MIPS64: Implement AddE lithium instruction to separate integer and address arithmetic.

This is required to have sign-extended int32 arithmetic operations by re-landing:
https://codereview.chromium.org/1161713003

TEST=cctest/test-api/ArrayBuffer_JSInternalToExternal
BUG=

Review URL: https://codereview.chromium.org/1153263012

Cr-Commit-Position: refs/heads/master@{#28845}

src/mips64/lithium-codegen-mips64.cc

@@ -1889,6 +1889,17 @@ void LCodeGen::DoSeqStringSetChar(LSeqStringSetChar* instr) {
 }
 
 
+void LCodeGen::DoAddE(LAddE* instr) {
+  LOperand* result = instr->result();
+  LOperand* left = instr->left();
+  LOperand* right = instr->right();
+
+  DCHECK(!instr->hydrogen()->CheckFlag(HValue::kCanOverflow));
+  DCHECK(right->IsRegister() || right->IsConstantOperand());
+  __ Daddu(ToRegister(result), ToRegister(left), ToOperand(right));
+}
+
+
 void LCodeGen::DoAddI(LAddI* instr) {
   LOperand* left = instr->left();
   LOperand* right = instr->right();
@@ -1896,18 +1907,12 @@ void LCodeGen::DoAddI(LAddI* instr) {
   bool can_overflow = instr->hydrogen()->CheckFlag(HValue::kCanOverflow);
 
   if (!can_overflow) {
-    if (right->IsStackSlot()) {
-      Register right_reg = EmitLoadRegister(right, at);
-      __ Daddu(ToRegister(result), ToRegister(left), Operand(right_reg));
-    } else {
-      DCHECK(right->IsRegister() || right->IsConstantOperand());
+    DCHECK(right->IsRegister());
     __ Daddu(ToRegister(result), ToRegister(left), ToOperand(right));
-    }
   } else {  // can_overflow.
     Register overflow = scratch0();
     Register scratch = scratch1();
-    if (right->IsStackSlot() ||
-        right->IsConstantOperand()) {
+    if (right->IsConstantOperand()) {
       Register right_reg = EmitLoadRegister(right, scratch);
       __ AdduAndCheckForOverflow(ToRegister(result),
                                  ToRegister(left),

src/mips64/lithium-mips64.cc

@@ -1593,7 +1593,7 @@ LInstruction* LChunkBuilder::DoAdd(HAdd* instr) {
     DCHECK(instr->left()->representation().Equals(instr->representation()));
     DCHECK(instr->right()->representation().Equals(instr->representation()));
     LOperand* left = UseRegisterAtStart(instr->BetterLeftOperand());
-    LOperand* right = UseOrConstantAtStart(instr->BetterRightOperand());
+    LOperand* right = UseRegisterOrConstantAtStart(instr->BetterRightOperand());
     LAddI* add = new(zone()) LAddI(left, right);
     LInstruction* result = DefineAsRegister(add);
     if (instr->CheckFlag(HValue::kCanOverflow)) {
@@ -1605,10 +1605,8 @@ LInstruction* LChunkBuilder::DoAdd(HAdd* instr) {
     DCHECK(instr->right()->representation().IsInteger32());
     DCHECK(!instr->CheckFlag(HValue::kCanOverflow));
     LOperand* left = UseRegisterAtStart(instr->left());
-    LOperand* right = UseOrConstantAtStart(instr->right());
-    LAddI* add = new(zone()) LAddI(left, right);
-    LInstruction* result = DefineAsRegister(add);
-    return result;
+    LOperand* right = UseRegisterOrConstantAtStart(instr->right());
+    return DefineAsRegister(new (zone()) LAddE(left, right));
   } else if (instr->representation().IsDouble()) {
     if (kArchVariant == kMips64r2) {
       if (instr->left()->IsMul())

src/mips64/lithium-mips64.h

@@ -20,6 +20,7 @@ class LCodeGen;
 #define LITHIUM_CONCRETE_INSTRUCTION_LIST(V) \
   V(AccessArgumentsAt)                       \
   V(AddI)                                    \
+  V(AddE)                                    \
   V(Allocate)                                \
   V(AllocateBlockContext)                    \
   V(ApplyArguments)                          \
@@ -1421,6 +1422,21 @@ class LSeqStringSetChar final : public LTemplateInstruction<1, 4, 0> {
 };
 
 
+class LAddE final : public LTemplateInstruction<1, 2, 0> {
+ public:
+  LAddE(LOperand* left, LOperand* right) {
+    inputs_[0] = left;
+    inputs_[1] = right;
+  }
+
+  LOperand* left() { return inputs_[0]; }
+  LOperand* right() { return inputs_[1]; }
+
+  DECLARE_CONCRETE_INSTRUCTION(AddE, "add-e")
+  DECLARE_HYDROGEN_ACCESSOR(Add)
+};
+
+
 class LAddI final : public LTemplateInstruction<1, 2, 0> {
  public:
   LAddI(LOperand* left, LOperand* right) {