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Makefile.in (tree-switch-conversion.o): Add.

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2008-07-01  Martin Jambor  <mjambor@suse.cz>
        * Makefile.in (tree-switch-conversion.o): Add.
        (OBJS-common): Add tree-swtch-conversion.o.
        * passes.c (init_optimization_passes): Add pass_convert_switch.
        * tree-pass.h: (pass_convert_switch): Add.
        * tree-switch-conversion.c: New file.
        * gcc.dg/tree-ssa/cswtch.c: New testcase.
        * common.opt (ftree-cswtch): New option.
        * params.h (PARAM_SWITCH_CONVERSION_BRANCH_RATIO): New parameter.
        * params.def (PARAM_SWITCH_CONVERSION_BRANCH_RATIO): New parameter.
        * opts.c (decode_options): Set flag_tree_switch_conversion when
        optimization level is >= 2.
        * doc/invoke.texi (Optimize Options): Added description of
        -ftree-swtch-conversion and switch-conversion-max-branch-ratio.

From-SVN: r137313
This commit is contained in:
Martin Jambor 2008-07-01 10:54:18 +02:00 • committed by Martin Jambor
parent ab652c7235
commit b6e99746ac
11 changed files with 1013 additions and 4 deletions
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15
gcc/ChangeLog
View file

@ -1,3 +1,18 @@
2008-07-01 Martin Jambor <mjambor@suse.cz>
* Makefile.in (tree-switch-conversion.o): Add.
(OBJS-common): Add tree-swtch-conversion.o.
* passes.c (init_optimization_passes): Add pass_convert_switch.
* tree-pass.h: (pass_convert_switch): Add.
* tree-switch-conversion.c: New file.
* gcc.dg/tree-ssa/cswtch.c: New testcase.
* common.opt (ftree-cswtch): New option.
* params.h (PARAM_SWITCH_CONVERSION_BRANCH_RATIO): New parameter.
* params.def (PARAM_SWITCH_CONVERSION_BRANCH_RATIO): New parameter.
* opts.c (decode_options): Set flag_tree_switch_conversion when
optimization level is >= 2.
* doc/invoke.texi (Optimize Options): Added description of
-ftree-swtch-conversion and switch-conversion-max-branch-ratio.
2008-06-30 Kaveh R. Ghazi <ghazi@caip.rutgers.edu>
* config/darwin-driver.c (darwin_default_min_version): Fix

6
gcc/Makefile.in
View file

@ -1176,6 +1176,7 @@ OBJS-common = \
tree-profile.o \
tree-scalar-evolution.o \
tree-sra.o \
tree-switch-conversion.o \
tree-ssa-address.o \
tree-ssa-alias.o \
tree-ssa-alias-warnings.o \
@ -2629,6 +2630,11 @@ tree-sra.o : tree-sra.c $(CONFIG_H) $(SYSTEM_H) $(TREE_H) $(RTL_H) \
$(TIMEVAR_H) $(TM_H) coretypes.h $(TREE_DUMP_H) $(TREE_GIMPLE_H) \
langhooks.h tree-pass.h $(FLAGS_H) $(EXPR_H) $(BASIC_BLOCK_H) \
bitmap.h $(GGC_H) hard-reg-set.h $(OBSTACK_H) $(PARAMS_H) $(TARGET_H)
tree-switch-conversion.o : tree-switch-conversion.c $(CONFIG_H) $(SYSTEM_H) \
$(TREE_H) $(TM_P_H) $(TREE_FLOW_H) $(DIAGNOSTIC_H) $(TREE_INLINE_H) \
$(TIMEVAR_H) $(TM_H) coretypes.h $(TREE_DUMP_H) $(TREE_GIMPLE_H) \
tree-pass.h $(FLAGS_H) $(EXPR_H) $(BASIC_BLOCK_H) output.h \
$(GGC_H) $(OBSTACK_H) $(PARAMS_H) $(CPPLIB_H) $(PARAMS_H)
tree-complex.o : tree-complex.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TREE_H) \
$(TM_H) $(RTL_H) $(REAL_H) $(FLAGS_H) $(TREE_FLOW_H) $(TREE_GIMPLE_H) \
tree-iterator.h tree-pass.h tree-ssa-propagate.h $(DIAGNOSTIC_H)

4
gcc/common.opt
View file

@ -1088,6 +1088,10 @@ ftree-cselim
Common Report Var(flag_tree_cselim) Init(2) Optimization
Transform condition stores into unconditional ones
ftree-switch-conversion
Common Report Var(flag_tree_switch_conversion) Optimization
Perform conversions of switch initializations.
ftree-dce
Common Report Var(flag_tree_dce) Optimization
Enable SSA dead code elimination optimization on trees

19
gcc/doc/invoke.texi
View file

@ -359,10 +359,10 @@ Objective-C and Objective-C++ Dialects}.
-ftree-loop-distribution @gol
-ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
-ftree-parallelize-loops=@var{n} -ftree-pre -ftree-reassoc @gol
-ftree-sink -ftree-sra -ftree-store-ccp -ftree-ter @gol
-ftree-vect-loop-version -ftree-vectorize -ftree-vrp -funit-at-a-time @gol
-funroll-all-loops -funroll-loops -funsafe-loop-optimizations @gol
-funsafe-math-optimizations -funswitch-loops @gol
-ftree-sink -ftree-sra -ftree-store-ccp -ftree-switch-conversion @gol
-ftree-ter -ftree-vect-loop-version -ftree-vectorize -ftree-vrp @gol
-funit-at-a-time -funroll-all-loops -funroll-loops @gol
-funsafe-loop-optimizations -funsafe-math-optimizations -funswitch-loops @gol
-fvariable-expansion-in-unroller -fvect-cost-model -fvpt -fweb @gol
-fwhole-program @gol
--param @var{name}=@var{value}
@ -5194,6 +5194,7 @@ also turns on the following optimization flags:
-fsched-interblock -fsched-spec @gol
-fschedule-insns -fschedule-insns2 @gol
-fstrict-aliasing -fstrict-overflow @gol
-ftree-switch-conversion @gol
-ftree-pre @gol
-ftree-vrp}
@ -5868,6 +5869,11 @@ pass operates on both local scalar variables and memory stores and
loads (global variables, structures, arrays, etc). This flag is
enabled by default at @option{-O2} and higher.
@item -ftree-switch-conversion
Perform conversion of simple initializations in a switch to
initializations from a scalar array. This flag is enabled by default
at @option{-O2} and higher.
@item -ftree-dce
@opindex ftree-dce
Perform dead code elimination (DCE) on trees. This flag is enabled by
@ -7344,6 +7350,11 @@ mechanism for comparing types in C++ and Objective-C++. However, if
bugs in the canonical type system are causing compilation failures,
set this value to 0 to disable canonical types.
@item switch-conversion-max-branch-ratio
Switch initialization conversion will refuse to create arrays that are
bigger than @option{cswtch-max-branch-ratio} times the number of
branches in the switch.
@item max-partial-antic-length
Maximum length of the partial antic set computed during the tree
partial redundancy elimination optimization (@option{-ftree-pre}) when

1
gcc/opts.c
View file

@ -891,6 +891,7 @@ decode_options (unsigned int argc, const char **argv)
flag_reorder_functions = 1;
flag_tree_store_ccp = 1;
flag_tree_vrp = 1;
flag_tree_switch_conversion = 1;
if (!optimize_size)
{

9
gcc/params.def
View file

@ -710,6 +710,15 @@ DEFPARAM (PARAM_DF_DOUBLE_QUEUE_THRESHOLD_FACTOR,
"Multiplier used for determining the double-queueing threshold",
2, 0, 0)
/* Switch initialization conversion will refuse to create arrays that are
bigger than this parameter times the number of switch branches. */
DEFPARAM (PARAM_SWITCH_CONVERSION_BRANCH_RATIO,
"switch-conversion-max-branch-ratio",
"The maximum ratio between array size and switch branches for "
"a switch conversion to take place",
8, 1, 0)
/*
Local variables:
mode:c

2
gcc/params.h
View file

@ -167,4 +167,6 @@ typedef enum compiler_param
PARAM_VALUE (PARAM_L2_CACHE_SIZE)
#define USE_CANONICAL_TYPES \
PARAM_VALUE (PARAM_USE_CANONICAL_TYPES)
#define SWITCH_CONVERSION_BRANCH_RATIO \
PARAM_VALUE (PARAM_SWITCH_CONVERSION_BRANCH_RATIO)
#endif /* ! GCC_PARAMS_H */

1
gcc/passes.c
View file

@ -572,6 +572,7 @@ init_optimization_passes (void)
NEXT_PASS (pass_update_address_taken);
NEXT_PASS (pass_simple_dse);
NEXT_PASS (pass_tail_recursion);
NEXT_PASS (pass_convert_switch);
NEXT_PASS (pass_profile);
NEXT_PASS (pass_release_ssa_names);
}

81
gcc/testsuite/gcc.dg/tree-ssa/cswtch.c Normal file
View file

@ -0,0 +1,81 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-switchconv" } */
/* { dg-do run } */
extern void abort (void);
static int X, Y;
int check(int param)
{
int a = 0;
int b = 1;
switch (param)
{
case -2:
a = 0;
b = -1;
break;
case 1:
case 2:
a = 8;
b = 6;
break;
case 3:
a = 9;
b = 5;
break;
case 6:
a = 10;
b = 4;
break;
default:
a = 16;
b = 1;
}
X = a;
Y = b;
return 0;
}
void assertions(int a, int b)
{
if (X != a || Y != b)
abort();
return;
}
int main ()
{
check (-10);
assertions (16, 1);
check (-2);
assertions (0, -1);
check(1);
assertions (8, 6);
check(2);
assertions (8, 6);
check(3);
assertions (9, 5);
check(5);
assertions (16, 1);
check(6);
assertions (10, 4);
check(12);
assertions (16, 1);
return 0;
}
/* { dg-final { scan-tree-dump "Switch converted" "switchconv" } } */
/* { dg-final { cleanup-tree-dump "switchconv" } } */

1
gcc/tree-pass.h
View file

@ -508,6 +508,7 @@ extern struct gimple_opt_pass pass_O0_always_inline;
extern struct gimple_opt_pass pass_inline_parameters;
extern struct gimple_opt_pass pass_all_early_optimizations;
extern struct gimple_opt_pass pass_update_address_taken;
extern struct gimple_opt_pass pass_convert_switch;
/* The root of the compilation pass tree, once constructed. */
extern struct opt_pass *all_passes, *all_ipa_passes, *all_lowering_passes;

878
gcc/tree-switch-conversion.c Normal file
View file

@ -0,0 +1,878 @@
/* Switch Conversion converts variable initializations based on switch
statements to initializations from a static array.
Copyright (C) 2006, 2008 Free Software Foundation, Inc.
Contributed by Martin Jambor <jamborm@suse.cz>
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3, or (at your option) any
later version.
GCC is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA. */
/*
Switch initialization conversion
The following pass changes simple initializations of scalars in a switch
statement into initializations from a static array. Obviously, the values must
be constant and known at compile time and a default branch must be
provided. For example, the following code:
int a,b;
switch (argc)
{
case 1:
case 2:
a_1 = 8;
b_1 = 6;
break;
case 3:
a_2 = 9;
b_2 = 5;
break;
case 12:
a_3 = 10;
b_3 = 4;
break;
default:
a_4 = 16;
b_4 = 1;
}
a_5 = PHI <a_1, a_2, a_3, a_4>
b_5 = PHI <b_1, b_2, b_3, b_4>
is changed into:
static const int = CSWTCH01[] = {6, 6, 5, 1, 1, 1, 1, 1, 1, 1, 1, 4};
static const int = CSWTCH02[] = {8, 8, 9, 16, 16, 16, 16, 16, 16, 16,
16, 16, 10};
if (((unsigned) argc) - 1 < 11)
{
a_6 = CSWTCH02[argc - 1];
b_6 = CSWTCH01[argc - 1];
}
else
{
a_7 = 16;
b_7 = 1;
}
a_5 = PHI <a_6, a_7>
b_b = PHI <b_6, b_7>
There are further constraints. Specifically, the range of values across all
case labels must not be bigger than SWITCH_CONVERSION_BRANCH_RATIO (default
eight) times the number of the actual switch branches. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include <signal.h>
#include "line-map.h"
#include "params.h"
#include "flags.h"
#include "tree.h"
#include "basic-block.h"
#include "tree-flow.h"
#include "tree-flow-inline.h"
#include "tree-ssa-operands.h"
#include "output.h"
#include "input.h"
#include "tree-pass.h"
#include "diagnostic.h"
#include "tree-dump.h"
/* The main structure of the pass. */
struct switch_conv_info
{
/* The expression used to decide the switch branch. (It is subsequently used
as the index to the created array.) */
tree index_expr;
/* The following integer constants store the minimum value covered by the
cases. */
tree range_min;
/* The difference of between the above two numbers, i.e. The size of the array
that would have to be created by the transformation. */
tree range_size;
/* Basic block that contains the actual SWITCH_EXPR. */
basic_block switch_bb;
/* All branches of the switch statement must have a single successor stored in
the following variable. */
basic_block final_bb;
/* Number of phi nodes in the final bb (that we'll be replacing). */
int phi_count;
/* Array of default values, n the same order as phi nodes. */
tree *default_values;
/* Constructors of new static arrays. */
VEC (constructor_elt, gc) **constructors;
/* Array of ssa names that are initialized with a value from a new static
array. */
tree *target_inbound_names;
/* Array of ssa names that are initialized with the default value if the
switch expression is out of range. */
tree *target_outbound_names;
/* The probability of the default edge in the replaced switch. */
int default_prob;
/* The count of the default edge in the replaced switch. */
gcov_type default_count;
/* Combined count of all other (non-default) edges in the replaced switch. */
gcov_type other_count;
/* The last load statement that loads a temporary from a new static array. */
tree arr_ref_first;
/* The last load statement that loads a temporary from a new static array. */
tree arr_ref_last;
/* String reason why the case wasn't a good candidate that is written to the
dump file, if there is one. */
const char *reason;
};
/* Global pass info. */
static struct switch_conv_info info;
/* Checks whether the range given by individual case statements of the SWTCH
switch statement isn't too big and whether the number of branches actually
satisfies the size of the new array. */
static bool
check_range (tree swtch)
{
tree min_case, max_case;
tree cases = SWITCH_LABELS (swtch);
unsigned int branch_num = TREE_VEC_LENGTH (cases);
tree range_max;
/* The gimplifier has already sorted the cases by CASE_LOW and ensured there
is a default label which is the last in the vector. */
min_case = TREE_VEC_ELT (cases, 0);
info.range_min = CASE_LOW (min_case);
gcc_assert (branch_num > 1);
gcc_assert (CASE_LOW (TREE_VEC_ELT (cases, branch_num - 1)) == NULL_TREE);
max_case = TREE_VEC_ELT (cases, branch_num - 2);
if (CASE_HIGH (max_case) != NULL_TREE)
range_max = CASE_HIGH (max_case);
else
range_max = CASE_LOW (max_case);
gcc_assert (info.range_min);
gcc_assert (range_max);
info.range_size = int_const_binop (MINUS_EXPR, range_max, info.range_min, 0);
gcc_assert (info.range_size);
if (!host_integerp (info.range_size, 1))
{
info.reason = "index range way too large or otherwise unusable.\n";
return false;
}
if ((unsigned HOST_WIDE_INT) tree_low_cst (info.range_size, 1)
> ((unsigned) branch_num * SWITCH_CONVERSION_BRANCH_RATIO))
{
info.reason = "the maximum range-branch ratio exceeded.\n";
return false;
}
return true;
}
/* Checks the given CS switch case whether it is suitable for conversion
(whether all but the default basic blocks are empty and so on). If it is,
adds the case to the branch list along with values for the defined variables
and returns true. Otherwise returns false. */
static bool
check_process_case (tree cs)
{
tree ldecl;
basic_block label_bb, following_bb;
edge e;
ldecl = CASE_LABEL (cs);
label_bb = label_to_block (ldecl);
e = find_edge (info.switch_bb, label_bb);
gcc_assert (e);
if (CASE_LOW (cs) == NULL_TREE)
{
/* Default branch. */
info.default_prob = e->probability;
info.default_count = e->count;
}
else
info.other_count += e->count;
if (!label_bb)
{
info.reason = " Bad case - cs BB label is NULL\n";
return false;
}
if (!single_pred_p (label_bb))
{
if (info.final_bb && info.final_bb != label_bb)
{
info.reason = " Bad case - a non-final BB has two predecessors\n";
return false; /* sth complex going on in this branch */
}
following_bb = label_bb;
}
else
{
if (!empty_block_p (label_bb))
{
info.reason = " Bad case - a non-final BB not empty\n";
return false;
}
e = single_succ_edge (label_bb);
following_bb = single_succ (label_bb);
}
if (!info.final_bb)
info.final_bb = following_bb;
else if (info.final_bb != following_bb)
{
info.reason = " Bad case - different final BB\n";
return false; /* the only successor is not common for all the branches */
}
return true;
}
/* This function checks whether all required values in phi nodes in final_bb
are constants. Required values are those that correspond to a basic block
which is a part of the examined switch statement. It returns true if the
phi nodes are OK, otherwise false. */
static bool
check_final_bb (void)
{
tree phi;
info.phi_count = 0;
for (phi = phi_nodes (info.final_bb); phi; phi = PHI_CHAIN (phi))
{
int i;
info.phi_count++;
for (i = 0; i < PHI_NUM_ARGS (phi); i++)
{
basic_block bb = PHI_ARG_EDGE (phi, i)->src;
if ((bb == info.switch_bb
|| (single_pred_p (bb) && single_pred (bb) == info.switch_bb))
&& !is_gimple_min_invariant (PHI_ARG_ELT (phi, i).def))
{
info.reason = " Non-invariant value from a case\n";
return false; /* non invariant argument */
}
}
}
return true;
}
/* The following function allocates default_values, target_{in,out}_names and
constructors arrays. The last one is also populated with pointers to
vectors that will become constructors of new arrays. */
static void
create_temp_arrays (void)
{
int i;
info.default_values = (tree *) xcalloc (info.phi_count, sizeof (tree));
info.constructors = (VEC (constructor_elt, gc) **) xcalloc (info.phi_count,
sizeof (tree));
info.target_inbound_names = (tree *) xcalloc (info.phi_count, sizeof (tree));
info.target_outbound_names = (tree *) xcalloc (info.phi_count,
sizeof (tree));
for (i = 0; i < info.phi_count; i++)
{
info.constructors[i] = VEC_alloc (constructor_elt, gc,
tree_low_cst (info.range_size, 1) + 1);
}
}
/* Free the arrays created by create_temp_arrays(). The vectors that are
created by that function are not freed here, however, because they have
already become constructors and must be preserved. */
static void
free_temp_arrays (void)
{
free (info.constructors);
free (info.default_values);
free (info.target_inbound_names);
free (info.target_outbound_names);
}
/* Populate the array of default values in the order of phi nodes.
DEFAULT_CASE is the CASE_LABEL_EXPR for the default switch branch. */
static void
gather_default_values (tree default_case)
{
tree phi;
basic_block bb = label_to_block (CASE_LABEL (default_case));
edge e;
int i;
gcc_assert (CASE_LOW (default_case) == NULL_TREE);
if (bb == info.final_bb)
e = find_edge (info.switch_bb, bb);
else
e = single_succ_edge (bb);
for (phi = phi_nodes (info.final_bb), i = 0; phi; phi = PHI_CHAIN (phi), i++)
{
tree val = PHI_ARG_DEF_FROM_EDGE (phi, e);
gcc_assert (val);
info.default_values[i] = val;
}
}
/* The following function populates the vectors in the constructors array with
future contents of the static arrays. The vectors are populated in the
order of phi nodes. SWTCH is the switch statement being converted. */
static void
build_constructors (tree swtch)
{
int i;
tree cases = SWITCH_LABELS (swtch);
tree pos = info.range_min;
for (i = 0; i < TREE_VEC_LENGTH (cases) - 1; i++)
{
tree cs = TREE_VEC_ELT (cases, i);
basic_block bb = label_to_block (CASE_LABEL (cs));
edge e;
tree phi, high;
int j;
if (bb == info.final_bb)
e = find_edge (info.switch_bb, bb);
else
e = single_succ_edge (bb);
gcc_assert (e);
while (tree_int_cst_lt (pos, CASE_LOW (cs)))
{
int k;
for (k = 0; k < info.phi_count; k++)
{
constructor_elt *elt;
elt = VEC_quick_push (constructor_elt,
info.constructors[k], NULL);
elt->index = int_const_binop (MINUS_EXPR, pos, info.range_min, 0);
elt->value = info.default_values[k];
}
pos = int_const_binop (PLUS_EXPR, pos, integer_one_node, 0);
}
gcc_assert (tree_int_cst_equal (pos, CASE_LOW(cs)));
j = 0;
if (CASE_HIGH (cs))
high = CASE_HIGH (cs);
else
high = CASE_LOW(cs);
for (phi = phi_nodes (info.final_bb); phi; phi = PHI_CHAIN (phi))
{
tree val = PHI_ARG_DEF_FROM_EDGE (phi, e);
pos = CASE_LOW (cs);
while (!tree_int_cst_lt (high, pos))
{
constructor_elt *elt;
elt = VEC_quick_push (constructor_elt,
info.constructors[j], NULL);
elt->index = int_const_binop (MINUS_EXPR, pos, info.range_min, 0);
elt->value = val;
pos = int_const_binop (PLUS_EXPR, pos, integer_one_node, 0);
}
j++;
}
}
}
/* Create an appropriate array type and declaration and assemble a static array
variable. Also create a load statement that initializes the variable in
question with a value from the static array. SWTCH is the switch statement
being converted, NUM is the index to arrays of constructors, default values
and target SSA names for this particular array. ARR_INDEX_TYPE is the type
of the index of the new array, PHI is the phi node of the final BB that
corresponds to the value that will be loaded from the created array. TIDX
is a temporary variable holding the index for loads from the new array. */
static void
build_one_array (tree swtch, int num, tree arr_index_type, tree phi, tree tidx)
{
tree array_type;
tree ctor;
tree decl;
tree value_type;
tree name;
tree fetch, load;
block_stmt_iterator bsi;
gcc_assert (info.default_values[num]);
value_type = TREE_TYPE (info.default_values[num]);
array_type = build_array_type (value_type, arr_index_type);
ctor = build_constructor (array_type, info.constructors[num]);
TREE_CONSTANT (ctor) = true;
decl = build_decl (VAR_DECL, NULL_TREE, array_type);
TREE_STATIC (decl) = 1;
DECL_INITIAL (decl) = ctor;
DECL_NAME (decl) = create_tmp_var_name ("CSWTCH");
DECL_ARTIFICIAL (decl) = 1;
TREE_CONSTANT (decl) = 1;
add_referenced_var (decl);
assemble_variable (decl, 0, 0, 0);
mark_sym_for_renaming (decl);
name = make_ssa_name (SSA_NAME_VAR (PHI_RESULT (phi)), NULL_TREE);
info.target_inbound_names[num] = name;
fetch = build4 (ARRAY_REF, value_type, decl, tidx, NULL_TREE,
NULL_TREE);
load = build2 (GIMPLE_MODIFY_STMT, void_type_node, name, fetch);
SSA_NAME_DEF_STMT (name) = load;
bsi = bsi_for_stmt (swtch);
bsi_insert_before (&bsi, load, BSI_SAME_STMT);
mark_symbols_for_renaming (load);
info.arr_ref_last = load;
return;
}
/* Builds and initializes static arrays initialized with values gathered from
the SWTCH switch statement. Also creates statements that load values from
them. */
static void
build_arrays (tree swtch)
{
tree arr_index_type;
tree tidx, sub;
block_stmt_iterator bsi;
tree phi = phi_nodes (info.final_bb);
int i;
arr_index_type = build_index_type (info.range_size);
tidx = make_rename_temp (arr_index_type, "csti");
sub = build2 (MINUS_EXPR, TREE_TYPE (info.index_expr), info.index_expr,
fold_convert (TREE_TYPE (info.index_expr), info.range_min));
sub = build2 (GIMPLE_MODIFY_STMT, void_type_node, tidx, sub);
bsi = bsi_for_stmt (swtch);
bsi_insert_before (&bsi, sub, BSI_SAME_STMT);
mark_symbols_for_renaming (sub);
info.arr_ref_first = sub;
for (phi = phi_nodes (info.final_bb), i = 0; phi; phi = PHI_CHAIN (phi), i++)
build_one_array (swtch, i, arr_index_type, phi, tidx);
return;
}
/* Generates and appropriately inserts loads of default values at the position
given by BSI. Returns the last inserted statement. */
static tree
gen_def_assigns (block_stmt_iterator *bsi)
{
int i;
tree assign = NULL_TREE;
for (i = 0; i < info.phi_count; i++)
{
tree name = make_ssa_name (SSA_NAME_VAR (info.target_inbound_names[i]),
NULL_TREE);
info.target_outbound_names[i] = name;
assign = build2 (GIMPLE_MODIFY_STMT, void_type_node, name,
info.default_values[i]);
SSA_NAME_DEF_STMT (name) = assign;
bsi_insert_before (bsi, assign, BSI_SAME_STMT);
find_new_referenced_vars (&assign);
mark_symbols_for_renaming (assign);
}
return assign;
}
/* Deletes the unused bbs and edges that now contain the switch statement and
its empty branch bbs. BBD is the now dead BB containing the original switch
statement, FINAL is the last BB of the converted switch statement (in terms
of succession). */
static void
prune_bbs (basic_block bbd, basic_block final)
{
edge_iterator ei;
edge e;
for (ei = ei_start (bbd->succs); (e = ei_safe_edge (ei)); )
{
basic_block bb;
bb = e->dest;
remove_edge (e);
if (bb != final)
delete_basic_block (bb);
}
delete_basic_block (bbd);
}
/* Add values to phi nodes in final_bb for the two new edges. E1F is the edge
from the basic block loading values from an array and E2F from the basic
block loading default values. BBF is the last switch basic block (see the
bbf description in the comment below). */
static void
fix_phi_nodes (edge e1f, edge e2f, basic_block bbf)
{
tree phi;
int i;
for (phi = phi_nodes (bbf), i = 0; phi; phi = PHI_CHAIN (phi), i++)
{
add_phi_arg (phi, info.target_inbound_names[i], e1f);
add_phi_arg (phi, info.target_outbound_names[i], e2f);
}
}
/* Creates a check whether the switch expression value actually falls into the
range given by all the cases. If it does not, the temporaries are loaded
with default values instead. SWTCH is the switch statement being converted.
bb0 is the bb with the switch statement, however, we'll end it with a
condition instead.
bb1 is the bb to be used when the range check went ok. It is derived from
the switch BB
bb2 is the bb taken when the expression evaluated outside of the range
covered by the created arrays. It is populated by loads of default
values.
bbF is a fall through for both bb1 and bb2 and contains exactly what
originally followed the switch statement.
bbD contains the switch statement (in the end). It is unreachable but we
still need to strip off its edges.
*/
static void
gen_inbound_check (tree swtch)
{
tree label_decl1 = create_artificial_label ();
tree label_decl2 = create_artificial_label ();
tree label_decl3 = create_artificial_label ();
tree label1, label2, label3;
tree utype = unsigned_type_for (TREE_TYPE (info.index_expr));
tree tmp_u;
tree cast, cast_assign;
tree ulb, minus, minus_assign;
tree bound;
tree if_expr;
tree last_assign;
block_stmt_iterator bsi;
basic_block bb0, bb1, bb2, bbf, bbd;
edge e01, e02, e21, e1d, e1f, e2f;
gcc_assert (info.default_values);
bb0 = bb_for_stmt (swtch);
/* (end of) block 0 */
bsi = bsi_for_stmt (info.arr_ref_first);
tmp_u = make_rename_temp (utype, "csui");
cast = build1 (NOP_EXPR, utype, info.index_expr);
cast_assign = build2 (GIMPLE_MODIFY_STMT, void_type_node, tmp_u, cast);
find_new_referenced_vars (&cast_assign);
bsi_insert_before (&bsi, cast_assign, BSI_SAME_STMT);
mark_symbols_for_renaming (cast_assign);
ulb = fold_convert (utype, info.range_min);
minus = build2 (MINUS_EXPR, utype, tmp_u, ulb);
minus_assign = build2 (GIMPLE_MODIFY_STMT, void_type_node, tmp_u, minus);
find_new_referenced_vars (&minus_assign);
bsi_insert_before (&bsi, minus_assign, BSI_SAME_STMT);
mark_symbols_for_renaming (minus_assign);
bound = fold_convert (utype, info.range_size);
if_expr = build3 (COND_EXPR, void_type_node,
build2 (LE_EXPR, boolean_type_node, tmp_u, bound),
NULL_TREE, NULL_TREE);
find_new_referenced_vars (&if_expr);
bsi_insert_before (&bsi, if_expr, BSI_SAME_STMT);
mark_symbols_for_renaming (if_expr);
/* block 2 */
bsi = bsi_for_stmt (info.arr_ref_first);
label2 = build1 (LABEL_EXPR, void_type_node, label_decl2);
bsi_insert_before (&bsi, label2, BSI_SAME_STMT);
last_assign = gen_def_assigns (&bsi);
/* block 1 */
bsi = bsi_for_stmt (info.arr_ref_first);
label1 = build1 (LABEL_EXPR, void_type_node, label_decl1);
bsi_insert_before (&bsi, label1, BSI_SAME_STMT);
/* block F */
bsi = bsi_start (info.final_bb);
label3 = build1 (LABEL_EXPR, void_type_node, label_decl3);
bsi_insert_before (&bsi, label3, BSI_SAME_STMT);
/* cfg fix */
e02 = split_block (bb0, if_expr);
bb2 = e02->dest;
e21 = split_block (bb2, last_assign);
bb1 = e21->dest;
remove_edge (e21);
e1d = split_block (bb1, info.arr_ref_last);
bbd = e1d->dest;
remove_edge (e1d);
/* flags and profiles of the edge for in-range values */
e01 = make_edge (bb0, bb1, EDGE_TRUE_VALUE);
e01->probability = REG_BR_PROB_BASE - info.default_prob;
e01->count = info.other_count;
/* flags and profiles of the edge taking care of out-of-range values */
e02->flags &= ~EDGE_FALLTHRU;
e02->flags |= EDGE_FALSE_VALUE;
e02->probability = info.default_prob;
e02->count = info.default_count;
bbf = info.final_bb;
e1f = make_edge (bb1, bbf, EDGE_FALLTHRU);
e1f->probability = REG_BR_PROB_BASE;
e1f->count = info.other_count;
e2f = make_edge (bb2, bbf, EDGE_FALLTHRU);
e2f->probability = REG_BR_PROB_BASE;
e2f->count = info.default_count;
/* frequencies of the new BBs */
bb1->frequency = EDGE_FREQUENCY (e01);
bb2->frequency = EDGE_FREQUENCY (e02);
bbf->frequency = EDGE_FREQUENCY (e1f) + EDGE_FREQUENCY (e2f);
prune_bbs (bbd, info.final_bb); /* to keep calc_dfs_tree() in dominance.c
happy */
fix_phi_nodes (e1f, e2f, bbf);
free_dominance_info (CDI_DOMINATORS);
free_dominance_info (CDI_POST_DOMINATORS);
}
/* The following function is invoked on every switch statement (the current one
is given in SWTCH) and runs the individual phases of switch conversion on it
one after another until one fails or the conversion is completed. */
static bool
process_switch (tree swtch)
{
int i;
tree cases;
tree index_type;
/* Operand 2 is either NULL_TREE or a vector of cases (stmt.c). */
if (TREE_OPERAND (swtch, 2) == NULL_TREE)
{
info.reason = "swtch has no labels\n";
return false;
}
/* Comment from stmt.c:
The switch body is lowered in gimplify.c, we should never have switches
with a non-NULL SWITCH_BODY here. */
gcc_assert (!SWITCH_BODY (swtch));
cases = SWITCH_LABELS (swtch);
info.final_bb = NULL;
info.switch_bb = bb_for_stmt (swtch);
info.index_expr = SWITCH_COND (swtch);
index_type = TREE_TYPE (info.index_expr);
info.arr_ref_first = NULL_TREE;
info.arr_ref_last = NULL_TREE;
info.default_prob = 0;
info.default_count = 0;
info.other_count = 0;
/* An ERROR_MARK occurs for various reasons including invalid data type.
(comment from stmt.c) */
if (index_type == error_mark_node)
{
info.reason = "index error.\n";
return false;
}
/* Check the case label values are within reasonable range: */
if (!check_range (swtch))
return false;
/* For all the cases, see whether they are empty, the assignments they
represent constant and so on... */
for (i = 0; i < TREE_VEC_LENGTH (cases); i++)
{
tree part_case = TREE_VEC_ELT (cases, i);
if (!check_process_case (part_case))
{
if (dump_file)
fprintf (dump_file, "Processing of case %i failed\n", i);
return false;
}
}
if (!check_final_bb ())
return false;
/* At this point all checks have passed and we can proceed with the
transformation. */
create_temp_arrays ();
gather_default_values (TREE_VEC_ELT (cases, TREE_VEC_LENGTH (cases) - 1));
build_constructors (swtch);
build_arrays (swtch); /* Build the static arrays and assignments. */
gen_inbound_check (swtch); /* Build the bounds check. */
/* Cleanup: */
free_temp_arrays ();
return true;
}
/* The main function of the pass scans statements for switches and invokes
process_switch on them. */
static unsigned int
do_switchconv (void)
{
basic_block bb;
FOR_EACH_BB (bb)
{
tree stmt = last_stmt (bb);
if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
{
expanded_location loc = expand_location (EXPR_LOCATION (stmt));
if (dump_file)
{
fprintf (dump_file, "beginning to process the following "
"SWITCH statement (%s:%d) : ------- \n",
loc.file, loc.line);
print_generic_stmt (dump_file, stmt, 2);
fprintf (dump_file, "\n");
}
info.reason = NULL;
if (process_switch (stmt))
{
if (dump_file)
{
fprintf (dump_file, "Switch converted\n");
fprintf (dump_file, "--------------------------------\n");
}
}
else
{
if (dump_file)
{
gcc_assert (info.reason);
fprintf (dump_file, "Bailing out - ");
fprintf (dump_file, info.reason);
fprintf (dump_file, "--------------------------------\n");
}
}
}
}
return 0;
}
/* The pass gate. */
static bool
switchconv_gate (void)
{
return flag_tree_switch_conversion != 0;
}
struct gimple_opt_pass pass_convert_switch =
{
{
GIMPLE_PASS,
"switchconv", /* name */
switchconv_gate, /* gate */
do_switchconv, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* static_pass_number */
0, /* tv_id */
PROP_cfg | PROP_ssa, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_update_ssa | TODO_dump_func
| TODO_ggc_collect | TODO_verify_ssa /* todo_flags_finish */
}
};