re PR middle-end/29272 (memcpy optimization causes wrong-code)

	PR middle-end/29272
	* builtins.c (var_decl_component_p): New function.
	(fold_builtin_memset, fold_builtin_memory_op): Restrict
	single entry optimization to variables and components thereof.

	* gcc.c-torture/execute/20060930-2.c: New test.

From-SVN: r117599

4 files changed, 63 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b8c8d40..bc051ea 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2006-10-10  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/29272
+	* builtins.c (var_decl_component_p): New function.
+	(fold_builtin_memset, fold_builtin_memory_op): Restrict
+	single entry optimization to variables and components thereof.
+
 2006-10-10  Richard Guenther  <rguenther@suse.de>
 
 	PR rtl-optimization/29323
diff --git a/gcc/builtins.c b/gcc/builtins.c
index 2997462..46f97f9 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -7893,6 +7893,17 @@ fold_builtin_exponent (tree fndecl, tree arglist,
   return 0;
 }
 
+/* Return true if VAR is a VAR_DECL or a component thereof.  */
+
+static bool
+var_decl_component_p (tree var)
+{
+  tree inner = var;
+  while (handled_component_p (inner))
+    inner = TREE_OPERAND (inner, 0);
+  return SSA_VAR_P (inner);
+}
+
 /* Fold function call to builtin memset.  Return
    NULL_TREE if no simplification can be made.  */
 
@@ -7933,6 +7944,9 @@ fold_builtin_memset (tree arglist, tree type, bool ignore)
       && !POINTER_TYPE_P (TREE_TYPE (var)))
     return 0;
 
+  if (! var_decl_component_p (var))
+    return 0;
+
   length = tree_low_cst (len, 1);
   if (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (var))) != length
       || get_pointer_alignment (dest, BIGGEST_ALIGNMENT) / BITS_PER_UNIT
@@ -8044,6 +8058,9 @@ fold_builtin_memory_op (tree arglist, tree type, bool ignore, int endp)
 	  && !SCALAR_FLOAT_TYPE_P (TREE_TYPE (destvar)))
 	return 0;
 
+      if (! var_decl_component_p (destvar))
+	return 0;
+
       srcvar = src;
       STRIP_NOPS (srcvar);
       if (TREE_CODE (srcvar) != ADDR_EXPR)
@@ -8058,6 +8075,9 @@ fold_builtin_memory_op (tree arglist, tree type, bool ignore, int endp)
 	  && !SCALAR_FLOAT_TYPE_P (TREE_TYPE (srcvar)))
 	return 0;
 
+      if (! var_decl_component_p (srcvar))
+	return 0;
+
       length = tree_low_cst (len, 1);
       if (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (destvar))) != length
 	  || get_pointer_alignment (dest, BIGGEST_ALIGNMENT) / BITS_PER_UNIT
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f60a8ee..6cbfd6c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2006-10-10  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/29272
+	* gcc.c-torture/execute/20060930-2.c: New test.
+
 2006-10-09  Richard Henderson  <rth@redhat.com>
 
 	Revert emutls patch.
diff --git a/gcc/testsuite/gcc.c-torture/execute/20060930-2.c b/gcc/testsuite/gcc.c-torture/execute/20060930-2.c
new file mode 100644
index 0000000..498f781
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/20060930-2.c
@@ -0,0 +1,31 @@
+/* PR middle-end/29272 */
+
+extern void abort (void);
+
+struct S { struct S *s; } s;
+struct T { struct T *t; } t;
+
+static inline void
+foo (void *s)
+{
+  struct T *p = s;
+  __builtin_memcpy (&p->t, &t.t, sizeof (t.t));
+}
+
+void *
+__attribute__((noinline))
+bar (void *p, struct S *q)
+{
+  q->s = &s;
+  foo (p);
+  return q->s;
+}
+
+int
+main (void)
+{
+  t.t = &t;
+  if (bar (&s, &s) != (void *) &t)
+    abort ();
+  return 0;
+}