[gcc r14-9318] LoongArch: Allow s9 as a register alias

[gcc r14-9318] LoongArch: Allow s9 as a register alias

[Xi Ruoyao]

https://gcc.gnu.org/g:f628a30f4dbdee9b4531314d72c7762f1fbcf8ff

commit r14-9318-gf628a30f4dbdee9b4531314d72c7762f1fbcf8ff
Author: Xi Ruoyao <xry111@xry111.site>
Date:   Thu Jan 25 23:49:13 2024 +0800

    LoongArch: Allow s9 as a register alias
    
    The psABI allows using s9 as an alias of r22.
    
    gcc/ChangeLog:
    
            * config/loongarch/loongarch.h (ADDITIONAL_REGISTER_NAMES): Add
            s9 as an alias of r22.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/loongarch/regname-fp-s9.c: New test.

Diff:
---
 gcc/config/loongarch/loongarch.h                   | 1 +
 gcc/testsuite/gcc.target/loongarch/regname-fp-s9.c | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/gcc/config/loongarch/loongarch.h b/gcc/config/loongarch/loongarch.h
index 8b453ab3140..bf2351f0968 100644
--- a/gcc/config/loongarch/loongarch.h
+++ b/gcc/config/loongarch/loongarch.h
@@ -931,6 +931,7 @@ typedef struct {
   { "t8",	20 + GP_REG_FIRST },					\
   { "x",	21 + GP_REG_FIRST },					\
   { "fp",	22 + GP_REG_FIRST },					\
+  { "s9",	22 + GP_REG_FIRST },					\
   { "s0",	23 + GP_REG_FIRST },					\
   { "s1",	24 + GP_REG_FIRST },					\
   { "s2",	25 + GP_REG_FIRST },					\
diff --git a/gcc/testsuite/gcc.target/loongarch/regname-fp-s9.c b/gcc/testsuite/gcc.target/loongarch/regname-fp-s9.c
new file mode 100644
index 00000000000..d2e3b80f83c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/loongarch/regname-fp-s9.c
@@ -0,0 +1,3 @@
+/* { dg-do compile } */
+register long s9 asm("s9"); /* { dg-note "conflicts with 's9'" } */
+register long fp asm("fp"); /* { dg-warning "register of 'fp' used for multiple global register variables" } */