re PR tree-optimization/72824 (Signed floating point zero semantics broken at optimiz...

	PR tree-optimization/72824
	* tree-loop-distribution.c (const_with_all_bytes_same): Verify
	real_zerop is not negative.

	* gcc.c-torture/execute/ieee/pr72824.c: New test.

From-SVN: r239275

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2d96f88466a78ba61ebb3dc9bb9db0ea5961f1eb..e71b548253ef25002454e547f87459aaccb05958 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-08-09  Jakub Jelinek  <jakub@redhat.com>
+
+       PR tree-optimization/72824
+       * tree-loop-distribution.c (const_with_all_bytes_same): Verify
+       real_zerop is not negative.
+
 2016-08-09  Richard Biener  <rguenther@suse.de>
 
        PR tree-optimization/71802

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 9ba1052e76806641a34eedb92899073bd30dabc2..711778bfb8ebc65d5296e91c2a07efcc0e611d9a 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-08-09  Jakub Jelinek  <jakub@redhat.com>
+
+       PR tree-optimization/72824
+       * gcc.c-torture/execute/ieee/pr72824.c: New test.
+
 2016-08-09  Richard Biener  <rguenther@suse.de>
 
        PR tree-optimization/71802

diff --git a/gcc/testsuite/gcc.c-torture/execute/ieee/pr72824.c b/gcc/testsuite/gcc.c-torture/execute/ieee/pr72824.c
new file mode 100644 (file)
index 0000000..1c21373
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/ieee/pr72824.c
@@ -0,0 +1,19 @@
+/* PR tree-optimization/72824 */
+
+static inline void
+foo (float *x, float value)
+{
+  int i;
+  for (i = 0; i < 32; ++i)
+    x[i] = value;
+}
+
+int
+main ()
+{
+  float x[32];
+  foo (x, -0.f);
+  if (__builtin_copysignf (1.0, x[3]) != -1.0f)
+    __builtin_abort ();
+  return 0;
+}

diff --git a/gcc/tree-loop-distribution.c b/gcc/tree-loop-distribution.c
index 181e4e9ed7d8b43be2e482c1ed68e98590868930..342b9647fe71b1975fb30946cedc2990ba9206ec 100644 (file)
--- a/gcc/tree-loop-distribution.c
+++ b/gcc/tree-loop-distribution.c
@@ -750,12 +750,40 @@ const_with_all_bytes_same (tree val)
   int i, len;
 
   if (integer_zerop (val)
-      || real_zerop (val)
       || (TREE_CODE (val) == CONSTRUCTOR
           && !TREE_CLOBBER_P (val)
           && CONSTRUCTOR_NELTS (val) == 0))
     return 0;
 
+  if (real_zerop (val))
+    {
+      /* Only return 0 for +0.0, not for -0.0, which doesn't have
+        an all bytes same memory representation.  Don't transform
+        -0.0 stores into +0.0 even for !HONOR_SIGNED_ZEROS.  */
+      switch (TREE_CODE (val))
+       {
+       case REAL_CST:
+         if (!real_isneg (TREE_REAL_CST_PTR (val)))
+           return 0;
+         break;
+       case COMPLEX_CST:
+         if (!const_with_all_bytes_same (TREE_REALPART (val))
+             && !const_with_all_bytes_same (TREE_IMAGPART (val)))
+           return 0;
+         break;
+       case VECTOR_CST:
+         unsigned int j;
+         for (j = 0; j < VECTOR_CST_NELTS (val); ++j)
+           if (const_with_all_bytes_same (VECTOR_CST_ELT (val, i)))
+             break;
+         if (j == VECTOR_CST_NELTS (val))
+           return 0;
+         break;
+       default:
+         break;
+       }
+    }
+
   if (CHAR_BIT != 8 || BITS_PER_UNIT != 8)
     return -1;