I noticed we fail to valueize the RHS when looking for same-valued
stores.
Bootstrap / regtest running on x86_64-unknown-linux-gnu.
Richard.
2019-07-05 Richard Biener <rguent...@suse.de>
* tree-ssa-sccvn.c (vn_reference_lookup_3): Valueize RHS
when comparing against a store with possibly the same value.
* gcc.dg/tree-ssa/ssa-fre-77.c: New testcase.
Index: gcc/tree-ssa-sccvn.c
===================================================================
--- gcc/tree-ssa-sccvn.c (revision 273083)
+++ gcc/tree-ssa-sccvn.c (working copy)
@@ -2012,9 +2268,11 @@ vn_reference_lookup_3 (ao_ref *ref, tree
if (res && res != (void *)-1)
{
vn_reference_t vnresult = (vn_reference_t) res;
+ tree rhs = gimple_assign_rhs1 (def_stmt);
+ if (TREE_CODE (rhs) == SSA_NAME)
+ rhs = SSA_VAL (rhs);
if (vnresult->result
- && operand_equal_p (vnresult->result,
- gimple_assign_rhs1 (def_stmt), 0))
+ && operand_equal_p (vnresult->result, rhs, 0))
return res;
}
}
Index: gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-77.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-77.c (nonexistent)
+++ gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-77.c (working copy)
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-fre1" } */
+
+int foo (int *p, int *q)
+{
+ int x;
+ *p = 1;
+ x = *p;
+ *q = x;
+ return *p;
+}
+
+/* { dg-final { scan-tree-dump "return 1;" "fre1" } } */
