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* [gcc r14-9234] LoongArch: Remove unneeded sign extension after crc/crcc instructions
@ 2024-02-29 6:49 Xi Ruoyao
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From: Xi Ruoyao @ 2024-02-29 6:49 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:aab1c5dcd23f014f39b127f74aecd04913945a7f
commit r14-9234-gaab1c5dcd23f014f39b127f74aecd04913945a7f
Author: Xi Ruoyao <xry111@xry111.site>
Date: Sun Feb 25 20:44:34 2024 +0800
LoongArch: Remove unneeded sign extension after crc/crcc instructions
The specification of crc/crcc instructions is clear that the output is
sign-extended to GRLEN. Add a define_insn to tell the compiler this
fact and allow it to remove the unneeded sign extension on crc/crcc
output. As crc/crcc instructions are usually used in a tight loop,
this should produce a significant performance gain.
gcc/ChangeLog:
* config/loongarch/loongarch.md
(loongarch_<crc>_w_<size>_w_extended): New define_insn.
gcc/testsuite/ChangeLog:
* gcc.target/loongarch/crc-sext.c: New test;
Diff:
---
gcc/config/loongarch/loongarch.md | 11 +++++++++++
gcc/testsuite/gcc.target/loongarch/crc-sext.c | 13 +++++++++++++
2 files changed, 24 insertions(+)
diff --git a/gcc/config/loongarch/loongarch.md b/gcc/config/loongarch/loongarch.md
index 9646fa90eab..f3b5c641fce 100644
--- a/gcc/config/loongarch/loongarch.md
+++ b/gcc/config/loongarch/loongarch.md
@@ -4264,6 +4264,17 @@
[(set_attr "type" "unknown")
(set_attr "mode" "<MODE>")])
+(define_insn "loongarch_<crc>_w_<size>_w_extended"
+ [(set (match_operand:DI 0 "register_operand" "=r")
+ (sign_extend:DI
+ (unspec:SI [(match_operand:QHSD 1 "register_operand" "r")
+ (match_operand:SI 2 "register_operand" "r")]
+ CRC)))]
+ "TARGET_64BIT"
+ "<crc>.w.<size>.w\t%0,%1,%2"
+ [(set_attr "type" "unknown")
+ (set_attr "mode" "<MODE>")])
+
;; With normal or medium code models, if the only use of a pc-relative
;; address is for loading or storing a value, then relying on linker
;; relaxation is not better than emitting the machine instruction directly.
diff --git a/gcc/testsuite/gcc.target/loongarch/crc-sext.c b/gcc/testsuite/gcc.target/loongarch/crc-sext.c
new file mode 100644
index 00000000000..9ade5a8e4ca
--- /dev/null
+++ b/gcc/testsuite/gcc.target/loongarch/crc-sext.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=loongarch64" } */
+/* { dg-final { check-function-bodies "**" "" } } */
+
+/*
+**my_crc:
+** crc.w.d.w \$r4,\$r4,\$r5
+** jr \$r1
+*/
+int my_crc(long long dword, int crc)
+{
+ return __builtin_loongarch_crc_w_d_w(dword, crc);
+}
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