From b84f8a5e0a7ef3e5bd0d186fc7e280d9c43c5b7f Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Thu, 1 Feb 2024 09:18:47 +0100
Subject: [PATCH] tree-optimization/113693 - LC SSA and region VN
The following fixes LC SSA preserving with region VN which was broken
when availability checking was enhanced to treat not visited value
numbers as available. The following makes sure to honor availability
data we put in place for LC SSA preserving instead.
PR tree-optimization/113693
* tree-ssa-sccvn.cc (rpo_elim::eliminate_avail): Honor avail
data when available.
* gcc.dg/pr113693.c: New testcase.
---
gcc/testsuite/gcc.dg/pr113693.c | 13 +++++++++++++
gcc/tree-ssa-sccvn.cc | 11 +++++++----
2 files changed, 20 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr113693.c
diff --git a/gcc/testsuite/gcc.dg/pr113693.c b/gcc/testsuite/gcc.dg/pr113693.c
new file mode 100644
index 000000000000..a6f55199d0ff
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr113693.c
@@ -0,0 +1,13 @@
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-O2 -fdbg-cnt=vect_loop:1" } */
+
+_BitInt(837) g, h;
+
+void
+fn1(void)
+{
+ for (; g; g++)
+ for (; h; h++)
+ ;
+}
+/* { dg-message "dbgcnt" "" { target *-*-* } 0 } */
diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index 9bed9b3cc69c..bbcf86588f9f 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -7723,12 +7723,15 @@ rpo_elim::eliminate_avail (basic_block bb, tree op)
if (SSA_NAME_IS_DEFAULT_DEF (valnum))
return valnum;
vn_ssa_aux_t valnum_info = VN_INFO (valnum);
- /* See above. */
- if (!valnum_info->visited)
- return valnum;
vn_avail *av = valnum_info->avail;
if (!av)
- return NULL_TREE;
+ {
+ /* See above. But when there's availability info prefer
+ what we recorded there for example to preserve LC SSA. */
+ if (!valnum_info->visited)
+ return valnum;
+ return NULL_TREE;
+ }
if (av->location == bb->index)
/* On tramp3d 90% of the cases are here. */
return ssa_name (av->leader);
--
GitLab