[ia32] Optimize index calculation for certain checked load/stores.

It reduces the add operation for certain checked load/stores by pre-do the add in compiling phase.

BUG=

Review-Url: https://codereview.chromium.org/2563483005
Cr-Commit-Position: refs/heads/master@{#41671}

src/compiler/ia32/instruction-selector-ia32.cc

@@ -395,18 +395,25 @@ void InstructionSelector::VisitCheckedLoad(Node* node) {
       UNREACHABLE();
       return;
   }
-  InstructionOperand offset_operand = g.UseRegister(offset);
+  Int32Matcher mbuffer(buffer);
+  InstructionOperand buffer_operand =
+      mbuffer.HasValue() ? g.UseImmediate(buffer) : g.UseRegister(buffer);
+  if (offset->opcode() == IrOpcode::kInt32Add && CanCover(node, offset)) {
+    Int32Matcher mlength(length);
+    Int32BinopMatcher moffset(offset);
+    if (mlength.HasValue() && moffset.right().HasValue() &&
+        moffset.right().Value() > 0 &&
+        mlength.Value() >= moffset.right().Value()) {
+      Emit(opcode, g.DefineAsRegister(node), buffer_operand,
+           g.UseRegister(moffset.left().node()),
+           g.UseImmediate(moffset.right().node()), g.UseImmediate(length));
+      return;
+    }
+  }
   InstructionOperand length_operand =
       g.CanBeImmediate(length) ? g.UseImmediate(length) : g.UseRegister(length);
-  if (g.CanBeImmediate(buffer)) {
-    Emit(opcode | AddressingModeField::encode(kMode_MRI),
-         g.DefineAsRegister(node), offset_operand, length_operand,
-         offset_operand, g.UseImmediate(buffer));
-  } else {
-    Emit(opcode | AddressingModeField::encode(kMode_MR1),
-         g.DefineAsRegister(node), offset_operand, length_operand,
-         g.UseRegister(buffer), offset_operand);
-  }
+  Emit(opcode, g.DefineAsRegister(node), buffer_operand, g.UseRegister(offset),
+       g.TempImmediate(0), length_operand);
 }
 
 
@@ -450,18 +457,26 @@ void InstructionSelector::VisitCheckedStore(Node* node) {
                                   rep == MachineRepresentation::kBit)
                                      ? g.UseByteRegister(value)
                                      : g.UseRegister(value));
-  InstructionOperand offset_operand = g.UseRegister(offset);
+  Int32Matcher mbuffer(buffer);
+  InstructionOperand buffer_operand =
+      mbuffer.HasValue() ? g.UseImmediate(buffer) : g.UseRegister(buffer);
+  if (offset->opcode() == IrOpcode::kInt32Add && CanCover(node, offset)) {
+    Int32Matcher mlength(length);
+    Int32BinopMatcher moffset(offset);
+    if (mlength.HasValue() && moffset.right().HasValue() &&
+        moffset.right().Value() > 0 &&
+        mlength.Value() >= moffset.right().Value()) {
+      Emit(opcode, g.NoOutput(), buffer_operand,
+           g.UseRegister(moffset.left().node()),
+           g.UseImmediate(moffset.right().node()), g.UseImmediate(length),
+           value_operand);
+      return;
+    }
+  }
   InstructionOperand length_operand =
       g.CanBeImmediate(length) ? g.UseImmediate(length) : g.UseRegister(length);
-  if (g.CanBeImmediate(buffer)) {
-    Emit(opcode | AddressingModeField::encode(kMode_MRI), g.NoOutput(),
-         offset_operand, length_operand, value_operand, offset_operand,
-         g.UseImmediate(buffer));
-  } else {
-    Emit(opcode | AddressingModeField::encode(kMode_MR1), g.NoOutput(),
-         offset_operand, length_operand, value_operand, g.UseRegister(buffer),
-         offset_operand);
-  }
+  Emit(opcode, g.NoOutput(), buffer_operand, g.UseRegister(offset),
+       g.TempImmediate(0), length_operand, value_operand);
 }
 
 namespace {