[mips64] Fix TestFastJSWasmCall_MultipleArgs failure

Add register t3 to ALLOCATABLE_GENERAL_REGISTERS,
and change kSpeculationPoisonRegister from a7 to t3.

Change-Id: I199c1b837d5fdd0b47f0865ac3146e47e4ddb68f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2726050
Auto-Submit: Liu yu <liuyu@loongson.cn>
Reviewed-by: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Commit-Queue: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Cr-Commit-Position: refs/heads/master@{#73123}

src/builtins/mips64/builtins-mips64.cc

@@ -1478,7 +1478,9 @@ void Generate_ContinueToBuiltinHelper(MacroAssembler* masm,
                                       bool with_result) {
   const RegisterConfiguration* config(RegisterConfiguration::Default());
   int allocatable_register_count = config->num_allocatable_general_registers();
-  Register scratch = t3;
+  UseScratchRegisterScope temps(masm);
+  Register scratch = temps.Acquire();
+
   if (with_result) {
   if (java_script_builtin) {
     __ mov(scratch, v0);

src/codegen/mips64/register-mips64.h

@@ -21,7 +21,7 @@ namespace internal {
 
 #define ALLOCATABLE_GENERAL_REGISTERS(V) \
   V(a0)  V(a1)  V(a2)  V(a3) \
-  V(a4)  V(a5)  V(a6)  V(a7)  V(t0)  V(t1)  V(t2) V(s7) \
+  V(a4)  V(a5)  V(a6)  V(a7)  V(t0)  V(t1)  V(t2)  V(t3)  V(s7) \
   V(v0)  V(v1)
 
 #define DOUBLE_REGISTERS(V)                               \
@@ -368,7 +368,7 @@ constexpr Register kReturnRegister2 = a0;
 constexpr Register kJSFunctionRegister = a1;
 constexpr Register kContextRegister = s7;
 constexpr Register kAllocateSizeRegister = a0;
-constexpr Register kSpeculationPoisonRegister = a7;
+constexpr Register kSpeculationPoisonRegister = t3;
 constexpr Register kInterpreterAccumulatorRegister = v0;
 constexpr Register kInterpreterBytecodeOffsetRegister = t0;
 constexpr Register kInterpreterBytecodeArrayRegister = t1;