https://gcc.gnu.org/g:06829e593d2e5611e7924624cb8228795691e2b7
commit r14-10439-g06829e593d2e5611e7924624cb8228795691e2b7
Author: Richard Biener <rguent...@suse.de>
Date: Mon Jul 15 13:50:58 2024 +0200
tree-optimization/115843 - fix wrong-code with fully-masked loop and peeling
When AVX512 uses a fully masked loop and peeling we fail to create the
correct initial loop mask when the mask is composed of multiple
components in some cases. The following fixes this by properly applying
the bias for the component to the shift amount.
PR tree-optimization/115843
* tree-vect-loop-manip.cc
(vect_set_loop_condition_partial_vectors_avx512): Properly
bias the shift of the initial mask for alignment peeling.
* gcc.dg/vect/pr115843.c: New testcase.
(cherry picked from commit a177be05f6952c3f7e62186d2e138d96c475b81a)
Diff:
---
gcc/testsuite/gcc.dg/vect/pr115843.c | 41 ++++++++++++++++++++++++++++++++++++
gcc/tree-vect-loop-manip.cc | 8 +++++--
2 files changed, 47 insertions(+), 2 deletions(-)
diff --git a/gcc/testsuite/gcc.dg/vect/pr115843.c
b/gcc/testsuite/gcc.dg/vect/pr115843.c
new file mode 100644
index 000000000000..3dbb6c792788
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr115843.c
@@ -0,0 +1,41 @@
+/* { dg-additional-options "-mavx512f --param vect-partial-vector-usage=2" {
target avx512f_runtime } } */
+
+#include "tree-vect.h"
+
+typedef __UINT64_TYPE__ BITBOARD;
+BITBOARD KingPressureMask1[64], KingSafetyMask1[64];
+
+void __attribute__((noinline))
+foo()
+{
+ for (int i = 0; i < 64; i++)
+ {
+ if ((i & 7) == 0)
+ KingPressureMask1[i] = KingSafetyMask1[i + 1];
+ else if ((i & 7) == 7)
+ KingPressureMask1[i] = KingSafetyMask1[i - 1];
+ else
+ KingPressureMask1[i] = KingSafetyMask1[i];
+ }
+}
+
+BITBOARD verify[64]
+ = {1, 1, 2, 3, 4, 5, 6, 6, 9, 9, 10, 11, 12, 13, 14, 14, 17, 17, 18, 19,
+ 20, 21, 22, 22, 25, 25, 26, 27, 28, 29, 30, 30, 33, 33, 34, 35, 36, 37, 38,
+ 38, 41, 41, 42, 43, 44, 45, 46, 46, 49, 49, 50, 51, 52, 53, 54, 54, 57, 57,
+ 58, 59, 60, 61, 62, 62};
+
+int main()
+{
+ check_vect ();
+
+#pragma GCC novector
+ for (int i = 0; i < 64; ++i)
+ KingSafetyMask1[i] = i;
+ foo ();
+#pragma GCC novector
+ for (int i = 0; i < 64; ++i)
+ if (KingPressureMask1[i] != verify[i])
+ __builtin_abort ();
+ return 0;
+}
diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
index 43c7881c640d..1ece4a58bd50 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -1149,10 +1149,14 @@ vect_set_loop_condition_partial_vectors_avx512 (class
loop *loop,
/* ??? But when the shift amount isn't constant this requires
a round-trip to GRPs. We could apply the bias to either
side of the compare instead. */
- tree shift = gimple_build (&preheader_seq, MULT_EXPR,
+ tree shift = gimple_build (&preheader_seq, MINUS_EXPR,
TREE_TYPE (niters_skip), niters_skip,
build_int_cst (TREE_TYPE (niters_skip),
-
rgc.max_nscalars_per_iter));
+ bias));
+ shift = gimple_build (&preheader_seq, MULT_EXPR,
+ TREE_TYPE (niters_skip), shift,
+ build_int_cst (TREE_TYPE (niters_skip),
+ rgc.max_nscalars_per_iter));
init_ctrl = gimple_build (&preheader_seq, LSHIFT_EXPR,
TREE_TYPE (init_ctrl),
init_ctrl, shift);
