RISC-V: Allow LICM hoist POLY_INT configuration code sequence
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Commit Message
Realize in recent benchmark evaluation (coremark-pro zip-test):
vid.v v2
vmv.v.i v5,0
.L9:
vle16.v v3,0(a4)
vrsub.vx v4,v2,a6 ---> LICM failed to hoist it outside the loop.
The root cause is:
(insn 56 47 57 4 (set (subreg:DI (reg:HI 220) 0)
(reg:DI 223)) "rvv.c":11:9 208 {*movdi_64bit} -> Its result used by the following vrsub.vx then supress the hoist of the vrsub.vx
(nil))
(insn 57 56 59 4 (set (reg:RVVMF2HI 216)
(if_then_else:RVVMF2HI (unspec:RVVMF32BI [
(const_vector:RVVMF32BI repeat [
(const_int 1 [0x1])
])
(reg:DI 350)
(const_int 2 [0x2]) repeated x2
(const_int 1 [0x1])
(reg:SI 66 vl)
(reg:SI 67 vtype)
] UNSPEC_VPREDICATE)
(minus:RVVMF2HI (vec_duplicate:RVVMF2HI (reg:HI 220))
(reg:RVVMF2HI 217))
(unspec:RVVMF2HI [
(reg:DI 0 zero)
] UNSPEC_VUNDEF))) "rvv.c":11:9 6938 {pred_subrvvmf2hi_reverse_scalar}
(expr_list:REG_DEAD (reg:HI 220)
(nil)))
This patch fixes it generate (set (reg:HI) (subreg:HI (reg:DI))) instead of (set (subreg:DI (reg:DI)) (reg:DI)).
After this patch:
vid.v v2
vrsub.vx v2,v2,a7
vmv.v.i v4,0
.L3:
vle16.v v3,0(a4)
Tested on both RV32 and RV64 no regression.
gcc/ChangeLog:
* config/riscv/riscv.cc (riscv_legitimize_move): Fix poly_int dest generation.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/rvv/autovec/poly_licm-1.c: New test.
* gcc.target/riscv/rvv/autovec/poly_licm-2.c: New test.
---
gcc/config/riscv/riscv.cc | 9 ++++---
.../riscv/rvv/autovec/poly_licm-1.c | 18 +++++++++++++
.../riscv/rvv/autovec/poly_licm-2.c | 27 +++++++++++++++++++
3 files changed, 50 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-1.c
create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-2.c
Comments
LGTM :)
On Thu, Feb 1, 2024 at 11:46 PM Juzhe-Zhong <juzhe.zhong@rivai.ai> wrote:
>
> Realize in recent benchmark evaluation (coremark-pro zip-test):
>
> vid.v v2
> vmv.v.i v5,0
> .L9:
> vle16.v v3,0(a4)
> vrsub.vx v4,v2,a6 ---> LICM failed to hoist it outside the loop.
>
> The root cause is:
>
> (insn 56 47 57 4 (set (subreg:DI (reg:HI 220) 0)
> (reg:DI 223)) "rvv.c":11:9 208 {*movdi_64bit} -> Its result used by the following vrsub.vx then supress the hoist of the vrsub.vx
> (nil))
>
> (insn 57 56 59 4 (set (reg:RVVMF2HI 216)
> (if_then_else:RVVMF2HI (unspec:RVVMF32BI [
> (const_vector:RVVMF32BI repeat [
> (const_int 1 [0x1])
> ])
> (reg:DI 350)
> (const_int 2 [0x2]) repeated x2
> (const_int 1 [0x1])
> (reg:SI 66 vl)
> (reg:SI 67 vtype)
> ] UNSPEC_VPREDICATE)
> (minus:RVVMF2HI (vec_duplicate:RVVMF2HI (reg:HI 220))
> (reg:RVVMF2HI 217))
> (unspec:RVVMF2HI [
> (reg:DI 0 zero)
> ] UNSPEC_VUNDEF))) "rvv.c":11:9 6938 {pred_subrvvmf2hi_reverse_scalar}
> (expr_list:REG_DEAD (reg:HI 220)
> (nil)))
>
> This patch fixes it generate (set (reg:HI) (subreg:HI (reg:DI))) instead of (set (subreg:DI (reg:DI)) (reg:DI)).
>
> After this patch:
>
> vid.v v2
> vrsub.vx v2,v2,a7
> vmv.v.i v4,0
> .L3:
> vle16.v v3,0(a4)
>
> Tested on both RV32 and RV64 no regression.
>
> gcc/ChangeLog:
>
> * config/riscv/riscv.cc (riscv_legitimize_move): Fix poly_int dest generation.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/riscv/rvv/autovec/poly_licm-1.c: New test.
> * gcc.target/riscv/rvv/autovec/poly_licm-2.c: New test.
>
> ---
> gcc/config/riscv/riscv.cc | 9 ++++---
> .../riscv/rvv/autovec/poly_licm-1.c | 18 +++++++++++++
> .../riscv/rvv/autovec/poly_licm-2.c | 27 +++++++++++++++++++
> 3 files changed, 50 insertions(+), 4 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-1.c
> create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-2.c
>
> diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
> index 529ef5e84b7..6e22b43e618 100644
> --- a/gcc/config/riscv/riscv.cc
> +++ b/gcc/config/riscv/riscv.cc
> @@ -2711,16 +2711,17 @@ riscv_legitimize_move (machine_mode mode, rtx dest, rtx src)
> (const_poly_int:HI [m, n])
> (const_poly_int:SI [m, n]). */
> rtx tmp = gen_reg_rtx (Pmode);
> - riscv_legitimize_poly_move (Pmode, gen_lowpart (Pmode, dest), tmp,
> - src);
> + rtx tmp2 = gen_reg_rtx (Pmode);
> + riscv_legitimize_poly_move (Pmode, tmp2, tmp, src);
> + emit_move_insn (dest, gen_lowpart (mode, tmp2));
> }
> else
> {
> /* In RV32 system, handle (const_poly_int:SI [m, n])
> (const_poly_int:DI [m, n]).
> In RV64 system, handle (const_poly_int:DI [m, n]).
> - FIXME: Maybe we could gen SImode in RV32 and then sign-extend to DImode,
> - the offset should not exceed 4GiB in general. */
> + FIXME: Maybe we could gen SImode in RV32 and then sign-extend to
> + DImode, the offset should not exceed 4GiB in general. */
> rtx tmp = gen_reg_rtx (mode);
> riscv_legitimize_poly_move (mode, dest, tmp, src);
> }
> diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-1.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-1.c
> new file mode 100644
> index 00000000000..b7da65f0996
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-1.c
> @@ -0,0 +1,18 @@
> +/* { dg-do compile } */
> +/* { dg-options "-march=rv64gcv -mabi=lp64d -O3 -fno-schedule-insns -fno-schedule-insns2" } */
> +
> +extern int wsize;
> +
> +typedef unsigned short Posf;
> +#define NIL 0
> +
> +void foo (Posf *p)
> +{
> + register unsigned n, m;
> + do {
> + m = *--p;
> + *p = (Posf)(m >= wsize ? m-wsize : NIL);
> + } while (--n);
> +}
> +
> +/* { dg-final { scan-assembler-times {vid\.v\s+v[0-9]+\s+addi\s+\s*[a-x0-9]+,\s*[a-x0-9]+,\s*-1\s+vrsub\.vx\s+} 1 } } */
> diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-2.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-2.c
> new file mode 100644
> index 00000000000..ffb3c63149f
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-2.c
> @@ -0,0 +1,27 @@
> +/* { dg-do compile } */
> +/* { dg-options "-march=rv64gcv -mabi=lp64d -O3 -fno-schedule-insns -fno-schedule-insns2" } */
> +
> +typedef unsigned short uint16_t;
> +
> +void AAA (uint16_t *x, uint16_t *y, unsigned wsize, unsigned count)
> +{
> + unsigned m = 0, n = count;
> + register uint16_t *p;
> +
> + p = x;
> +
> + do {
> + m = *--p;
> + *p = (uint16_t)(m >= wsize ? m-wsize : 0);
> + } while (--n);
> +
> + n = wsize;
> + p = y;
> +
> + do {
> + m = *--p;
> + *p = (uint16_t)(m >= wsize ? m-wsize : 0);
> + } while (--n);
> +}
> +
> +/* { dg-final { scan-assembler-times {vid\.v\s+v[0-9]+\s+vrsub\.vx\s+} 2 } } */
> --
> 2.36.1
>
Hi, kito and Robin and Jeff.
I didn't commit this patch yet since I found there is an ICE caused by this patch:
during RTL pass: loop2_unroll
dump file: bug.c.286r.loop2_unroll
bug.c: In function 'crashIt':
bug.c:23:1: internal compiler error: in decompose, at wide-int.h:1049
23 | }
| ^
0x1043946 wi::int_traits<generic_wide_int<wide_int_ref_storage<false, false> > >::decompose(long*, unsigned int, generic_wide_int<wide_int_ref_storage<false, false> > const&)
../../../../gcc/gcc/wide-int.h:1049
0x1043a80 wide_int_ref_storage<false, false>::wide_int_ref_storage<generic_wide_int<wide_int_ref_storage<false, false> > >(generic_wide_int<wide_int_ref_storage<false, false> > const&, unsigned int)
../../../../gcc/gcc/wide-int.h:1099
0x1042f72 generic_wide_int<wide_int_ref_storage<false, false> >::generic_wide_int<generic_wide_int<wide_int_ref_storage<false, false> > >(generic_wide_int<wide_int_ref_storage<false, false> > const&, unsigned int)
../../../../gcc/gcc/wide-int.h:855
0x145b5d0 wi::binary_traits<generic_wide_int<wide_int_ref_storage<false, false> >, generic_wide_int<wide_int_ref_storage<false, false> >, wi::int_traits<generic_wide_int<wide_int_ref_storage<false, false> > >::precision_type, wi::int_traits<generic_wide_int<wide_int_ref_storage<false, false> > >::precision_type>::result_type wi::add<generic_wide_int<wide_int_ref_storage<false, false> >, generic_wide_int<wide_int_ref_storage<false, false> > >(generic_wide_int<wide_int_ref_storage<false, false> > const&, generic_wide_int<wide_int_ref_storage<false, false> > const&)
../../../../gcc/gcc/wide-int.h:2872
0x1458439 wi::binary_traits<generic_wide_int<wide_int_ref_storage<false, false> >, generic_wide_int<wide_int_ref_storage<false, false> >, wi::int_traits<generic_wide_int<wide_int_ref_storage<false, false> > >::precision_type, wi::int_traits<generic_wide_int<wide_int_ref_storage<false, false> > >::precision_type>::operator_result operator+<generic_wide_int<wide_int_ref_storage<false, false> >, generic_wide_int<wide_int_ref_storage<false, false> > >(generic_wide_int<wide_int_ref_storage<false, false> > const&, generic_wide_int<wide_int_ref_storage<false, false> > const&)
../../../../gcc/gcc/wide-int.h:3857
0x195f866 poly_int<2u, poly_result<generic_wide_int<wide_int_ref_storage<false, false> >, generic_wide_int<wide_int_ref_storage<false, false> >, poly_coeff_pair_traits<generic_wide_int<wide_int_ref_storage<false, false> >, generic_wide_int<wide_int_ref_storage<false, false> > >::result_kind>::type> operator+<2u, generic_wide_int<wide_int_ref_storage<false, false> >, generic_wide_int<wide_int_ref_storage<false, false> > >(poly_int<2u, generic_wide_int<wide_int_ref_storage<false, false> > > const&, poly_int<2u, generic_wide_int<wide_int_ref_storage<false, false> > > const&)
../../../../gcc/gcc/poly-int.h:772
0x194d423 simplify_const_binary_operation(rtx_code, machine_mode, rtx_def*, rtx_def*)
../../../../gcc/gcc/simplify-rtx.cc:5392
0x1940374 simplify_context::simplify_binary_operation(rtx_code, machine_mode, rtx_def*, rtx_def*)
../../../../gcc/gcc/simplify-rtx.cc:2664
0x1936e62 simplify_context::simplify_gen_binary(rtx_code, machine_mode, rtx_def*, rtx_def*)
../../../../gcc/gcc/simplify-rtx.cc:182
0x11b43f6 simplify_gen_binary(rtx_code, machine_mode, rtx_def*, rtx_def*)
../../../../gcc/gcc/rtl.h:3529
0x16c0e35 get_biv_step_1
../../../../gcc/gcc/loop-iv.cc:788
0x16c0c97 get_biv_step_1
../../../../gcc/gcc/loop-iv.cc:758
0x16c0f68 get_biv_step
../../../../gcc/gcc/loop-iv.cc:828
0x16c1390 iv_analyze_biv
../../../../gcc/gcc/loop-iv.cc:921
0x16c1e7d iv_analyze_op
../../../../gcc/gcc/loop-iv.cc:1187
0x16c1d71 iv_analyze_op
../../../../gcc/gcc/loop-iv.cc:1157
0x16c15e0 iv_analyze_expr(rtx_insn*, scalar_int_mode, rtx_def*, rtx_iv*)
../../../../gcc/gcc/loop-iv.cc:976
0x16c1757 iv_analyze_expr(rtx_insn*, scalar_int_mode, rtx_def*, rtx_iv*)
../../../../gcc/gcc/loop-iv.cc:1020
0x16c1757 iv_analyze_expr(rtx_insn*, scalar_int_mode, rtx_def*, rtx_iv*)
../../../../gcc/gcc/loop-iv.cc:1020
0x16c1b83 iv_analyze_def
../../../../gcc/gcc/loop-iv.cc:1115
To reproduce this ICE:
with compile option: -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions
typedef unsigned short (FUNC_P) (void *, unsigned char *, unsigned short);
void crashIt(int id, FUNC_P *func, unsigned char *funcparm)
{
unsigned char buff[5], reverse[4];
unsigned char *bp = buff;
unsigned char *rp = reverse;
unsigned short int count = 0;
unsigned short cnt;
while (id > 0)
{
*rp++ = (unsigned char) (id & 0x7F);
id >>= 7;
count++;
}
cnt = count + 1;
while ((count--) > 1)
{
*bp++ = (unsigned char)(*(--rp) | 0x80);
}
*bp++ = *(--rp);
(void)(*func)(funcparm, buff, cnt);
}
The root cause is this following RTL pattern, after fwprop1:
(insn 82 78 84 9 (set (reg:DI 230)
(sign_extend:DI (minus:SI (subreg/s/v:SI (reg:DI 150 [ niters.10 ]) 0)
(subreg:SI (reg:DI 221) 0)))) 13 {subsi3_extended}
(expr_list:REG_EQUAL (sign_extend:DI (plus:SI (subreg/s/v:SI (reg:DI 150 [ niters.10 ]) 0)
(const_poly_int:SI [-16, -16])))
(nil)))
The highlight (const_poly_int:SI [-16, -16])
causes ICE.
This RTL is because:
(insn 69 68 71 8 (set (reg:DI 221)
(const_poly_int:DI [16, 16])) 208 {*movdi_64bit}
(nil))
(insn 82 78 84 9 (set (reg:DI 230)
(sign_extend:DI (minus:SI (subreg/s/v:SI (reg:DI 150 [ niters.10 ]) 0)
(subreg:SI (reg:DI 221) 0)))) 13 {subsi3_extended} ----> (subreg:SI (const_poly_int:SI [-16, -16])) fwprop1 add (const_poly_int:SI [-16, -16]) reg_equal
(expr_list:REG_EQUAL (sign_extend:DI (plus:SI (subreg/s/v:SI (reg:DI 150 [ niters.10 ]) 0)
(const_poly_int:SI [-16, -16])))
(nil)))
Previously, we are doing:
(set (subreg:DI (reg:SI) (DI: poly value)). --> outer mode bigger than inner mode in dest operand.
We never has (subreg: (poly_value)), so we won't have ICE. However, I don't think our previous approach is correct.
Actually, I believe we should apply this following which should be better:
(set (reg:SI) (subreg:SI (DI: poly value))) but it causes ICE that I mentioned above.
Also, I try this following which can fix this issue:
diff --git a/gcc/loop-iv.cc b/gcc/loop-iv.cc
index eb7e923a38b..09750951845 100644
--- a/gcc/loop-iv.cc
+++ b/gcc/loop-iv.cc
@@ -646,10 +646,10 @@ get_biv_step_1 (df_ref def, scalar_int_mode outer_mode, rtx reg,
if (!set)
return false;
- rhs = find_reg_equal_equiv_note (insn);
- if (rhs)
- rhs = XEXP (rhs, 0);
- else
+ //rhs = find_reg_equal_equiv_note (insn);
+ //if (rhs)
+ // rhs = XEXP (rhs, 0);
+ //else
rhs = SET_SRC (set);
Any thoughts ?
juzhe.zhong@rivai.ai
From: Kito Cheng
Date: 2024-02-02 16:50
To: Juzhe-Zhong
CC: gcc-patches; kito.cheng; jeffreyalaw; rdapp.gcc
Subject: Re: [PATCH] RISC-V: Allow LICM hoist POLY_INT configuration code sequence
LGTM :)
On Thu, Feb 1, 2024 at 11:46 PM Juzhe-Zhong <juzhe.zhong@rivai.ai> wrote:
>
> Realize in recent benchmark evaluation (coremark-pro zip-test):
>
> vid.v v2
> vmv.v.i v5,0
> .L9:
> vle16.v v3,0(a4)
> vrsub.vx v4,v2,a6 ---> LICM failed to hoist it outside the loop.
>
> The root cause is:
>
> (insn 56 47 57 4 (set (subreg:DI (reg:HI 220) 0)
> (reg:DI 223)) "rvv.c":11:9 208 {*movdi_64bit} -> Its result used by the following vrsub.vx then supress the hoist of the vrsub.vx
> (nil))
>
> (insn 57 56 59 4 (set (reg:RVVMF2HI 216)
> (if_then_else:RVVMF2HI (unspec:RVVMF32BI [
> (const_vector:RVVMF32BI repeat [
> (const_int 1 [0x1])
> ])
> (reg:DI 350)
> (const_int 2 [0x2]) repeated x2
> (const_int 1 [0x1])
> (reg:SI 66 vl)
> (reg:SI 67 vtype)
> ] UNSPEC_VPREDICATE)
> (minus:RVVMF2HI (vec_duplicate:RVVMF2HI (reg:HI 220))
> (reg:RVVMF2HI 217))
> (unspec:RVVMF2HI [
> (reg:DI 0 zero)
> ] UNSPEC_VUNDEF))) "rvv.c":11:9 6938 {pred_subrvvmf2hi_reverse_scalar}
> (expr_list:REG_DEAD (reg:HI 220)
> (nil)))
>
> This patch fixes it generate (set (reg:HI) (subreg:HI (reg:DI))) instead of (set (subreg:DI (reg:DI)) (reg:DI)).
>
> After this patch:
>
> vid.v v2
> vrsub.vx v2,v2,a7
> vmv.v.i v4,0
> .L3:
> vle16.v v3,0(a4)
>
> Tested on both RV32 and RV64 no regression.
>
> gcc/ChangeLog:
>
> * config/riscv/riscv.cc (riscv_legitimize_move): Fix poly_int dest generation.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/riscv/rvv/autovec/poly_licm-1.c: New test.
> * gcc.target/riscv/rvv/autovec/poly_licm-2.c: New test.
>
> ---
> gcc/config/riscv/riscv.cc | 9 ++++---
> .../riscv/rvv/autovec/poly_licm-1.c | 18 +++++++++++++
> .../riscv/rvv/autovec/poly_licm-2.c | 27 +++++++++++++++++++
> 3 files changed, 50 insertions(+), 4 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-1.c
> create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-2.c
>
> diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
> index 529ef5e84b7..6e22b43e618 100644
> --- a/gcc/config/riscv/riscv.cc
> +++ b/gcc/config/riscv/riscv.cc
> @@ -2711,16 +2711,17 @@ riscv_legitimize_move (machine_mode mode, rtx dest, rtx src)
> (const_poly_int:HI [m, n])
> (const_poly_int:SI [m, n]). */
> rtx tmp = gen_reg_rtx (Pmode);
> - riscv_legitimize_poly_move (Pmode, gen_lowpart (Pmode, dest), tmp,
> - src);
> + rtx tmp2 = gen_reg_rtx (Pmode);
> + riscv_legitimize_poly_move (Pmode, tmp2, tmp, src);
> + emit_move_insn (dest, gen_lowpart (mode, tmp2));
> }
> else
> {
> /* In RV32 system, handle (const_poly_int:SI [m, n])
> (const_poly_int:DI [m, n]).
> In RV64 system, handle (const_poly_int:DI [m, n]).
> - FIXME: Maybe we could gen SImode in RV32 and then sign-extend to DImode,
> - the offset should not exceed 4GiB in general. */
> + FIXME: Maybe we could gen SImode in RV32 and then sign-extend to
> + DImode, the offset should not exceed 4GiB in general. */
> rtx tmp = gen_reg_rtx (mode);
> riscv_legitimize_poly_move (mode, dest, tmp, src);
> }
> diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-1.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-1.c
> new file mode 100644
> index 00000000000..b7da65f0996
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-1.c
> @@ -0,0 +1,18 @@
> +/* { dg-do compile } */
> +/* { dg-options "-march=rv64gcv -mabi=lp64d -O3 -fno-schedule-insns -fno-schedule-insns2" } */
> +
> +extern int wsize;
> +
> +typedef unsigned short Posf;
> +#define NIL 0
> +
> +void foo (Posf *p)
> +{
> + register unsigned n, m;
> + do {
> + m = *--p;
> + *p = (Posf)(m >= wsize ? m-wsize : NIL);
> + } while (--n);
> +}
> +
> +/* { dg-final { scan-assembler-times {vid\.v\s+v[0-9]+\s+addi\s+\s*[a-x0-9]+,\s*[a-x0-9]+,\s*-1\s+vrsub\.vx\s+} 1 } } */
> diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-2.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-2.c
> new file mode 100644
> index 00000000000..ffb3c63149f
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/poly_licm-2.c
> @@ -0,0 +1,27 @@
> +/* { dg-do compile } */
> +/* { dg-options "-march=rv64gcv -mabi=lp64d -O3 -fno-schedule-insns -fno-schedule-insns2" } */
> +
> +typedef unsigned short uint16_t;
> +
> +void AAA (uint16_t *x, uint16_t *y, unsigned wsize, unsigned count)
> +{
> + unsigned m = 0, n = count;
> + register uint16_t *p;
> +
> + p = x;
> +
> + do {
> + m = *--p;
> + *p = (uint16_t)(m >= wsize ? m-wsize : 0);
> + } while (--n);
> +
> + n = wsize;
> + p = y;
> +
> + do {
> + m = *--p;
> + *p = (uint16_t)(m >= wsize ? m-wsize : 0);
> + } while (--n);
> +}
> +
> +/* { dg-final { scan-assembler-times {vid\.v\s+v[0-9]+\s+vrsub\.vx\s+} 2 } } */
> --
> 2.36.1
>
> The root cause is this following RTL pattern, after fwprop1:
>
> (insn 82 78 84 9 (set (reg:DI 230)
> (sign_extend:DI (minus:SI (subreg/s/v:SI (reg:DI 150 [ niters.10 ]) 0)
> (subreg:SI (reg:DI 221) 0)))) 13 {subsi3_extended}
> (expr_list:REG_EQUAL (sign_extend:DI (plus:SI (subreg/s/v:SI (reg:DI 150 [ niters.10 ]) 0)
> *(const_poly_int:SI [-16, -16])*))
> (nil)))
>
> The highlight *(const_poly_int:SI [-16, -16])*
> causes ICE.
>
> This RTL is because:
> (insn 69 68 71 8 (set (reg:DI 221)
> (const_poly_int:DI [16, 16])) 208 {*movdi_64bit}
> (nil))
> (insn 82 78 84 9 (set (reg:DI 230)
> (sign_extend:DI (minus:SI (subreg/s/v:SI (reg:DI 150 [ niters.10 ]) 0)
> (subreg:SI (reg:DI 221) 0)))) 13 {subsi3_extended} ----> (subreg:SI (const_poly_int:SI [-16, -16])) fwprop1 add (const_poly_int:SI [-16, -16]) reg_equal
> (expr_list:REG_EQUAL (sign_extend:DI (plus:SI (subreg/s/v:SI (reg:DI 150 [ niters.10 ]) 0)
> (const_poly_int:SI [-16, -16])))
> (nil)))
I'm seeing a slightly different pattern but that doesn't change
the problem.
> (set (reg:SI) (subreg:SI (DI: poly value))) but it causes ICE that I
> mentioned above.
That's indeed a bit more idiomatic and I wouldn't oppose that.
The problem causing the ICE is that we want to simplify a PLUS
with (const_poly_int:SI [16, 16]) and (const_int 0) but the mode
is DImode. My suspicion is that this is caused by our
addsi3_extended pattern and we fail to deduce the proper mode
for analysis.
I'm just speculating but maybe that's because we assert that a
plus is of the form simple_reg_p (op0) && CONSTANT_P (op1).
Usually, constants don't have a mode and can just be used.
poly_int_csts do have one and need to be explicitly converted
(kind of).
We can only analyze this zero_extended plus at all since Jeff
added the addsi3_extended handling for loop-iv. Maybe we could
punt like
diff --git a/gcc/loop-iv.cc b/gcc/loop-iv.cc
index eb7e923a38b..796413c25a3 100644
--- a/gcc/loop-iv.cc
+++ b/gcc/loop-iv.cc
@@ -714,6 +714,9 @@ get_biv_step_1 (df_ref def, scalar_int_mode outer_mode, rtx reg,
if (!simple_reg_p (op0) || !CONSTANT_P (op1))
return false;
+ if (CONST_POLY_INT_P (op1) && GET_MODE (op1) != outer_mode)
+ return false;
+
This helps for your test case but I haven't done any further
testing. I'd think this is relatively safe because it's only
a missed analysis/optimization in the worst case.
Still, generally, I don't see a reason why we wouldn't be able
to analyze this?
Regards
Robin
Hi, Robin. Could you continue on this LICM issue ?
I am not sure whether my fix is correct, or you may find another way to make LICM works ?
juzhe.zhong@rivai.ai
From: Robin Dapp
Date: 2024-02-06 21:14
To: juzhe.zhong@rivai.ai; kito.cheng
CC: rdapp.gcc; gcc-patches; Kito.cheng; jeffreyalaw
Subject: Re: [PATCH] RISC-V: Allow LICM hoist POLY_INT configuration code sequence
> The root cause is this following RTL pattern, after fwprop1:
>
> (insn 82 78 84 9 (set (reg:DI 230)
> (sign_extend:DI (minus:SI (subreg/s/v:SI (reg:DI 150 [ niters.10 ]) 0)
> (subreg:SI (reg:DI 221) 0)))) 13 {subsi3_extended}
> (expr_list:REG_EQUAL (sign_extend:DI (plus:SI (subreg/s/v:SI (reg:DI 150 [ niters.10 ]) 0)
> *(const_poly_int:SI [-16, -16])*))
> (nil)))
>
> The highlight *(const_poly_int:SI [-16, -16])*
> causes ICE.
>
> This RTL is because:
> (insn 69 68 71 8 (set (reg:DI 221)
> (const_poly_int:DI [16, 16])) 208 {*movdi_64bit}
> (nil))
> (insn 82 78 84 9 (set (reg:DI 230)
> (sign_extend:DI (minus:SI (subreg/s/v:SI (reg:DI 150 [ niters.10 ]) 0)
> (subreg:SI (reg:DI 221) 0)))) 13 {subsi3_extended} ----> (subreg:SI (const_poly_int:SI [-16, -16])) fwprop1 add (const_poly_int:SI [-16, -16]) reg_equal
> (expr_list:REG_EQUAL (sign_extend:DI (plus:SI (subreg/s/v:SI (reg:DI 150 [ niters.10 ]) 0)
> (const_poly_int:SI [-16, -16])))
> (nil)))
I'm seeing a slightly different pattern but that doesn't change
the problem.
> (set (reg:SI) (subreg:SI (DI: poly value))) but it causes ICE that I
> mentioned above.
That's indeed a bit more idiomatic and I wouldn't oppose that.
The problem causing the ICE is that we want to simplify a PLUS
with (const_poly_int:SI [16, 16]) and (const_int 0) but the mode
is DImode. My suspicion is that this is caused by our
addsi3_extended pattern and we fail to deduce the proper mode
for analysis.
I'm just speculating but maybe that's because we assert that a
plus is of the form simple_reg_p (op0) && CONSTANT_P (op1).
Usually, constants don't have a mode and can just be used.
poly_int_csts do have one and need to be explicitly converted
(kind of).
We can only analyze this zero_extended plus at all since Jeff
added the addsi3_extended handling for loop-iv. Maybe we could
punt like
diff --git a/gcc/loop-iv.cc b/gcc/loop-iv.cc
index eb7e923a38b..796413c25a3 100644
--- a/gcc/loop-iv.cc
+++ b/gcc/loop-iv.cc
@@ -714,6 +714,9 @@ get_biv_step_1 (df_ref def, scalar_int_mode outer_mode, rtx reg,
if (!simple_reg_p (op0) || !CONSTANT_P (op1))
return false;
+ if (CONST_POLY_INT_P (op1) && GET_MODE (op1) != outer_mode)
+ return false;
+
This helps for your test case but I haven't done any further
testing. I'd think this is relatively safe because it's only
a missed analysis/optimization in the worst case.
Still, generally, I don't see a reason why we wouldn't be able
to analyze this?
Regards
Robin
@@ -2711,16 +2711,17 @@ riscv_legitimize_move (machine_mode mode, rtx dest, rtx src)
(const_poly_int:HI [m, n])
(const_poly_int:SI [m, n]). */
rtx tmp = gen_reg_rtx (Pmode);
- riscv_legitimize_poly_move (Pmode, gen_lowpart (Pmode, dest), tmp,
- src);
+ rtx tmp2 = gen_reg_rtx (Pmode);
+ riscv_legitimize_poly_move (Pmode, tmp2, tmp, src);
+ emit_move_insn (dest, gen_lowpart (mode, tmp2));
}
else
{
/* In RV32 system, handle (const_poly_int:SI [m, n])
(const_poly_int:DI [m, n]).
In RV64 system, handle (const_poly_int:DI [m, n]).
- FIXME: Maybe we could gen SImode in RV32 and then sign-extend to DImode,
- the offset should not exceed 4GiB in general. */
+ FIXME: Maybe we could gen SImode in RV32 and then sign-extend to
+ DImode, the offset should not exceed 4GiB in general. */
rtx tmp = gen_reg_rtx (mode);
riscv_legitimize_poly_move (mode, dest, tmp, src);
}
new file mode 100644
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gcv -mabi=lp64d -O3 -fno-schedule-insns -fno-schedule-insns2" } */
+
+extern int wsize;
+
+typedef unsigned short Posf;
+#define NIL 0
+
+void foo (Posf *p)
+{
+ register unsigned n, m;
+ do {
+ m = *--p;
+ *p = (Posf)(m >= wsize ? m-wsize : NIL);
+ } while (--n);
+}
+
+/* { dg-final { scan-assembler-times {vid\.v\s+v[0-9]+\s+addi\s+\s*[a-x0-9]+,\s*[a-x0-9]+,\s*-1\s+vrsub\.vx\s+} 1 } } */
new file mode 100644
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gcv -mabi=lp64d -O3 -fno-schedule-insns -fno-schedule-insns2" } */
+
+typedef unsigned short uint16_t;
+
+void AAA (uint16_t *x, uint16_t *y, unsigned wsize, unsigned count)
+{
+ unsigned m = 0, n = count;
+ register uint16_t *p;
+
+ p = x;
+
+ do {
+ m = *--p;
+ *p = (uint16_t)(m >= wsize ? m-wsize : 0);
+ } while (--n);
+
+ n = wsize;
+ p = y;
+
+ do {
+ m = *--p;
+ *p = (uint16_t)(m >= wsize ? m-wsize : 0);
+ } while (--n);
+}
+
+/* { dg-final { scan-assembler-times {vid\.v\s+v[0-9]+\s+vrsub\.vx\s+} 2 } } */