After Eric reminded me how things go with the middle-end and bit-offsets
the following adjusts VN accordingly.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
Richard.
2018-05-23 Richard Biener <rguent...@suse.de>
* tree-ssa-sccvn.c (vn_reference_lookup_3): Remove restriction
of fixed offset from memset VN.
* gcc.dg/tree-ssa/ssa-fre-66.c: New testcase.
On branch slpcost
Your branch is ahead of 'origin/trunk' by 1 commit.
(use "git push" to publish your local commits)
Changes to be committed:
(use "git reset HEAD <file>..." to unstage)
new file: testsuite/gcc.dg/tree-ssa/ssa-fre-66.c
modified: tree-ssa-sccvn.c
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-66.c
b/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-66.c
new file mode 100644
index 00000000000..1c86a1f3866
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-66.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-fre1" } */
+
+int foo (int i)
+{
+ int a[16];
+ __builtin_memset (a, 42, sizeof (a));
+ return a[i];
+}
+
+/* { dg-final { scan-tree-dump "return 707406378;" "fre1" { target { int32plus
} } } } */
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index 96e80c7b5a3..73e8fc5df49 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -1962,7 +1962,6 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_,
|| ((TREE_CODE (gimple_call_arg (def_stmt, 1)) == INTEGER_CST
|| (INTEGRAL_TYPE_P (vr->type) && known_eq (ref->size, 8)))
&& CHAR_BIT == 8 && BITS_PER_UNIT == 8
- && known_eq (ref->size, maxsize)
&& offset.is_constant (&offseti)
&& offseti % BITS_PER_UNIT == 0))
&& poly_int_tree_p (gimple_call_arg (def_stmt, 2))
