re PR middle-end/66110 (uint8_t memory access not optimized)

2015-05-13  Richard Biener  <rguenther@suse.de>

	PR middle-end/66110
	* alias.c (alias_sets_conflict_p): Do not treat has_zero_child
	specially.
	* Makefile.in (dfp.o-warn): Add -Wno-strict-aliasing.

	* gcc.dg/alias-2.c: Adjust.
	* gcc.dg/tree-ssa/ssa-dse-17.c: New testcase.

From-SVN: r223126

gcc/ChangeLog

+2015-05-13  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/66110
+	* alias.c (alias_sets_conflict_p): Do not treat has_zero_child
+	specially.
+	* Makefile.in (dfp.o-warn): Add -Wno-strict-aliasing.
+
 2015-05-13  Michael Haubenwallner  <michael.haubenwallner@ssi-schaefer.com>
 
 	* doc/install.texi: Bump latest automake 1.11 version to 1.11.6.

gcc/Makefile.in

@@ -211,6 +211,7 @@ libgcov-driver-tool.o-warn = -Wno-error
 libgcov-merge-tool.o-warn = -Wno-error
 gimple-match.o-warn = -Wno-unused
 generic-match.o-warn = -Wno-unused
+dfp.o-warn = -Wno-strict-aliasing
 
 # All warnings have to be shut off in stage1 if the compiler used then
 # isn't gcc; configure determines that.  WARN_CFLAGS will be either

gcc/alias.c

@@ -470,15 +470,13 @@ alias_sets_conflict_p (alias_set_type set1, alias_set_type set2)
   /* See if the first alias set is a subset of the second.  */
   ase = get_alias_set_entry (set1);
   if (ase != 0
-      && (ase->has_zero_child
-	  || ase->children->get (set2)))
+      && ase->children->get (set2))
     return 1;
 
   /* Now do the same, but with the alias sets reversed.  */
   ase = get_alias_set_entry (set2);
   if (ase != 0
-      && (ase->has_zero_child
-	  || ase->children->get (set1)))
+      && ase->children->get (set1))
     return 1;
 
   /* The two alias sets are distinct and neither one is the

gcc/testsuite/ChangeLog

+2015-05-13  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/66110
+	* gcc.dg/alias-2.c: Adjust.
+	* gcc.dg/tree-ssa/ssa-dse-17.c: New testcase.
+
 2015-05-13  Ilya Enkovich  <ilya.enkovich@intel.com>
 
 	PR target/65103

gcc/testsuite/gcc.dg/alias-2.c

@@ -11,6 +11,6 @@ struct foo {
 int
 sub1 (long long int foobar)
 {
-  struct foo *tmp = (struct foo *) &foobar; // { dg-warning "type-punned pointer might" "" }
+  struct foo *tmp = (struct foo *) &foobar; // { dg-warning "type-punned pointer will" "" }
   return tmp->i;
 }

gcc/testsuite/gcc.dg/tree-ssa/ssa-dse-17.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-dse1" } */
+
+struct s1 {
+    unsigned short f1;
+    unsigned char f2;
+};
+
+struct s2 {
+    struct s1 *p1;
+};
+
+void f1(struct s2 *p)
+{
+  p->p1->f2 = 9;
+  p->p1->f2 = 10;
+}
+
+/* { dg-final { scan-tree-dump-times "f2 =" 1 "dse1" } } */
+/* { dg-final { cleanup-tree-dump "dse1" } } */