re PR tree-optimization/69556 (forwprop4/match.pd undoing work from recip)

2016-02-01  Richard Biener  <rguenther@suse.de>

	PR middle-end/69556
	* match.pd: Guard (C1/X)*C2 -> (C1*C2)/X with single_use.

	* gcc.dg/tree-ssa/recip-8.c: New testcase.

From-SVN: r233040

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 15baad3a186899f19470ed648d06ac116850e139..e17d3c54fb81143cff0d05d27ab1cd309f67d51d 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2016-02-01  Richard Biener  <rguenther@suse.de>
+
+       PR middle-end/69556
+       * match.pd: Guard (C1/X)*C2 -> (C1*C2)/X with single_use.
+
 2016-02-01  Richard Biener  <rguenther@suse.de>
 
        PR tree-optimization/69574

diff --git a/gcc/match.pd b/gcc/match.pd
index 63134114bdb6b9e7aaaa5eb059c6099fca727d2d..491f769c1ddb44aaa2605248a26329df6b9f4b09 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -445,8 +445,9 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 
 /* Fold (C1/X)*C2 into (C1*C2)/X.  */
 (simplify
- (mult (rdiv:s REAL_CST@0 @1) REAL_CST@2)
-  (if (flag_associative_math)
+ (mult (rdiv@3 REAL_CST@0 @1) REAL_CST@2)
+  (if (flag_associative_math
+       && single_use (@3))
    (with
     { tree tem = const_binop (MULT_EXPR, type, @0, @2); }
     (if (tem)

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 68278d13f851863d0f24bbdefcb2acad64d774c1..bfd6e9f6ce47ab92caa40bf0925019208cf8b229 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-02-01  Richard Biener  <rguenther@suse.de>
+
+       PR middle-end/69556
+       * gcc.dg/tree-ssa/recip-8.c: New testcase.
+
 2016-02-01  Richard Biener  <rguenther@suse.de>
 
        PR tree-optimization/69574

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/recip-8.c b/gcc/testsuite/gcc.dg/tree-ssa/recip-8.c
new file mode 100644 (file)
index 0000000..f8aecc1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/recip-8.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -ffast-math -fdump-tree-optimized" } */
+
+double bar (double, double, double, double, double);
+
+double
+foo (double a)
+{
+  return bar (1.0/a, 2.0/a, 4.0/a, 8.0/a, 16.0/a);
+}
+
+/* { dg-final { scan-tree-dump-times "/" 1 "optimized"  } } */