[loong64][mips32] Fix implementation of fcopysign in simulator on loong64

FPUCanonalizeOperation will output standard qNaN when the lvalue is nan
in simulator, and this implementation is inconsistent with physical
machine.

Besides, fix a wrong register request in i64_add on mips32.

Change-Id: Icddb1fc6d0e03a51d4fb4ba13ecb39f11a645af0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3580103
Auto-Submit: Yu Liu <liuyu@loongson.cn>
Reviewed-by: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Commit-Queue: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Cr-Commit-Position: refs/heads/main@{#79902}

src/execution/loong64/simulator-loong64.cc

@@ -4272,22 +4272,14 @@ void Simulator::DecodeTypeOp17() {
                    FPURegisters::Name(fd_reg()), fd_float(),
                    FPURegisters::Name(fj_reg()), fj_float(),
                    FPURegisters::Name(fk_reg()), fk_float());
-      SetFPUFloatResult(fd_reg(), FPUCanonalizeOperation(
-                                      [](float lhs, float rhs) {
-                                        return std::copysign(lhs, rhs);
-                                      },
-                                      fj_float(), fk_float()));
+      SetFPUFloatResult(fd_reg(), std::copysign(fj_float(), fk_float()));
     } break;
     case FCOPYSIGN_D: {
       printf_instr("FCOPYSIGN_d\t %s: %016f, %s, %016f, %s, %016f\n",
                    FPURegisters::Name(fd_reg()), fd_double(),
                    FPURegisters::Name(fj_reg()), fj_double(),
                    FPURegisters::Name(fk_reg()), fk_double());
-      SetFPUDoubleResult(fd_reg(), FPUCanonalizeOperation(
-                                       [](double lhs, double rhs) {
-                                         return std::copysign(lhs, rhs);
-                                       },
-                                       fj_double(), fk_double()));
+      SetFPUDoubleResult(fd_reg(), std::copysign(fj_double(), fk_double()));
     } break;
     default:
       UNREACHABLE();

src/wasm/baseline/mips/liftoff-assembler-mips.h

@@ -1022,7 +1022,8 @@ I32_SHIFTOP_I(shr, srl)
 
 void LiftoffAssembler::emit_i64_addi(LiftoffRegister dst, LiftoffRegister lhs,
                                      int64_t imm) {
-  LiftoffRegister imm_reg = GetUnusedRegister(kFpReg, LiftoffRegList{dst, lhs});
+  LiftoffRegister imm_reg =
+      GetUnusedRegister(kGpRegPair, LiftoffRegList{dst, lhs});
   int32_t imm_low_word = static_cast<int32_t>(imm);
   int32_t imm_high_word = static_cast<int32_t>(imm >> 32);
   TurboAssembler::li(imm_reg.low_gp(), imm_low_word);