From: Jakub Jelinek <jakub@redhat.com>
Date: Tue, 30 May 2017 07:07:25 +0000 (+0200)
Subject: backport: re PR tree-optimization/72824 (Signed floating point zero semantics broken... 
X-Git-Tag: releases/gcc-5.5.0~315
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d051687828de7b0162a8095cfa087fa79354d2ba;p=thirdparty%2Fgcc.git

backport: re PR tree-optimization/72824 (Signed floating point zero semantics broken at optimization level -O3 (tree-loop-distribute-patterns))

	Backported from mainline
	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.

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

From-SVN: r248593
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a7cb8d67ce19..afc11fa2bf01 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,6 +1,12 @@
 2017-05-30  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	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.
+
 	2016-07-21  Jakub Jelinek  <jakub@redhat.com>
 
 	PR sanitizer/71953
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f9c9aaa751bb..317787d928d0 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2017-05-30  Jakub Jelinek  <jakub@redhat.com>
+
+	Backported from mainline
+	2016-08-09  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/72824
+	* gcc.c-torture/execute/ieee/pr72824.c: New test.
+
 2017-05-29  Martin Liska  <mliska@suse.cz>
 
 	Backport from mainline
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
index 000000000000..1c213733ca1a
--- /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 904f4e8db60b..e5e4d3c4e1a9 100644
--- a/gcc/tree-loop-distribution.c
+++ b/gcc/tree-loop-distribution.c
@@ -90,6 +90,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-pass.h"
 #include "gimple-pretty-print.h"
 #include "tree-vectorizer.h"
+#include "real.h"
 
 
 /* A Reduced Dependence Graph (RDG) vertex representing a statement.  */
@@ -775,12 +776,40 @@ 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;