Tsung Chun Lin <[email protected]> writes:
> Address Richard's comment.
>
> Thanks
> Jim
>
> Richard Sandiford <[email protected]> 於 2024年12月30日 週一 下午7:50寫道：
>>
>> Tsung Chun Lin <[email protected]> writes:
>> > From ddb7852c92dc0222af9eeec1deafce753b3a7067 Mon Sep 17 00:00:00 2001
>> > From: Jim Tsung-Chun Lin <[email protected]>
>> > Date: Mon, 30 Dec 2024 15:32:12 +0800
>> > Subject: [PATCH] Prefer scalar_int_mode if the size - 1 is equal to
>> > UNITS_PER_WORD.
>> >
>> > Don't use the QI vector if its size is equal to UNITS_PER_WORD for
>> > better code generation.
>>
>> That makes sense, but...
>>
>> > Before patch:
>> >
>> > vsetivli zero,4,e8,mf4,ta,ma
>> > vmv.v.i v1,0
>> > addi a4,sp,12
>> > vse8.v v1,0(a4)
>> >
>> > After patch:
>> >
>> > sw zero,12(sp)
>> > ---
>> > gcc/expr.cc | 2 +-
>> > gcc/testsuite/gcc.target/riscv/rvv/autovec/pr113469.c | 1 -
>> > 2 files changed, 1 insertion(+), 2 deletions(-)
>> >
>> > diff --git a/gcc/expr.cc b/gcc/expr.cc
>> > index babf00f34dc..e2abef1f544 100644
>> > --- a/gcc/expr.cc
>> > +++ b/gcc/expr.cc
>> > @@ -1062,7 +1062,7 @@ widest_fixed_size_mode_for_size (unsigned int size,
>> > by_pieces_operation op)
>> > gcc_checking_assert (size > 1);
>> >
>> > /* Use QI vector only if size is wider than a WORD. */
>> > - if (can_use_qi_vectors (op) && size > UNITS_PER_WORD)
>> > + if (can_use_qi_vectors (op) && (size - 1) > UNITS_PER_WORD)
>>
>> ...it looks like this will still use UNITS_PER_WORD QI vectors for
>> size == UNITS_PER_WORD + 2.
>>
>> How about instead removing the size > UNITS_PER_WORD check above and
>> instead checking:
>>
>> if (is_a<fixed_size_mode> (mode, &candidate)
>> && GET_MODE_SIZE (candidate) > UNITS_PER_WORD
>> && GET_MODE_INNER (candidate) == QImode)
>>
>> in the loop (with the second line being new)?
>>
>> Thanks,
>> Richard
>>
>> > {
>> > machine_mode mode;
>> > fixed_size_mode candidate;
>> > diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr113469.c
>> > b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr113469.c
>> > index 52e2580c53e..6549ae61c67 100644
>> > --- a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr113469.c
>> > +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr113469.c
>> > @@ -51,5 +51,4 @@ void p(int buf, __builtin_va_list ab, int q) {
>> > } while (k);
>> > }
>> >
>> > -/* { dg-final { scan-assembler-times
>> > {vsetivli\tzero,\s*4,\s*e8,\s*mf4,\s*t[au],\s*m[au]} 1 } } */
>> > /* { dg-final { scan-assembler-times
>> > {vsetivli\tzero,\s*8,\s*e8,\s*mf2,\s*t[au],\s*m[au]} 1 } } */
>
> From 6dce42681ace1282d3201e906187697dcff8e9b1 Mon Sep 17 00:00:00 2001
> From: Jim Tsung-Chun Lin <[email protected]>
> Date: Mon, 30 Dec 2024 15:32:12 +0800
> Subject: [PATCH] Prefer scalar_int_mode if the size of QI vector is equal to
> UNITS_PER_WORD.
>
> Don't use the QI vector if its size is equal to UNITS_PER_WORD for
> better code generation.
>
> Before patch:
>
> vsetivli zero,4,e8,mf4,ta,ma
> vmv.v.i v1,0
> addi a4,sp,12
> vse8.v v1,0(a4)
>
> After patch:
>
> sw zero,12(sp)
> ---
> gcc/expr.cc | 3 ++-
> gcc/testsuite/gcc.target/riscv/rvv/autovec/pr113469.c | 1 -
> 2 files changed, 2 insertions(+), 2 deletions(-)
Thanks, the expr.cc change looks good to me. I'd like sign-off from a
RISC-V maintainer on the testsuite changes before pushing to trunk though.
Richard
>
> diff --git a/gcc/expr.cc b/gcc/expr.cc
> index babf00f34dc..422e2b2ebc9 100644
> --- a/gcc/expr.cc
> +++ b/gcc/expr.cc
> @@ -1062,12 +1062,13 @@ widest_fixed_size_mode_for_size (unsigned int size,
> by_pieces_operation op)
> gcc_checking_assert (size > 1);
>
> /* Use QI vector only if size is wider than a WORD. */
> - if (can_use_qi_vectors (op) && size > UNITS_PER_WORD)
> + if (can_use_qi_vectors (op))
> {
> machine_mode mode;
> fixed_size_mode candidate;
> FOR_EACH_MODE_IN_CLASS (mode, MODE_VECTOR_INT)
> if (is_a<fixed_size_mode> (mode, &candidate)
> + && GET_MODE_SIZE (candidate) > UNITS_PER_WORD
> && GET_MODE_INNER (candidate) == QImode)
> {
> if (GET_MODE_SIZE (candidate) >= size)
> diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr113469.c
> b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr113469.c
> index 52e2580c53e..6549ae61c67 100644
> --- a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr113469.c
> +++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr113469.c
> @@ -51,5 +51,4 @@ void p(int buf, __builtin_va_list ab, int q) {
> } while (k);
> }
>
> -/* { dg-final { scan-assembler-times
> {vsetivli\tzero,\s*4,\s*e8,\s*mf4,\s*t[au],\s*m[au]} 1 } } */
> /* { dg-final { scan-assembler-times
> {vsetivli\tzero,\s*8,\s*e8,\s*mf2,\s*t[au],\s*m[au]} 1 } } */
