[gcc r14-7161] LoongArch: Redundant sign extension elimination optimization 2.

[LuluCheng]

https://gcc.gnu.org/g:ee005e72f5fbd258262a93499bdd49a60c0f9714

commit r14-7161-gee005e72f5fbd258262a93499bdd49a60c0f9714
Author: Li Wei <liwei@loongson.cn>
Date:   Thu Jan 11 19:36:33 2024 +0800

    LoongArch: Redundant sign extension elimination optimization 2.
    
    Eliminate the redundant sign extension that exists after the conditional
    move when the target register is SImode.
    
    gcc/ChangeLog:
    
            * config/loongarch/loongarch.cc (loongarch_expand_conditional_move):
            Adjust.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/loongarch/sign-extend-2.c: Adjust.

Diff:
---
 gcc/config/loongarch/loongarch.cc                  | 6 ++++++
 gcc/testsuite/gcc.target/loongarch/sign-extend-2.c | 5 +++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/gcc/config/loongarch/loongarch.cc b/gcc/config/loongarch/loongarch.cc
index 27435aa5b50..3b8559bfdc8 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -5371,6 +5371,12 @@ loongarch_expand_conditional_move (rtx *operands)
 	  rtx temp3 = gen_reg_rtx (mode);
 	  emit_insn (gen_rtx_SET (temp3, gen_rtx_IOR (mode, temp, temp2)));
 	  temp3 = gen_lowpart (GET_MODE (operands[0]), temp3);
+	  /* Nonzero in a subreg if it was made when accessing an object that
+	     was promoted to a wider mode in accord with the PROMOTED_MODE
+	     machine description macro.  */
+	  SUBREG_PROMOTED_VAR_P (temp3) = 1;
+	  /* Sets promoted mode for SUBREG_PROMOTED_VAR_P.  */
+	  SUBREG_PROMOTED_SET (temp3, SRP_SIGNED);
 	  loongarch_emit_move (operands[0], temp3);
 	}
       else
diff --git a/gcc/testsuite/gcc.target/loongarch/sign-extend-2.c b/gcc/testsuite/gcc.target/loongarch/sign-extend-2.c
index a45dde4f73f..e57a2727d0c 100644
--- a/gcc/testsuite/gcc.target/loongarch/sign-extend-2.c
+++ b/gcc/testsuite/gcc.target/loongarch/sign-extend-2.c
@@ -1,6 +1,7 @@
 /* { dg-do compile } */
-/* { dg-options "-mabi=lp64d -O2" } */
-/* { dg-final { scan-assembler-times "slli.w\t\\\$r\[0-9\]+,\\\$r\[0-9\]+,0" 1 } } */
+/* { dg-options "-mabi=lp64d -O2 -fdump-rtl-expand" } */
+/* { dg-final { scan-rtl-dump "subreg/s" "expand" } } */
+/* { dg-final { scan-assembler-not "slli.w\t\\\$r\[0-9\]+,\\\$r\[0-9\]+,0" } } */
 
 #include <stdint.h>
 #define my_min(x, y) ((x) < (y) ? (x) : (y))