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* [gcc r14-8984] middle-end: inspect all exits for additional annotations for loop.
@ 2024-02-14 16:14 Tamar Christina
0 siblings, 0 replies; only message in thread
From: Tamar Christina @ 2024-02-14 16:14 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:16ae5efedd389e8952f35bb10665518c22a9251c
commit r14-8984-g16ae5efedd389e8952f35bb10665518c22a9251c
Author: Tamar Christina <tamar.christina@arm.com>
Date: Wed Feb 14 16:13:51 2024 +0000
middle-end: inspect all exits for additional annotations for loop.
Attaching a pragma to a loop which has a complex condition often gets the pragma
dropped. e.g.
#pragma GCC novector
while (i < N && parse_tables_n--)
before lowering this is represented as:
if (ANNOTATE_EXPR <i <= 305 && parse_tables_n-- != 0, no-vector>) ...
But after lowering the condition is broken appart and attached to the final
component of the expression:
if (parse_tables_n.2_2 != 0) goto <D.4456>; else goto <D.4453>;
<D.4456>:
iftmp.1D.4452 = 1;
goto <D.4454>;
<D.4453>:
iftmp.1D.4452 = 0;
<D.4454>:
D.4451 = .ANNOTATE (iftmp.1D.4452, 2, 0);
if (D.4451 != 0) goto <D.4442>; else goto <D.4440>;
<D.4440>:
and it's never heard from again because during replace_loop_annotate we only
inspect the loop header and latch for annotations.
Since annotations were supposed to apply to the loop as a whole this fixes it
by checking the loop exit src blocks for annotations instead.
gcc/ChangeLog:
* tree-cfg.cc (replace_loop_annotate): Inspect loop edges for annotations.
gcc/testsuite/ChangeLog:
* gcc.dg/vect/vect-novect_gcond.c: New test.
Diff:
---
gcc/testsuite/gcc.dg/vect/vect-novect_gcond.c | 39 +++++++++++++++++++++++++++
gcc/tree-cfg.cc | 9 +++----
2 files changed, 42 insertions(+), 6 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/vect/vect-novect_gcond.c b/gcc/testsuite/gcc.dg/vect/vect-novect_gcond.c
new file mode 100644
index 000000000000..01e69cbef9d5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-novect_gcond.c
@@ -0,0 +1,39 @@
+/* { dg-add-options vect_early_break } */
+/* { dg-require-effective-target vect_early_break_hw } */
+/* { dg-require-effective-target vect_int } */
+/* { dg-additional-options "-O3" } */
+
+/* { dg-final { scan-tree-dump-not "LOOP VECTORIZED" "vect" } } */
+
+#include "tree-vect.h"
+
+#define N 306
+#define NEEDLE 136
+
+int table[N];
+
+__attribute__ ((noipa))
+int foo (int i, unsigned short parse_tables_n)
+{
+ parse_tables_n >>= 9;
+ parse_tables_n += 11;
+#pragma GCC novector
+ while (i < N && parse_tables_n--)
+ table[i++] = 0;
+
+ return table[NEEDLE];
+}
+
+int main ()
+{
+ check_vect ();
+
+#pragma GCC novector
+ for (int j = 0; j < N; j++)
+ table[j] = -1;
+
+ if (foo (0, 0xFFFF) != 0)
+ __builtin_abort ();
+
+ return 0;
+}
diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index cdd439fe7506..bdffc3b4ed27 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -320,12 +320,9 @@ replace_loop_annotate (void)
for (auto loop : loops_list (cfun, 0))
{
- /* First look into the header. */
- replace_loop_annotate_in_block (loop->header, loop);
-
- /* Then look into the latch, if any. */
- if (loop->latch)
- replace_loop_annotate_in_block (loop->latch, loop);
+ /* Check all exit source blocks for annotations. */
+ for (auto e : get_loop_exit_edges (loop))
+ replace_loop_annotate_in_block (e->src, loop);
/* Push the global flag_finite_loops state down to individual loops. */
loop->finite_p = flag_finite_loops;
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