Hi!
On the following testcase associate_plusminus optimizes
A + ~A into INTEGER_CST { -1, -1 } with type unsigned short, which
confuses enough following passes on (int) cast of that into
assuming it is -1 instead of 65535.
Fixed by using build_int_cst_type, which is what e.g. fold-const.c
uses when optimizing X + ~X.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk
and 4.6 (where the bug is just latent)? 4.5 didn't have
associate_plusminus.
2011-04-22 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/48717
* tree-ssa-forwprop.c (associate_plusminus): For A + ~A and
~A + A optimizations use build_int_cst_type instead of build_int_cst.
* gcc.c-torture/execute/pr48717.c: New test.
--- gcc/tree-ssa-forwprop.c.jj 2011-04-01 23:09:21.000000000 +0200
+++ gcc/tree-ssa-forwprop.c 2011-04-22 11:57:10.000000000 +0200
@@ -1815,7 +1815,7 @@ associate_plusminus (gimple stmt)
{
/* ~A + A -> -1. */
code = INTEGER_CST;
- rhs1 = build_int_cst (TREE_TYPE (rhs2), -1);
+ rhs1 = build_int_cst_type (TREE_TYPE (rhs2), -1);
rhs2 = NULL_TREE;
gimple_assign_set_rhs_with_ops (&gsi, code, rhs1, NULL_TREE);
gcc_assert (gsi_stmt (gsi) == stmt);
@@ -1915,7 +1915,7 @@ associate_plusminus (gimple stmt)
{
/* A + ~A -> -1. */
code = INTEGER_CST;
- rhs1 = build_int_cst (TREE_TYPE (rhs1), -1);
+ rhs1 = build_int_cst_type (TREE_TYPE (rhs1), -1);
rhs2 = NULL_TREE;
gimple_assign_set_rhs_with_ops (&gsi, code, rhs1, NULL_TREE);
gcc_assert (gsi_stmt (gsi) == stmt);
--- gcc/testsuite/gcc.c-torture/execute/pr48717.c.jj 2011-04-22
11:59:23.000000000 +0200
+++ gcc/testsuite/gcc.c-torture/execute/pr48717.c 2011-04-22
11:58:48.000000000 +0200
@@ -0,0 +1,26 @@
+/* PR tree-optimization/48717 */
+
+extern void abort (void);
+
+int v = 1, w;
+
+unsigned short
+foo (unsigned short x, unsigned short y)
+{
+ return x + y;
+}
+
+void
+bar (void)
+{
+ v = foo (~w, w);
+}
+
+int
+main ()
+{
+ bar ();
+ if (v != (unsigned short) -1)
+ abort ();
+ return 0;
+}
Jakub
