Ping this patch which is simple fix on VSETVL PASS.
Ok for trunk ?
juzhe.zh...@rivai.ai
From: Juzhe-Zhong
Date: 2024-02-01 17:02
To: gcc-patches
CC: kito.cheng; kito.cheng; jeffreyalaw; rdapp.gcc; Juzhe-Zhong
Subject: [PATCH v2] RISC-V: Suppress the vsetvl fusion for conflict successors
Update in v2: Add dump information.
This patch fixes the following ineffective vsetvl insertion:
#include "riscv_vector.h"
void f (int32_t * restrict in, int32_t * restrict out, size_t n, size_t cond,
size_t cond2)
{
for (size_t i = 0; i < n; i++)
{
if (i == cond) {
vint8mf8_t v = *(vint8mf8_t*)(in + i + 100);
*(vint8mf8_t*)(out + i + 100) = v;
} else if (i == cond2) {
vfloat32mf2_t v = *(vfloat32mf2_t*)(in + i + 200);
*(vfloat32mf2_t*)(out + i + 200) = v;
} else if (i == (cond2 - 1)) {
vuint16mf2_t v = *(vuint16mf2_t*)(in + i + 300);
*(vuint16mf2_t*)(out + i + 300) = v;
} else {
vint8mf4_t v = *(vint8mf4_t*)(in + i + 400);
*(vint8mf4_t*)(out + i + 400) = v;
}
}
}
Before this patch:
f:
.LFB0:
.cfi_startproc
beq a2,zero,.L12
addi a7,a0,400
addi a6,a1,400
addi a0,a0,1600
addi a1,a1,1600
li a5,0
addi t6,a4,-1
vsetvli t3,zero,e8,mf8,ta,ma ---> ineffective uplift
.L7:
beq a3,a5,.L15
beq a4,a5,.L16
beq t6,a5,.L17
vsetvli t1,zero,e8,mf4,ta,ma
vle8.v v1,0(a0)
vse8.v v1,0(a1)
vsetvli t3,zero,e8,mf8,ta,ma
.L4:
addi a5,a5,1
addi a7,a7,4
addi a6,a6,4
addi a0,a0,4
addi a1,a1,4
bne a2,a5,.L7
.L12:
ret
.L15:
vle8.v v1,0(a7)
vse8.v v1,0(a6)
j .L4
.L17:
vsetvli t1,zero,e8,mf4,ta,ma
addi t5,a0,-400
addi t4,a1,-400
vle16.v v1,0(t5)
vse16.v v1,0(t4)
vsetvli t3,zero,e8,mf8,ta,ma
j .L4
.L16:
addi t5,a0,-800
addi t4,a1,-800
vle32.v v1,0(t5)
vse32.v v1,0(t4)
j .L4
It's obvious that we are hoisting the e8mf8 vsetvl to the top. It's ineffective
since e8mf8 comes from
low probability block which is if (i == cond).
For this case, we disable such fusion.
After this patch:
f:
beq a2,zero,.L12
addi a7,a0,400
addi a6,a1,400
addi a0,a0,1600
addi a1,a1,1600
li a5,0
addi t6,a4,-1
.L7:
beq a3,a5,.L15
beq a4,a5,.L16
beq t6,a5,.L17
vsetvli t1,zero,e8,mf4,ta,ma
vle8.v v1,0(a0)
vse8.v v1,0(a1)
.L4:
addi a5,a5,1
addi a7,a7,4
addi a6,a6,4
addi a0,a0,4
addi a1,a1,4
bne a2,a5,.L7
.L12:
ret
.L15:
vsetvli t3,zero,e8,mf8,ta,ma
vle8.v v1,0(a7)
vse8.v v1,0(a6)
j .L4
.L17:
addi t5,a0,-400
addi t4,a1,-400
vsetvli t1,zero,e8,mf4,ta,ma
vle16.v v1,0(t5)
vse16.v v1,0(t4)
j .L4
.L16:
addi t5,a0,-800
addi t4,a1,-800
vsetvli t3,zero,e32,mf2,ta,ma
vle32.v v1,0(t5)
vse32.v v1,0(t4)
j .L4
Tested on both RV32/RV64 no regression. Ok for trunk ?
PR target/113696
gcc/ChangeLog:
* config/riscv/riscv-vsetvl.cc (pre_vsetvl::earliest_fuse_vsetvl_info):
Suppress vsetvl fusion.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/rvv/vsetvl/pr113696.c: New test.
---
gcc/config/riscv/riscv-vsetvl.cc | 25 ++++++++++++++++++
.../gcc.target/riscv/rvv/vsetvl/pr113696.c | 26 +++++++++++++++++++
2 files changed, 51 insertions(+)
create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/vsetvl/pr113696.c
diff --git a/gcc/config/riscv/riscv-vsetvl.cc b/gcc/config/riscv/riscv-vsetvl.cc
index cec862329c5..28b7534d970 100644
--- a/gcc/config/riscv/riscv-vsetvl.cc
+++ b/gcc/config/riscv/riscv-vsetvl.cc
@@ -2959,6 +2959,31 @@ pre_vsetvl::earliest_fuse_vsetvl_info (int iter)
src_block_info.set_empty_info ();
src_block_info.probability
= profile_probability::uninitialized ();
+ /* See PR113696, we should reset immediate dominator to
+ empty since we may uplift ineffective vsetvl which
+ locate at low probability block. */
+ basic_block dom
+ = get_immediate_dominator (CDI_DOMINATORS, eg->src);
+ auto &dom_block_info = get_block_info (dom);
+ if (dom_block_info.has_info ()
+ && !m_dem.compatible_p (
+ dom_block_info.get_exit_info (), curr_info))
+ {
+ dom_block_info.set_empty_info ();
+ dom_block_info.probability
+ = profile_probability::uninitialized ();
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file,
+ " Reset dominator bb %u:",
+ dom->index);
+ prev_info.dump (dump_file, " ");
+ fprintf (dump_file,
+ " due to (same probability or no "
+ "compatible reaching):");
+ curr_info.dump (dump_file, " ");
+ }
+ }
changed = true;
}
/* Choose the one with higher probability. */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/pr113696.c
b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/pr113696.c
new file mode 100644
index 00000000000..5d7c5f52ead
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/vsetvl/pr113696.c
@@ -0,0 +1,26 @@
+/* { dg-do compile } */
+/* { dg-options "--param=riscv-autovec-preference=scalable -march=rv64gcv
-mabi=lp64d -O3" } */
+
+#include "riscv_vector.h"
+
+void f (int32_t * restrict in, int32_t * restrict out, size_t n, size_t cond,
size_t cond2)
+{
+ for (size_t i = 0; i < n; i++)
+ {
+ if (i == cond) {
+ vint8mf8_t v = *(vint8mf8_t*)(in + i + 100);
+ *(vint8mf8_t*)(out + i + 100) = v;
+ } else if (i == cond2) {
+ vfloat32mf2_t v = *(vfloat32mf2_t*)(in + i + 200);
+ *(vfloat32mf2_t*)(out + i + 200) = v;
+ } else if (i == (cond2 - 1)) {
+ vuint16mf2_t v = *(vuint16mf2_t*)(in + i + 300);
+ *(vuint16mf2_t*)(out + i + 300) = v;
+ } else {
+ vint8mf4_t v = *(vint8mf4_t*)(in + i + 400);
+ *(vint8mf4_t*)(out + i + 400) = v;
+ }
+ }
+}
+
+/* { dg-final { scan-assembler-times {vsetvli} 4 { target { no-opts "-O0"
no-opts "-Os" no-opts "-Oz" no-opts "-funroll-loops" no-opts "-g" } } } } */
--
2.36.1
