Check in tree-dce enh to trunk
From-SVN: r135463
This commit is contained in:
Xinliang David Li
Xinliang David Li
parent
b61eacd60f
commit
30da41ed0e
8 changed files with 798 additions and 7 deletions
11
ChangeLog
11
ChangeLog
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@ -1,3 +1,14 @@
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2008-05-17 Xinliang David Li <davidxl@google.com>
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* gcc/tree-ssa-dce.c : conditional dead call elimination
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* gcc/opts.c : enable the optimization at >=O2
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* gcc/common.opt : new flag for control the optimization
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* gcc/doc/invoke.texi : documentation change
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* gcc/testsuite/gcc.dg/cdce1.c : new test case
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* gcc/testsuite/gcc.dg/cdce2.c : new test case
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*MAINTAINERS : Add myself (write after approval)
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2008-05-15 Janus Weil <janus@gcc.gnu.org>
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* MAINTAINERS (Write After Approval): Add myself.
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@ -372,6 +372,7 @@ Manuel L
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Dave Love d.love@dl.ac.uk
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Martin v. Löwis loewis@informatik.hu-berlin.de
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H.J. Lu hjl.tools@gmail.com
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Xinliang David Li davidxl@google.com
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William Maddox maddox@google.com
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Ziga Mahkovec ziga.mahkovec@klika.si
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Simon Martin simartin@users.sourceforge.net
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@ -1259,6 +1259,10 @@ fweb
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Common Report Var(flag_web) Init(2) Optimization
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Construct webs and split unrelated uses of single variable
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ftree-builtin-dce
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Common Report Var(flag_tree_builtin_dce) Init(0) Optimization
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Enable conditional dead code elimination for builtin calls.
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fwhole-program
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Common Report Var(flag_whole_program) Init(0) Optimization
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Perform whole program optimizations
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@ -353,7 +353,7 @@ Objective-C and Objective-C++ Dialects}.
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-fsignaling-nans -fsingle-precision-constant -fsplit-ivs-in-unroller @gol
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-fsplit-wide-types -fstack-protector -fstack-protector-all @gol
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-fstrict-aliasing -fstrict-overflow -fthread-jumps -ftracer -ftree-ccp @gol
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-ftree-ch -ftree-copy-prop -ftree-copyrename -ftree-dce @gol
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-ftree-ch -ftree-copy-prop -ftree-copyrename -ftree-dce -ftree-builtin-dce@gol
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-ftree-dominator-opts -ftree-dse -ftree-fre -ftree-loop-im @gol
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-ftree-loop-distribution @gol
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-ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
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@ -5157,6 +5157,7 @@ compilation time.
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-ftree-ch @gol
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-ftree-copyrename @gol
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-ftree-dce @gol
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-ftree-builtin-dce @gol
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-ftree-dominator-opts @gol
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-ftree-dse @gol
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-ftree-fre @gol
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@ -5873,6 +5874,12 @@ enabled by default at @option{-O2} and higher.
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Perform dead code elimination (DCE) on trees. This flag is enabled by
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default at @option{-O} and higher.
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@item -ftree-builtin-dce
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@opindex ftree-builtin-dce
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Perform conditional dead code elimination (DCE) on builtin calls that
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may set errno but are otherwise side-effect free. This flag is enabled by
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default at @option{-O} and higher.
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@item -ftree-dominator-opts
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@opindex ftree-dominator-opts
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Perform a variety of simple scalar cleanups (constant/copy
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@ -886,6 +886,7 @@ decode_options (unsigned int argc, const char **argv)
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flag_reorder_functions = 1;
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flag_tree_store_ccp = 1;
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flag_tree_vrp = 1;
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flag_tree_builtin_dce = 1;
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if (!optimize_size)
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{
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81
gcc/testsuite/gcc.dg/cdce1.c
Normal file
81
gcc/testsuite/gcc.dg/cdce1.c
Normal file
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@ -0,0 +1,81 @@
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/* { dg-do run } */
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/* { dg-options "-O2 -fdump-tree-dce1-details -lm" } */
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/* { dg-message "note: function call is shrink-wrapped into error conditions\." "Missing conditional dce" {target "*-*-*"} 15 } */
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#include <stdlib.h>
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#include <math.h>
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#include <errno.h>
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#include <stdio.h>
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int total_err_count = 0;
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double foo_opt(int x, double y) __attribute__((noinline));
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double foo_opt(int x, double y)
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{
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double yy = 0;
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errno = 0;
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yy = pow(x,y);
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return 0;
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}
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double foo(int x, double y) __attribute__((noinline));
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double foo(int x, double y)
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{
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double yy = 0;
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errno = 0;
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yy = pow(x,y);
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return yy;
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}
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int test(double (*fp)(int x, double y))
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{
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int i,x;
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x = 127;
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for (i = 30; i < 300; i++)
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{
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fp(x,i);
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if (errno)
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total_err_count ++;
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}
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x = -300;
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for (i = 100; i < 300; i++)
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{
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fp(x,i);
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if (errno)
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total_err_count ++;
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}
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x = 65577;
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for (i = 60; i < 200; i++)
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{
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fp(x,i);
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if (errno)
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total_err_count ++;
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}
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x = 65577*127;
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for (i = 1; i < 100; i++)
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{
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fp(x,i);
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if (errno)
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total_err_count ++;
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}
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return total_err_count;
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}
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int main()
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{
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int en1, en2;
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total_err_count = 0;
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en1 = test(foo_opt);
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total_err_count = 0;
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en2 = test(foo);
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printf("total number of errors = %d, %d\n", en1, en2);
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if (en1 != en2)
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abort();
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return 0;
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}
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56
gcc/testsuite/gcc.dg/cdce2.c
Normal file
56
gcc/testsuite/gcc.dg/cdce2.c
Normal file
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@ -0,0 +1,56 @@
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/* { dg-do run } */
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/* { dg-options "-O2 -fdump-tree-dce1-details -lm" } */
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/* { dg-message "note: function call is shrink-wrapped into error conditions\." "Missing conditional dce" {target "*-*-*"} 15 } */
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#include <stdlib.h>
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#include <math.h>
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#include <errno.h>
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#include <stdio.h>
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int total_err_count = 0;
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double foo_opt(double y) __attribute__((noinline));
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double foo_opt(double y)
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{
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double yy = 0;
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errno = 0;
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yy = log(y);
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return 0;
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}
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double foo(double y) __attribute__((noinline));
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double foo(double y)
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{
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double yy = 0;
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errno = 0;
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yy = log(y);
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return yy;
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}
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int test(double (*fp)(double y) )
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{
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int i,x;
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for (i = -100; i < 100; i++)
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{
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fp(i);
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if (errno)
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total_err_count ++;
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}
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return total_err_count;
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}
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int main()
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{
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int en1, en2;
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double yy;
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total_err_count = 0;
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en1 = test(foo_opt);
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total_err_count = 0;
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en2 = test(foo);
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if (en1 != en2)
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abort();
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return 0;
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}
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@ -48,7 +48,8 @@ along with GCC; see the file COPYING3. If not see
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#include "coretypes.h"
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#include "tm.h"
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#include "ggc.h"
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#include "diagnostic.h"
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#include "toplev.h"
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/* These RTL headers are needed for basic-block.h. */
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#include "rtl.h"
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#include "tm_p.h"
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@ -75,7 +76,9 @@ static struct stmt_stats
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int removed_phis;
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} stats;
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static VEC(tree,heap) *worklist;
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static VEC (tree, heap) *worklist;
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static VEC (tree, heap) *cond_dead_built_in_calls;
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/* Vector indicating an SSA name has already been processed and marked
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as necessary. */
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@ -199,6 +202,189 @@ find_all_control_dependences (struct edge_list *el)
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#define NECESSARY(stmt) stmt->base.asm_written_flag
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/* Conditional dead call elimination
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Some builtin functions can set errno on error conditions, but they
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are otherwise pure. If the result of a call to such a function is
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not used, the compiler can still not eliminate the call without
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powerful interprocedural analysis to prove that the errno is not
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checked. However, if the conditions under which the error occurs
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are known, compiler can conditionally dead code eliminate the calls
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by shrink-wrapping the semi-dead calls into the error condition:
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built_in_call(args)
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==>
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if (error_cond(args))
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built_in_call(args)
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( An actual simple exampl is :
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log (x); // Mostly dead call
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==>
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if (x < 0)
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log(x);
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With this change, call to log(x) is effectively eliminated, as
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in majority of the cases, log won't be called with x out of
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range. The branch is totally predicatible, so the branch cost
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is low. Such optimization improves the performance of
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an important application in a big search company by 20% )
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Note that library functions are not supposed to clear errno to zero without
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error.
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In this implementation, only 'pow' and 'log' are handled. ('sin' and 'cos'
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seem to be wrongly handled by gcc -- they are treated as not touching errno
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which is not correct.)
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The condition wrapping the builtin call is conservatively set to avoid too
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aggressive (wrong) shrink wrapping. The optimization is called conditional
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dead call elimination because the call is eliminated under the condition
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that the input arguments would not lead to domain or range error (for
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instance when x <= 0 for a log(x) call), however the chances that the error
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condition is hit is very low (those builtin calls which are conditionally
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dead are usually part of the C++ abstraction penalty exposed after
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inlining). */
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static bool
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check_pow (tree pow_call)
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{
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tree base, expn;
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enum tree_code bc, ec;
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gcc_assert (TREE_CODE (pow_call) == CALL_EXPR);
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if (call_expr_nargs (pow_call) != 2)
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return false;
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base = CALL_EXPR_ARG (pow_call, 0);
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expn = CALL_EXPR_ARG (pow_call, 1);
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bc = TREE_CODE (base);
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ec = TREE_CODE (expn);
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gcc_assert (TREE_CODE_CLASS (bc) != tcc_constant
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|| bc == REAL_CST);
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gcc_assert (TREE_CODE_CLASS (ec) != tcc_constant
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|| ec == REAL_CST);
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/* Folding candidates are not interesting. */
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if (ec == REAL_CST && bc == REAL_CST)
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return false;
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if (bc == REAL_CST)
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{
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/* Only handle a fixed range of constant. */
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REAL_VALUE_TYPE mv;
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REAL_VALUE_TYPE bcv = TREE_REAL_CST (base);
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if (REAL_VALUES_EQUAL (bcv, dconst1))
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return false;
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if (REAL_VALUES_LESS (bcv, dconst1))
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return false;
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real_from_integer (&mv, VOIDmode,256,0,1);
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if (REAL_VALUES_LESS (mv, bcv))
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return false;
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return true;
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}
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else if (bc == SSA_NAME)
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{
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tree def, nm, rhs, rhs0, var, typ;
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int sz;
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def = SSA_NAME_DEF_STMT (base);
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if (TREE_CODE (def) != GIMPLE_MODIFY_STMT)
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return false;
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nm = GIMPLE_STMT_OPERAND (def,0);
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gcc_assert (TREE_CODE (nm) == SSA_NAME);
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if (nm != base)
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return false;
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rhs = GIMPLE_STMT_OPERAND (def,1);
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if (TREE_CODE (rhs) != FLOAT_EXPR)
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return false;
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rhs0 = TREE_OPERAND (rhs,0);
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if (TREE_CODE (rhs0) != SSA_NAME)
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return false;
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var = SSA_NAME_VAR (rhs0);
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if (TREE_CODE (var) != VAR_DECL &&
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TREE_CODE (var) != PARM_DECL)
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return false;
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typ = TREE_TYPE (var);
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if (TREE_CODE (typ) != INTEGER_TYPE)
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return false;
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sz = int_size_in_bytes (typ);
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if (sz == -1 || sz > INT_TYPE_SIZE)
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return false;
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return true;
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}
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else
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return false;
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}
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static bool
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check_log (tree log_call)
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{
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tree arg_typ;
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gcc_assert (TREE_CODE (log_call) == CALL_EXPR);
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if (call_expr_nargs (log_call) != 1)
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return false;
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arg_typ = TREE_TYPE (CALL_EXPR_ARG (log_call, 0));
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if (!is_gimple_reg_type (arg_typ))
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return false;
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return true;
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}
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/* A helper function to determine if a builtin function
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call is a candidate for conditional DCE. */
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static bool
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is_unnecessary_except_errno_call (tree call)
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{
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tree fn;
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bool is_unnecessary_except_errno = false;
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enum built_in_function fnc;
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if (!flag_tree_builtin_dce)
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return false;
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gcc_assert (call);
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gcc_assert (!DECL_P (call));
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gcc_assert (TREE_CODE (call) == CALL_EXPR);
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fn = get_callee_fndecl (call);
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if (!fn || !DECL_BUILT_IN (fn))
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return false;
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fnc = DECL_FUNCTION_CODE (fn);
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switch (fnc)
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{
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CASE_FLT_FN (BUILT_IN_POW):
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if (check_pow (call))
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is_unnecessary_except_errno = true;
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break;
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CASE_FLT_FN (BUILT_IN_LOG):
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if (check_log (call))
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is_unnecessary_except_errno = true;
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break;
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default :
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is_unnecessary_except_errno = false;
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break;
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}
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if (!is_unnecessary_except_errno)
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return false;
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return is_unnecessary_except_errno;
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}
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/* If STMT is not already marked necessary, mark it, and add it to the
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worklist if ADD_TO_WORKLIST is true. */
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static inline void
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@ -244,6 +430,13 @@ mark_operand_necessary (tree op)
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if (NECESSARY (stmt) || IS_EMPTY_STMT (stmt))
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return;
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if (dump_file && (dump_flags & TDF_DETAILS))
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{
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fprintf (dump_file, " Marked as necessary: ");
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print_generic_stmt (dump_file, stmt, TDF_SLIM);
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fprintf (dump_file, "\n");
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}
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NECESSARY (stmt) = 1;
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VEC_safe_push (tree, heap, worklist, stmt);
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}
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@ -294,15 +487,16 @@ mark_stmt_if_obviously_necessary (tree stmt, bool aggressive)
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/* Most, but not all function calls are required. Function calls that
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produce no result and have no side effects (i.e. const pure
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functions) are unnecessary. */
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if (TREE_SIDE_EFFECTS (stmt))
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mark_stmt_necessary (stmt, true);
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if (TREE_SIDE_EFFECTS (stmt))
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mark_stmt_necessary (stmt, true);
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return;
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case GIMPLE_MODIFY_STMT:
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op = get_call_expr_in (stmt);
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if (op && TREE_SIDE_EFFECTS (op))
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{
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mark_stmt_necessary (stmt, true);
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mark_stmt_necessary (stmt, true);
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return;
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}
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@ -523,6 +717,421 @@ propagate_necessity (struct edge_list *el)
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}
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}
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/* Method to generate conditional statements for guarding condionally
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dead calls to pow. One or more statements can be generated for
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each logical condition. Statement groups of different conditions
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are separated by a NULL tree. */
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static void
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gen_conditions_for_pow (tree pow_call, enum built_in_function fnc,
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VEC (tree, heap)* conds, unsigned * nconds)
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{
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tree base, expn;
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enum tree_code bc, ec;
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gcc_assert (TREE_CODE (pow_call) == CALL_EXPR);
|
||||
gcc_assert (call_expr_nargs (pow_call) == 2);
|
||||
gcc_assert (fnc == BUILT_IN_POW);
|
||||
|
||||
*nconds = 0;
|
||||
|
||||
base = CALL_EXPR_ARG (pow_call, 0);
|
||||
expn = CALL_EXPR_ARG (pow_call, 1);
|
||||
|
||||
bc = TREE_CODE (base);
|
||||
ec = TREE_CODE (expn);
|
||||
|
||||
gcc_assert (TREE_CODE_CLASS (bc) != tcc_constant ||
|
||||
bc == REAL_CST);
|
||||
gcc_assert (TREE_CODE_CLASS (ec) != tcc_constant ||
|
||||
ec == REAL_CST);
|
||||
|
||||
if (bc == REAL_CST)
|
||||
{
|
||||
tree float_typ, max_exp_real_cst;
|
||||
tree temp, tempn, tempc, tempcn, stmt1, stmt2, stmt3;
|
||||
REAL_VALUE_TYPE mv;
|
||||
|
||||
/* See candidate selection in check_pow.
|
||||
Since the candidates have a given range
|
||||
of base values, the guard code generated
|
||||
for such calls: pow(const,y) are simple:
|
||||
if ( y > max_y )
|
||||
pow(const, y);
|
||||
max_y can be computed separately for each
|
||||
const base, but in this implemetation, we
|
||||
choose to compute it using the max base
|
||||
in the allowed range. */
|
||||
|
||||
REAL_VALUE_TYPE bcv = TREE_REAL_CST (base);
|
||||
gcc_assert (!REAL_VALUES_EQUAL (bcv, dconst1));
|
||||
gcc_assert (!REAL_VALUES_LESS (bcv, dconst1));
|
||||
real_from_integer (&mv, VOIDmode,256,0,1),
|
||||
gcc_assert (!REAL_VALUES_LESS (mv, bcv));
|
||||
float_typ = TREE_TYPE (expn);
|
||||
|
||||
max_exp_real_cst = build_real (float_typ, mv);
|
||||
temp = create_tmp_var (float_typ, "DCE_COND");
|
||||
stmt1 = build_gimple_modify_stmt (temp, expn);
|
||||
tempn = make_ssa_name (temp, stmt1);
|
||||
GIMPLE_STMT_OPERAND (stmt1, 0) = tempn;
|
||||
|
||||
tempc = create_tmp_var (boolean_type_node, "DCE_COND_TEST");
|
||||
stmt2 = build_gimple_modify_stmt (tempc,
|
||||
build2 (GT_EXPR,
|
||||
boolean_type_node,
|
||||
tempn, max_exp_real_cst));
|
||||
tempcn = make_ssa_name (tempc, stmt2);
|
||||
GIMPLE_STMT_OPERAND (stmt2, 0) = tempcn;
|
||||
|
||||
stmt3 = build3 (COND_EXPR, void_type_node,
|
||||
tempcn, NULL_TREE, NULL_TREE);
|
||||
VEC_safe_push (tree, heap, conds, stmt1);
|
||||
VEC_safe_push (tree, heap, conds, stmt2);
|
||||
VEC_safe_push (tree, heap, conds, stmt3);
|
||||
(*nconds)++;
|
||||
|
||||
}
|
||||
else if (bc == SSA_NAME)
|
||||
{
|
||||
tree def, nm, rhs, rhs0, var, int_typ, float_typ;
|
||||
tree max_exp_cst, max_exp_real_cst;
|
||||
tree temp1, temp1n, temp2, temp2n, temp2c, temp2cn;
|
||||
tree cst0, stmt1, stmt2, stmt3;
|
||||
int sz, max_exp;
|
||||
|
||||
/* Generate error condition code for pow calls with
|
||||
non constant base value. The candidates selected
|
||||
have their base argument value converted from
|
||||
integer (see check_pow) value (1,2,4 bytes), and
|
||||
the max exp value is computed based on the size
|
||||
of the integer type. The code below first does
|
||||
sanity check and then does code generation. */
|
||||
|
||||
def = SSA_NAME_DEF_STMT (base);
|
||||
gcc_assert (TREE_CODE (def) == GIMPLE_MODIFY_STMT);
|
||||
|
||||
nm = GIMPLE_STMT_OPERAND (def,0);
|
||||
gcc_assert (TREE_CODE (nm) == SSA_NAME);
|
||||
gcc_assert (nm == base);
|
||||
|
||||
rhs = GIMPLE_STMT_OPERAND (def,1);
|
||||
|
||||
gcc_assert (TREE_CODE (rhs) == FLOAT_EXPR);
|
||||
rhs0 = TREE_OPERAND (rhs,0);
|
||||
gcc_assert (TREE_CODE (rhs0) == SSA_NAME);
|
||||
|
||||
var = SSA_NAME_VAR (rhs0);
|
||||
gcc_assert (TREE_CODE (var) == VAR_DECL
|
||||
|| TREE_CODE (var) == PARM_DECL);
|
||||
|
||||
int_typ = TREE_TYPE (var);
|
||||
gcc_assert (TREE_CODE (int_typ) == INTEGER_TYPE);
|
||||
|
||||
sz = int_size_in_bytes (int_typ);
|
||||
gcc_assert (sz > 0 && sz <= INT_TYPE_SIZE) ;
|
||||
|
||||
|
||||
float_typ = TREE_TYPE (SSA_NAME_VAR (expn));
|
||||
if (sz == 1)
|
||||
max_exp = 128;
|
||||
else if (sz == 2)
|
||||
max_exp = 64;
|
||||
else
|
||||
{
|
||||
gcc_assert (sz == 4);
|
||||
max_exp = 32;
|
||||
}
|
||||
max_exp_cst = build_int_cst (integer_type_node, max_exp);
|
||||
max_exp_real_cst = build_real_from_int_cst (float_typ, max_exp_cst);
|
||||
|
||||
/* For pow ((dobule)x,y), generate the following conditions:
|
||||
cond 1:
|
||||
temp1 = x;
|
||||
if (temp1 <= 0)
|
||||
|
||||
cond 2:
|
||||
temp2 = y;
|
||||
if (temp2 > max_exp_real_cst) */
|
||||
|
||||
temp2 = create_tmp_var (float_typ, "DCE_COND2");
|
||||
stmt1 = build_gimple_modify_stmt (temp2, expn);
|
||||
temp2n = make_ssa_name (temp2, stmt1);
|
||||
GIMPLE_STMT_OPERAND (stmt1,0) = temp2n;
|
||||
|
||||
temp2c = create_tmp_var (boolean_type_node, "DCE_COND2_TEST");
|
||||
stmt2 = build_gimple_modify_stmt (temp2c,
|
||||
build2 (GT_EXPR,
|
||||
boolean_type_node,
|
||||
temp2n, max_exp_real_cst));
|
||||
temp2cn = make_ssa_name (temp2c, stmt2);
|
||||
GIMPLE_STMT_OPERAND (stmt2, 0) = temp2cn;
|
||||
|
||||
stmt3 = build3 (COND_EXPR, void_type_node,
|
||||
temp2cn, NULL_TREE, NULL_TREE);
|
||||
VEC_safe_push (tree, heap, conds, stmt1);
|
||||
VEC_safe_push (tree, heap, conds, stmt2);
|
||||
VEC_safe_push (tree, heap, conds, stmt3);
|
||||
(*nconds)++;
|
||||
|
||||
/* now a seperator*/
|
||||
VEC_safe_push (tree, heap, conds, NULL);
|
||||
|
||||
temp1 = create_tmp_var (int_typ, "DCE_COND1");
|
||||
cst0 = build_int_cst (int_typ, 0);
|
||||
stmt1 = build_gimple_modify_stmt (temp1, rhs0);
|
||||
temp1n = make_ssa_name (temp1, stmt1);
|
||||
GIMPLE_STMT_OPERAND (stmt1,0) = temp1n;
|
||||
stmt2 = build3 (COND_EXPR, void_type_node,
|
||||
build2 (LE_EXPR, boolean_type_node, temp1n, cst0),
|
||||
NULL_TREE, NULL_TREE);
|
||||
|
||||
VEC_safe_push (tree, heap, conds, stmt1);
|
||||
VEC_safe_push (tree, heap, conds, stmt2);
|
||||
(*nconds)++;
|
||||
|
||||
}
|
||||
else
|
||||
gcc_unreachable ();
|
||||
}
|
||||
|
||||
/* The method to generate error condition guard code for log(x)
|
||||
calls. */
|
||||
static void
|
||||
gen_conditions_for_log (tree call, enum built_in_function fnc,
|
||||
VEC (tree, heap)* conds, unsigned * nconds)
|
||||
{
|
||||
tree arg, cst0, temp, tempn, tempc, tempcn, stmt1, stmt2, stmt3;
|
||||
gcc_assert (TREE_CODE (call) == CALL_EXPR);
|
||||
gcc_assert (fnc == BUILT_IN_LOG || fnc == BUILT_IN_LOGF || fnc == BUILT_IN_LOGL);
|
||||
|
||||
*nconds = 0;
|
||||
|
||||
/* for log(x),
|
||||
Generate condition
|
||||
|
||||
temp = x
|
||||
if (x <= 0)
|
||||
*/
|
||||
arg = CALL_EXPR_ARG (call, 0);
|
||||
cst0 = build_real (TREE_TYPE (arg), dconst0);
|
||||
temp = create_tmp_var (TREE_TYPE (arg), "DCE_COND");
|
||||
stmt1 = build_gimple_modify_stmt (temp, arg);
|
||||
tempn = make_ssa_name (temp, stmt1);
|
||||
GIMPLE_STMT_OPERAND (stmt1,0) = tempn;
|
||||
|
||||
tempc = create_tmp_var (boolean_type_node, "DCE_COND_TEST");
|
||||
stmt2 = build_gimple_modify_stmt (tempc,
|
||||
build2 (LE_EXPR,
|
||||
boolean_type_node,
|
||||
tempn, cst0));
|
||||
tempcn = make_ssa_name (tempc, stmt2);
|
||||
GIMPLE_STMT_OPERAND (stmt2, 0) = tempcn;
|
||||
|
||||
stmt3 = build3 (COND_EXPR, void_type_node, tempcn,
|
||||
NULL_TREE, NULL_TREE);
|
||||
|
||||
VEC_safe_push (tree, heap, conds, stmt1);
|
||||
VEC_safe_push (tree, heap, conds, stmt2);
|
||||
VEC_safe_push (tree, heap, conds, stmt3);
|
||||
(*nconds)++;
|
||||
|
||||
}
|
||||
|
||||
|
||||
/* The method to generate shrink wrap conditions for partially
|
||||
a dead builtin call whose return value is not used anywhere,
|
||||
but has to be kept live due to potential error condition.
|
||||
|
||||
BI_CALL: the builtin call
|
||||
CONDS : the vector of statements for condition code
|
||||
NCODES : the pointer to the number of logical conditions,
|
||||
which may be different from the length of CONDS
|
||||
vector. Statements belonging to different logical
|
||||
condition are separated by NULL tree in the vector
|
||||
*/
|
||||
|
||||
static void
|
||||
gen_shrink_wrap_conditions (tree bi_call, VEC (tree, heap)* conds, unsigned int * nconds)
|
||||
{
|
||||
tree call, fn;
|
||||
enum built_in_function fnc;
|
||||
gcc_assert (nconds && conds);
|
||||
gcc_assert (VEC_length(tree, conds) == 0);
|
||||
gcc_assert (TREE_CODE (bi_call) == GIMPLE_MODIFY_STMT ||
|
||||
TREE_CODE (bi_call) == CALL_EXPR);
|
||||
|
||||
call = bi_call;
|
||||
if (TREE_CODE (call) == GIMPLE_MODIFY_STMT)
|
||||
call = get_call_expr_in (bi_call);
|
||||
|
||||
fn = get_callee_fndecl (call);
|
||||
gcc_assert (fn && DECL_BUILT_IN (fn));
|
||||
fnc = DECL_FUNCTION_CODE (fn);
|
||||
*nconds = 0;
|
||||
|
||||
switch (fnc)
|
||||
{
|
||||
/*CASE_FLT_FN(BUILT_IN_POW)*/
|
||||
case BUILT_IN_POW:
|
||||
gen_conditions_for_pow (call, fnc, conds, nconds);
|
||||
break;
|
||||
/*CASE_FLT_FN(BUILT_IN_LOG):*/
|
||||
case BUILT_IN_LOG:
|
||||
case BUILT_IN_LOGF:
|
||||
case BUILT_IN_LOGL:
|
||||
gen_conditions_for_log (call, fnc, conds, nconds);
|
||||
break;
|
||||
default :
|
||||
gcc_assert (0);
|
||||
break;
|
||||
}
|
||||
|
||||
gcc_assert (*nconds);
|
||||
return;
|
||||
}
|
||||
|
||||
|
||||
#define ERR_PROB 0.01
|
||||
|
||||
/* The method to shrink wrap a partially dead builtin call
|
||||
whose return value is not used anywhere, but has to be kept
|
||||
live due to potential error condition. */
|
||||
static void
|
||||
shrink_wrap_one_built_in_call (tree bi_call)
|
||||
{
|
||||
block_stmt_iterator bi_call_bsi, join_tgt_bsi;
|
||||
basic_block bi_call_bb, join_tgt_bb, guard_bb, guard_bb0;
|
||||
edge join_tgt_in_edge_from_call, join_tgt_in_edge_fall_thru;
|
||||
tree join_tgt_label_decl, join_tgt_label;
|
||||
edge bi_call_in_edge0, guard_bb_in_edge;
|
||||
VEC (tree, heap) *conds;
|
||||
unsigned tn_cond_stmts, nconds;
|
||||
unsigned ci;
|
||||
tree cond_expr = NULL;
|
||||
tree cond_expr_start;
|
||||
tree bi_call_label_decl;
|
||||
tree bi_call_label;
|
||||
|
||||
conds = VEC_alloc (tree, heap, 10);
|
||||
gen_shrink_wrap_conditions (bi_call, conds, &nconds);
|
||||
|
||||
gcc_assert (nconds > 0);
|
||||
/* Make sure no reallocation happens. */
|
||||
gcc_assert (VEC_length (tree, conds) <= 10);
|
||||
gcc_assert (VEC_length (tree, conds) >= nconds);
|
||||
bi_call_bb = bb_for_stmt (bi_call);
|
||||
|
||||
/* Now find the join target bb -- split
|
||||
bi_call_bb if needed */
|
||||
bi_call_bsi = bsi_for_stmt (bi_call);
|
||||
|
||||
gcc_assert (!bsi_end_p (bi_call_bsi));
|
||||
join_tgt_in_edge_from_call = split_block (bi_call_bb, bi_call);
|
||||
bi_call_bsi = bsi_for_stmt (bi_call);
|
||||
|
||||
join_tgt_bb = join_tgt_in_edge_from_call->dest;
|
||||
join_tgt_label_decl = create_artificial_label ();
|
||||
join_tgt_label = build1 (LABEL_EXPR, void_type_node, join_tgt_label_decl);
|
||||
join_tgt_bsi = bsi_start (join_tgt_bb);
|
||||
bsi_insert_before (&join_tgt_bsi, join_tgt_label, BSI_SAME_STMT);
|
||||
|
||||
/* Now it is time to insert the first condtional expression
|
||||
into bi_call_bb and split this bb so that bi_call is
|
||||
shrink-wrapped*/
|
||||
tn_cond_stmts = VEC_length (tree, conds);
|
||||
cond_expr = NULL;
|
||||
cond_expr_start = VEC_index (tree, conds,0);
|
||||
for (ci = 0; ci < tn_cond_stmts; ci++)
|
||||
{
|
||||
tree c = VEC_index (tree, conds, ci);
|
||||
gcc_assert ( c || ci != 0 );
|
||||
if (!c) break;
|
||||
bsi_insert_before (&bi_call_bsi, c, BSI_SAME_STMT);
|
||||
cond_expr = c;
|
||||
}
|
||||
nconds --;
|
||||
ci ++;
|
||||
gcc_assert (cond_expr && TREE_CODE (cond_expr) == COND_EXPR);
|
||||
|
||||
/* now the label*/
|
||||
bi_call_label_decl = create_artificial_label ();
|
||||
bi_call_label = build1 (LABEL_EXPR, void_type_node, bi_call_label_decl);
|
||||
bsi_insert_before (&bi_call_bsi, bi_call_label, BSI_SAME_STMT);
|
||||
|
||||
bi_call_in_edge0 = split_block (bi_call_bb, cond_expr);
|
||||
bi_call_in_edge0->flags &= ~EDGE_FALLTHRU;
|
||||
bi_call_in_edge0->flags |= EDGE_TRUE_VALUE;
|
||||
guard_bb0 = bi_call_bb;
|
||||
bi_call_bb = bi_call_in_edge0->dest;
|
||||
join_tgt_in_edge_fall_thru = make_edge (guard_bb0, join_tgt_bb, EDGE_FALSE_VALUE);
|
||||
|
||||
bi_call_in_edge0->probability = REG_BR_PROB_BASE*ERR_PROB;
|
||||
join_tgt_in_edge_fall_thru->probability =
|
||||
REG_BR_PROB_BASE - bi_call_in_edge0->probability;
|
||||
|
||||
/* code generation for the rest of the conditions */
|
||||
guard_bb = guard_bb0;
|
||||
for (; nconds > 0; )
|
||||
{
|
||||
unsigned ci0;
|
||||
edge bi_call_in_edge;
|
||||
block_stmt_iterator guard_bsi = bsi_for_stmt (cond_expr_start);
|
||||
ci0 = ci;
|
||||
cond_expr_start = VEC_index (tree, conds, ci0);
|
||||
for (; ci < tn_cond_stmts; ci++)
|
||||
{
|
||||
tree c = VEC_index (tree, conds, ci);
|
||||
gcc_assert ( c || ci != ci0 );
|
||||
if (!c)
|
||||
break;
|
||||
bsi_insert_before (&guard_bsi, c, BSI_SAME_STMT);
|
||||
cond_expr = c;
|
||||
}
|
||||
nconds --;
|
||||
ci ++;
|
||||
gcc_assert (cond_expr && TREE_CODE (cond_expr) == COND_EXPR);
|
||||
guard_bb_in_edge = split_block (guard_bb, cond_expr);
|
||||
guard_bb_in_edge->flags &= ~EDGE_FALLTHRU;
|
||||
guard_bb_in_edge->flags |= EDGE_FALSE_VALUE;
|
||||
|
||||
bi_call_in_edge = make_edge (guard_bb, bi_call_bb, EDGE_TRUE_VALUE);
|
||||
|
||||
bi_call_in_edge->probability = REG_BR_PROB_BASE*ERR_PROB;
|
||||
guard_bb_in_edge->probability =
|
||||
REG_BR_PROB_BASE - bi_call_in_edge->probability;
|
||||
|
||||
}
|
||||
|
||||
VEC_free (tree, heap, conds);
|
||||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||||
{
|
||||
location_t loc;
|
||||
loc = EXPR_LOCATION (bi_call);
|
||||
inform (
|
||||
"%Hfunction call is shrink-wrapped into error conditions.",
|
||||
&loc);
|
||||
}
|
||||
}
|
||||
|
||||
/* The top level method for conditional dead code shrink
|
||||
wrapping transformation. */
|
||||
|
||||
static bool
|
||||
shrink_wrap_conditional_dead_built_in_calls (void)
|
||||
{
|
||||
unsigned i = 0;
|
||||
unsigned n = VEC_length (tree, cond_dead_built_in_calls);
|
||||
if (n == 0) return false;
|
||||
|
||||
for (; i < n ; i++)
|
||||
{
|
||||
tree bi_call = VEC_index (tree, cond_dead_built_in_calls, i);
|
||||
shrink_wrap_one_built_in_call (bi_call);
|
||||
}
|
||||
|
||||
cfg_altered = true;
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
/* Remove dead PHI nodes from block BB. */
|
||||
|
||||
|
|
@ -711,6 +1320,18 @@ eliminate_unnecessary_stmts (void)
|
|||
print_generic_stmt (dump_file, t, TDF_SLIM);
|
||||
fprintf (dump_file, "\n");
|
||||
}
|
||||
|
||||
if (is_unnecessary_except_errno_call (call))
|
||||
{
|
||||
if (dump_file && (dump_flags & TDF_DETAILS))
|
||||
{
|
||||
fprintf (dump_file, "Found conditional dead call: ");
|
||||
print_generic_stmt (dump_file, t, TDF_SLIM);
|
||||
fprintf (dump_file, "\n");
|
||||
}
|
||||
VEC_safe_push (tree, heap, cond_dead_built_in_calls, call);
|
||||
}
|
||||
|
||||
push_stmt_changes (bsi_stmt_ptr (i));
|
||||
TREE_BLOCK (call) = TREE_BLOCK (t);
|
||||
bsi_replace (&i, call, false);
|
||||
|
|
@ -718,6 +1339,8 @@ eliminate_unnecessary_stmts (void)
|
|||
mark_symbols_for_renaming (call);
|
||||
pop_stmt_changes (bsi_stmt_ptr (i));
|
||||
release_ssa_name (oldlhs);
|
||||
|
||||
|
||||
}
|
||||
notice_special_calls (call);
|
||||
}
|
||||
|
|
@ -726,6 +1349,9 @@ eliminate_unnecessary_stmts (void)
|
|||
}
|
||||
}
|
||||
|
||||
something_changed |=
|
||||
shrink_wrap_conditional_dead_built_in_calls ();
|
||||
|
||||
return something_changed;
|
||||
}
|
||||
|
||||
|
|
@ -776,7 +1402,9 @@ tree_dce_init (bool aggressive)
|
|||
sbitmap_zero (processed);
|
||||
|
||||
worklist = VEC_alloc (tree, heap, 64);
|
||||
cond_dead_built_in_calls = VEC_alloc (tree, heap,64);
|
||||
cfg_altered = false;
|
||||
|
||||
}
|
||||
|
||||
/* Cleanup after this pass. */
|
||||
|
|
@ -799,7 +1427,9 @@ tree_dce_done (bool aggressive)
|
|||
sbitmap_free (processed);
|
||||
|
||||
VEC_free (tree, heap, worklist);
|
||||
VEC_free (tree, heap, cond_dead_built_in_calls);
|
||||
}
|
||||
|
||||
|
||||
/* Main routine to eliminate dead code.
|
||||
|
||||
|
|
@ -841,7 +1471,7 @@ perform_tree_ssa_dce (bool aggressive)
|
|||
find_obviously_necessary_stmts (el);
|
||||
|
||||
propagate_necessity (el);
|
||||
|
||||
|
||||
something_changed |= eliminate_unnecessary_stmts ();
|
||||
something_changed |= cfg_altered;
|
||||
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue