Committed, thanks!
On Tue, Feb 28, 2023 at 12:36 PM Sinan <sinan....@linux.alibaba.com> wrote:
>
> From 73e743348a49a7fffcf2e328b8179e8dbbc3b2b4 Mon Sep 17 00:00:00 2001
> From: Lin Sinan <sinan....@linux.alibaba.com>
> Date: Tue, 28 Feb 2023 00:44:55 +0800
> Subject: [PATCH] RISC-V: Allow const0_rtx operand in max/min
>
> Optimize cases that use max[u]/min[u] against a zero constant.
> E.g., the case int f(int x) { return x >= 0 ? x : 0; }
> the current asm output in rv64gc_zba_zbb
> li rtmp,0
> max a0,a0,rtmp
> could be optimized into
> max a0,a0,zero
>
> gcc/ChangeLog:
>
> * config/riscv/bitmanip.md: allow 0 constant in max/min
> pattern.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/riscv/zbb-min-max-03.c: New test.
>
> ---
> gcc/config/riscv/bitmanip.md | 4 ++--
> gcc/testsuite/gcc.target/riscv/zbb-min-max-03.c | 10 ++++++++++
> 2 files changed, 12 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/riscv/zbb-min-max-03.c
>
> diff --git a/gcc/config/riscv/bitmanip.md b/gcc/config/riscv/bitmanip.md
> index 58a86bd929f..f771835369c 100644
> --- a/gcc/config/riscv/bitmanip.md
> +++ b/gcc/config/riscv/bitmanip.md
> @@ -363,9 +363,9 @@
> (define_insn "<bitmanip_optab><mode>3"
> [(set (match_operand:X 0 "register_operand" "=r")
> (bitmanip_minmax:X (match_operand:X 1 "register_operand" "r")
> - (match_operand:X 2 "register_operand" "r")))]
> + (match_operand:X 2 "reg_or_0_operand" "rJ")))]
> "TARGET_ZBB"
> - "<bitmanip_insn>\t%0,%1,%2"
> + "<bitmanip_insn>\t%0,%1,%z2"
> [(set_attr "type" "bitmanip")])
>
> ;; Optimize the common case of a SImode min/max against a constant
> diff --git a/gcc/testsuite/gcc.target/riscv/zbb-min-max-03.c
> b/gcc/testsuite/gcc.target/riscv/zbb-min-max-03.c
> new file mode 100644
> index 00000000000..947300d599d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/riscv/zbb-min-max-03.c
> @@ -0,0 +1,10 @@
> +/* { dg-do compile } */
> +/* { dg-options "-march=rv64gc_zba_zbb -mabi=lp64d" } */
> +/* { dg-skip-if "" { *-*-* } { "-O0" } } */
> +
> +int f(int x) {
> + return x >= 0 ? x : 0;
> +}
> +
> +/* { dg-final { scan-assembler-times "max\t" 1 } } */
> +/* { dg-final { scan-assembler-not "li\t" } } */
> --
> 2.34.1
>
