https://gcc.gnu.org/g:e93f02828faf7dc0df6a4d67b1b6b2a30bd713cb
commit r15-9778-ge93f02828faf7dc0df6a4d67b1b6b2a30bd713cb
Author: Richard Biener <rguent...@suse.de>
Date: Wed May 14 16:36:29 2025 +0200
Fix regression from x86 multi-epilogue tuning
With the avx512_two_epilogues tuning enabled for zen4 and zen5
the gcc.target/i386/vect-epilogues-5.c testcase below regresses
and ends up using AVX2 sized vectors for the masked epilogue
rather than AVX512 sized vectors. The following patch rectifies
this and adds coverage for the intended behavior.
* config/i386/i386.cc (ix86_vector_costs::finish_cost):
Do not suggest a first epilogue mode for AVX512 sized
main loops with X86_TUNE_AVX512_TWO_EPILOGUES as that
interferes with using a masked epilogue.
* gcc.target/i386/vect-epilogues-1.c: New testcase.
* gcc.target/i386/vect-epilogues-2.c: Likewise.
* gcc.target/i386/vect-epilogues-3.c: Likewise.
* gcc.target/i386/vect-epilogues-4.c: Likewise.
* gcc.target/i386/vect-epilogues-5.c: Likewise.
(cherry picked from commit 75c7f90bfe6fa8e6c1a70b784e98a3412861646d)
Diff:
---
gcc/config/i386/i386.cc | 10 +++-------
gcc/testsuite/gcc.target/i386/vect-epilogues-1.c | 14 ++++++++++++++
gcc/testsuite/gcc.target/i386/vect-epilogues-2.c | 15 +++++++++++++++
gcc/testsuite/gcc.target/i386/vect-epilogues-3.c | 15 +++++++++++++++
gcc/testsuite/gcc.target/i386/vect-epilogues-4.c | 13 +++++++++++++
gcc/testsuite/gcc.target/i386/vect-epilogues-5.c | 13 +++++++++++++
6 files changed, 73 insertions(+), 7 deletions(-)
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 38df84f7db24..a6f0a582c3d2 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -25545,14 +25545,10 @@ ix86_vector_costs::finish_cost (const vector_costs
*scalar_costs)
/* When X86_TUNE_AVX512_TWO_EPILOGUES is enabled arrange for both
a AVX2 and a SSE epilogue for AVX512 vectorized loops. */
if (loop_vinfo
+ && LOOP_VINFO_EPILOGUE_P (loop_vinfo)
+ && GET_MODE_SIZE (loop_vinfo->vector_mode) == 32
&& ix86_tune_features[X86_TUNE_AVX512_TWO_EPILOGUES])
- {
- if (GET_MODE_SIZE (loop_vinfo->vector_mode) == 64)
- m_suggested_epilogue_mode = V32QImode;
- else if (LOOP_VINFO_EPILOGUE_P (loop_vinfo)
- && GET_MODE_SIZE (loop_vinfo->vector_mode) == 32)
- m_suggested_epilogue_mode = V16QImode;
- }
+ m_suggested_epilogue_mode = V16QImode;
/* When a 128bit SSE vectorized epilogue still has a VF of 16 or larger
enable a 64bit SSE epilogue. */
if (loop_vinfo
diff --git a/gcc/testsuite/gcc.target/i386/vect-epilogues-1.c
b/gcc/testsuite/gcc.target/i386/vect-epilogues-1.c
new file mode 100644
index 000000000000..a7f5f12c71bc
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/vect-epilogues-1.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -mavx2 -mno-avx512f -mtune=generic
-fdump-tree-vect-optimized" } */
+
+int test (signed char *data, int n)
+{
+ int sum = 0;
+ for (int i = 0; i < n; ++i)
+ sum += data[i];
+ return sum;
+}
+
+/* { dg-final { scan-tree-dump "loop vectorized using 32 byte vectors" "vect"
} } */
+/* { dg-final { scan-tree-dump "loop vectorized using 16 byte vectors" "vect"
} } */
+/* { dg-final { scan-tree-dump "loop vectorized using 8 byte vectors" "vect" {
target { ! ia32 } } } } */
diff --git a/gcc/testsuite/gcc.target/i386/vect-epilogues-2.c
b/gcc/testsuite/gcc.target/i386/vect-epilogues-2.c
new file mode 100644
index 000000000000..d6c06edcacd1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/vect-epilogues-2.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -mavx512bw -mtune=generic -fdump-tree-vect-optimized" } */
+
+int test (signed char *data, int n)
+{
+ int sum = 0;
+ for (int i = 0; i < n; ++i)
+ sum += data[i];
+ return sum;
+}
+
+/* { dg-final { scan-tree-dump "loop vectorized using 64 byte vectors" "vect"
} } */
+/* { dg-final { scan-tree-dump "loop vectorized using 32 byte vectors" "vect"
} } */
+/* { dg-final { scan-tree-dump-not "loop vectorized using 16 byte vectors"
"vect" } } */
+/* { dg-final { scan-tree-dump-not "loop vectorized using 8 byte vectors"
"vect" } } */
diff --git a/gcc/testsuite/gcc.target/i386/vect-epilogues-3.c
b/gcc/testsuite/gcc.target/i386/vect-epilogues-3.c
new file mode 100644
index 000000000000..0ee610f5e3ef
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/vect-epilogues-3.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -mavx512bw -mtune=znver4 -fdump-tree-vect-optimized" } */
+
+int test (signed char *data, int n)
+{
+ int sum = 0;
+ for (int i = 0; i < n; ++i)
+ sum += data[i];
+ return sum;
+}
+
+/* { dg-final { scan-tree-dump "loop vectorized using 64 byte vectors" "vect"
} } */
+/* { dg-final { scan-tree-dump "loop vectorized using 32 byte vectors" "vect"
} } */
+/* { dg-final { scan-tree-dump "loop vectorized using 16 byte vectors" "vect"
} } */
+/* { dg-final { scan-tree-dump "loop vectorized using 8 byte vectors" "vect" {
target { ! ia32 } } } } */
diff --git a/gcc/testsuite/gcc.target/i386/vect-epilogues-4.c
b/gcc/testsuite/gcc.target/i386/vect-epilogues-4.c
new file mode 100644
index 000000000000..498db6b5a13c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/vect-epilogues-4.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -mavx512bw -mtune=generic --param
vect-partial-vector-usage=1 -fdump-tree-vect-optimized" } */
+
+int test (signed char *data, int n)
+{
+ int sum = 0;
+ for (int i = 0; i < n; ++i)
+ sum += data[i];
+ return sum;
+}
+
+/* { dg-final { scan-tree-dump-times "loop vectorized using 64 byte vectors" 2
"vect" } } */
+/* { dg-final { scan-tree-dump-not "loop vectorized using 32 byte vectors"
"vect" } } */
diff --git a/gcc/testsuite/gcc.target/i386/vect-epilogues-5.c
b/gcc/testsuite/gcc.target/i386/vect-epilogues-5.c
new file mode 100644
index 000000000000..6772cabeb4a4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/vect-epilogues-5.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -mavx512bw -mtune=znver4 --param
vect-partial-vector-usage=1 -fdump-tree-vect-optimized" } */
+
+int test (signed char *data, int n)
+{
+ int sum = 0;
+ for (int i = 0; i < n; ++i)
+ sum += data[i];
+ return sum;
+}
+
+/* { dg-final { scan-tree-dump-times "loop vectorized using 64 byte vectors" 2
"vect" } } */
+/* { dg-final { scan-tree-dump-not "loop vectorized using 32 byte vectors"
"vect" } } */
