From: Jakub Jelinek <jakub@redhat.com>
Date: Mon, 25 Jun 2018 17:45:48 +0000 (+0200)
Subject: backport: re PR tree-optimization/85257 (wrong code with -O -fno-tree-ccp and reading... 
X-Git-Tag: releases/gcc-6.5.0~191
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f094d95dbc4698dbdfd4b3b0490679f547cf6d41;p=thirdparty%2Fgcc.git

backport: re PR tree-optimization/85257 (wrong code with -O -fno-tree-ccp and reading zeroed vector member)

	Backported from mainline
	2018-04-07  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/85257
	* fold-const.c (native_encode_vector): If not all elts could fit
	and off is -1, return 0 rather than offset.
	* tree-ssa-sccvn.c (vn_reference_lookup_3): Pass
	(offset - offset2) / BITS_PER_UNIT as 4th argument to
	native_encode_expr.  Verify len * BITS_PER_UNIT >= maxsizei.  Don't
	adjust buffer in native_interpret_expr call.

	* gcc.dg/pr85257.c: New test.

From-SVN: r262094
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a2d2fce6d47b..d5e68d916467 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,6 +1,16 @@
 2018-06-25  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2018-04-07  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/85257
+	* fold-const.c (native_encode_vector): If not all elts could fit
+	and off is -1, return 0 rather than offset.
+	* tree-ssa-sccvn.c (vn_reference_lookup_3): Pass
+	(offset - offset2) / BITS_PER_UNIT as 4th argument to
+	native_encode_expr.  Verify len * BITS_PER_UNIT >= maxsizei.  Don't
+	adjust buffer in native_interpret_expr call.
+
 	2018-04-06  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/85252
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 5bb4e2acb470..6cc04ac26985 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -7358,7 +7358,7 @@ native_encode_vector (const_tree expr, unsigned char *ptr, int len, int off)
 	return 0;
       offset += res;
       if (offset >= len)
-	return offset;
+	return (off == -1 && i < count - 1) ? 0 : offset;
       if (off != -1)
 	off = 0;
     }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 07eeb6fb3996..db94bdc3fd9b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,6 +1,11 @@
 2018-06-25  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2018-04-07  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/85257
+	* gcc.dg/pr85257.c: New test.
+
 	2018-04-06  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/85252
diff --git a/gcc/testsuite/gcc.dg/pr85257.c b/gcc/testsuite/gcc.dg/pr85257.c
new file mode 100644
index 000000000000..75fafd96fd3f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr85257.c
@@ -0,0 +1,20 @@
+/* PR tree-optimization/85257 */
+/* { dg-do run { target int128 } } */
+/* { dg-options "-O2 -fno-tree-ccp" } */
+
+typedef __int128 V __attribute__ ((__vector_size__ (16 * sizeof (__int128))));
+
+__int128 __attribute__ ((noinline, noclone))
+foo (void)
+{
+  V v = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
+  return v[5];
+}
+
+int
+main ()
+{
+  if (foo () != 6)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index 15838975f371..0c648b2d051a 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -1814,8 +1814,9 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_,
 	  int len;
 
 	  len = native_encode_expr (gimple_assign_rhs1 (def_stmt),
-				    buffer, sizeof (buffer));
-	  if (len > 0)
+				    buffer, sizeof (buffer),
+				    (offset - offset2) / BITS_PER_UNIT);
+	  if (len > 0 && len * BITS_PER_UNIT >= ref->size)
 	    {
 	      tree type = vr->type;
 	      /* Make sure to interpret in a type that has a range
@@ -1824,10 +1825,7 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_,
 		  && ref->size != TYPE_PRECISION (vr->type))
 		type = build_nonstandard_integer_type (ref->size,
 						       TYPE_UNSIGNED (type));
-	      tree val = native_interpret_expr (type,
-						buffer
-						+ ((offset - offset2)
-						   / BITS_PER_UNIT),
+	      tree val = native_interpret_expr (type, buffer,
 						ref->size / BITS_PER_UNIT);
 	      /* If we chop off bits because the types precision doesn't
 		 match the memory access size this is ok when optimizing