf (dump_file, "\n");
|
|
}
|
|
|
|
fprintf (dump_file, "\n;; Register-to-candidate mapping:\n;;\n");
|
|
unsigned int regno;
|
|
bitmap_iterator bi;
|
|
EXECUTE_IF_SET_IN_BITMAP (&m_candidate_regnos, 0, regno, bi)
|
|
{
|
|
fprintf (dump_file, ";; %5d:", regno);
|
|
dump_candidate_bitmap (m_regno_to_candidates[regno]);
|
|
fprintf (dump_file, "\n");
|
|
}
|
|
}
|
|
|
|
/* Print the predecessors or successors of BB to the dump file, with a
|
|
leading space. DO_SUCC is true to print successors and false to print
|
|
predecessors. */
|
|
|
|
void
|
|
early_remat::dump_edge_list (basic_block bb, bool do_succ)
|
|
{
|
|
edge e;
|
|
edge_iterator ei;
|
|
FOR_EACH_EDGE (e, ei, do_succ ? bb->succs : bb->preds)
|
|
dump_edge_info (dump_file, e, TDF_NONE, do_succ);
|
|
}
|
|
|
|
/* Print information about basic block BB to the dump file. */
|
|
|
|
void
|
|
early_remat::dump_block_info (basic_block bb)
|
|
{
|
|
remat_block_info *info = &m_block_info[bb->index];
|
|
fprintf (dump_file, ";;\n;; Block %d:", bb->index);
|
|
int width = 25;
|
|
|
|
fprintf (dump_file, "\n;;%*s:", width, "predecessors");
|
|
dump_edge_list (bb, false);
|
|
|
|
fprintf (dump_file, "\n;;%*s:", width, "successors");
|
|
dump_edge_list (bb, true);
|
|
|
|
fprintf (dump_file, "\n;;%*s: %d", width, "frequency",
|
|
bb->count.to_frequency (m_fn));
|
|
|
|
if (info->last_call)
|
|
fprintf (dump_file, "\n;;%*s: %d", width, "last call",
|
|
INSN_UID (info->last_call));
|
|
|
|
if (!empty_p (info->rd_in))
|
|
{
|
|
fprintf (dump_file, "\n;;%*s:", width, "RD in");
|
|
dump_candidate_bitmap (info->rd_in);
|
|
}
|
|
if (!empty_p (info->rd_kill))
|
|
{
|
|
fprintf (dump_file, "\n;;%*s:", width, "RD kill");
|
|
dump_candidate_bitmap (info->rd_kill);
|
|
}
|
|
if (!empty_p (info->rd_gen))
|
|
{
|
|
fprintf (dump_file, "\n;;%*s:", width, "RD gen");
|
|
dump_candidate_bitmap (info->rd_gen);
|
|
}
|
|
if (!empty_p (info->rd_after_call))
|
|
{
|
|
fprintf (dump_file, "\n;;%*s:", width, "RD after call");
|
|
dump_candidate_bitmap (info->rd_after_call);
|
|
}
|
|
if (!empty_p (info->rd_out))
|
|
{
|
|
fprintf (dump_file, "\n;;%*s:", width, "RD out");
|
|
if (info->rd_in == info->rd_out)
|
|
fprintf (dump_file, " RD in");
|
|
else
|
|
dump_candidate_bitmap (info->rd_out);
|
|
}
|
|
if (!empty_p (info->available_in))
|
|
{
|
|
fprintf (dump_file, "\n;;%*s:", width, "available in");
|
|
dump_candidate_bitmap (info->available_in);
|
|
}
|
|
if (!empty_p (info->available_locally))
|
|
{
|
|
fprintf (dump_file, "\n;;%*s:", width, "available locally");
|
|
dump_candidate_bitmap (info->available_locally);
|
|
}
|
|
if (!empty_p (info->available_out))
|
|
{
|
|
fprintf (dump_file, "\n;;%*s:", width, "available out");
|
|
if (info->available_in == info->available_out)
|
|
fprintf (dump_file, " available in");
|
|
else if (info->available_locally == info->available_out)
|
|
fprintf (dump_file, " available locally");
|
|
else
|
|
dump_candidate_bitmap (info->available_out);
|
|
}
|
|
if (!empty_p (info->required_in))
|
|
{
|
|
fprintf (dump_file, "\n;;%*s:", width, "required in");
|
|
dump_candidate_bitmap (info->required_in);
|
|
}
|
|
if (!empty_p (info->required_after_call))
|
|
{
|
|
fprintf (dump_file, "\n;;%*s:", width, "required after call");
|
|
dump_candidate_bitmap (info->required_after_call);
|
|
}
|
|
fprintf (dump_file, "\n");
|
|
}
|
|
|
|
/* Print information about all basic blocks to the dump file. */
|
|
|
|
void
|
|
early_remat::dump_all_blocks (void)
|
|
{
|
|
basic_block bb;
|
|
FOR_EACH_BB_FN (bb, m_fn)
|
|
dump_block_info (bb);
|
|
}
|
|
|
|
/* Return true if REGNO is worth rematerializing. */
|
|
|
|
bool
|
|
early_remat::interesting_regno_p (unsigned int regno)
|
|
{
|
|
/* Ignore unused registers. */
|
|
rtx reg = regno_reg_rtx[regno];
|
|
if (!reg || DF_REG_DEF_COUNT (regno) == 0)
|
|
return false;
|
|
|
|
/* Make sure the register has a mode that we want to rematerialize. */
|
|
if (!bitmap_bit_p (m_selected_modes, GET_MODE (reg)))
|
|
return false;
|
|
|
|
/* Ignore values that might sometimes be used uninitialized. We could
|
|
instead add dummy candidates for the entry block definition, and so
|
|
handle uses that are definitely not uninitialized, but the combination
|
|
of the two should be rare in practice. */
|
|
if (bitmap_bit_p (DF_LR_OUT (ENTRY_BLOCK_PTR_FOR_FN (m_fn)), regno))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/* Record the set of register REGNO in instruction INSN as a
|
|
rematerialization candidate. CAN_COPY_P is true unless we already
|
|
know that rematerialization is impossible (in which case the candidate
|
|
only exists for the reaching definition calculation).
|
|
|
|
The candidate's index is not fixed at this stage. */
|
|
|
|
remat_candidate *
|
|
early_remat::add_candidate (rtx_insn *insn, unsigned int regno,
|
|
bool can_copy_p)
|
|
{
|
|
remat_candidate cand;
|
|
memset (&cand, 0, sizeof (cand));
|
|
cand.regno = regno;
|
|
cand.insn = insn;
|
|
cand.remat_rtx = PATTERN (insn);
|
|
cand.can_copy_p = can_copy_p;
|
|
m_candidates.safe_push (cand);
|
|
|
|
bitmap_set_bit (&m_candidate_regnos, regno);
|
|
|
|
return &m_candidates.last ();
|
|
}
|
|
|
|
/* Return true if we can rematerialize the set of register REGNO in
|
|
instruction INSN, and add it as a candidate if so. When returning
|
|
false, print the reason to the dump file. */
|
|
|
|
bool
|
|
early_remat::maybe_add_candidate (rtx_insn *insn, unsigned int regno)
|
|
{
|
|
#define FAILURE_FORMAT ";; Can't rematerialize set of reg %d in %d[bb:%d]: "
|
|
#define FAILURE_ARGS regno, INSN_UID (insn), BLOCK_FOR_INSN (insn)->index
|
|
|
|
/* The definition must come from an ordinary instruction. */
|
|
basic_block bb = BLOCK_FOR_INSN (insn);
|
|
if (!NONJUMP_INSN_P (insn)
|
|
|| (insn == BB_END (bb)
|
|
&& has_abnormal_or_eh_outgoing_edge_p (bb)))
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, FAILURE_FORMAT "insn alters control flow\n",
|
|
FAILURE_ARGS);
|
|
return false;
|
|
}
|
|
|
|
/* Prefer to rematerialize constants directly -- it's much easier. */
|
|
machine_mode mode = GET_MODE (regno_reg_rtx[regno]);
|
|
if (rtx note = find_reg_equal_equiv_note (insn))
|
|
{
|
|
rtx val = XEXP (note, 0);
|
|
if (CONSTANT_P (val)
|
|
&& targetm.legitimate_constant_p (mode, val))
|
|
{
|
|
remat_candidate *cand = add_candidate (insn, regno, true);
|
|
cand->constant_p = true;
|
|
cand->remat_rtx = val;
|
|
return true;
|
|
}
|
|
}
|
|
|
|
/* See whether the target has reasons to prevent a copy. */
|
|
if (targetm.cannot_copy_insn_p && targetm.cannot_copy_insn_p (insn))
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, FAILURE_FORMAT "target forbids copying\n",
|
|
FAILURE_ARGS);
|
|
return false;
|
|
}
|
|
|
|
/* We can't copy trapping instructions. */
|
|
rtx pat = PATTERN (insn);
|
|
if (may_trap_p (pat))
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, FAILURE_FORMAT "insn might trap\n", FAILURE_ARGS);
|
|
return false;
|
|
}
|
|
|
|
/* We can't copy instructions that read memory, unless we know that
|
|
the contents never change. */
|
|
subrtx_iterator::array_type array;
|
|
FOR_EACH_SUBRTX (iter, array, pat, ALL)
|
|
if (MEM_P (*iter) && !MEM_READONLY_P (*iter))
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, FAILURE_FORMAT "insn references non-constant"
|
|
" memory\n", FAILURE_ARGS);
|
|
return false;
|
|
}
|
|
|
|
/* Check each defined register. */
|
|
df_ref ref;
|
|
FOR_EACH_INSN_DEF (ref, insn)
|
|
{
|
|
unsigned int def_regno = DF_REF_REGNO (ref);
|
|
if (def_regno == regno)
|
|
{
|
|
/* Make sure the definition is write-only. (Partial definitions,
|
|
such as setting the low part and clobbering the high part,
|
|
are otherwise OK.) */
|
|
if (DF_REF_FLAGS_IS_SET (ref, DF_REF_READ_WRITE))
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, FAILURE_FORMAT "destination is"
|
|
" read-modify-write\n", FAILURE_ARGS);
|
|
return false;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* The instruction can set additional registers, provided that
|
|
they're hard registers. This is useful for instructions
|
|
that alter the condition codes. */
|
|
if (!HARD_REGISTER_NUM_P (def_regno))
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, FAILURE_FORMAT "insn also sets"
|
|
" pseudo reg %d\n", FAILURE_ARGS, def_regno);
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* If the instruction uses fixed hard registers, check that those
|
|
registers have the same value throughout the function. If the
|
|
instruction uses non-fixed hard registers, check that we can
|
|
replace them with pseudos. */
|
|
FOR_EACH_INSN_USE (ref, insn)
|
|
{
|
|
unsigned int use_regno = DF_REF_REGNO (ref);
|
|
if (HARD_REGISTER_NUM_P (use_regno) && fixed_regs[use_regno])
|
|
{
|
|
if (rtx_unstable_p (DF_REF_REAL_REG (ref)))
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, FAILURE_FORMAT "insn uses fixed hard reg"
|
|
" %d\n", FAILURE_ARGS, use_regno);
|
|
return false;
|
|
}
|
|
}
|
|
else if (HARD_REGISTER_NUM_P (use_regno))
|
|
{
|
|
/* Allocate a dummy pseudo register and temporarily install it.
|
|
Make the register number depend on the mode, which should
|
|
provide enough sharing for match_dup while also weeding
|
|
out cases in which operands with different modes are
|
|
explicitly tied. */
|
|
rtx *loc = DF_REF_REAL_LOC (ref);
|
|
unsigned int size = RTX_CODE_SIZE (REG);
|
|
rtx new_reg = (rtx) alloca (size);
|
|
memset (new_reg, 0, size);
|
|
PUT_CODE (new_reg, REG);
|
|
set_mode_and_regno (new_reg, GET_MODE (*loc),
|
|
LAST_VIRTUAL_REGISTER + 1 + GET_MODE (*loc));
|
|
validate_change (insn, loc, new_reg, 1);
|
|
}
|
|
}
|
|
bool ok_p = verify_changes (0);
|
|
cancel_changes (0);
|
|
if (!ok_p)
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, FAILURE_FORMAT "insn does not allow hard"
|
|
" register inputs to be replaced\n", FAILURE_ARGS);
|
|
return false;
|
|
}
|
|
|
|
#undef FAILURE_ARGS
|
|
#undef FAILURE_FORMAT
|
|
|
|
add_candidate (insn, regno, true);
|
|
return true;
|
|
}
|
|
|
|
/* Calculate the set of rematerialization candidates. Return true if
|
|
we find at least one. */
|
|
|
|
bool
|
|
early_remat::collect_candidates (void)
|
|
{
|
|
unsigned int nregs = DF_REG_SIZE (df);
|
|
for (unsigned int regno = FIRST_PSEUDO_REGISTER; regno < nregs; ++regno)
|
|
if (interesting_regno_p (regno))
|
|
{
|
|
/* Create candidates for all suitable definitions. */
|
|
bitmap_clear (&m_tmp_bitmap);
|
|
unsigned int bad = 0;
|
|
unsigned int id = 0;
|
|
for (df_ref ref = DF_REG_DEF_CHAIN (regno); ref;
|
|
ref = DF_REF_NEXT_REG (ref))
|
|
{
|
|
rtx_insn *insn = DF_REF_INSN (ref);
|
|
if (maybe_add_candidate (insn, regno))
|
|
bitmap_set_bit (&m_tmp_bitmap, id);
|
|
else
|
|
bad += 1;
|
|
id += 1;
|
|
}
|
|
|
|
/* If we found at least one suitable definition, add dummy
|
|
candidates for the rest, so that we can see which definitions
|
|
are live where. */
|
|
if (!bitmap_empty_p (&m_tmp_bitmap) && bad)
|
|
{
|
|
id = 0;
|
|
for (df_ref ref = DF_REG_DEF_CHAIN (regno); ref;
|
|
ref = DF_REF_NEXT_REG (ref))
|
|
{
|
|
if (!bitmap_bit_p (&m_tmp_bitmap, id))
|
|
add_candidate (DF_REF_INSN (ref), regno, false);
|
|
id += 1;
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
return !m_candidates.is_empty ();
|
|
}
|
|
|
|
/* Initialize the m_block_info array. */
|
|
|
|
void
|
|
early_remat::init_block_info (void)
|
|
{
|
|
unsigned int n_blocks = last_basic_block_for_fn (m_fn);
|
|
m_block_info.safe_grow_cleared (n_blocks);
|
|
}
|
|
|
|
/* Maps basic block indices to their position in the post order. */
|
|
static unsigned int *postorder_index;
|
|
|
|
/* Order remat_candidates X_IN and Y_IN according to the cfg postorder. */
|
|
|
|
static int
|
|
compare_candidates (const void *x_in, const void *y_in)
|
|
{
|
|
const remat_candidate *x = (const remat_candidate *) x_in;
|
|
const remat_candidate *y = (const remat_candidate *) y_in;
|
|
basic_block x_bb = BLOCK_FOR_INSN (x->insn);
|
|
basic_block y_bb = BLOCK_FOR_INSN (y->insn);
|
|
if (x_bb != y_bb)
|
|
/* Make X and Y follow block postorder. */
|
|
return postorder_index[x_bb->index] - postorder_index[y_bb->index];
|
|
|
|
/* Make X and Y follow a backward traversal of the containing block. */
|
|
return DF_INSN_LUID (y->insn) - DF_INSN_LUID (x->insn);
|
|
}
|
|
|
|
/* Sort the collected rematerialization candidates so that they follow
|
|
cfg postorder. */
|
|
|
|
void
|
|
early_remat::sort_candidates (void)
|
|
{
|
|
/* Make sure the DF LUIDs are up-to-date for all the blocks we
|
|
care about. */
|
|
bitmap_clear (&m_tmp_bitmap);
|
|
unsigned int cand_index;
|
|
remat_candidate *cand;
|
|
FOR_EACH_VEC_ELT (m_candidates, cand_index, cand)
|
|
{
|
|
basic_block bb = BLOCK_FOR_INSN (cand->insn);
|
|
if (bitmap_set_bit (&m_tmp_bitmap, bb->index))
|
|
df_recompute_luids (bb);
|
|
}
|
|
|
|
/* Create a mapping from block numbers to their position in the
|
|
postorder. */
|
|
unsigned int n_blocks = last_basic_block_for_fn (m_fn);
|
|
int *postorder = df_get_postorder (DF_BACKWARD);
|
|
unsigned int postorder_len = df_get_n_blocks (DF_BACKWARD);
|
|
postorder_index = new unsigned int[n_blocks];
|
|
for (unsigned int i = 0; i < postorder_len; ++i)
|
|
postorder_index[postorder[i]] = i;
|
|
|
|
m_candidates.qsort (compare_candidates);
|
|
|
|
delete postorder_index;
|
|
}
|
|
|
|
/* Commit to the current candidate indices and initialize cross-references. */
|
|
|
|
void
|
|
early_remat::finalize_candidate_indices (void)
|
|
{
|
|
/* Create a bitmap for each candidate register. */
|
|
m_regno_to_candidates.safe_grow (max_reg_num ());
|
|
unsigned int regno;
|
|
bitmap_iterator bi;
|
|
EXECUTE_IF_SET_IN_BITMAP (&m_candidate_regnos, 0, regno, bi)
|
|
m_regno_to_candidates[regno] = alloc_bitmap ();
|
|
|
|
/* Go through each candidate and record its index. */
|
|
unsigned int cand_index;
|
|
remat_candidate *cand;
|
|
FOR_EACH_VEC_ELT (m_candidates, cand_index, cand)
|
|
{
|
|
basic_block bb = BLOCK_FOR_INSN (cand->insn);
|
|
remat_block_info *info = &m_block_info[bb->index];
|
|
info->num_candidates += 1;
|
|
info->first_candidate = cand_index;
|
|
bitmap_set_bit (m_regno_to_candidates[cand->regno], cand_index);
|
|
}
|
|
}
|
|
|
|
/* Record that candidates CAND1_INDEX and CAND2_INDEX are equivalent.
|
|
CAND1_INDEX might already have an equivalence class, but CAND2_INDEX
|
|
doesn't. */
|
|
|
|
void
|
|
early_remat::record_equiv_candidates (unsigned int cand1_index,
|
|
unsigned int cand2_index)
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, ";; Candidate %d is equivalent to candidate %d\n",
|
|
cand2_index, cand1_index);
|
|
|
|
remat_candidate *cand1 = &m_candidates[cand1_index];
|
|
remat_candidate *cand2 = &m_candidates[cand2_index];
|
|
gcc_checking_assert (!cand2->equiv_class);
|
|
|
|
remat_equiv_class *ec = cand1->equiv_class;
|
|
if (!ec)
|
|
{
|
|
ec = XOBNEW (&m_obstack.obstack, remat_equiv_class);
|
|
ec->members = alloc_bitmap ();
|
|
bitmap_set_bit (ec->members, cand1_index);
|
|
ec->earliest = cand1_index;
|
|
ec->representative = cand1_index;
|
|
cand1->equiv_class = ec;
|
|
}
|
|
cand2->equiv_class = ec;
|
|
bitmap_set_bit (ec->members, cand2_index);
|
|
if (cand2_index > ec->representative)
|
|
ec->representative = cand2_index;
|
|
}
|
|
|
|
/* Propagate information from the rd_out set of E->src to the rd_in set
|
|
of E->dest, when computing global reaching definitions. Return true
|
|
if something changed. */
|
|
|
|
bool
|
|
early_remat::rd_confluence_n (edge e)
|
|
{
|
|
remat_block_info *src = &er->m_block_info[e->src->index];
|
|
remat_block_info *dest = &er->m_block_info[e->dest->index];
|
|
|
|
/* available_in temporarily contains the set of candidates whose
|
|
registers are live on entry. */
|
|
if (empty_p (src->rd_out) || empty_p (dest->available_in))
|
|
return false;
|
|
|
|
return bitmap_ior_and_into (er->get_bitmap (&dest->rd_in),
|
|
src->rd_out, dest->available_in);
|
|
}
|
|
|
|
/* Propagate information from the rd_in set of block BB_INDEX to rd_out.
|
|
Return true if something changed. */
|
|
|
|
bool
|
|
early_remat::rd_transfer (int bb_index)
|
|
{
|
|
remat_block_info *info = &er->m_block_info[bb_index];
|
|
|
|
if (empty_p (info->rd_in))
|
|
return false;
|
|
|
|
if (empty_p (info->rd_kill))
|
|
{
|
|
gcc_checking_assert (empty_p (info->rd_gen));
|
|
if (!info->rd_out)
|
|
info->rd_out = info->rd_in;
|
|
else
|
|
gcc_checking_assert (info->rd_out == info->rd_in);
|
|
/* Assume that we only get called if something changed. */
|
|
return true;
|
|
}
|
|
|
|
if (empty_p (info->rd_gen))
|
|
return bitmap_and_compl (er->get_bitmap (&info->rd_out),
|
|
info->rd_in, info->rd_kill);
|
|
|
|
return bitmap_ior_and_compl (er->get_bitmap (&info->rd_out), info->rd_gen,
|
|
info->rd_in, info->rd_kill);
|
|
}
|
|
|
|
/* Calculate the rd_* sets for each block. */
|
|
|
|
void
|
|
early_remat::compute_rd (void)
|
|
{
|
|
/* First calculate the rd_kill and rd_gen sets, using the fact
|
|
that m_candidates is sorted in order of decreasing LUID. */
|
|
unsigned int cand_index;
|
|
remat_candidate *cand;
|
|
FOR_EACH_VEC_ELT_REVERSE (m_candidates, cand_index, cand)
|
|
{
|
|
rtx_insn *insn = cand->insn;
|
|
basic_block bb = BLOCK_FOR_INSN (insn);
|
|
remat_block_info *info = &m_block_info[bb->index];
|
|
bitmap kill = m_regno_to_candidates[cand->regno];
|
|
bitmap_ior_into (get_bitmap (&info->rd_kill), kill);
|
|
if (bitmap_bit_p (DF_LR_OUT (bb), cand->regno))
|
|
{
|
|
bitmap_and_compl_into (get_bitmap (&info->rd_gen), kill);
|
|
bitmap_set_bit (info->rd_gen, cand_index);
|
|
}
|
|
}
|
|
|
|
/* Set up the initial values of the other sets. */
|
|
basic_block bb;
|
|
FOR_EACH_BB_FN (bb, m_fn)
|
|
{
|
|
remat_block_info *info = &m_block_info[bb->index];
|
|
unsigned int regno;
|
|
bitmap_iterator bi;
|
|
EXECUTE_IF_AND_IN_BITMAP (DF_LR_IN (bb), &m_candidate_regnos,
|
|
0, regno, bi)
|
|
{
|
|
/* Use available_in to record the set of candidates whose
|
|
registers are live on entry (i.e. a maximum bound on rd_in). */
|
|
bitmap_ior_into (get_bitmap (&info->available_in),
|
|
m_regno_to_candidates[regno]);
|
|
|
|
/* Add registers that die in a block to the block's kill set,
|
|
so that we don't needlessly propagate them through the rest
|
|
of the function. */
|
|
if (!bitmap_bit_p (DF_LR_OUT (bb), regno))
|
|
bitmap_ior_into (get_bitmap (&info->rd_kill),
|
|
m_regno_to_candidates[regno]);
|
|
}
|
|
|
|
/* Initialize each block's rd_out to the minimal set (the set of
|
|
local definitions). */
|
|
if (!empty_p (info->rd_gen))
|
|
bitmap_copy (get_bitmap (&info->rd_out), info->rd_gen);
|
|
}
|
|
|
|
/* Iterate until we reach a fixed point. */
|
|
er = this;
|
|
bitmap_clear (&m_tmp_bitmap);
|
|
bitmap_set_range (&m_tmp_bitmap, 0, last_basic_block_for_fn (m_fn));
|
|
df_simple_dataflow (DF_FORWARD, NULL, NULL, rd_confluence_n, rd_transfer,
|
|
&m_tmp_bitmap, df_get_postorder (DF_FORWARD),
|
|
df_get_n_blocks (DF_FORWARD));
|
|
er = 0;
|
|
|
|
/* Work out which definitions reach which candidates, again taking
|
|
advantage of the candidate order. */
|
|
bitmap_head reaching;
|
|
bitmap_initialize (&reaching, &m_obstack);
|
|
basic_block old_bb = NULL;
|
|
FOR_EACH_VEC_ELT_REVERSE (m_candidates, cand_index, cand)
|
|
{
|
|
bb = BLOCK_FOR_INSN (cand->insn);
|
|
if (bb != old_bb)
|
|
{
|
|
/* Get the definitions that reach the start of the new block. */
|
|
remat_block_info *info = &m_block_info[bb->index];
|
|
if (info->rd_in)
|
|
bitmap_copy (&reaching, info->rd_in);
|
|
else
|
|
bitmap_clear (&reaching);
|
|
old_bb = bb;
|
|
}
|
|
else
|
|
{
|
|
/* Process the definitions of the previous instruction. */
|
|
bitmap kill = m_regno_to_candidates[cand[1].regno];
|
|
bitmap_and_compl_into (&reaching, kill);
|
|
bitmap_set_bit (&reaching, cand_index + 1);
|
|
}
|
|
|
|
if (cand->can_copy_p && !cand->constant_p)
|
|
{
|
|
df_ref ref;
|
|
FOR_EACH_INSN_USE (ref, cand->insn)
|
|
{
|
|
unsigned int regno = DF_REF_REGNO (ref);
|
|
if (bitmap_bit_p (&m_candidate_regnos, regno))
|
|
{
|
|
bitmap defs = m_regno_to_candidates[regno];
|
|
bitmap_and (&m_tmp_bitmap, defs, &reaching);
|
|
bitmap_ior_into (get_bitmap (&cand->uses), &m_tmp_bitmap);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
bitmap_clear (&reaching);
|
|
}
|
|
|
|
/* If CAND_INDEX is in an equivalence class, return the representative
|
|
of the class, otherwise return CAND_INDEX. */
|
|
|
|
inline unsigned int
|
|
early_remat::canon_candidate (unsigned int cand_index)
|
|
{
|
|
if (remat_equiv_class *ec = m_candidates[cand_index].equiv_class)
|
|
return ec->representative;
|
|
return cand_index;
|
|
}
|
|
|
|
/* Make candidate set *PTR refer to candidates using the representative
|
|
of each equivalence class. */
|
|
|
|
void
|
|
early_remat::canon_bitmap (bitmap *ptr)
|
|
{
|
|
bitmap old_set = *ptr;
|
|
if (empty_p (old_set))
|
|
return;
|
|
|
|
bitmap new_set = NULL;
|
|
unsigned int old_index;
|
|
bitmap_iterator bi;
|
|
EXECUTE_IF_SET_IN_BITMAP (old_set, 0, old_index, bi)
|
|
{
|
|
unsigned int new_index = canon_candidate (old_index);
|
|
if (old_index != new_index)
|
|
{
|
|
if (!new_set)
|
|
{
|
|
new_set = alloc_bitmap ();
|
|
bitmap_copy (new_set, old_set);
|
|
}
|
|
bitmap_clear_bit (new_set, old_index);
|
|
bitmap_set_bit (new_set, new_index);
|
|
}
|
|
}
|
|
if (new_set)
|
|
{
|
|
BITMAP_FREE (*ptr);
|
|
*ptr = new_set;
|
|
}
|
|
}
|
|
|
|
/* If the candidates in REACHING all have the same value, return the
|
|
earliest instance of that value (i.e. the first one to be added
|
|
to m_value_table), otherwise return MULTIPLE_CANDIDATES. */
|
|
|
|
unsigned int
|
|
early_remat::resolve_reaching_def (bitmap reaching)
|
|
{
|
|
unsigned int cand_index = bitmap_first_set_bit (reaching);
|
|
if (remat_equiv_class *ec = m_candidates[cand_index].equiv_class)
|
|
{
|
|
if (!bitmap_intersect_compl_p (reaching, ec->members))
|
|
return ec->earliest;
|
|
}
|
|
else if (bitmap_single_bit_set_p (reaching))
|
|
return cand_index;
|
|
|
|
return MULTIPLE_CANDIDATES;
|
|
}
|
|
|
|
/* Check whether all candidate registers used by candidate CAND_INDEX have
|
|
unique definitions. Return true if so, replacing the candidate's uses
|
|
set with the appropriate form for value numbering. */
|
|
|
|
bool
|
|
early_remat::check_candidate_uses (unsigned int cand_index)
|
|
{
|
|
remat_candidate *cand = &m_candidates[cand_index];
|
|
|
|
/* Process the uses for each register in turn. */
|
|
bitmap_head uses;
|
|
bitmap_initialize (&uses, &m_obstack);
|
|
bitmap_copy (&uses, cand->uses);
|
|
bitmap uses_ec = alloc_bitmap ();
|
|
while (!bitmap_empty_p (&uses))
|
|
{
|
|
/* Get the register for the lowest-indexed candidate remaining,
|
|
and the reaching definitions of that register. */
|
|
unsigned int first = bitmap_first_set_bit (&uses);
|
|
unsigned int regno = m_candidates[first].regno;
|
|
bitmap_and (&m_tmp_bitmap, &uses, m_regno_to_candidates[regno]);
|
|
|
|
/* See whether all reaching definitions have the same value and if
|
|
so get the index of the first candidate we saw with that value. */
|
|
unsigned int def = resolve_reaching_def (&m_tmp_bitmap);
|
|
if (def == MULTIPLE_CANDIDATES)
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, ";; Removing candidate %d because there is"
|
|
" more than one reaching definition of reg %d\n",
|
|
cand_index, regno);
|
|
cand->can_copy_p = false;
|
|
break;
|
|
}
|
|
bitmap_set_bit (uses_ec, def);
|
|
bitmap_and_compl_into (&uses, &m_tmp_bitmap);
|
|
}
|
|
BITMAP_FREE (cand->uses);
|
|
cand->uses = uses_ec;
|
|
return cand->can_copy_p;
|
|
}
|
|
|
|
/* Calculate the set of hard registers that would be clobbered by
|
|
rematerializing candidate CAND_INDEX. At this point the candidate's
|
|
set of uses is final. */
|
|
|
|
void
|
|
early_remat::compute_clobbers (unsigned int cand_index)
|
|
{
|
|
remat_candidate *cand = &m_candidates[cand_index];
|
|
if (cand->uses)
|
|
{
|
|
unsigned int use_index;
|
|
bitmap_iterator bi;
|
|
EXECUTE_IF_SET_IN_BITMAP (cand->uses, 0, use_index, bi)
|
|
if (bitmap clobbers = m_candidates[use_index].clobbers)
|
|
bitmap_ior_into (get_bitmap (&cand->clobbers), clobbers);
|
|
}
|
|
|
|
df_ref ref;
|
|
FOR_EACH_INSN_DEF (ref, cand->insn)
|
|
{
|
|
unsigned int def_regno = DF_REF_REGNO (ref);
|
|
if (def_regno != cand->regno)
|
|
bitmap_set_bit (get_bitmap (&cand->clobbers), def_regno);
|
|
}
|
|
}
|
|
|
|
/* Mark candidate CAND_INDEX as validated and add it to the value table. */
|
|
|
|
void
|
|
early_remat::assign_value_number (unsigned int cand_index)
|
|
{
|
|
remat_candidate *cand = &m_candidates[cand_index];
|
|
gcc_checking_assert (cand->can_copy_p && !cand->validated_p);
|
|
|
|
compute_clobbers (cand_index);
|
|
cand->validated_p = true;
|
|
|
|
inchash::hash h;
|
|
h.add_int (cand->regno);
|
|
inchash::add_rtx (cand->remat_rtx, h);
|
|
cand->hash = h.end ();
|
|
|
|
remat_candidate **slot
|
|
= m_value_table.find_slot_with_hash (cand, cand->hash, INSERT);
|
|
if (!*slot)
|
|
{
|
|
*slot = cand;
|
|
if (dump_file)
|
|
fprintf (dump_file, ";; Candidate %d is not equivalent to"
|
|
" others seen so far\n", cand_index);
|
|
}
|
|
else
|
|
record_equiv_candidates (*slot - m_candidates.address (), cand_index);
|
|
}
|
|
|
|
/* Make a final decision about which candidates are valid and assign
|
|
value numbers to those that are. */
|
|
|
|
void
|
|
early_remat::decide_candidate_validity (void)
|
|
{
|
|
auto_vec<unsigned int, 16> stack;
|
|
unsigned int cand1_index;
|
|
remat_candidate *cand1;
|
|
FOR_EACH_VEC_ELT_REVERSE (m_candidates, cand1_index, cand1)
|
|
{
|
|
if (!cand1->can_copy_p || cand1->validated_p)
|
|
continue;
|
|
|
|
if (empty_p (cand1->uses))
|
|
{
|
|
assign_value_number (cand1_index);
|
|
continue;
|
|
}
|
|
|
|
stack.safe_push (cand1_index);
|
|
while (!stack.is_empty ())
|
|
{
|
|
unsigned int cand2_index = stack.last ();
|
|
unsigned int watermark = stack.length ();
|
|
remat_candidate *cand2 = &m_candidates[cand2_index];
|
|
if (!cand2->can_copy_p || cand2->validated_p)
|
|
{
|
|
stack.pop ();
|
|
continue;
|
|
}
|
|
cand2->visited_p = true;
|
|
unsigned int cand3_index;
|
|
bitmap_iterator bi;
|
|
EXECUTE_IF_SET_IN_BITMAP (cand2->uses, 0, cand3_index, bi)
|
|
{
|
|
remat_candidate *cand3 = &m_candidates[cand3_index];
|
|
if (!cand3->can_copy_p)
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, ";; Removing candidate %d because"
|
|
" it uses removed candidate %d\n", cand2_index,
|
|
cand3_index);
|
|
cand2->can_copy_p = false;
|
|
break;
|
|
}
|
|
if (!cand3->validated_p)
|
|
{
|
|
if (empty_p (cand3->uses))
|
|
assign_value_number (cand3_index);
|
|
else if (cand3->visited_p)
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, ";; Removing candidate %d"
|
|
" because its definition is cyclic\n",
|
|
cand2_index);
|
|
cand2->can_copy_p = false;
|
|
break;
|
|
}
|
|
else
|
|
stack.safe_push (cand3_index);
|
|
}
|
|
}
|
|
if (!cand2->can_copy_p)
|
|
{
|
|
cand2->visited_p = false;
|
|
stack.truncate (watermark - 1);
|
|
}
|
|
else if (watermark == stack.length ())
|
|
{
|
|
cand2->visited_p = false;
|
|
if (check_candidate_uses (cand2_index))
|
|
assign_value_number (cand2_index);
|
|
stack.pop ();
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Ensure that the candidates always use the same candidate index
|
|
to refer to an equivalence class. */
|
|
FOR_EACH_VEC_ELT_REVERSE (m_candidates, cand1_index, cand1)
|
|
if (cand1->can_copy_p && !empty_p (cand1->uses))
|
|
{
|
|
canon_bitmap (&cand1->uses);
|
|
gcc_checking_assert (bitmap_first_set_bit (cand1->uses) > cand1_index);
|
|
}
|
|
}
|
|
|
|
/* Remove any candidates in CANDIDATES that would clobber a register in
|
|
UNAVAIL_REGS. */
|
|
|
|
void
|
|
early_remat::restrict_remat_for_unavail_regs (bitmap candidates,
|
|
const_bitmap unavail_regs)
|
|
{
|
|
bitmap_clear (&m_tmp_bitmap);
|
|
unsigned int cand_index;
|
|
bitmap_iterator bi;
|
|
EXECUTE_IF_SET_IN_BITMAP (candidates, 0, cand_index, bi)
|
|
{
|
|
remat_candidate *cand = &m_candidates[cand_index];
|
|
if (cand->clobbers
|
|
&& bitmap_intersect_p (cand->clobbers, unavail_regs))
|
|
bitmap_set_bit (&m_tmp_bitmap, cand_index);
|
|
}
|
|
bitmap_and_compl_into (candidates, &m_tmp_bitmap);
|
|
}
|
|
|
|
/* Remove any candidates in CANDIDATES that would clobber a register
|
|
that is potentially live across CALL. */
|
|
|
|
void
|
|
early_remat::restrict_remat_for_call (bitmap candidates, rtx_insn *call)
|
|
{
|
|
/* We don't know whether partially-clobbered registers are live
|
|
across the call or not, so assume that they are. */
|
|
bitmap_view<HARD_REG_SET> call_preserved_regs
|
|
(~insn_callee_abi (call).full_reg_clobbers ());
|
|
restrict_remat_for_unavail_regs (candidates, call_preserved_regs);
|
|
}
|
|
|
|
/* Assuming that every path reaching a point P contains a copy of a
|
|
use U of REGNO, return true if another copy of U at P would have
|
|
access to the same value of REGNO. */
|
|
|
|
bool
|
|
early_remat::stable_use_p (unsigned int regno)
|
|
{
|
|
/* Conservatively assume not for hard registers. */
|
|
if (HARD_REGISTER_NUM_P (regno))
|
|
return false;
|
|
|
|
/* See if REGNO has a single definition and is never used uninitialized.
|
|
In this case the definition of REGNO dominates the common dominator
|
|
of the uses U, which in turn dominates P. */
|
|
if (DF_REG_DEF_COUNT (regno) == 1
|
|
&& !bitmap_bit_p (DF_LR_OUT (ENTRY_BLOCK_PTR_FOR_FN (m_fn)), regno))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/* Emit a copy from register DEST to register SRC before candidate
|
|
CAND_INDEX's instruction. */
|
|
|
|
void
|
|
early_remat::emit_copy_before (unsigned int cand_index, rtx dest, rtx src)
|
|
{
|
|
remat_candidate *cand = &m_candidates[cand_index];
|
|
if (dump_file)
|
|
{
|
|
fprintf (dump_file, ";; Stabilizing insn ");
|
|
dump_insn_id (cand->insn);
|
|
fprintf (dump_file, " by copying source reg %d:%s to temporary reg %d\n",
|
|
REGNO (src), GET_MODE_NAME (GET_MODE (src)), REGNO (dest));
|
|
}
|
|
emit_insn_before (gen_move_insn (dest, src), cand->insn);
|
|
}
|
|
|
|
/* Check whether any inputs to candidate CAND_INDEX's instruction could
|
|
change at rematerialization points and replace them with new pseudo
|
|
registers if so. */
|
|
|
|
void
|
|
early_remat::stabilize_pattern (unsigned int cand_index)
|
|
{
|
|
remat_candidate *cand = &m_candidates[cand_index];
|
|
if (cand->stabilized_p)
|
|
return;
|
|
|
|
remat_equiv_class *ec = cand->equiv_class;
|
|
gcc_checking_assert (!ec || cand_index == ec->representative);
|
|
|
|
/* Record the replacements we've made so far, so that we don't
|
|
create two separate registers for match_dups. Lookup is O(n),
|
|
but the n is very small. */
|
|
typedef std::pair<rtx, rtx> reg_pair;
|
|
auto_vec<reg_pair, 16> reg_map;
|
|
|
|
rtx_insn *insn = cand->insn;
|
|
df_ref ref;
|
|
FOR_EACH_INSN_USE (ref, insn)
|
|
{
|
|
unsigned int old_regno = DF_REF_REGNO (ref);
|
|
rtx *loc = DF_REF_REAL_LOC (ref);
|
|
|
|
if (HARD_REGISTER_NUM_P (old_regno) && fixed_regs[old_regno])
|
|
{
|
|
/* We checked when adding the candidate that the value is stable. */
|
|
gcc_checking_assert (!rtx_unstable_p (*loc));
|
|
continue;
|
|
}
|
|
|
|
if (bitmap_bit_p (&m_candidate_regnos, old_regno))
|
|
/* We already know which candidate provides the definition
|
|
and will handle it during copying. */
|
|
continue;
|
|
|
|
if (stable_use_p (old_regno))
|
|
/* We can continue to use the existing register. */
|
|
continue;
|
|
|
|
/* We need to replace the register. See whether we've already
|
|
created a suitable copy. */
|
|
rtx old_reg = *loc;
|
|
rtx new_reg = NULL_RTX;
|
|
machine_mode mode = GET_MODE (old_reg);
|
|
reg_pair *p;
|
|
unsigned int pi;
|
|
FOR_EACH_VEC_ELT (reg_map, pi, p)
|
|
if (REGNO (p->first) == old_regno
|
|
&& GET_MODE (p->first) == mode)
|
|
{
|
|
new_reg = p->second;
|
|
break;
|
|
}
|
|
|
|
if (!new_reg)
|
|
{
|
|
/* Create a new register and initialize it just before
|
|
the instruction. */
|
|
new_reg = gen_reg_rtx (mode);
|
|
reg_map.safe_push (reg_pair (old_reg, new_reg));
|
|
if (ec)
|
|
{
|
|
unsigned int member_index;
|
|
bitmap_iterator bi;
|
|
EXECUTE_IF_SET_IN_BITMAP (ec->members, 0, member_index, bi)
|
|
emit_copy_before (member_index, new_reg, old_reg);
|
|
}
|
|
else
|
|
emit_copy_before (cand_index, new_reg, old_reg);
|
|
}
|
|
validate_change (insn, loc, new_reg, true);
|
|
}
|
|
if (num_changes_pending ())
|
|
{
|
|
if (!apply_change_group ())
|
|
/* We checked when adding the candidates that the pattern allows
|
|
hard registers to be replaced. Nothing else should make the
|
|
changes invalid. */
|
|
gcc_unreachable ();
|
|
|
|
if (ec)
|
|
{
|
|
/* Copy the new pattern to other members of the equivalence
|
|
class. */
|
|
unsigned int member_index;
|
|
bitmap_iterator bi;
|
|
EXECUTE_IF_SET_IN_BITMAP (ec->members, 0, member_index, bi)
|
|
if (cand_index != member_index)
|
|
{
|
|
rtx_insn *other_insn = m_candidates[member_index].insn;
|
|
if (!validate_change (other_insn, &PATTERN (other_insn),
|
|
copy_insn (PATTERN (insn)), 0))
|
|
/* If the original instruction was valid then the copy
|
|
should be too. */
|
|
gcc_unreachable ();
|
|
}
|
|
}
|
|
}
|
|
|
|
cand->stabilized_p = true;
|
|
}
|
|
|
|
/* Change CAND's instruction so that it sets CAND->copy_regno instead
|
|
of CAND->regno. */
|
|
|
|
void
|
|
early_remat::replace_dest_with_copy (unsigned int cand_index)
|
|
{
|
|
remat_candidate *cand = &m_candidates[cand_index];
|
|
df_ref def;
|
|
FOR_EACH_INSN_DEF (def, cand->insn)
|
|
if (DF_REF_REGNO (def) == cand->regno)
|
|
validate_change (cand->insn, DF_REF_REAL_LOC (def),
|
|
regno_reg_rtx[cand->copy_regno], 1);
|
|
}
|
|
|
|
/* Make sure that the candidates used by candidate CAND_INDEX are available.
|
|
There are two ways of doing this for an input candidate I:
|
|
|
|
(1) Using the existing register number and ensuring that I is available.
|
|
|
|
(2) Using a new register number (recorded in copy_regno) and adding I
|
|
to VIA_COPY. This guarantees that making I available does not
|
|
conflict with other uses of the original register.
|
|
|
|
REQUIRED is the set of candidates that are required but not available
|
|
before the copy of CAND_INDEX. AVAILABLE is the set of candidates
|
|
that are already available before the copy of CAND_INDEX. REACHING
|
|
is the set of candidates that reach the copy of CAND_INDEX. VIA_COPY
|
|
is the set of candidates that will use new register numbers recorded
|
|
in copy_regno instead of the original ones. */
|
|
|
|
void
|
|
early_remat::stabilize_candidate_uses (unsigned int cand_index,
|
|
bitmap required, bitmap available,
|
|
bitmap reaching, bitmap via_copy)
|
|
{
|
|
remat_candidate *cand = &m_candidates[cand_index];
|
|
df_ref use;
|
|
FOR_EACH_INSN_USE (use, cand->insn)
|
|
{
|
|
unsigned int regno = DF_REF_REGNO (use);
|
|
if (!bitmap_bit_p (&m_candidate_regnos, regno))
|
|
continue;
|
|
|
|
/* Work out which candidate provides the definition. */
|
|
bitmap defs = m_regno_to_candidates[regno];
|
|
bitmap_and (&m_tmp_bitmap, cand->uses, defs);
|
|
gcc_checking_assert (bitmap_single_bit_set_p (&m_tmp_bitmap));
|
|
unsigned int def_index = bitmap_first_set_bit (&m_tmp_bitmap);
|
|
|
|
/* First see if DEF_INDEX is the only reaching definition of REGNO
|
|
at this point too and if it is or will become available. We can
|
|
continue to use REGNO if so. */
|
|
bitmap_and (&m_tmp_bitmap, reaching, defs);
|
|
if (bitmap_single_bit_set_p (&m_tmp_bitmap)
|
|
&& bitmap_first_set_bit (&m_tmp_bitmap) == def_index
|
|
&& ((available && bitmap_bit_p (available, def_index))
|
|
|| bitmap_bit_p (required, def_index)))
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, ";; Keeping reg %d for use of candidate %d"
|
|
" in candidate %d\n", regno, def_index, cand_index);
|
|
continue;
|
|
}
|
|
|
|
/* Otherwise fall back to using a copy. There are other cases
|
|
in which we *could* continue to use REGNO, but there's not
|
|
really much point. Using a separate register ought to make
|
|
things easier for the register allocator. */
|
|
remat_candidate *def_cand = &m_candidates[def_index];
|
|
rtx *loc = DF_REF_REAL_LOC (use);
|
|
rtx new_reg;
|
|
if (bitmap_set_bit (via_copy, def_index))
|
|
{
|
|
new_reg = gen_reg_rtx (GET_MODE (*loc));
|
|
def_cand->copy_regno = REGNO (new_reg);
|
|
if (dump_file)
|
|
fprintf (dump_file, ";; Creating reg %d for use of candidate %d"
|
|
" in candidate %d\n", REGNO (new_reg), def_index,
|
|
cand_index);
|
|
}
|
|
else
|
|
new_reg = regno_reg_rtx[def_cand->copy_regno];
|
|
validate_change (cand->insn, loc, new_reg, 1);
|
|
}
|
|
}
|
|
|
|
/* Rematerialize the candidates in REQUIRED after instruction INSN,
|
|
given that the candidates in AVAILABLE are already available
|
|
and that REACHING is the set of candidates live after INSN.
|
|
REQUIRED and AVAILABLE are disjoint on entry.
|
|
|
|
Clear REQUIRED on exit. */
|
|
|
|
void
|
|
early_remat::emit_remat_insns (bitmap required, bitmap available,
|
|
bitmap reaching, rtx_insn *insn)
|
|
{
|
|
/* Quick exit if there's nothing to do. */
|
|
if (empty_p (required))
|
|
return;
|
|
|
|
/* Only reaching definitions should be available or required. */
|
|
gcc_checking_assert (!bitmap_intersect_compl_p (required, reaching));
|
|
if (available)
|
|
gcc_checking_assert (!bitmap_intersect_compl_p (available, reaching));
|
|
|
|
bitmap_head via_copy;
|
|
bitmap_initialize (&via_copy, &m_obstack);
|
|
while (!bitmap_empty_p (required) || !bitmap_empty_p (&via_copy))
|
|
{
|
|
/* Pick the lowest-indexed candidate left. */
|
|
unsigned int required_index = (bitmap_empty_p (required)
|
|
? ~0U : bitmap_first_set_bit (required));
|
|
unsigned int via_copy_index = (bitmap_empty_p (&via_copy)
|
|
? ~0U : bitmap_first_set_bit (&via_copy));
|
|
unsigned int cand_index = MIN (required_index, via_copy_index);
|
|
remat_candidate *cand = &m_candidates[cand_index];
|
|
|
|
bool via_copy_p = (cand_index == via_copy_index);
|
|
if (via_copy_p)
|
|
bitmap_clear_bit (&via_copy, cand_index);
|
|
else
|
|
{
|
|
/* Remove all candidates for the same register from REQUIRED. */
|
|
bitmap_and (&m_tmp_bitmap, reaching,
|
|
m_regno_to_candidates[cand->regno]);
|
|
bitmap_and_compl_into (required, &m_tmp_bitmap);
|
|
gcc_checking_assert (!bitmap_bit_p (required, cand_index));
|
|
|
|
/* Only rematerialize if we have a single reaching definition
|
|
of the register. */
|
|
if (!bitmap_single_bit_set_p (&m_tmp_bitmap))
|
|
{
|
|
if (dump_file)
|
|
{
|
|
fprintf (dump_file, ";; Can't rematerialize reg %d after ",
|
|
cand->regno);
|
|
dump_insn_id (insn);
|
|
fprintf (dump_file, ": more than one reaching definition\n");
|
|
}
|
|
continue;
|
|
}
|
|
|
|
/* Skip candidates that can't be rematerialized. */
|
|
if (!cand->can_copy_p)
|
|
continue;
|
|
|
|
/* Check the function precondition. */
|
|
gcc_checking_assert (!available
|
|
|| !bitmap_bit_p (available, cand_index));
|
|
}
|
|
|
|
/* Invalid candidates should have been weeded out by now. */
|
|
gcc_assert (cand->can_copy_p);
|
|
|
|
rtx new_pattern;
|
|
if (cand->constant_p)
|
|
{
|
|
/* Emit a simple move. */
|
|
unsigned int regno = via_copy_p ? cand->copy_regno : cand->regno;
|
|
new_pattern = gen_move_insn (regno_reg_rtx[regno], cand->remat_rtx);
|
|
}
|
|
else
|
|
{
|
|
/* If this is the first time we've copied the instruction, make
|
|
sure that any inputs will have the same value after INSN. */
|
|
stabilize_pattern (cand_index);
|
|
|
|
/* Temporarily adjust the original instruction so that it has
|
|
the right form for the copy. */
|
|
if (via_copy_p)
|
|
replace_dest_with_copy (cand_index);
|
|
if (cand->uses)
|
|
stabilize_candidate_uses (cand_index, required, available,
|
|
reaching, &via_copy);
|
|
|
|
/* Get the new instruction pattern. */
|
|
new_pattern = copy_insn (cand->remat_rtx);
|
|
|
|
/* Undo the temporary changes. */
|
|
cancel_changes (0);
|
|
}
|
|
|
|
/* Emit the new instruction. */
|
|
rtx_insn *new_insn = emit_insn_after (new_pattern, insn);
|
|
|
|
if (dump_file)
|
|
{
|
|
fprintf (dump_file, ";; Rematerializing candidate %d after ",
|
|
cand_index);
|
|
dump_insn_id (insn);
|
|
if (via_copy_p)
|
|
fprintf (dump_file, " with new destination reg %d",
|
|
cand->copy_regno);
|
|
fprintf (dump_file, ":\n\n");
|
|
print_rtl_single (dump_file, new_insn);
|
|
fprintf (dump_file, "\n");
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Recompute INFO's available_out set, given that it's distinct from
|
|
available_in and available_locally. */
|
|
|
|
bool
|
|
early_remat::set_available_out (remat_block_info *info)
|
|
{
|
|
if (empty_p (info->available_locally))
|
|
return bitmap_and_compl (get_bitmap (&info->available_out),
|
|
info->available_in, info->rd_kill);
|
|
|
|
if (empty_p (info->rd_kill))
|
|
return bitmap_ior (get_bitmap (&info->available_out),
|
|
info->available_locally, info->available_in);
|
|
|
|
return bitmap_ior_and_compl (get_bitmap (&info->available_out),
|
|
info->available_locally, info->available_in,
|
|
info->rd_kill);
|
|
}
|
|
|
|
/* If BB has more than one call, decide which candidates should be
|
|
rematerialized after the non-final calls and emit the associated
|
|
instructions. Record other information about the block in preparation
|
|
for the global phase. */
|
|
|
|
void
|
|
early_remat::process_block (basic_block bb)
|
|
{
|
|
remat_block_info *info = &m_block_info[bb->index];
|
|
rtx_insn *last_call = NULL;
|
|
rtx_insn *insn;
|
|
|
|
/* Ensure that we always use the same candidate index to refer to an
|
|
equivalence class. */
|
|
if (info->rd_out == info->rd_in)
|
|
{
|
|
canon_bitmap (&info->rd_in);
|
|
info->rd_out = info->rd_in;
|
|
}
|
|
else
|
|
{
|
|
canon_bitmap (&info->rd_in);
|
|
canon_bitmap (&info->rd_out);
|
|
}
|
|
canon_bitmap (&info->rd_kill);
|
|
canon_bitmap (&info->rd_gen);
|
|
|
|
/* The set of candidates that should be rematerialized on entry to the
|
|
block or after the previous call (whichever is more recent). */
|
|
init_temp_bitmap (&m_required);
|
|
|
|
/* The set of candidates that reach the current instruction (i.e. are
|
|
live just before the instruction). */
|
|
bitmap_head reaching;
|
|
bitmap_initialize (&reaching, &m_obstack);
|
|
if (info->rd_in)
|
|
bitmap_copy (&reaching, info->rd_in);
|
|
|
|
/* The set of candidates that are live and available without
|
|
rematerialization just before the current instruction. This only
|
|
accounts for earlier candidates in the block, or those that become
|
|
available by being added to M_REQUIRED. */
|
|
init_temp_bitmap (&m_available);
|
|
|
|
/* Get the range of candidates in the block. */
|
|
unsigned int next_candidate = info->first_candidate;
|
|
unsigned int num_candidates = info->num_candidates;
|
|
remat_candidate *next_def = (num_candidates > 0
|
|
? &m_candidates[next_candidate]
|
|
: NULL);
|
|
|
|
FOR_BB_INSNS (bb, insn)
|
|
{
|
|
if (!NONDEBUG_INSN_P (insn))
|
|
continue;
|
|
|
|
/* First process uses, since this is a forward walk. */
|
|
df_ref ref;
|
|
FOR_EACH_INSN_USE (ref, insn)
|
|
{
|
|
unsigned int regno = DF_REF_REGNO (ref);
|
|
if (bitmap_bit_p (&m_candidate_regnos, regno))
|
|
{
|
|
bitmap defs = m_regno_to_candidates[regno];
|
|
bitmap_and (&m_tmp_bitmap, defs, &reaching);
|
|
gcc_checking_assert (!bitmap_empty_p (&m_tmp_bitmap));
|
|
if (!bitmap_intersect_p (defs, m_available))
|
|
{
|
|
/* There has been no definition of the register since
|
|
the last call or the start of the block (whichever
|
|
is most recent). Mark the reaching definitions
|
|
as required at that point and thus available here. */
|
|
bitmap_ior_into (m_required, &m_tmp_bitmap);
|
|
bitmap_ior_into (m_available, &m_tmp_bitmap);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (CALL_P (insn))
|
|
{
|
|
if (!last_call)
|
|
{
|
|
/* The first call in the block. Record which candidates are
|
|
required at the start of the block. */
|
|
copy_temp_bitmap (&info->required_in, &m_required);
|
|
init_temp_bitmap (&m_required);
|
|
}
|
|
else
|
|
{
|
|
/* The fully-local case: candidates that need to be
|
|
rematerialized after a previous call in the block. */
|
|
restrict_remat_for_call (m_required, last_call);
|
|
emit_remat_insns (m_required, NULL, info->rd_after_call,
|
|
last_call);
|
|
}
|
|
last_call = insn;
|
|
bitmap_clear (m_available);
|
|
gcc_checking_assert (empty_p (m_required));
|
|
}
|
|
|
|
/* Now process definitions. */
|
|
if (next_def && insn == next_def->insn)
|
|
{
|
|
unsigned int gen = canon_candidate (next_candidate);
|
|
|
|
/* Other candidates with the same regno are not available
|
|
any more. */
|
|
bitmap kill = m_regno_to_candidates[next_def->regno];
|
|
bitmap_and_compl_into (m_available, kill);
|
|
bitmap_and_compl_into (&reaching, kill);
|
|
|
|
/* Record that this candidate is available without
|
|
rematerialization. */
|
|
bitmap_set_bit (m_available, gen);
|
|
bitmap_set_bit (&reaching, gen);
|
|
|
|
/* Find the next candidate in the block. */
|
|
num_candidates -= 1;
|
|
next_candidate -= 1;
|
|
if (num_candidates > 0)
|
|
next_def -= 1;
|
|
else
|
|
next_def = NULL;
|
|
}
|
|
|
|
if (insn == last_call)
|
|
bitmap_copy (get_bitmap (&info->rd_after_call), &reaching);
|
|
}
|
|
bitmap_clear (&reaching);
|
|
gcc_checking_assert (num_candidates == 0);
|
|
|
|
/* Remove values from the available set if they aren't live (and so
|
|
aren't interesting to successor blocks). */
|
|
if (info->rd_out)
|
|
bitmap_and_into (m_available, info->rd_out);
|
|
|
|
/* Record the accumulated information. */
|
|
info->last_call = last_call;
|
|
info->abnormal_call_p = (last_call
|
|
&& last_call == BB_END (bb)
|
|
&& has_abnormal_or_eh_outgoing_edge_p (bb));
|
|
copy_temp_bitmap (&info->available_locally, &m_available);
|
|
if (last_call)
|
|
copy_temp_bitmap (&info->required_after_call, &m_required);
|
|
else
|
|
copy_temp_bitmap (&info->required_in, &m_required);
|
|
|
|
/* Assume at first that all live-in values are available without
|
|
rematerialization (i.e. start with the most optimistic assumption). */
|
|
if (info->available_in)
|
|
{
|
|
if (info->rd_in)
|
|
bitmap_copy (info->available_in, info->rd_in);
|
|
else
|
|
BITMAP_FREE (info->available_in);
|
|
}
|
|
|
|
if (last_call || empty_p (info->available_in))
|
|
/* The values available on exit from the block are exactly those that
|
|
are available locally. This set doesn't change. */
|
|
info->available_out = info->available_locally;
|
|
else if (empty_p (info->available_locally) && empty_p (info->rd_kill))
|
|
/* The values available on exit are the same as those available on entry.
|
|
Updating one updates the other. */
|
|
info->available_out = info->available_in;
|
|
else
|
|
set_available_out (info);
|
|
}
|
|
|
|
/* Process each block as for process_block, visiting dominators before
|
|
the blocks they dominate. */
|
|
|
|
void
|
|
early_remat::local_phase (void)
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, "\n;; Local phase:\n");
|
|
|
|
int *postorder = df_get_postorder (DF_BACKWARD);
|
|
unsigned int postorder_len = df_get_n_blocks (DF_BACKWARD);
|
|
for (unsigned int i = postorder_len; i-- > 0; )
|
|
if (postorder[i] >= NUM_FIXED_BLOCKS)
|
|
process_block (BASIC_BLOCK_FOR_FN (m_fn, postorder[i]));
|
|
}
|
|
|
|
/* Return true if available values survive across edge E. */
|
|
|
|
static inline bool
|
|
available_across_edge_p (edge e)
|
|
{
|
|
return (e->flags & EDGE_EH) == 0;
|
|
}
|
|
|
|
/* Propagate information from the available_out set of E->src to the
|
|
available_in set of E->dest, when computing global availability.
|
|
Return true if something changed. */
|
|
|
|
bool
|
|
early_remat::avail_confluence_n (edge e)
|
|
{
|
|
remat_block_info *src = &er->m_block_info[e->src->index];
|
|
remat_block_info *dest = &er->m_block_info[e->dest->index];
|
|
|
|
if (!available_across_edge_p (e))
|
|
return false;
|
|
|
|
if (empty_p (dest->available_in))
|
|
return false;
|
|
|
|
if (!src->available_out)
|
|
{
|
|
bitmap_clear (dest->available_in);
|
|
return true;
|
|
}
|
|
|
|
return bitmap_and_into (dest->available_in, src->available_out);
|
|
}
|
|
|
|
/* Propagate information from the available_in set of block BB_INDEX
|
|
to available_out. Return true if something changed. */
|
|
|
|
bool
|
|
early_remat::avail_transfer (int bb_index)
|
|
{
|
|
remat_block_info *info = &er->m_block_info[bb_index];
|
|
|
|
if (info->available_out == info->available_locally)
|
|
return false;
|
|
|
|
if (info->available_out == info->available_in)
|
|
/* Assume that we are only called if the input changed. */
|
|
return true;
|
|
|
|
return er->set_available_out (info);
|
|
}
|
|
|
|
/* Compute global availability for the function, starting with the local
|
|
information computed by local_phase. */
|
|
|
|
void
|
|
early_remat::compute_availability (void)
|
|
{
|
|
/* We use df_simple_dataflow instead of the lcm routines for three reasons:
|
|
|
|
(1) it avoids recomputing the traversal order;
|
|
(2) many of the sets are likely to be sparse, so we don't necessarily
|
|
want to use sbitmaps; and
|
|
(3) it means we can avoid creating an explicit kill set for the call. */
|
|
er = this;
|
|
bitmap_clear (&m_tmp_bitmap);
|
|
bitmap_set_range (&m_tmp_bitmap, 0, last_basic_block_for_fn (m_fn));
|
|
df_simple_dataflow (DF_FORWARD, NULL, NULL,
|
|
avail_confluence_n, avail_transfer,
|
|
&m_tmp_bitmap, df_get_postorder (DF_FORWARD),
|
|
df_get_n_blocks (DF_FORWARD));
|
|
er = 0;
|
|
|
|
/* Restrict the required_in sets to values that aren't available. */
|
|
basic_block bb;
|
|
FOR_EACH_BB_FN (bb, m_fn)
|
|
{
|
|
remat_block_info *info = &m_block_info[bb->index];
|
|
if (info->required_in && info->available_in)
|
|
bitmap_and_compl_into (info->required_in, info->available_in);
|
|
}
|
|
}
|
|
|
|
/* Make sure that INFO's available_out and available_in sets are unique. */
|
|
|
|
inline void
|
|
early_remat::unshare_available_sets (remat_block_info *info)
|
|
{
|
|
if (info->available_in && info->available_in == info->available_out)
|
|
{
|
|
info->available_in = alloc_bitmap ();
|
|
bitmap_copy (info->available_in, info->available_out);
|
|
}
|
|
}
|
|
|
|
/* Return true if it is possible to move rematerializations from the
|
|
destination of E to the source of E. */
|
|
|
|
inline bool
|
|
early_remat::can_move_across_edge_p (edge e)
|
|
{
|
|
return (available_across_edge_p (e)
|
|
&& !m_block_info[e->src->index].abnormal_call_p);
|
|
}
|
|
|
|
/* Return true if it is cheaper to rematerialize values at the head of
|
|
block QUERY_BB_INDEX instead of rematerializing in its predecessors. */
|
|
|
|
bool
|
|
early_remat::local_remat_cheaper_p (unsigned int query_bb_index)
|
|
{
|
|
if (m_block_info[query_bb_index].remat_frequency_valid_p)
|
|
return m_block_info[query_bb_index].local_remat_cheaper_p;
|
|
|
|
/* Iteratively compute the cost of rematerializing values in the
|
|
predecessor blocks, then compare that with the cost of
|
|
rematerializing at the head of the block.
|
|
|
|
A cycle indicates that there is no call on that execution path,
|
|
so it isn't necessary to rematerialize on that path. */
|
|
auto_vec<basic_block, 16> stack;
|
|
stack.quick_push (BASIC_BLOCK_FOR_FN (m_fn, query_bb_index));
|
|
while (!stack.is_empty ())
|
|
{
|
|
basic_block bb = stack.last ();
|
|
remat_block_info *info = &m_block_info[bb->index];
|
|
if (info->remat_frequency_valid_p)
|
|
{
|
|
stack.pop ();
|
|
continue;
|
|
}
|
|
|
|
info->visited_p = true;
|
|
int frequency = 0;
|
|
bool can_move_p = true;
|
|
edge e;
|
|
edge_iterator ei;
|
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
|
if (!can_move_across_edge_p (e))
|
|
{
|
|
can_move_p = false;
|
|
break;
|
|
}
|
|
else if (m_block_info[e->src->index].last_call)
|
|
/* We'll rematerialize after the call. */
|
|
frequency += e->src->count.to_frequency (m_fn);
|
|
else if (m_block_info[e->src->index].remat_frequency_valid_p)
|
|
/* Add the cost of rematerializing at the head of E->src
|
|
or in its predecessors (whichever is cheaper). */
|
|
frequency += m_block_info[e->src->index].remat_frequency;
|
|
else if (!m_block_info[e->src->index].visited_p)
|
|
/* Queue E->src and then revisit this block again. */
|
|
stack.safe_push (e->src);
|
|
|
|
/* Come back to this block later if we need to process some of
|
|
its predecessors. */
|
|
if (stack.last () != bb)
|
|
continue;
|
|
|
|
/* If rematerializing in and before the block have equal cost, prefer
|
|
rematerializing in the block. This should shorten the live range. */
|
|
int bb_frequency = bb->count.to_frequency (m_fn);
|
|
if (!can_move_p || frequency >= bb_frequency)
|
|
{
|
|
info->local_remat_cheaper_p = true;
|
|
info->remat_frequency = bb_frequency;
|
|
}
|
|
else
|
|
info->remat_frequency = frequency;
|
|
info->remat_frequency_valid_p = true;
|
|
info->visited_p = false;
|
|
if (dump_file)
|
|
{
|
|
if (!can_move_p)
|
|
fprintf (dump_file, ";; Need to rematerialize at the head of"
|
|
" block %d; cannot move to predecessors.\n", bb->index);
|
|
else
|
|
{
|
|
fprintf (dump_file, ";; Block %d has frequency %d,"
|
|
" rematerializing in predecessors has frequency %d",
|
|
bb->index, bb_frequency, frequency);
|
|
if (info->local_remat_cheaper_p)
|
|
fprintf (dump_file, "; prefer to rematerialize"
|
|
" in the block\n");
|
|
else
|
|
fprintf (dump_file, "; prefer to rematerialize"
|
|
" in predecessors\n");
|
|
}
|
|
}
|
|
stack.pop ();
|
|
}
|
|
return m_block_info[query_bb_index].local_remat_cheaper_p;
|
|
}
|
|
|
|
/* Return true if we cannot rematerialize candidate CAND_INDEX at the head of
|
|
block BB_INDEX. */
|
|
|
|
bool
|
|
early_remat::need_to_move_candidate_p (unsigned int bb_index,
|
|
unsigned int cand_index)
|
|
{
|
|
remat_block_info *info = &m_block_info[bb_index];
|
|
remat_candidate *cand = &m_candidates[cand_index];
|
|
basic_block bb = BASIC_BLOCK_FOR_FN (m_fn, bb_index);
|
|
|
|
/* If there is more than one reaching definition of REGNO,
|
|
we'll need to rematerialize in predecessors instead. */
|
|
bitmap_and (&m_tmp_bitmap, info->rd_in, m_regno_to_candidates[cand->regno]);
|
|
if (!bitmap_single_bit_set_p (&m_tmp_bitmap))
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, ";; Cannot rematerialize %d at the"
|
|
" head of block %d because there is more than one"
|
|
" reaching definition of reg %d\n", cand_index,
|
|
bb_index, cand->regno);
|
|
return true;
|
|
}
|
|
|
|
/* Likewise if rematerializing CAND here would clobber a live register. */
|
|
if (cand->clobbers
|
|
&& bitmap_intersect_p (cand->clobbers, DF_LR_IN (bb)))
|
|
{
|
|
if (dump_file)
|
|
fprintf (dump_file, ";; Cannot rematerialize %d at the"
|
|
" head of block %d because it would clobber live"
|
|
" registers\n", cand_index, bb_index);
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/* Set REQUIRED to the minimum set of candidates that must be rematerialized
|
|
in predecessors of block BB_INDEX instead of at the start of the block. */
|
|
|
|
void
|
|
early_remat::compute_minimum_move_set (unsigned int bb_index,
|
|
bitmap required)
|
|
{
|
|
remat_block_info *info = &m_block_info[bb_index];
|
|
bitmap_head remaining;
|
|
|
|
bitmap_clear (required);
|
|
bitmap_initialize (&remaining, &m_obstack);
|
|
bitmap_copy (&remaining, info->required_in);
|
|
while (!bitmap_empty_p (&remaining))
|
|
{
|
|
unsigned int cand_index = bitmap_first_set_bit (&remaining);
|
|
remat_candidate *cand = &m_candidates[cand_index];
|
|
bitmap_clear_bit (&remaining, cand_index);
|
|
|
|
/* Leave invalid candidates where they are. */
|
|
if (!cand->can_copy_p)
|
|
continue;
|
|
|
|
/* Decide whether to move this candidate. */
|
|
if (!bitmap_bit_p (required, cand_index))
|
|
{
|
|
if (!need_to_move_candidate_p (bb_index, cand_index))
|
|
continue;
|
|
bitmap_set_bit (required, cand_index);
|
|
}
|
|
|
|
/* Also move values used by the candidate, so that we don't
|
|
rematerialize them twice. */
|
|
if (cand->uses)
|
|
{
|
|
bitmap_ior_and_into (required, cand->uses, info->required_in);
|
|
bitmap_ior_and_into (&remaining, cand->uses, info->required_in);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Make the predecessors of BB_INDEX rematerialize the candidates in
|
|
REQUIRED. Add any blocks whose required_in set changes to
|
|
PENDING_BLOCKS. */
|
|
|
|
void
|
|
early_remat::move_to_predecessors (unsigned int bb_index, bitmap required,
|
|
bitmap pending_blocks)
|
|
{
|
|
if (empty_p (required))
|
|
return;
|
|
remat_block_info *dest_info = &m_block_info[bb_index];
|
|
basic_block bb = BASIC_BLOCK_FOR_FN (m_fn, bb_index);
|
|
edge e;
|
|
edge_iterator ei;
|
|
FOR_EACH_EDGE (e, ei, bb->preds)
|
|
{
|
|
remat_block_info *src_info = &m_block_info[e->src->index];
|
|
|
|
/* Restrict the set we add to the reaching definitions. */
|
|
bitmap_and (&m_tmp_bitmap, required, src_info->rd_out);
|
|
if (bitmap_empty_p (&m_tmp_bitmap))
|
|
continue;
|
|
|
|
if (!can_move_across_edge_p (e))
|
|
{
|
|
/* We can't move the rematerialization and we can't do it at
|
|
the start of the block either. In this case we just give up
|
|
and rely on spilling to make the values available across E. */
|
|
if (dump_file)
|
|
{
|
|
fprintf (dump_file, ";; Cannot rematerialize the following"
|
|
" candidates in block %d:", e->src->index);
|
|
dump_candidate_bitmap (required);
|
|
fprintf (dump_file, "\n");
|
|
}
|
|
continue;
|
|
}
|
|
|
|
/* Remove candidates that are already available. */
|
|
if (src_info->available_out)
|
|
{
|
|
bitmap_and_compl_into (&m_tmp_bitmap, src_info->available_out);
|
|
if (bitmap_empty_p (&m_tmp_bitmap))
|
|
continue;
|
|
}
|
|
|
|
/* Add the remaining candidates to the appropriate required set. */
|
|
if (dump_file)
|
|
{
|
|
fprintf (dump_file, ";; Moving this set from block %d"
|
|
" to block %d:", bb_index, e->src->index);
|
|
dump_candidate_bitmap (&m_tmp_bitmap);
|
|
fprintf (dump_file, "\n");
|
|
}
|
|
/* If the source block contains a call, we want to rematerialize
|
|
after the call, otherwise we want to rematerialize at the start
|
|
of the block. */
|
|
bitmap src_required = get_bitmap (src_info->last_call
|
|
? &src_info->required_after_call
|
|
: &src_info->required_in);
|
|
if (bitmap_ior_into (src_required, &m_tmp_bitmap))
|
|
{
|
|
if (!src_info->last_call)
|
|
bitmap_set_bit (pending_blocks, e->src->index);
|
|
unshare_available_sets (src_info);
|
|
bitmap_ior_into (get_bitmap (&src_info->available_out),
|
|
&m_tmp_bitmap);
|
|
}
|
|
}
|
|
|
|
/* The candidates are now available on entry to the block. */
|
|
bitmap_and_compl_into (dest_info->required_in, required);
|
|
unshare_available_sets (dest_info);
|
|
bitmap_ior_into (get_bitmap (&dest_info->available_in), required);
|
|
}
|
|
|
|
/* Go through the candidates that are currently marked as being
|
|
rematerialized at the beginning of a block. Decide in each case
|
|
whether that's valid and profitable; if it isn't, move the
|
|
rematerialization to predecessor blocks instead. */
|
|
|
|
void
|
|
early_remat::choose_rematerialization_points (void)
|
|
{
|
|
bitmap_head required;
|
|
bitmap_head pending_blocks;
|
|
|
|
int *postorder = df_get_postorder (DF_BACKWARD);
|
|
unsigned int postorder_len = df_get_n_blocks (DF_BACKWARD);
|
|
bitmap_initialize (&required, &m_obstack);
|
|
bitmap_initialize (&pending_blocks, &m_obstack);
|
|
do
|
|
/* Process the blocks in postorder, to reduce the number of iterations
|
|
of the outer loop. */
|
|
for (unsigned int i = 0; i < postorder_len; ++i)
|
|
{
|
|
unsigned int bb_index = postorder[i];
|
|
remat_block_info *info = &m_block_info[bb_index];
|
|
bitmap_clear_bit (&pending_blocks, bb_index);
|
|
|
|
if (empty_p (info->required_in))
|
|
continue;
|
|
|
|
if (info->available_in)
|
|
gcc_checking_assert (!bitmap_intersect_p (info->required_in,
|
|
info->available_in));
|
|
|
|
if (local_remat_cheaper_p (bb_index))
|
|
{
|
|
/* We'd prefer to rematerialize at the head of the block.
|
|
Only move candidates if we need to. */
|
|
compute_minimum_move_set (bb_index, &required);
|
|
move_to_predecessors (bb_index, &required, &pending_blocks);
|
|
}
|
|
else
|
|
move_to_predecessors (bb_index, info->required_in,
|
|
&pending_blocks);
|
|
}
|
|
while (!bitmap_empty_p (&pending_blocks));
|
|
bitmap_clear (&required);
|
|
}
|
|
|
|
/* Emit all rematerialization instructions queued for BB. */
|
|
|
|
void
|
|
early_remat::emit_remat_insns_for_block (basic_block bb)
|
|
{
|
|
remat_block_info *info = &m_block_info[bb->index];
|
|
|
|
if (info->last_call && !empty_p (info->required_after_call))
|
|
{
|
|
restrict_remat_for_call (info->required_after_call, info->last_call);
|
|
emit_remat_insns (info->required_after_call, NULL,
|
|
info->rd_after_call, info->last_call);
|
|
}
|
|
|
|
if (!empty_p (info->required_in))
|
|
{
|
|
rtx_insn *insn = BB_HEAD (bb);
|
|
while (insn != BB_END (bb)
|
|
&& !INSN_P (NEXT_INSN (insn)))
|
|
insn = NEXT_INSN (insn);
|
|
restrict_remat_for_unavail_regs (info->required_in, DF_LR_IN (bb));
|
|
emit_remat_insns (info->required_in, info->available_in,
|
|
info->rd_in, insn);
|
|
}
|
|
}
|
|
|
|
/* Decide which candidates in each block's REQUIRED_IN set need to be
|
|
rematerialized and decide where the rematerialization instructions
|
|
should go. Emit queued rematerialization instructions at the start
|
|
of blocks and after the last calls in blocks. */
|
|
|
|
void
|
|
early_remat::global_phase (void)
|
|
{
|
|
compute_availability ();
|
|
if (dump_file)
|
|
{
|
|
fprintf (dump_file, "\n;; Blocks after computing global"
|
|
" availability:\n");
|
|
dump_all_blocks ();
|
|
}
|
|
|
|
choose_rematerialization_points ();
|
|
if (dump_file)
|
|
{
|
|
fprintf (dump_file, "\n;; Blocks after choosing rematerialization"
|
|
" points:\n");
|
|
dump_all_blocks ();
|
|
}
|
|
|
|
basic_block bb;
|
|
FOR_EACH_BB_FN (bb, m_fn)
|
|
emit_remat_insns_for_block (bb);
|
|
}
|
|
|
|
/* Main function for the pass. */
|
|
|
|
void
|
|
early_remat::run (void)
|
|
{
|
|
df_analyze ();
|
|
|
|
if (!collect_candidates ())
|
|
return;
|
|
|
|
init_block_info ();
|
|
sort_candidates ();
|
|
finalize_candidate_indices ();
|
|
if (dump_file)
|
|
dump_all_candidates ();
|
|
|
|
compute_rd ();
|
|
decide_candidate_validity ();
|
|
local_phase ();
|
|
global_phase ();
|
|
}
|
|
|
|
early_remat::early_remat (function *fn, sbitmap selected_modes)
|
|
: m_fn (fn),
|
|
m_selected_modes (selected_modes),
|
|
m_available (0),
|
|
m_required (0),
|
|
m_value_table (63)
|
|
{
|
|
bitmap_obstack_initialize (&m_obstack);
|
|
bitmap_initialize (&m_candidate_regnos, &m_obstack);
|
|
bitmap_initialize (&m_tmp_bitmap, &m_obstack);
|
|
}
|
|
|
|
early_remat::~early_remat ()
|
|
{
|
|
bitmap_obstack_release (&m_obstack);
|
|
}
|
|
|
|
namespace {
|
|
|
|
const pass_data pass_data_early_remat =
|
|
{
|
|
RTL_PASS, /* type */
|
|
"early_remat", /* name */
|
|
OPTGROUP_NONE, /* optinfo_flags */
|
|
TV_EARLY_REMAT, /* tv_id */
|
|
0, /* properties_required */
|
|
0, /* properties_provided */
|
|
0, /* properties_destroyed */
|
|
0, /* todo_flags_start */
|
|
TODO_df_finish, /* todo_flags_finish */
|
|
};
|
|
|
|
class pass_early_remat : public rtl_opt_pass
|
|
{
|
|
public:
|
|
pass_early_remat (gcc::context *ctxt)
|
|
: rtl_opt_pass (pass_data_early_remat, ctxt)
|
|
{}
|
|
|
|
/* opt_pass methods: */
|
|
virtual bool gate (function *)
|
|
{
|
|
return optimize > 1 && NUM_POLY_INT_COEFFS > 1;
|
|
}
|
|
|
|
virtual unsigned int execute (function *f)
|
|
{
|
|
auto_sbitmap selected_modes (NUM_MACHINE_MODES);
|
|
bitmap_clear (selected_modes);
|
|
targetm.select_early_remat_modes (selected_modes);
|
|
if (!bitmap_empty_p (selected_modes))
|
|
early_remat (f, selected_modes).run ();
|
|
return 0;
|
|
}
|
|
}; // class pass_early_remat
|
|
|
|
} // anon namespace
|
|
|
|
rtl_opt_pass *
|
|
make_pass_early_remat (gcc::context *ctxt)
|
|
{
|
|
return new pass_early_remat (ctxt);
|
|
}
|