When unrolling changes nesting relationship of loops we fail to
mark blocks as in need to change for LC SSA update. Specifically
the LC SSA PHI on a former inner loop exit might be misplaced
if that loop becomes a sibling of its outer loop.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
PR tree-optimization/118552
* cfgloopmanip.cc (fix_loop_placement): Properly mark
exit source blocks as to be scanned for LC SSA update when
the loops nesting relationship changed.
(fix_loop_placements): Adjust.
(fix_bb_placements): Likewise.
* gcc.dg/torture/pr118552.c: New testcase.
---
gcc/cfgloopmanip.cc | 13 +++++++---
gcc/testsuite/gcc.dg/torture/pr118552.c | 34 +++++++++++++++++++++++++
2 files changed, 44 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/pr118552.c
diff --git a/gcc/cfgloopmanip.cc b/gcc/cfgloopmanip.cc
index 17bcf9f4acc..573146b2e28 100644
--- a/gcc/cfgloopmanip.cc
+++ b/gcc/cfgloopmanip.cc
@@ -123,7 +123,8 @@ fix_bb_placement (basic_block bb)
invalidate the information about irreducible regions. */
static bool
-fix_loop_placement (class loop *loop, bool *irred_invalidated)
+fix_loop_placement (class loop *loop, bool *irred_invalidated,
+ bitmap loop_closed_ssa_invalidated)
{
unsigned i;
edge e;
@@ -153,6 +154,10 @@ fix_loop_placement (class loop *loop, bool
*irred_invalidated)
if (e->flags & EDGE_IRREDUCIBLE_LOOP)
*irred_invalidated = true;
rescan_loop_exit (e, false, false);
+ /* Any LC SSA PHIs on e->dest might now be on the wrong edge
+ if their defs were in a former outer loop. */
+ if (loop_closed_ssa_invalidated)
+ bitmap_set_bit (loop_closed_ssa_invalidated, e->src->index);
}
ret = true;
@@ -224,7 +229,8 @@ fix_bb_placements (basic_block from,
if (from->loop_father->header == from)
{
/* Subloop header, maybe move the loop upward. */
- if (!fix_loop_placement (from->loop_father, irred_invalidated))
+ if (!fix_loop_placement (from->loop_father, irred_invalidated,
+ loop_closed_ssa_invalidated))
continue;
target_loop = loop_outer (from->loop_father);
if (loop_closed_ssa_invalidated)
@@ -1057,7 +1063,8 @@ fix_loop_placements (class loop *loop, bool
*irred_invalidated,
while (loop_outer (loop))
{
outer = loop_outer (loop);
- if (!fix_loop_placement (loop, irred_invalidated))
+ if (!fix_loop_placement (loop, irred_invalidated,
+ loop_closed_ssa_invalidated))
break;
/* Changing the placement of a loop in the loop tree may alter the
diff --git a/gcc/testsuite/gcc.dg/torture/pr118552.c
b/gcc/testsuite/gcc.dg/torture/pr118552.c
new file mode 100644
index 00000000000..03ee0d0ca3f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr118552.c
@@ -0,0 +1,34 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-fno-tree-ch -fno-tree-ccp -fno-tree-fre" } */
+
+volatile int a;
+int b, c, d, e;
+int main() {
+ int f = 1, g = 1;
+h:
+ if (!d)
+ ;
+ else {
+ int i = 1;
+ j:
+ e = 0;
+ for (; e < 3; e++) {
+ if (e)
+ for (; g < 2; g++) {
+ if (c)
+ return 0;
+ if (f)
+ goto j;
+ }
+ a;
+ if (i)
+ continue;
+ f = i = 0;
+ }
+ }
+ f = 2;
+ b++;
+ if (c)
+ goto h;
+ return 0;
+}
--
2.43.0
