[gcc r14-3641] LoongArch: Optimize fixed-point and floating-point conversion operations.

[LuluCheng <chenglulu@gcc.gnu.org>]

https://gcc.gnu.org/g:26aa5d9017104ee3a72de418e9a0a1e5c1e30313

commit r14-3641-g26aa5d9017104ee3a72de418e9a0a1e5c1e30313
Author: Lulu Cheng <chenglulu@loongson.cn>
Date:   Thu Aug 31 19:11:23 2023 +0800

    LoongArch: Optimize fixed-point and floating-point conversion operations.
    
    Before optimization, the operation of taking fixed-point numbers from memory
    and then forcing type conversion needs to be loaded into fixed-point registers
    before conversion. After the optimization is completed, the fixed-point value
    is directly transferred to the floating-point register for type conversion.
    
    eg:
        extern int a;
        float
        test(void)
        {
          return (float)a;
        }
    
    Assembly code before optimization:
            pcalau12i       $r12,%got_pc_hi20(a)
            ld.d    $r12,$r12,%got_pc_lo12(a)
            ldptr.w $r12,$r12,0
            movgr2fr.w      $f0,$r12
            ffint.s.w       $f0,$f0
    
    Optimized assembly code:
            pcalau12i       $r12,%got_pc_hi20(a)
            ld.d    $r12,$r12,%got_pc_lo12(a)
            fld.s   $f0,$r12,0
            ffint.s.w       $f0,$f0
    
    gcc/ChangeLog:
    
            * config/loongarch/loongarch.md: Allows fixed-point values to be loaded
            from memory into floating-point registers.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/loongarch/float-load.c: New test.

Diff:
---
 gcc/config/loongarch/loongarch.md               |  4 ++--
 gcc/testsuite/gcc.target/loongarch/float-load.c | 11 +++++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/gcc/config/loongarch/loongarch.md b/gcc/config/loongarch/loongarch.md
index b37e070660f1..2936b4c664c0 100644
--- a/gcc/config/loongarch/loongarch.md
+++ b/gcc/config/loongarch/loongarch.md
@@ -1827,8 +1827,8 @@
 })
 
 (define_insn_and_split "*movsi_internal"
-  [(set (match_operand:SI 0 "nonimmediate_operand" "=r,r,r,w,*f,*f,*r,*m,*r,*z")
-	(match_operand:SI 1 "move_operand" "r,Yd,w,rJ,*r*J,*m,*f,*f,*z,*r"))]
+  [(set (match_operand:SI 0 "nonimmediate_operand" "=r,r,r,w,*f,f,*r,*m,*r,*z")
+	(match_operand:SI 1 "move_operand" "r,Yd,w,rJ,*r*J,m,*f,*f,*z,*r"))]
   "(register_operand (operands[0], SImode)
     || reg_or_0_operand (operands[1], SImode))"
   { return loongarch_output_move (operands[0], operands[1]); }
diff --git a/gcc/testsuite/gcc.target/loongarch/float-load.c b/gcc/testsuite/gcc.target/loongarch/float-load.c
new file mode 100644
index 000000000000..c757a795e214
--- /dev/null
+++ b/gcc/testsuite/gcc.target/loongarch/float-load.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler "fld\\.s" } } */
+
+extern int a;
+float
+test (void)
+{
+  return (float)a;
+}
+