[turbofan] x64 lea multiplication matching

src/compiler/x64/instruction-selector-x64.cc

Index: src/compiler/x64/instruction-selector-x64.cc
diff --git a/src/compiler/x64/instruction-selector-x64.cc b/src/compiler/x64/instruction-selector-x64.cc
index 82d1e33fa2398c06a89998a7d3b5b7a73b92f49e..04fdb7ef68599389a322a1c14bdc01c69ed9695a 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -54,6 +54,15 @@ class X64OperandGenerator FINAL : public OperandGenerator {
 };
 
 
+// Get the AddressingMode of scale factor N from the AddressingMode of scale
+// factor 1.
+static AddressingMode AdjustAddressingMode(AddressingMode base_mode,
+                                           int power) {
+  DCHECK(0 <= power && power < 4);
+  return static_cast<AddressingMode>(static_cast<int>(base_mode) + power);
+}
+
+
 class AddressingModeMatcher {
  public:
   AddressingModeMatcher(X64OperandGenerator* g, Node* base, Node* index)
@@ -98,15 +107,11 @@ class AddressingModeMatcher {
         }
       }
       // Adjust mode to actual scale factor.
-      mode_ = GetMode(mode_, matcher.power());
+      mode_ = AdjustAddressingMode(mode_, matcher.power());
     }
     DCHECK_NE(kMode_None, mode_);
   }
 
-  AddressingMode GetMode(AddressingMode one, int power) {
-    return static_cast<AddressingMode>(static_cast<int>(one) + power);
-  }
-
   size_t SetInputs(InstructionOperand** inputs) {
     size_t input_count = 0;
     // Compute inputs_ and input_count.
@@ -463,18 +468,42 @@ void InstructionSelector::VisitInt64Sub(Node* node) {
 static void VisitMul(InstructionSelector* selector, Node* node,
                      ArchOpcode opcode) {
   X64OperandGenerator g(selector);
-  Int32BinopMatcher m(node);
-  Node* left = m.left().node();
-  Node* right = m.right().node();
-  if (g.CanBeImmediate(right)) {
-    selector->Emit(opcode, g.DefineAsRegister(node), g.Use(left),
-                   g.UseImmediate(right));
+  LeaMultiplyMatcher lea(node);
+  // Try to match lea.
+  if (lea.Matches()) {
+    switch (opcode) {
+      case kX64Imul32:
+        opcode = kX64Lea32;
+        break;
+      case kX64Imul:
+        opcode = kX64Lea;
+        break;
+      default:
+        UNREACHABLE();
+    }
+    AddressingMode mode;
+    if (lea.Displacement() != 0) {
+      mode = kMode_MX1;
+    } else {
+      mode = kMode_M1;
+    }
+    mode = AdjustAddressingMode(mode, lea.Power());
+    selector->Emit(opcode | AddressingModeField::encode(mode),
+                   g.DefineAsRegister(node), g.UseRegister(lea.Left()));
   } else {
-    if (g.CanBeBetterLeftOperand(right)) {
-      std::swap(left, right);
+    Int32BinopMatcher m(node);
+    Node* left = m.left().node();
+    Node* right = m.right().node();
+    if (g.CanBeImmediate(right)) {
+      selector->Emit(opcode, g.DefineAsRegister(node), g.Use(left),
+                     g.UseImmediate(right));
+    } else {
+      if (g.CanBeBetterLeftOperand(right)) {
+        std::swap(left, right);
+      }
+      selector->Emit(opcode, g.DefineSameAsFirst(node), g.UseRegister(left),
+                     g.Use(right));
     }
-    selector->Emit(opcode, g.DefineSameAsFirst(node), g.UseRegister(left),
-                   g.Use(right));
   }
 }