re PR tree-optimization/38747 (Wrong code due to VIEW_CONVERT_EXPR)

2009-01-20  Andrew Pinski  <andrew_pinski@playstation.sony.com>
	Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/38747
	PR tree-optimization/38748
	* tree-ssa-forwprop.c (forward_propagate_addr_expr_1): Disable the VCE
	conversion if the base address is an indirect reference and the
	aliasing sets could cause issues.

	* gcc.dg/tree-ssa/struct-aliasing-1.c: New test.
	* gcc.dg/tree-ssa/struct-aliasing-2.c: Likewise.
	* gcc.c-torture/execute/struct-aliasing-1.c: Likewise.

Co-Authored-By: Richard Guenther <rguenther@suse.de>

From-SVN: r143523

6 files changed, 79 insertions, 4 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7b43b970..e4bb5c7 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2009-01-20  Andrew Pinski  <andrew_pinski@playstation.sony.com>
+	Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/38747
+	PR tree-optimization/38748
+	* tree-ssa-forwprop.c (forward_propagate_addr_expr_1): Disable the VCE
+	conversion if the base address is an indirect reference and the
+	aliasing sets could cause issues.
+
 2009-01-20  Sebastian Pop  <sebastian.pop@amd.com>
 
 	* common.opt (fgraphite, fgraphite-identity): Add comment for 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 55fc1c8..4754d1a 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,12 @@
+2009-01-20  Andrew Pinski  <andrew_pinski@playstation.sony.com>
+	Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/38747
+	PR tree-optimization/38748
+	* gcc.dg/tree-ssa/struct-aliasing-1.c: New test.
+	* gcc.dg/tree-ssa/struct-aliasing-2.c: Likewise.
+	* gcc.c-torture/execute/struct-aliasing-1.c: Likewise.
+
 2009-01-20  Kees Cook  <kees@ubuntu.com>
 	    H.J. Lu  <hongjiu.lu@intel.com>
 
diff --git a/gcc/testsuite/gcc.c-torture/execute/struct-aliasing-1.c b/gcc/testsuite/gcc.c-torture/execute/struct-aliasing-1.c
new file mode 100644
index 0000000..9786b44
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/struct-aliasing-1.c
@@ -0,0 +1,17 @@
+struct S { float f; };
+int __attribute__((noinline))
+foo (int *r, struct S *p)
+{
+  int *q = (int *)&p->f;
+  int i = *q;
+  *r = 0;
+  return i + *q;
+}
+extern void abort (void);
+int main()
+{
+  int i = 1;
+  if (foo (&i, (struct S *)&i) != 1)
+    abort ();
+  return (0);
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/struct-aliasing-1.c b/gcc/testsuite/gcc.dg/tree-ssa/struct-aliasing-1.c
new file mode 100644
index 0000000..78e92d7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/struct-aliasing-1.c
@@ -0,0 +1,15 @@
+/* { dg-do "compile" } */
+/* { dg-options "-O2 -fdump-tree-fre" } */
+
+struct S { float f; };
+int __attribute__((noinline))
+foo (float *r, struct S *p)
+{
+  int *q = (int *)&p->f;
+  int i = *q;
+  *r = 0.0;
+  return i + *q;
+}
+
+/* { dg-final { scan-tree-dump-times "\\\*q" 1 "fre" } } */
+/* { dg-final { cleanup-tree-dump "fre" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/struct-aliasing-2.c b/gcc/testsuite/gcc.dg/tree-ssa/struct-aliasing-2.c
new file mode 100644
index 0000000..aa9e142
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/struct-aliasing-2.c
@@ -0,0 +1,18 @@
+/* { dg-do "compile" } */
+/* { dg-options "-O2 -fdump-tree-fre" } */
+
+struct S { unsigned f; };
+
+int
+foo ( struct S *p)
+{
+  int *q = (int *)&p->f;
+  int i = *q;
+  return i + p->f;
+}
+
+
+/*  There should only be one load of p->f because fwprop can change *(int *)&p->f into just (int)p->f.  */
+/* { dg-final { scan-tree-dump-times "p_.\\\(D\\\)->f" 1 "fre" } } */
+/* { dg-final { cleanup-tree-dump "fre" } } */
+
diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index bfd7146..3826f1a 100644
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -777,7 +777,7 @@ forward_propagate_addr_expr_1 (tree name, tree def_rhs,
       && operand_equal_p (TYPE_SIZE (TREE_TYPE (rhs)),
 			  TYPE_SIZE (TREE_TYPE (TREE_OPERAND (def_rhs, 0))), 0)) 
    {
-     tree new_rhs = unshare_expr (TREE_OPERAND (def_rhs, 0));
+     tree def_rhs_base, new_rhs = unshare_expr (TREE_OPERAND (def_rhs, 0));
      new_rhs = fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (rhs), new_rhs);
      if (TREE_CODE (new_rhs) != VIEW_CONVERT_EXPR)
        {
@@ -788,16 +788,23 @@ forward_propagate_addr_expr_1 (tree name, tree def_rhs,
 	 new_rhs = force_gimple_operand_gsi (use_stmt_gsi, new_rhs, true, NULL,
 					     true, GSI_NEW_STMT);
 	 gimple_assign_set_rhs1 (use_stmt, new_rhs);
+	 tidy_after_forward_propagate_addr (use_stmt);
+	 return true;
        }
-     else
+     /* If the defining rhs comes from an indirect reference, then do not
+        convert into a VIEW_CONVERT_EXPR.  */
+     def_rhs_base = TREE_OPERAND (def_rhs, 0);
+     while (handled_component_p (def_rhs_base))
+       def_rhs_base = TREE_OPERAND (def_rhs_base, 0);
+     if (!INDIRECT_REF_P (def_rhs_base))
        {
 	 /* We may have arbitrary VIEW_CONVERT_EXPRs in a nested component
 	    reference.  Place it there and fold the thing.  */
 	 *rhsp = new_rhs;
 	 fold_stmt_inplace (use_stmt);
+	 tidy_after_forward_propagate_addr (use_stmt);
+	 return true;
        }
-     tidy_after_forward_propagate_addr (use_stmt);
-     return true;
    }
 
   /* If the use of the ADDR_EXPR is not a POINTER_PLUS_EXPR, there