https://gcc.gnu.org/g:1157d5de35b41eabe5ee51d532224864173c37bd
commit r14-9329-g1157d5de35b41eabe5ee51d532224864173c37bd
Author: Jakub Jelinek <ja...@redhat.com>
Date: Wed Mar 6 09:35:37 2024 +0100
i386: Fix up the vzeroupper REG_DEAD/REG_UNUSED note workaround [PR114190]
When writing the rest_of_handle_insert_vzeroupper workaround to manually
remove all the REG_DEAD/REG_UNUSED notes from the IL, I've missed that
there is a df_analyze () call right after it and that the problems added
earlier in the pass, like df_note_add_problem () done during mode switching,
doesn't affect just the next df_analyze () call right after it, but all
other df_analyze () calls until the end of the current pass where
df_finish_pass removes the optional problems.
So, as can be seen on the following patch, the workaround doesn't actually
work there, because while rest_of_handle_insert_vzeroupper carefully removes
all REG_DEAD/REG_UNUSED notes, the df_analyze () call at the end of the
function immediately adds them in again (so, I must say I have no idea
why the workaround worked on the earlier testcases).
Now, I could move the df_analyze () call just before the REG_DEAD/REG_UNUSED
note removal loop, but I think the following patch is better, because
the df_analyze () call doesn't have to recompute the problem when we don't
care about it and will actively strip all traces of it away.
2024-03-06 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/114190
* config/i386/i386-features.cc (rest_of_handle_insert_vzeroupper):
Call df_remove_problem for df_note before calling df_analyze.
* gcc.target/i386/avx-pr114190.c: New test.
Diff:
---
gcc/config/i386/i386-features.cc | 1 +
gcc/testsuite/gcc.target/i386/avx-pr114190.c | 27 +++++++++++++++++++++++++++
2 files changed, 28 insertions(+)
diff --git a/gcc/config/i386/i386-features.cc b/gcc/config/i386/i386-features.cc
index d3b9ae81025..1de2a07ed75 100644
--- a/gcc/config/i386/i386-features.cc
+++ b/gcc/config/i386/i386-features.cc
@@ -2690,6 +2690,7 @@ rest_of_handle_insert_vzeroupper (void)
}
}
+ df_remove_problem (df_note);
df_analyze ();
return 0;
}
diff --git a/gcc/testsuite/gcc.target/i386/avx-pr114190.c
b/gcc/testsuite/gcc.target/i386/avx-pr114190.c
new file mode 100644
index 00000000000..fc5b2615de2
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/avx-pr114190.c
@@ -0,0 +1,27 @@
+/* PR rtl-optimization/114190 */
+/* { dg-do run { target avx } } */
+/* { dg-options "-O2 -fno-dce -fharden-compares -mavx
--param=max-rtl-if-conversion-unpredictable-cost=136 -mno-avx512f -Wno-psabi" }
*/
+
+#include "avx-check.h"
+
+typedef unsigned char U __attribute__((vector_size (64)));
+typedef unsigned int V __attribute__((vector_size (64)));
+U u;
+
+V
+foo (V a, V b)
+{
+ u[0] = __builtin_sub_overflow (0, (int) a[0], &a[b[7] & 5]) ? -u[1] : -b[3];
+ b ^= 0 != b;
+ return (V) u + (V) a + (V) b;
+}
+
+static void
+avx_test (void)
+{
+ V x = foo ((V) { 1 }, (V) { 0, 0, 0, 1 });
+ if (x[0] != -1U)
+ __builtin_abort ();
+ if (x[3] != -2U)
+ __builtin_abort ();
+}
