[turbofan] Emit memory operands for cmp and test on ia32 and x64 when it makes sense.

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 f7a797c2d808dbe887fb087e57814214ca105b18..ae619b58b309dad84d44352d52e97248dda12c5f 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -1338,6 +1338,48 @@ bool InstructionSelector::IsTailCallAddressImmediate() { return true; }
 
 namespace {
 
+void VisitCompareWithMemoryOperand(InstructionSelector* selector,
+                                   InstructionCode opcode, Node* left,
+                                   InstructionOperand right,
+                                   FlagsContinuation* cont) {
+  DCHECK(left->opcode() == IrOpcode::kLoad);
+  X64OperandGenerator g(selector);
+  size_t input_count = 0;
+  InstructionOperand inputs[6];
+  AddressingMode addressing_mode =
+      g.GetEffectiveAddressMemoryOperand(left, inputs, &input_count);
+  opcode |= AddressingModeField::encode(addressing_mode);
+  opcode = cont->Encode(opcode);
+  inputs[input_count++] = right;
+
+  if (cont->IsBranch()) {
+    inputs[input_count++] = g.Label(cont->true_block());
+    inputs[input_count++] = g.Label(cont->false_block());
+    selector->Emit(opcode, 0, nullptr, input_count, inputs);
+  } else {
+    DCHECK(cont->IsSet());
+    InstructionOperand output = g.DefineAsRegister(cont->result());
+    selector->Emit(opcode, 1, &output, input_count, inputs);
+  }
+}
+
+// Determines if {input} of {node} can be replaced by a memory operand.
+bool CanUseMemoryOperand(InstructionSelector* selector, InstructionCode opcode,
+                         Node* node, Node* input) {
+  if (input->opcode() != IrOpcode::kLoad || !selector->CanCover(node, input)) {
+    return false;
+  }
+  MachineRepresentation rep =
+      LoadRepresentationOf(input->op()).representation();
+  if (rep == MachineRepresentation::kWord64 ||
+      rep == MachineRepresentation::kTagged) {
+    return opcode == kX64Cmp || opcode == kX64Test;
+  } else if (rep == MachineRepresentation::kWord32) {
+    return opcode == kX64Cmp32 || opcode == kX64Test32;
+  }
+  return false;
+}
+
 // Shared routine for multiple compare operations.
 void VisitCompare(InstructionSelector* selector, InstructionCode opcode,
                   InstructionOperand left, InstructionOperand right,
@@ -1375,14 +1417,21 @@ void VisitWordCompare(InstructionSelector* selector, Node* node,
 
   // Match immediates on left or right side of comparison.
   if (g.CanBeImmediate(right)) {
-    VisitCompare(selector, opcode, g.Use(left), g.UseImmediate(right), cont);
+    return VisitCompare(selector, opcode, g.Use(left), g.UseImmediate(right),
+                        cont);
   } else if (g.CanBeImmediate(left)) {
     if (!node->op()->HasProperty(Operator::kCommutative)) cont->Commute();
-    VisitCompare(selector, opcode, g.Use(right), g.UseImmediate(left), cont);
-  } else {
-    VisitCompare(selector, opcode, left, right, cont,
-                 node->op()->HasProperty(Operator::kCommutative));
+    return VisitCompare(selector, opcode, g.Use(right), g.UseImmediate(left),
+                        cont);
+  }
+  // TODO(epertoso): emit memory operands for comparisons againt immediates as
+  // well.
+  if (CanUseMemoryOperand(selector, opcode, node, left)) {
+    return VisitCompareWithMemoryOperand(selector, opcode, left,
+                                         g.UseRegister(right), cont);
   }
+  return VisitCompare(selector, opcode, left, right, cont,
+                      node->op()->HasProperty(Operator::kCommutative));
 }