[gcc r16-3177] LoongArch: Define hook TARGET_COMPUTE_PRESSURE_CLASSES[PR120476].

[LuluCheng via Gcc-cvs]

https://gcc.gnu.org/g:d94178d9b3fb1cb869b90d6f061990eae75c770e

commit r16-3177-gd94178d9b3fb1cb869b90d6f061990eae75c770e
Author: Lulu Cheng <chengl...@loongson.cn>
Date:   Wed Aug 13 11:04:35 2025 +0800

    LoongArch: Define hook TARGET_COMPUTE_PRESSURE_CLASSES[PR120476].
    
    The rtx cost value defined by the target backend affects the
    calculation of register pressure classes in the IRA, thus affecting
    scheduling.  This may cause program performance degradation.
    For example, OpenSSL 3.5.1 SHA512 and SPEC CPU 2017 exchange_r.
    
    This problem can be avoided by defining a set of register pressure
    classes in the target backend instead of using the default IRA to
    automatically calculate them.
    
    gcc/ChangeLog:
    
            PR target/120476
            * config/loongarch/loongarch.cc
            (loongarch_compute_pressure_classes): New function.
            (TARGET_COMPUTE_PRESSURE_CLASSES): Define.

Diff:
---
 gcc/config/loongarch/loongarch.cc | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/gcc/config/loongarch/loongarch.cc 
b/gcc/config/loongarch/loongarch.cc
index b169d2ffcd06..3b62ed9cfb9f 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -11182,6 +11182,18 @@ loongarch_bitint_type_info (int n, struct bitint_info 
*info)
   return true;
 }
 
+/* Implement TARGET_COMPUTE_PRESSURE_CLASSES.  */
+
+static int
+loongarch_compute_pressure_classes (reg_class *classes)
+{
+  int i = 0;
+  classes[i++] = GENERAL_REGS;
+  classes[i++] = FP_REGS;
+  classes[i++] = FCC_REGS;
+  return i;
+}
+
 /* Initialize the GCC target structure.  */
 #undef TARGET_ASM_ALIGNED_HI_OP
 #define TARGET_ASM_ALIGNED_HI_OP "\t.half\t"
@@ -11459,6 +11471,9 @@ loongarch_bitint_type_info (int n, struct bitint_info 
*info)
 #undef TARGET_C_BITINT_TYPE_INFO
 #define TARGET_C_BITINT_TYPE_INFO loongarch_bitint_type_info
 
+#undef TARGET_COMPUTE_PRESSURE_CLASSES
+#define TARGET_COMPUTE_PRESSURE_CLASSES loongarch_compute_pressure_classes
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 #include "gt-loongarch.h"