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* [gcc(refs/vendors/riscv/heads/gcc-13-with-riscv-opts)] RISC-V: Use VLS modes if the NITERS is known and smaller than VLS mode elements.
@ 2023-10-16 18:39 Jeff Law
0 siblings, 0 replies; only message in thread
From: Jeff Law @ 2023-10-16 18:39 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:559a2dd05eab4b9f4f24abb1e57140b5e5db24a4
commit 559a2dd05eab4b9f4f24abb1e57140b5e5db24a4
Author: Juzhe-Zhong <juzhe.zhong@rivai.ai>
Date: Mon Oct 16 16:25:04 2023 +0800
RISC-V: Use VLS modes if the NITERS is known and smaller than VLS mode elements.
void
foo8 (int64_t *restrict a)
{
for (int i = 0; i < 16; ++i)
a[i] = a[i]-16;
}
We use VLS modes instead of VLA modes even it is specified by dynamic LMUL.
gcc/ChangeLog:
* config/riscv/riscv-vector-costs.cc (costs::preferred_new_lmul_p): Use VLS modes.
gcc/testsuite/ChangeLog:
* gcc.dg/vect/costmodel/riscv/rvv/no-dynamic-lmul-1.c: New test.
(cherry picked from commit a5fe9f063de64aa2755c9ae9e90ed1ff64ee0f47)
Diff:
---
gcc/config/riscv/riscv-vector-costs.cc | 13 +++--
.../vect/costmodel/riscv/rvv/no-dynamic-lmul-1.c | 64 ++++++++++++++++++++++
2 files changed, 73 insertions(+), 4 deletions(-)
diff --git a/gcc/config/riscv/riscv-vector-costs.cc b/gcc/config/riscv/riscv-vector-costs.cc
index 878f72c85c57..0b8903965354 100644
--- a/gcc/config/riscv/riscv-vector-costs.cc
+++ b/gcc/config/riscv/riscv-vector-costs.cc
@@ -446,10 +446,6 @@ costs::preferred_new_lmul_p (const vector_costs *uncast_other) const
auto other_loop_vinfo = as_a<loop_vec_info> (other->m_vinfo);
class loop *loop = LOOP_VINFO_LOOP (this_loop_vinfo);
- if (!LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (this_loop_vinfo)
- && LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (other_loop_vinfo))
- return false;
-
if (loop_autovec_infos.get (loop) && loop_autovec_infos.get (loop)->end_p)
return false;
else if (loop_autovec_infos.get (loop))
@@ -483,6 +479,15 @@ costs::preferred_new_lmul_p (const vector_costs *uncast_other) const
machine_mode biggest_mode
= compute_local_live_ranges (program_points_per_bb, live_ranges_per_bb);
+ /* If we can use simple VLS modes to handle NITERS element.
+ We don't need to use VLA modes with partial vector auto-vectorization. */
+ if (LOOP_VINFO_NITERS_KNOWN_P (this_loop_vinfo)
+ && known_le (tree_to_poly_int64 (LOOP_VINFO_NITERS (this_loop_vinfo))
+ * GET_MODE_SIZE (biggest_mode).to_constant (),
+ (int) RVV_M8 * BYTES_PER_RISCV_VECTOR)
+ && pow2p_hwi (LOOP_VINFO_INT_NITERS (this_loop_vinfo)))
+ return vector_costs::better_main_loop_than_p (other);
+
/* Update live ranges according to PHI. */
update_local_live_ranges (other->m_vinfo, program_points_per_bb,
live_ranges_per_bb);
diff --git a/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/no-dynamic-lmul-1.c b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/no-dynamic-lmul-1.c
new file mode 100644
index 000000000000..7ede148396fe
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/no-dynamic-lmul-1.c
@@ -0,0 +1,64 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gcv_zvl4096b -mabi=lp64d -fdump-tree-vect-details" } */
+
+#include <stdint-gcc.h>
+
+void
+foo (int8_t *restrict a)
+{
+ for (int i = 0; i < 4096; ++i)
+ a[i] = a[i]-16;
+}
+
+void
+foo2 (int16_t *restrict a)
+{
+ for (int i = 0; i < 2048; ++i)
+ a[i] = a[i]-16;
+}
+
+void
+foo3 (int32_t *restrict a)
+{
+ for (int i = 0; i < 1024; ++i)
+ a[i] = a[i]-16;
+}
+
+void
+foo4 (int64_t *restrict a)
+{
+ for (int i = 0; i < 512; ++i)
+ a[i] = a[i]-16;
+}
+
+void
+foo5 (int8_t *restrict a)
+{
+ for (int i = 0; i < 16; ++i)
+ a[i] = a[i]-16;
+}
+
+void
+foo6 (int16_t *restrict a)
+{
+ for (int i = 0; i < 16; ++i)
+ a[i] = a[i]-16;
+}
+
+void
+foo7 (int32_t *restrict a)
+{
+ for (int i = 0; i < 16; ++i)
+ a[i] = a[i]-16;
+}
+
+void
+foo8 (int64_t *restrict a)
+{
+ for (int i = 0; i < 16; ++i)
+ a[i] = a[i]-16;
+}
+
+/* { dg-final { scan-tree-dump-not "Maximum lmul" "vect" } } */
+/* { dg-final { scan-assembler-times {vsetvli} 4 } } */
+/* { dg-final { scan-assembler-times {vsetivli} 4 } } */
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