https://gcc.gnu.org/g:90a447677a2abb934b683a012b477e6c52088e35
commit r14-10257-g90a447677a2abb934b683a012b477e6c52088e35
Author: Richard Biener <rguent...@suse.de>
Date: Tue May 21 09:48:04 2024 +0200
tree-optimization/115149 - VOP live and missing PHIs
The following fixes a bug in vop-live get_live_in which was using
NULL to indicate the first processed edge but at the same time
using it for the case the live-in virtual operand cannot be computed.
The following fixes this, avoiding sinking a load to a place where
we'd have to insert virtual PHIs to make the virtual operand SSA
web OK.
PR tree-optimization/115149
* tree-ssa-live.cc (virtual_operand_live::get_live_in):
Explicitly track the first processed edge.
* gcc.dg/pr115149.c: New testcase.
(cherry picked from commit ec9b8bafe20755d13ab9a1b834b5da79ae972c0e)
Diff:
---
gcc/testsuite/gcc.dg/pr115149.c | 16 ++++++++++++++++
gcc/tree-ssa-live.cc | 8 ++++++--
2 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/pr115149.c b/gcc/testsuite/gcc.dg/pr115149.c
new file mode 100644
index 00000000000..9f6bc97dbe6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr115149.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fno-inline -fno-tree-vrp -fno-ipa-sra -fno-tree-dce
-fno-tree-ch" } */
+
+int a, c, e, f, g, h[1], i;
+static int j(int b) { return 0; }
+static void k(int d) {}
+int main()
+{
+ if (h[0])
+ while (1) {
+ k(f && j(i && (h[g] = e)));
+ while (a)
+ c ^= 1;
+ }
+ return 0;
+}
diff --git a/gcc/tree-ssa-live.cc b/gcc/tree-ssa-live.cc
index d94e94eb3bc..122d8e245dd 100644
--- a/gcc/tree-ssa-live.cc
+++ b/gcc/tree-ssa-live.cc
@@ -1684,14 +1684,18 @@ virtual_operand_live::get_live_in (basic_block bb)
edge_iterator ei;
edge e;
tree livein = NULL_TREE;
+ bool first = true;
FOR_EACH_EDGE (e, ei, bb->preds)
if (e->flags & EDGE_DFS_BACK)
/* We can ignore backedges since if there's a def there it would
have forced a PHI in the source because it also acts as use
downstream. */
continue;
- else if (!livein)
- livein = get_live_out (e->src);
+ else if (first)
+ {
+ livein = get_live_out (e->src);
+ first = false;
+ }
else if (get_live_out (e->src) != livein)
/* When there's no virtual use downstream this indicates a point
where we'd insert a PHI merging the different live virtual
