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* [gcc r14-4774] RISC-V: Fix failed hoist in LICM of vmv.v.x instruction
@ 2023-10-20 3:57 Lehua Ding
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From: Lehua Ding @ 2023-10-20 3:57 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:f0e28d8c13713f509fde26fbe7dd13280b67fb87
commit r14-4774-gf0e28d8c13713f509fde26fbe7dd13280b67fb87
Author: Juzhe-Zhong <juzhe.zhong@rivai.ai>
Date: Wed Oct 18 18:25:33 2023 +0800
RISC-V: Fix failed hoist in LICM of vmv.v.x instruction
Confirm dynamic LMUL algorithm works well for choosing LMUL = 4 for the PR:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111848
But it generate horrible register spillings.
The root cause is that we didn't hoist the vmv.v.x outside the loop which
increase the SLP loop register pressure.
So, change the COSNT_VECTOR move into vec_duplicate splitter that we can gain better optimizations:
1. better LICM.
2. More opportunities of transforming 'vv' into 'vx' in the future.
Before this patch:
f3:
ble a4,zero,.L8
csrr t0,vlenb
slli t1,t0,4
csrr a6,vlenb
sub sp,sp,t1
csrr a5,vlenb
slli a6,a6,3
slli a5,a5,2
add a6,a6,sp
vsetvli a7,zero,e16,m8,ta,ma
slli a4,a4,3
vid.v v8
addi t6,a5,-1
vand.vi v8,v8,-2
neg t5,a5
vs8r.v v8,0(sp)
vadd.vi v8,v8,1
vs8r.v v8,0(a6)
j .L4
.L12:
vsetvli a7,zero,e16,m8,ta,ma
.L4:
csrr t0,vlenb
slli t0,t0,3
vl8re16.v v16,0(sp)
add t0,t0,sp
vmv.v.x v8,t6
mv t1,a4
vand.vv v24,v16,v8
mv a6,a4
vl8re16.v v16,0(t0)
vand.vv v8,v16,v8
bleu a4,a5,.L3
mv a6,a5
.L3:
vsetvli zero,a6,e8,m4,ta,ma
vle8.v v20,0(a2)
vle8.v v16,0(a3)
vsetvli a7,zero,e8,m4,ta,ma
vrgatherei16.vv v4,v20,v24
vadd.vv v4,v16,v4
vsetvli zero,a6,e8,m4,ta,ma
vse8.v v4,0(a0)
vle8.v v20,0(a2)
vsetvli a7,zero,e8,m4,ta,ma
vrgatherei16.vv v4,v20,v8
vadd.vv v4,v4,v16
vsetvli zero,a6,e8,m4,ta,ma
vse8.v v4,0(a1)
add a4,a4,t5
add a0,a0,a5
add a3,a3,a5
add a1,a1,a5
add a2,a2,a5
bgtu t1,a5,.L12
csrr t0,vlenb
slli t1,t0,4
add sp,sp,t1
jr ra
.L8:
ret
After this patch:
f3:
ble a4,zero,.L6
csrr a6,vlenb
csrr a5,vlenb
slli a6,a6,2
slli a5,a5,2
addi a6,a6,-1
slli a4,a4,3
neg t5,a5
vsetvli t1,zero,e16,m8,ta,ma
vmv.v.x v24,a6
vid.v v8
vand.vi v8,v8,-2
vadd.vi v16,v8,1
vand.vv v8,v8,v24
vand.vv v16,v16,v24
.L4:
mv t1,a4
mv a6,a4
bleu a4,a5,.L3
mv a6,a5
.L3:
vsetvli zero,a6,e8,m4,ta,ma
vle8.v v28,0(a2)
vle8.v v24,0(a3)
vsetvli a7,zero,e8,m4,ta,ma
vrgatherei16.vv v4,v28,v8
vadd.vv v4,v24,v4
vsetvli zero,a6,e8,m4,ta,ma
vse8.v v4,0(a0)
vle8.v v28,0(a2)
vsetvli a7,zero,e8,m4,ta,ma
vrgatherei16.vv v4,v28,v16
vadd.vv v4,v4,v24
vsetvli zero,a6,e8,m4,ta,ma
vse8.v v4,0(a1)
add a4,a4,t5
add a0,a0,a5
add a3,a3,a5
add a1,a1,a5
add a2,a2,a5
bgtu t1,a5,.L4
.L6:
ret
Note that this patch triggers multiple FAILs:
FAIL: gcc.target/riscv/rvv/autovec/cond/cond_arith_run-3.c execution test
FAIL: gcc.target/riscv/rvv/autovec/cond/cond_arith_run-3.c execution test
FAIL: gcc.target/riscv/rvv/autovec/cond/cond_arith_run-4.c execution test
FAIL: gcc.target/riscv/rvv/autovec/cond/cond_arith_run-4.c execution test
FAIL: gcc.target/riscv/rvv/autovec/cond/cond_arith_run-8.c execution test
FAIL: gcc.target/riscv/rvv/autovec/cond/cond_arith_run-8.c execution test
FAIL: gcc.target/riscv/rvv/autovec/gather-scatter/strided_load_run-1.c execution test
FAIL: gcc.target/riscv/rvv/autovec/gather-scatter/strided_load_run-1.c execution test
FAIL: gcc.target/riscv/rvv/autovec/gather-scatter/strided_load_run-2.c execution test
FAIL: gcc.target/riscv/rvv/autovec/gather-scatter/strided_load_run-2.c execution test
FAIL: gcc.target/riscv/rvv/autovec/gather-scatter/strided_store_run-1.c execution test
FAIL: gcc.target/riscv/rvv/autovec/gather-scatter/strided_store_run-1.c execution test
FAIL: gcc.target/riscv/rvv/autovec/gather-scatter/strided_store_run-2.c execution test
FAIL: gcc.target/riscv/rvv/autovec/gather-scatter/strided_store_run-2.c execution test
They failed are all because of bugs on VSETVL PASS:
10dd4: 0c707057 vsetvli zero,zero,e8,mf2,ta,ma
10dd8: 5e06b8d7 vmv.v.i v17,13
10ddc: 9ed030d7 vmv1r.v v1,v13
10de0: b21040d7 vncvt.x.x.w v1,v1 ----> raise illegal instruction since we don't have SEW = 8 -> SEW = 4 narrowing.
10de4: 5e0785d7 vmv.v.v v11,v15
Confirm the recent VSETVL refactor patch: https://gcc.gnu.org/pipermail/gcc-patches/2023-October/633231.html fixed all of them.
So this patch should be committed after the VSETVL refactor patch.
PR target/111848
gcc/ChangeLog:
* config/riscv/riscv-selftests.cc (run_const_vector_selftests): Adapt selftest.
* config/riscv/riscv-v.cc (expand_const_vector): Change it into vec_duplicate splitter.
gcc/testsuite/ChangeLog:
* gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul2-7.c: Adapt test.
* gcc.dg/vect/costmodel/riscv/rvv/pr111848.c: New test.
Diff:
---
gcc/config/riscv/riscv-selftests.cc | 14 ++++-----
gcc/config/riscv/riscv-v.cc | 27 +++++++++++++++--
.../vect/costmodel/riscv/rvv/dynamic-lmul2-7.c | 3 +-
.../gcc.dg/vect/costmodel/riscv/rvv/pr111848.c | 35 ++++++++++++++++++++++
4 files changed, 68 insertions(+), 11 deletions(-)
diff --git a/gcc/config/riscv/riscv-selftests.cc b/gcc/config/riscv/riscv-selftests.cc
index cdc863ee4f76..0ac17fb70a1f 100644
--- a/gcc/config/riscv/riscv-selftests.cc
+++ b/gcc/config/riscv/riscv-selftests.cc
@@ -267,15 +267,14 @@ run_const_vector_selftests (void)
rtx dup = gen_const_vec_duplicate (mode, GEN_INT (val));
emit_move_insn (dest, dup);
rtx_insn *insn = get_last_insn ();
- rtx src = XEXP (SET_SRC (PATTERN (insn)), 1);
+ rtx src = SET_SRC (PATTERN (insn));
/* 1. Should be vmv.v.i for in rang of -16 ~ 15.
2. Should be vmv.v.x for exceed -16 ~ 15. */
if (IN_RANGE (val, -16, 15))
- ASSERT_TRUE (rtx_equal_p (src, dup));
- else
ASSERT_TRUE (
- rtx_equal_p (src,
- gen_rtx_VEC_DUPLICATE (mode, XEXP (src, 0))));
+ rtx_equal_p (XEXP (SET_SRC (PATTERN (insn)), 1), dup));
+ else
+ ASSERT_TRUE (GET_CODE (src) == VEC_DUPLICATE);
end_sequence ();
}
}
@@ -294,10 +293,9 @@ run_const_vector_selftests (void)
rtx dup = gen_const_vec_duplicate (mode, ele);
emit_move_insn (dest, dup);
rtx_insn *insn = get_last_insn ();
- rtx src = XEXP (SET_SRC (PATTERN (insn)), 1);
+ rtx src = SET_SRC (PATTERN (insn));
/* Should always be vfmv.v.f. */
- ASSERT_TRUE (
- rtx_equal_p (src, gen_rtx_VEC_DUPLICATE (mode, XEXP (src, 0))));
+ ASSERT_TRUE (GET_CODE (src) == VEC_DUPLICATE);
end_sequence ();
}
}
diff --git a/gcc/config/riscv/riscv-v.cc b/gcc/config/riscv/riscv-v.cc
index 895c11d13fcd..6116f5df5044 100644
--- a/gcc/config/riscv/riscv-v.cc
+++ b/gcc/config/riscv/riscv-v.cc
@@ -1001,8 +1001,31 @@ expand_const_vector (rtx target, rtx src)
}
else
{
- rtx ops[] = {tmp, elt};
- emit_vlmax_insn (code_for_pred_broadcast (mode), UNARY_OP, ops);
+ /* Emit vec_duplicate<mode> split pattern before RA so that
+ we could have a better optimization opportunity in LICM
+ which will hoist vmv.v.x outside the loop and in fwprop && combine
+ which will transform 'vv' into 'vx' instruction.
+
+ The reason we don't emit vec_duplicate<mode> split pattern during
+ RA since the split stage after RA is a too late stage to generate
+ RVV instruction which need an additional register (We can't
+ allocate a new register after RA) for VL operand of vsetvl
+ instruction (vsetvl a5, zero). */
+ if (lra_in_progress)
+ {
+ rtx ops[] = {tmp, elt};
+ emit_vlmax_insn (code_for_pred_broadcast (mode), UNARY_OP, ops);
+ }
+ else
+ {
+ struct expand_operand ops[2];
+ enum insn_code icode = optab_handler (vec_duplicate_optab, mode);
+ gcc_assert (icode != CODE_FOR_nothing);
+ create_output_operand (&ops[0], tmp, mode);
+ create_input_operand (&ops[1], elt, GET_MODE_INNER (mode));
+ expand_insn (icode, 2, ops);
+ tmp = ops[0].value;
+ }
}
if (tmp != target)
diff --git a/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul2-7.c b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul2-7.c
index 3dfc6f16a250..2a735d8c6b65 100644
--- a/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul2-7.c
+++ b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul2-7.c
@@ -18,7 +18,8 @@ bar (int *x, int a, int b, int n)
}
/* { dg-final { scan-assembler {e32,m2} } } */
-/* { dg-final { scan-assembler-times {csrr} 1 } } */
+/* { dg-final { scan-assembler-not {jr} } } */
+/* { dg-final { scan-assembler-times {ret} 2 } } *
/* { dg-final { scan-tree-dump-times "Maximum lmul = 8" 1 "vect" } } */
/* { dg-final { scan-tree-dump-times "Maximum lmul = 4" 1 "vect" } } */
/* { dg-final { scan-tree-dump-times "Maximum lmul = 2" 1 "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/pr111848.c b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/pr111848.c
new file mode 100644
index 000000000000..b203ca907fa1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/pr111848.c
@@ -0,0 +1,35 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gcv -mabi=lp64d -fdump-tree-vect-details" } */
+
+void
+f3 (uint8_t *restrict a, uint8_t *restrict b,
+ uint8_t *restrict c, uint8_t *restrict d,
+ int n)
+{
+ for (int i = 0; i < n; ++i)
+ {
+ a[i * 8] = c[i * 8] + d[i * 8];
+ a[i * 8 + 1] = c[i * 8] + d[i * 8 + 1];
+ a[i * 8 + 2] = c[i * 8 + 2] + d[i * 8 + 2];
+ a[i * 8 + 3] = c[i * 8 + 2] + d[i * 8 + 3];
+ a[i * 8 + 4] = c[i * 8 + 4] + d[i * 8 + 4];
+ a[i * 8 + 5] = c[i * 8 + 4] + d[i * 8 + 5];
+ a[i * 8 + 6] = c[i * 8 + 6] + d[i * 8 + 6];
+ a[i * 8 + 7] = c[i * 8 + 6] + d[i * 8 + 7];
+ b[i * 8] = c[i * 8 + 1] + d[i * 8];
+ b[i * 8 + 1] = c[i * 8 + 1] + d[i * 8 + 1];
+ b[i * 8 + 2] = c[i * 8 + 3] + d[i * 8 + 2];
+ b[i * 8 + 3] = c[i * 8 + 3] + d[i * 8 + 3];
+ b[i * 8 + 4] = c[i * 8 + 5] + d[i * 8 + 4];
+ b[i * 8 + 5] = c[i * 8 + 5] + d[i * 8 + 5];
+ b[i * 8 + 6] = c[i * 8 + 7] + d[i * 8 + 6];
+ b[i * 8 + 7] = c[i * 8 + 7] + d[i * 8 + 7];
+ }
+}
+
+/* { dg-final { scan-assembler {e8,m4} } } */
+/* { dg-final { scan-assembler-not {jr} } } */
+/* { dg-final { scan-assembler-times {ret} 1 } } *
+/* { dg-final { scan-tree-dump-times "Maximum lmul = 4" 1 "vect" } } */
+/* { dg-final { scan-tree-dump-not "Maximum lmul = 2" "vect" } } */
+/* { dg-final { scan-tree-dump-not "Maximum lmul = 1" "vect" } } */
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