2007-05-24 Richard Guenther <rguenther@suse.de>

        Andrew Pinski  <andrew_pinski@playstation.sony.com>

	PR tree-optimization/31982
	* tree-ssa-forwprop.c
	(forward_propagate_addr_into_variable_array_index): Handle arrays
	with element size one.

	* gcc.dg/tree-ssa/forwprop-2.c: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@125058 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 56 insertions, 19 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 25eb0013b2b..2342dad7d04 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2007-05-25  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/31982
+	* tree-ssa-forwprop.c
+	(forward_propagate_addr_into_variable_array_index): Handle arrays
+	with element size one.
+
 2007-05-24  Andrew Pinski  <andrew_pinski@playstation.sony.com>
 
 	* config/spu/spu.md (smulsi3_highpart): Unshare the rtl chain.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 47f40dff2bf..c0cbf9b3158 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2007-05-25  Richard Guenther  <rguenther@suse.de>
+	Andrew Pinski  <andrew_pinski@playstation.sony.com>
+
+	PR tree-optimization/31982
+	* gcc.dg/tree-ssa/forwprop-2.c: New testcase.
+
 2007-05-25  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/32047
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/forwprop-2.c b/gcc/testsuite/gcc.dg/tree-ssa/forwprop-2.c
new file mode 100644
index 00000000000..95aa77eb3f7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/forwprop-2.c
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-forwprop" }  */
+
+/* We should be able to optimize this to b->t[i] = 1 during
+   early optimizations.  */
+
+struct a
+{
+  char t[10];
+};
+
+struct a *b;
+
+void f(__SIZE_TYPE__ i)
+{
+  char *c = b->t;
+  c[i] = 1;
+}
+
+/* { dg-final { scan-tree-dump "t\\\[i.*\\\] = 1;" "forwprop1" { xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump "t\\\[i.*\\\] = 1;" "forwprop2" } } */
+/* { dg-final { cleanup-tree-dump "forwprop?" } } */
diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index 2afdd9a6332..95f1c003c25 100644
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -513,28 +513,30 @@ forward_propagate_addr_into_variable_array_index (tree offset, tree lhs,
   if (TREE_CODE (offset) != SSA_NAME)
     return false;
 
-  /* Get the defining statement of the offset before type
-     conversion.  */
-  offset = SSA_NAME_DEF_STMT (offset);
+  /* Try to find an expression for a proper index.  This is either
+     a multiplication expression by the element size or just the
+     ssa name we came along in case the element size is one.  */
+  if (integer_onep (TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (lhs)))))
+    index = offset;
+  else
+    {
+      offset = SSA_NAME_DEF_STMT (offset);
 
-  /* The statement which defines OFFSET before type conversion
-     must be a simple GIMPLE_MODIFY_STMT.  */
-  if (TREE_CODE (offset) != GIMPLE_MODIFY_STMT)
-    return false;
+      /* The RHS of the statement which defines OFFSET must be a
+	 multiplication of an object by the size of the array elements.  */
+      if (TREE_CODE (offset) != GIMPLE_MODIFY_STMT)
+	return false;
 
-  /* The RHS of the statement which defines OFFSET must be a
-     multiplication of an object by the size of the array elements. 
-     This implicitly verifies that the size of the array elements
-     is constant.  */
-  offset = GIMPLE_STMT_OPERAND (offset, 1);
-  if (TREE_CODE (offset) != MULT_EXPR
-      || TREE_CODE (TREE_OPERAND (offset, 1)) != INTEGER_CST
-      || !simple_cst_equal (TREE_OPERAND (offset, 1),
-			    TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (lhs)))))
-    return false;
+      offset = GIMPLE_STMT_OPERAND (offset, 1);
+      if (TREE_CODE (offset) != MULT_EXPR
+	  || TREE_CODE (TREE_OPERAND (offset, 1)) != INTEGER_CST
+	  || !simple_cst_equal (TREE_OPERAND (offset, 1),
+				TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (lhs)))))
+	return false;
 
-  /* The first operand to the MULT_EXPR is the desired index.  */
-  index = TREE_OPERAND (offset, 0);
+      /* The first operand to the MULT_EXPR is the desired index.  */
+      index = TREE_OPERAND (offset, 0);
+    }
 
   /* Replace the pointer addition with array indexing.  */
   GIMPLE_STMT_OPERAND (use_stmt, 1) = unshare_expr (def_rhs);