2010-03-22 Richard Guenther <rguenther@suse.de>

	PR middle-end/40106
	* builtins.c (expand_builtin_pow): Expand pow (x, 1.5) as
	x * sqrt (x) even when optimizing for size if the target
	has native support for sqrt.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@157623 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4131a49..077b6e6 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2010-03-22  Richard Guenther  <rguenther@suse.de>
+
+       PR middle-end/40106
+       * builtins.c (expand_builtin_pow): Expand pow (x, 1.5) as
+       x * sqrt (x) even when optimizing for size if the target
+       has native support for sqrt.
+
 2010-03-22  Jakub Jelinek  <jakub@redhat.com>
 
        * varasm.c (make_decl_rtl_for_debug): Also clear

diff --git a/gcc/builtins.c b/gcc/builtins.c
index a68e743..7787f69 100644 (file)
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -2984,10 +2984,16 @@ expand_builtin_pow (tree exp, rtx target, rtx subtarget)
          && ((flag_unsafe_math_optimizations
               && optimize_insn_for_speed_p ()
               && powi_cost (n/2) <= POWI_MAX_MULTS)
-             /* Even the c==0.5 case cannot be done unconditionally
+             /* Even the c == 0.5 case cannot be done unconditionally
                 when we need to preserve signed zeros, as
                 pow (-0, 0.5) is +0, while sqrt(-0) is -0.  */
-             || (!HONOR_SIGNED_ZEROS (mode) && n == 1)))
+             || (!HONOR_SIGNED_ZEROS (mode) && n == 1)
+             /* For c == 1.5 we can assume that x * sqrt (x) is always
+                smaller than pow (x, 1.5) if sqrt will not be expanded
+                as a call.  */
+             || (n == 3
+                 && (optab_handler (sqrt_optab, mode)->insn_code
+                     != CODE_FOR_nothing))))
        {
          tree call_expr = build_call_nofold (fn, 1, narg0);
          /* Use expand_expr in case the newly built call expression