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* [gcc r13-6483] RISC-V: Allow const0_rtx operand in max/min
@ 2023-03-05 9:17 Kito Cheng
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From: Kito Cheng @ 2023-03-05 9:17 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:602cfc746e9e0447221896a3d93608c6db3a89e5
commit r13-6483-g602cfc746e9e0447221896a3d93608c6db3a89e5
Author: Lin Sinan <sinan.lin@linux.alibaba.com>
Date: Sun Mar 5 16:09:50 2023 +0800
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.
Diff:
---
gcc/config/riscv/bitmanip.md | 4 ++--
gcc/testsuite/gcc.target/riscv/zbb-min-max-03.c | 10 ++++++++++
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/gcc/config/riscv/bitmanip.md b/gcc/config/riscv/bitmanip.md
index 58a86bd929f..cfdb9eb4689 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..c7de1004048
--- /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" } } */
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