[mips] Do not use SimInstructionBase's implicit copy constructor

Change-Id: I99351dd92dacf4d8d9160b2e33213b830657516e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3131952Reviewed-by: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Commit-Queue: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Auto-Submit: Liu yu <liuyu@loongson.cn>
Cr-Commit-Position: refs/heads/main@{#76595}

src/execution/mips/simulator-mips.cc

@@ -6865,14 +6865,16 @@ void Simulator::DecodeTypeImmediate() {
 
 // Type 3: instructions using a 26 bytes immediate. (e.g. j, jal).
 void Simulator::DecodeTypeJump() {
-  SimInstruction simInstr = instr_;
+  // instr_ will be overwritten by BranchDelayInstructionDecode(), so we save
+  // the result of IsLinkingInstruction now.
+  bool isLinkingInstr = instr_.IsLinkingInstruction();
   // Get current pc.
   int32_t current_pc = get_pc();
   // Get unchanged bits of pc.
   int32_t pc_high_bits = current_pc & 0xF0000000;
   // Next pc.
 
-  int32_t next_pc = pc_high_bits | (simInstr.Imm26Value() << 2);
+  int32_t next_pc = pc_high_bits | (instr_.Imm26Value() << 2);
 
   // Execute branch delay slot.
   // We don't check for end_sim_pc. First it should not be met as the current pc
@@ -6883,7 +6885,7 @@ void Simulator::DecodeTypeJump() {
 
   // Update pc and ra if necessary.
   // Do this after the branch delay execution.
-  if (simInstr.IsLinkingInstruction()) {
+  if (isLinkingInstr) {
     set_register(31, current_pc + 2 * kInstrSize);
   }
   set_pc(next_pc);

src/execution/mips64/simulator-mips64.cc

@@ -7285,13 +7285,15 @@ void Simulator::DecodeTypeImmediate() {
 
 // Type 3: instructions using a 26 bytes immediate. (e.g. j, jal).
 void Simulator::DecodeTypeJump() {
-  SimInstruction simInstr = instr_;
+  // instr_ will be overwritten by BranchDelayInstructionDecode(), so we save
+  // the result of IsLinkingInstruction now.
+  bool isLinkingInstr = instr_.IsLinkingInstruction();
   // Get current pc.
   int64_t current_pc = get_pc();
   // Get unchanged bits of pc.
   int64_t pc_high_bits = current_pc & 0xFFFFFFFFF0000000;
   // Next pc.
-  int64_t next_pc = pc_high_bits | (simInstr.Imm26Value() << 2);
+  int64_t next_pc = pc_high_bits | (instr_.Imm26Value() << 2);
 
   // Execute branch delay slot.
   // We don't check for end_sim_pc. First it should not be met as the current pc
@@ -7302,7 +7304,7 @@ void Simulator::DecodeTypeJump() {
 
   // Update pc and ra if necessary.
   // Do this after the branch delay execution.
-  if (simInstr.IsLinkingInstruction()) {
+  if (isLinkingInstr) {
     set_register(31, current_pc + 2 * kInstrSize);
   }
   set_pc(next_pc);