MIPS; Improve checked load/store operators for constant offset and length.

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

Index: src/compiler/mips64/instruction-selector-mips64.cc
diff --git a/src/compiler/mips64/instruction-selector-mips64.cc b/src/compiler/mips64/instruction-selector-mips64.cc
index 7cf12b67b0b5c5f1debf0ae0a70fb506604a1da7..1d08bdf6045a897c10b17e3e74f436dd019ea916 100644
--- a/src/compiler/mips64/instruction-selector-mips64.cc
+++ b/src/compiler/mips64/instruction-selector-mips64.cc
@@ -708,9 +708,18 @@ void InstructionSelector::VisitCheckedLoad(Node* node) {
       UNREACHABLE();
       return;
   }
-  InstructionOperand* offset_operand = g.UseRegister(offset);
+  InstructionOperand* offset_operand = g.CanBeImmediate(offset, opcode)
+                                           ? g.UseImmediate(offset)
+                                           : g.UseRegister(offset);
+
+  InstructionOperand* length_operand =
+      (!g.CanBeImmediate(offset, opcode)) ? g.CanBeImmediate(length, opcode)
+      ? g.UseImmediate(length)
+      : g.UseRegister(length)
+      : g.UseRegister(length);
+
   Emit(opcode | AddressingModeField::encode(kMode_MRI),
-       g.DefineAsRegister(node), offset_operand, g.UseRegister(length),
+       g.DefineAsRegister(node), offset_operand, length_operand,
        g.UseRegister(buffer));
 }
 
@@ -743,9 +752,18 @@ void InstructionSelector::VisitCheckedStore(Node* node) {
       UNREACHABLE();
       return;
   }
-  InstructionOperand* offset_operand = g.UseRegister(offset);
+  InstructionOperand* offset_operand = g.CanBeImmediate(offset, opcode)
+                                           ? g.UseImmediate(offset)
+                                           : g.UseRegister(offset);
+
+  InstructionOperand* length_operand =
+      (!g.CanBeImmediate(offset, opcode)) ? g.CanBeImmediate(length, opcode)
+      ? g.UseImmediate(length)
+      : g.UseRegister(length)
+      : g.UseRegister(length);
+
   Emit(opcode | AddressingModeField::encode(kMode_MRI), nullptr, offset_operand,
-       g.UseRegister(length), g.UseRegister(value), g.UseRegister(buffer));
+       length_operand, g.UseRegister(value), g.UseRegister(buffer));
 }