MIPS: [turbofan] Make Int32Div and Uint32Div safe.

TEST=
BUG=

Review URL: https://codereview.chromium.org/1503053002

Cr-Commit-Position: refs/heads/master@{#32685}

src/compiler/mips/code-generator-mips.cc

@@ -633,9 +633,19 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       break;
     case kMipsDiv:
       __ Div(i.OutputRegister(), i.InputRegister(0), i.InputOperand(1));
+      if (IsMipsArchVariant(kMips32r6)) {
+        __ seleqz(i.OutputRegister(), i.InputRegister(0), i.InputRegister(0));
+      } else {
+        __ Movz(i.OutputRegister(), i.InputRegister(1), i.InputRegister(1));
+      }
       break;
     case kMipsDivU:
       __ Divu(i.OutputRegister(), i.InputRegister(0), i.InputOperand(1));
+      if (IsMipsArchVariant(kMips32r6)) {
+        __ seleqz(i.OutputRegister(), i.InputRegister(0), i.InputRegister(0));
+      } else {
+        __ Movz(i.OutputRegister(), i.InputRegister(1), i.InputRegister(1));
+      }
       break;
     case kMipsMod:
       __ Mod(i.OutputRegister(), i.InputRegister(0), i.InputOperand(1));

src/compiler/mips/instruction-selector-mips.cc

@@ -468,7 +468,7 @@ void InstructionSelector::VisitUint32MulHigh(Node* node) {
 void InstructionSelector::VisitInt32Div(Node* node) {
   MipsOperandGenerator g(this);
   Int32BinopMatcher m(node);
-  Emit(kMipsDiv, g.DefineAsRegister(node), g.UseRegister(m.left().node()),
+  Emit(kMipsDiv, g.DefineSameAsFirst(node), g.UseRegister(m.left().node()),
        g.UseRegister(m.right().node()));
 }
 
@@ -476,7 +476,7 @@ void InstructionSelector::VisitInt32Div(Node* node) {
 void InstructionSelector::VisitUint32Div(Node* node) {
   MipsOperandGenerator g(this);
   Int32BinopMatcher m(node);
-  Emit(kMipsDivU, g.DefineAsRegister(node), g.UseRegister(m.left().node()),
+  Emit(kMipsDivU, g.DefineSameAsFirst(node), g.UseRegister(m.left().node()),
        g.UseRegister(m.right().node()));
 }
 
@@ -1272,7 +1272,9 @@ InstructionSelector::SupportedMachineOperatorFlags() {
              MachineOperatorBuilder::kFloat64RoundTruncate |
              MachineOperatorBuilder::kFloat64RoundTiesEven;
   }
-  return flags | MachineOperatorBuilder::kWord32ShiftIsSafe |
+  return flags | MachineOperatorBuilder::kInt32DivIsSafe |
+         MachineOperatorBuilder::kUint32DivIsSafe |
+         MachineOperatorBuilder::kWord32ShiftIsSafe |
          MachineOperatorBuilder::kFloat64Min |
          MachineOperatorBuilder::kFloat64Max |
          MachineOperatorBuilder::kFloat32Min |

src/compiler/mips64/code-generator-mips64.cc

@@ -646,9 +646,19 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       break;
     case kMips64Div:
       __ Div(i.OutputRegister(), i.InputRegister(0), i.InputOperand(1));
+      if (kArchVariant == kMips64r6) {
+        __ seleqz(i.OutputRegister(), i.InputRegister(0), i.InputRegister(0));
+      } else {
+        __ Movz(i.OutputRegister(), i.InputRegister(1), i.InputRegister(1));
+      }
       break;
     case kMips64DivU:
       __ Divu(i.OutputRegister(), i.InputRegister(0), i.InputOperand(1));
+      if (kArchVariant == kMips64r6) {
+        __ seleqz(i.OutputRegister(), i.InputRegister(0), i.InputRegister(0));
+      } else {
+        __ Movz(i.OutputRegister(), i.InputRegister(1), i.InputRegister(1));
+      }
       break;
     case kMips64Mod:
       __ Mod(i.OutputRegister(), i.InputRegister(0), i.InputOperand(1));
@@ -661,9 +671,19 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       break;
     case kMips64Ddiv:
       __ Ddiv(i.OutputRegister(), i.InputRegister(0), i.InputOperand(1));
+      if (kArchVariant == kMips64r6) {
+        __ seleqz(i.OutputRegister(), i.InputRegister(0), i.InputRegister(0));
+      } else {
+        __ Movz(i.OutputRegister(), i.InputRegister(1), i.InputRegister(1));
+      }
       break;
     case kMips64DdivU:
       __ Ddivu(i.OutputRegister(), i.InputRegister(0), i.InputOperand(1));
+      if (kArchVariant == kMips64r6) {
+        __ seleqz(i.OutputRegister(), i.InputRegister(0), i.InputRegister(0));
+      } else {
+        __ Movz(i.OutputRegister(), i.InputRegister(1), i.InputRegister(1));
+      }
       break;
     case kMips64Dmod:
       __ Dmod(i.OutputRegister(), i.InputRegister(0), i.InputOperand(1));

src/compiler/mips64/instruction-selector-mips64.cc

@@ -722,7 +722,7 @@ void InstructionSelector::VisitInt32Div(Node* node) {
       }
     }
   }
-  Emit(kMips64Div, g.DefineAsRegister(node), g.UseRegister(m.left().node()),
+  Emit(kMips64Div, g.DefineSameAsFirst(node), g.UseRegister(m.left().node()),
        g.UseRegister(m.right().node()));
 }
 
@@ -730,7 +730,7 @@ void InstructionSelector::VisitInt32Div(Node* node) {
 void InstructionSelector::VisitUint32Div(Node* node) {
   Mips64OperandGenerator g(this);
   Int32BinopMatcher m(node);
-  Emit(kMips64DivU, g.DefineAsRegister(node), g.UseRegister(m.left().node()),
+  Emit(kMips64DivU, g.DefineSameAsFirst(node), g.UseRegister(m.left().node()),
        g.UseRegister(m.right().node()));
 }
 
@@ -769,7 +769,7 @@ void InstructionSelector::VisitUint32Mod(Node* node) {
 void InstructionSelector::VisitInt64Div(Node* node) {
   Mips64OperandGenerator g(this);
   Int64BinopMatcher m(node);
-  Emit(kMips64Ddiv, g.DefineAsRegister(node), g.UseRegister(m.left().node()),
+  Emit(kMips64Ddiv, g.DefineSameAsFirst(node), g.UseRegister(m.left().node()),
        g.UseRegister(m.right().node()));
 }
 
@@ -777,7 +777,7 @@ void InstructionSelector::VisitInt64Div(Node* node) {
 void InstructionSelector::VisitUint64Div(Node* node) {
   Mips64OperandGenerator g(this);
   Int64BinopMatcher m(node);
-  Emit(kMips64DdivU, g.DefineAsRegister(node), g.UseRegister(m.left().node()),
+  Emit(kMips64DdivU, g.DefineSameAsFirst(node), g.UseRegister(m.left().node()),
        g.UseRegister(m.right().node()));
 }
 
@@ -1742,6 +1742,8 @@ void InstructionSelector::VisitFloat64InsertHighWord32(Node* node) {
 MachineOperatorBuilder::Flags
 InstructionSelector::SupportedMachineOperatorFlags() {
   return MachineOperatorBuilder::kWord32ShiftIsSafe |
+         MachineOperatorBuilder::kInt32DivIsSafe |
+         MachineOperatorBuilder::kUint32DivIsSafe |
          MachineOperatorBuilder::kFloat64Min |
          MachineOperatorBuilder::kFloat64Max |
          MachineOperatorBuilder::kFloat32Min |