Check in tree-dce enh to trunk

From-SVN: r135463

ChangeLog

+
+2008-05-17 Xinliang David Li   <davidxl@google.com>
+
+        * gcc/tree-ssa-dce.c : conditional dead call elimination
+        * gcc/opts.c         : enable the optimization at >=O2
+        * gcc/common.opt      : new flag for control the optimization
+        * gcc/doc/invoke.texi : documentation change
+        * gcc/testsuite/gcc.dg/cdce1.c : new test case
+        * gcc/testsuite/gcc.dg/cdce2.c : new test case
+        *MAINTAINERS  : Add myself (write after approval) 
+
 2008-05-15  Janus Weil  <janus@gcc.gnu.org>
 
 	* MAINTAINERS (Write After Approval): Add myself.

MAINTAINERS

@@ -372,6 +372,7 @@ Manuel Lpez-Ibez                             manu@gcc.gnu.org
 Dave Love					d.love@dl.ac.uk
 Martin v. Lwis					loewis@informatik.hu-berlin.de
 H.J. Lu						hjl.tools@gmail.com
+Xinliang David Li                               davidxl@google.com
 William Maddox					maddox@google.com
 Ziga Mahkovec					ziga.mahkovec@klika.si
 Simon Martin					simartin@users.sourceforge.net

gcc/common.opt

@@ -1259,6 +1259,10 @@ fweb
 Common Report Var(flag_web) Init(2) Optimization
 Construct webs and split unrelated uses of single variable
 
+ftree-builtin-dce
+Common Report Var(flag_tree_builtin_dce) Init(0) Optimization
+Enable conditional dead code elimination for builtin calls.
+
 fwhole-program
 Common Report Var(flag_whole_program) Init(0) Optimization
 Perform whole program optimizations

gcc/doc/invoke.texi

@@ -353,7 +353,7 @@ Objective-C and Objective-C++ Dialects}.
 -fsignaling-nans -fsingle-precision-constant -fsplit-ivs-in-unroller @gol
 -fsplit-wide-types -fstack-protector -fstack-protector-all @gol
 -fstrict-aliasing -fstrict-overflow -fthread-jumps -ftracer -ftree-ccp @gol
--ftree-ch -ftree-copy-prop -ftree-copyrename -ftree-dce @gol
+-ftree-ch -ftree-copy-prop -ftree-copyrename -ftree-dce -ftree-builtin-dce@gol
 -ftree-dominator-opts -ftree-dse -ftree-fre -ftree-loop-im @gol
 -ftree-loop-distribution @gol
 -ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
@@ -5157,6 +5157,7 @@ compilation time.
 -ftree-ch @gol
 -ftree-copyrename @gol
 -ftree-dce @gol
+-ftree-builtin-dce @gol
 -ftree-dominator-opts @gol
 -ftree-dse @gol
 -ftree-fre @gol
@@ -5873,6 +5874,12 @@ enabled by default at @option{-O2} and higher.
 Perform dead code elimination (DCE) on trees.  This flag is enabled by
 default at @option{-O} and higher.
 
+@item -ftree-builtin-dce
+@opindex ftree-builtin-dce
+Perform conditional dead code elimination (DCE) on builtin calls that
+may set errno but are otherwise side-effect free.  This flag is enabled by
+default at @option{-O} and higher.
+
 @item -ftree-dominator-opts
 @opindex ftree-dominator-opts
 Perform a variety of simple scalar cleanups (constant/copy

gcc/opts.c

@@ -886,6 +886,7 @@ decode_options (unsigned int argc, const char **argv)
       flag_reorder_functions = 1;
       flag_tree_store_ccp = 1;
       flag_tree_vrp = 1;
+      flag_tree_builtin_dce = 1;
 
       if (!optimize_size)
 	{

gcc/testsuite/gcc.dg/cdce1.c

+/* { dg-do  run } */
+/* { dg-options "-O2 -fdump-tree-dce1-details  -lm" } */
+/* { dg-message  "note: function call is shrink-wrapped into error conditions\." "Missing conditional dce" {target "*-*-*"} 15 } */
+ 
+#include <stdlib.h>
+#include <math.h>
+#include <errno.h>
+#include <stdio.h>
+int total_err_count = 0;
+double foo_opt(int x, double y) __attribute__((noinline));
+double foo_opt(int x, double y)
+{
+    double yy = 0;
+    errno = 0;
+    yy = pow(x,y);
+    return 0;
+}
+
+double foo(int x, double y) __attribute__((noinline));
+double foo(int x, double y)
+{
+    double yy = 0;
+    errno = 0;
+    yy = pow(x,y);
+    return yy;
+}
+
+int test(double (*fp)(int x, double y))
+{
+   int i,x;
+
+   x = 127; 
+   for (i = 30; i < 300; i++)
+   {  
+      fp(x,i);
+      if (errno)
+         total_err_count ++;
+   }
+
+   x = -300; 
+   for (i = 100; i < 300; i++)
+   {  
+      fp(x,i);
+      if (errno)
+         total_err_count ++;
+   }
+
+   x = 65577;
+   for (i = 60; i < 200; i++)
+   {  
+      fp(x,i);
+      if (errno)
+         total_err_count ++;
+   }
+
+   x = 65577*127;
+   for (i = 1; i < 100; i++)
+   {  
+      fp(x,i);
+      if (errno)
+         total_err_count ++;
+   }
+
+   return total_err_count;
+}
+
+int main()
+{
+  int en1, en2;
+  total_err_count = 0;
+  en1 = test(foo_opt);
+  total_err_count = 0;
+  en2 = test(foo);
+  
+  printf("total number of errors = %d, %d\n", en1, en2);
+  if (en1 != en2)
+     abort();
+
+  return 0;
+
+}

gcc/testsuite/gcc.dg/cdce2.c

+/* { dg-do  run } */
+/* { dg-options "-O2 -fdump-tree-dce1-details  -lm" } */
+/* { dg-message  "note: function call is shrink-wrapped into error conditions\." "Missing conditional dce" {target "*-*-*"} 15 } */
+ 
+#include <stdlib.h>
+#include <math.h>
+#include <errno.h>
+#include <stdio.h>
+int total_err_count = 0;
+double foo_opt(double y) __attribute__((noinline));
+double foo_opt(double y)
+{
+    double yy = 0;
+    errno = 0;
+    yy = log(y);
+    return 0;
+}
+
+double foo(double y) __attribute__((noinline));
+double foo(double y)
+{
+    double yy = 0;
+    errno = 0;
+    yy = log(y);
+    return yy;
+}
+
+int test(double (*fp)(double y) )
+{
+   int i,x;
+
+   for (i = -100; i < 100; i++)
+   {  
+      fp(i);
+      if (errno)
+         total_err_count ++;
+   }
+
+  return total_err_count;
+}
+
+int main()
+{
+  int en1, en2;
+  double yy;
+  total_err_count = 0;
+  en1 = test(foo_opt);
+  total_err_count = 0;
+  en2 = test(foo);
+
+  if (en1 != en2)
+     abort();
+
+  return 0;
+
+}