[gentoo-commits] gentoo commit in src/patchsets/gcc/4.7.2/gentoo: 96_all_pr56125_4.7.3_ffast-math-pow.patch README.history

[Ryan Hill (dirtyepic)]

dirtyepic    13/02/26 01:09:10

  Modified:             README.history
  Added:                96_all_pr56125_4.7.3_ffast-math-pow.patch
  Log:
  Add patch for PR56125.

Revision  Changes    Path
1.10                 src/patchsets/gcc/4.7.2/gentoo/README.history

file : http://sources.gentoo.org/viewvc.cgi/gentoo/src/patchsets/gcc/4.7.2/gentoo/README.history?rev=1.10&view=markup
plain: http://sources.gentoo.org/viewvc.cgi/gentoo/src/patchsets/gcc/4.7.2/gentoo/README.history?rev=1.10&content-type=text/plain
diff : http://sources.gentoo.org/viewvc.cgi/gentoo/src/patchsets/gcc/4.7.2/gentoo/README.history?r1=1.9&r2=1.10

Index: README.history
===================================================================
RCS file: /var/cvsroot/gentoo/src/patchsets/gcc/4.7.2/gentoo/README.history,v
retrieving revision 1.9
retrieving revision 1.10
diff -u -r1.9 -r1.10
--- README.history	25 Feb 2013 03:49:18 -0000	1.9
+++ README.history	26 Feb 2013 01:09:10 -0000	1.10
@@ -1,3 +1,6 @@
+1.5		pending
+	+ 96_all_pr56125_4.7.3_ffast-math-pow.patch
+
 1.4		24 Jan 2013
 	- 03_all_java-nomulti.patch
 	+ 48_all_x86_pr53113_libitm-avx.patch



1.1                  src/patchsets/gcc/4.7.2/gentoo/96_all_pr56125_4.7.3_ffast-math-pow.patch

file : http://sources.gentoo.org/viewvc.cgi/gentoo/src/patchsets/gcc/4.7.2/gentoo/96_all_pr56125_4.7.3_ffast-math-pow.patch?rev=1.1&view=markup
plain: http://sources.gentoo.org/viewvc.cgi/gentoo/src/patchsets/gcc/4.7.2/gentoo/96_all_pr56125_4.7.3_ffast-math-pow.patch?rev=1.1&content-type=text/plain

Index: 96_all_pr56125_4.7.3_ffast-math-pow.patch
===================================================================
-O2 -ffast-math generates bad code when dividing a double by the square of another double.

http://gcc.gnu.org/PR56125


commit a42ec1527275f12e8584e1640bc6b16a9d2ca858
Author: jakub <jakub@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Fri Feb 1 14:17:50 2013 +0000

    	Backported from mainline
    	2013-01-28  Jakub Jelinek  <jakub@××××××.com>
    
    	PR tree-optimization/56125
    	* tree-ssa-math-opts.c (gimple_expand_builtin_pow): Don't optimize
    	pow(x,c) into sqrt(x) * powi(x, n/2) or
    	1.0 / (sqrt(x) * powi(x, abs(n/2))) if c is an integer or when
    	optimizing for size.
    	Don't optimize pow(x,c) into powi(x, n/3) * powi(cbrt(x), n%3) or
    	1.0 / (powi(x, abs(n)/3) * powi(cbrt(x), abs(n)%3)) if 2c is an
    	integer.
    
    	* gcc.dg/pr56125.c: New test.
    
    
    git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_7-branch@195664 138bc75d-0d04-0410-961f-82ee72b054a4
---
 gcc/ChangeLog                  | 11 +++++++++++
 gcc/testsuite/ChangeLog        |  5 +++++
 gcc/testsuite/gcc.dg/pr56125.c | 21 +++++++++++++++++++++
 gcc/tree-ssa-math-opts.c       | 14 ++++++++++----
 4 files changed, 47 insertions(+), 4 deletions(-)

--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr56125.c
@@ -0,0 +1,21 @@
+/* PR tree-optimization/56125 */
+/* { dg-do run } */
+/* { dg-options "-O2 -ffast-math" } */
+
+extern void abort (void);
+extern double fabs (double);
+
+__attribute__((cold)) double
+foo (double x, double n)
+{
+  double u = x / (n * n);
+  return u;
+}
+
+int
+main ()
+{
+  if (fabs (foo (29, 2) - 7.25) > 0.001)
+    abort ();
+  return 0;
+}
--- a/gcc/tree-ssa-math-opts.c
+++ b/gcc/tree-ssa-math-opts.c
@@ -1113,7 +1113,7 @@ gimple_expand_builtin_pow (gimple_stmt_iterator *gsi, location_t loc,
   tree type, sqrtfn, cbrtfn, sqrt_arg0, sqrt_sqrt, result, cbrt_x, powi_cbrt_x;
   tree target = NULL_TREE;
   enum machine_mode mode;
-  bool hw_sqrt_exists;
+  bool hw_sqrt_exists, c_is_int, c2_is_int;
 
   /* If the exponent isn't a constant, there's nothing of interest
      to be done.  */
@@ -1125,8 +1125,9 @@ gimple_expand_builtin_pow (gimple_stmt_iterator *gsi, location_t loc,
   c = TREE_REAL_CST (arg1);
   n = real_to_integer (&c);
   real_from_integer (&cint, VOIDmode, n, n < 0 ? -1 : 0, 0);
+  c_is_int = real_identical (&c, &cint);
 
-  if (real_identical (&c, &cint)
+  if (c_is_int
       && ((n >= -1 && n <= 2)
 	  || (flag_unsafe_math_optimizations
 	      && optimize_insn_for_speed_p ()
@@ -1224,7 +1225,8 @@ gimple_expand_builtin_pow (gimple_stmt_iterator *gsi, location_t loc,
       return build_and_insert_call (gsi, loc, &target, cbrtfn, sqrt_arg0);
     }
 
-  /* Optimize pow(x,c), where n = 2c for some nonzero integer n, into
+  /* Optimize pow(x,c), where n = 2c for some nonzero integer n
+     and c not an integer, into
 
        sqrt(x) * powi(x, n/2),                n > 0;
        1.0 / (sqrt(x) * powi(x, abs(n/2))),   n < 0.
@@ -1233,10 +1235,13 @@ gimple_expand_builtin_pow (gimple_stmt_iterator *gsi, location_t loc,
   real_arithmetic (&c2, MULT_EXPR, &c, &dconst2);
   n = real_to_integer (&c2);
   real_from_integer (&cint, VOIDmode, n, n < 0 ? -1 : 0, 0);
+  c2_is_int = real_identical (&c2, &cint);
 
   if (flag_unsafe_math_optimizations
       && sqrtfn
-      && real_identical (&c2, &cint))
+      && c2_is_int
+      && !c_is_int
+      && optimize_function_for_speed_p (cfun))
     {
       tree powi_x_ndiv2 = NULL_TREE;
 
@@ -1289,6 +1294,7 @@ gimple_expand_builtin_pow (gimple_stmt_iterator *gsi, location_t loc,
       && cbrtfn
       && (gimple_val_nonnegative_real_p (arg0) || !HONOR_NANS (mode))
       && real_identical (&c2, &c)
+      && !c2_is_int
       && optimize_function_for_speed_p (cfun)
       && powi_cost (n / 3) <= POWI_MAX_MULTS)
     {