Introduce 'top-of-stack caching' to the toplevel code generator by...

src/arm/fast-codegen-arm.cc

Index: src/arm/fast-codegen-arm.cc
===================================================================
--- src/arm/fast-codegen-arm.cc	(revision 3626)
+++ src/arm/fast-codegen-arm.cc	(working copy)
@@ -214,20 +214,57 @@
 }
 
 
-void FastCodeGenerator::Apply(Expression::Context context,
-                              Slot* slot,
-                              Register scratch) {
+void FastCodeGenerator::Apply(Expression::Context context, Register reg) {
   switch (context) {
     case Expression::kUninitialized:
       UNREACHABLE();
+
     case Expression::kEffect:
+      // Nothing to do.
       break;
+
     case Expression::kValue:
+      // Move value into place.
+      switch (location_) {
+        case kAccumulator:
+          if (!reg.is(result_register())) __ mov(result_register(), reg);
+          break;
+        case kStack:
+          __ push(reg);
+          break;
+      }
+      break;
+
+    case Expression::kValueTest:
+    case Expression::kTestValue:
+      // Push an extra copy of the value in case it's needed.
+      __ push(reg);
+      // Fall through.
+
     case Expression::kTest:
+      // We always call the runtime on ARM, so push the value as argument.
+      __ push(reg);
+      DoTest(context);
+      break;
+  }
+}
+
+
+void FastCodeGenerator::Apply(Expression::Context context, Slot* slot) {
+  switch (context) {
+    case Expression::kUninitialized:
+      UNREACHABLE();
+    case Expression::kEffect:
+      // Nothing to do.
+      break;
+    case Expression::kValue:
+    case Expression::kTest:
     case Expression::kValueTest:
     case Expression::kTestValue:
-      Move(scratch, slot);
-      Apply(context, scratch);
+      // On ARM we have to move the value into a register to do anything
+      // with it.
+      Move(result_register(), slot);
+      Apply(context, result_register());
       break;
   }
 }
@@ -239,12 +276,15 @@
       UNREACHABLE();
     case Expression::kEffect:
       break;
+      // Nothing to do.
     case Expression::kValue:
     case Expression::kTest:
     case Expression::kValueTest:
     case Expression::kTestValue:
-      __ mov(ip, Operand(lit->handle()));
-      Apply(context, ip);
+      // On ARM we have to move the value into a register to do anything
+      // with it.
+      __ mov(result_register(), Operand(lit->handle()));
+      Apply(context, result_register());
       break;
   }
 }
@@ -254,32 +294,31 @@
   switch (context) {
     case Expression::kUninitialized:
       UNREACHABLE();
+
     case Expression::kEffect:
       __ Drop(1);
       break;
+
     case Expression::kValue:
+      switch (location_) {
+        case kAccumulator:
+          __ pop(result_register());
+          break;
+        case kStack:
+          break;
+      }
       break;
+
+    case Expression::kValueTest:
+    case Expression::kTestValue:
+      // Duplicate the value on the stack in case it's needed.
+      __ ldr(ip, MemOperand(sp));
+      __ push(ip);
+      // Fall through.
+
     case Expression::kTest:
-      __ pop(r0);
-      TestAndBranch(r0, true_label_, false_label_);
+      DoTest(context);
       break;
-    case Expression::kValueTest: {
-      Label discard;
-      __ ldr(r0, MemOperand(sp, 0));
-      TestAndBranch(r0, true_label_, &discard);
-      __ bind(&discard);
-      __ Drop(1);
-      __ jmp(false_label_);
-      break;
-    }
-    case Expression::kTestValue: {
-      Label discard;
-      __ ldr(r0, MemOperand(sp, 0));
-      TestAndBranch(r0, &discard, false_label_);
-      __ bind(&discard);
-      __ Drop(1);
-      __ jmp(true_label_);
-    }
   }
 }
 
@@ -292,32 +331,161 @@
   switch (context) {
     case Expression::kUninitialized:
       UNREACHABLE();
+
     case Expression::kEffect:
       __ Drop(count);
       break;
+
     case Expression::kValue:
+      switch (location_) {
+        case kAccumulator:
+          __ Drop(count);
+          if (!reg.is(result_register())) __ mov(result_register(), reg);
+          break;
+        case kStack:
+          if (count > 1) __ Drop(count - 1);
+          __ str(reg, MemOperand(sp));
+          break;
+      }
+      break;
+
+    case Expression::kTest:
       if (count > 1) __ Drop(count - 1);
       __ str(reg, MemOperand(sp));
+      DoTest(context);
       break;
+
+    case Expression::kValueTest:
+    case Expression::kTestValue:
+      if (count == 1) {
+        __ str(reg, MemOperand(sp));
+        __ push(reg);
+      } else {  // count > 1
+        __ Drop(count - 2);
+        __ str(reg, MemOperand(sp, kPointerSize));
+        __ str(reg, MemOperand(sp));
+      }
+      DoTest(context);
+      break;
+  }
+}
+
+
+void FastCodeGenerator::Apply(Expression::Context context,
+                              Label* materialize_true,
+                              Label* materialize_false) {
+  switch (context) {
+    case Expression::kUninitialized:
+
+    case Expression::kEffect:
+      ASSERT_EQ(materialize_true, materialize_false);
+      __ bind(materialize_true);
+      break;
+
+    case Expression::kValue: {
+      Label done;
+      __ bind(materialize_true);
+      __ mov(result_register(), Operand(Factory::true_value()));
+      __ jmp(&done);
+      __ bind(materialize_false);
+      __ mov(result_register(), Operand(Factory::false_value()));
+      __ bind(&done);
+      switch (location_) {
+        case kAccumulator:
+          break;
+        case kStack:
+          __ push(result_register());
+          break;
+      }
+      break;
+    }
+
     case Expression::kTest:
-      __ Drop(count);
-      TestAndBranch(reg, true_label_, false_label_);
       break;
+
+    case Expression::kValueTest:
+      __ bind(materialize_true);
+      __ mov(result_register(), Operand(Factory::true_value()));
+      switch (location_) {
+        case kAccumulator:
+          break;
+        case kStack:
+          __ push(result_register());
+          break;
+      }
+      __ jmp(true_label_);
+      break;
+
+    case Expression::kTestValue:
+      __ bind(materialize_false);
+      __ mov(result_register(), Operand(Factory::false_value()));
+      switch (location_) {
+        case kAccumulator:
+          break;
+        case kStack:
+          __ push(result_register());
+          break;
+      }
+      __ jmp(false_label_);
+      break;
+  }
+}
+
+
+void FastCodeGenerator::DoTest(Expression::Context context) {
+  // The value to test is pushed on the stack, and duplicated on the stack
+  // if necessary (for value/test and test/value contexts).
+  ASSERT_NE(NULL, true_label_);
+  ASSERT_NE(NULL, false_label_);
+
+  // Call the runtime to find the boolean value of the source and then
+  // translate it into control flow to the pair of labels.
+  __ CallRuntime(Runtime::kToBool, 1);
+  __ LoadRoot(ip, Heap::kTrueValueRootIndex);
+  __ cmp(r0, ip);
+
+  // Complete based on the context.
+  switch (context) {
+    case Expression::kUninitialized:
+    case Expression::kEffect:
+    case Expression::kValue:
+      UNREACHABLE();
+
+    case Expression::kTest:
+      __ b(eq, true_label_);
+      __ jmp(false_label_);
+      break;
+
     case Expression::kValueTest: {
       Label discard;
-      if (count > 1) __ Drop(count - 1);
-      __ str(reg, MemOperand(sp));
-      TestAndBranch(reg, true_label_, &discard);
+      switch (location_) {
+        case kAccumulator:
+          __ b(ne, &discard);
+          __ pop(result_register());
+          __ jmp(true_label_);
+          break;
+        case kStack:
+          __ b(eq, true_label_);
+          break;
+      }
       __ bind(&discard);
       __ Drop(1);
       __ jmp(false_label_);
       break;
     }
+
     case Expression::kTestValue: {
       Label discard;
-      if (count > 1) __ Drop(count - 1);
-      __ str(reg, MemOperand(sp));
-      TestAndBranch(reg, &discard, false_label_);
+      switch (location_) {
+        case kAccumulator:
+          __ b(eq, &discard);
+          __ pop(result_register());
+          __ jmp(false_label_);
+          break;
+        case kStack:
+          __ b(ne, false_label_);
+          break;
+      }
       __ bind(&discard);
       __ Drop(1);
       __ jmp(true_label_);
@@ -348,12 +516,11 @@
 
 void FastCodeGenerator::Move(Register destination, Slot* source) {
   // Use destination as scratch.
-  MemOperand location = EmitSlotSearch(source, destination);
-  __ ldr(destination, location);
+  MemOperand slot_operand = EmitSlotSearch(source, destination);
+  __ ldr(destination, slot_operand);
 }
 
 
-
 void FastCodeGenerator::Move(Slot* dst,
                              Register src,
                              Register scratch1,
@@ -370,23 +537,6 @@
 }
 
 
-
-void FastCodeGenerator::TestAndBranch(Register source,
-                                      Label* true_label,
-                                      Label* false_label) {
-  ASSERT_NE(NULL, true_label);
-  ASSERT_NE(NULL, false_label);
-  // Call the runtime to find the boolean value of the source and then
-  // translate it into control flow to the pair of labels.
-  __ push(source);
-  __ CallRuntime(Runtime::kToBool, 1);
-  __ LoadRoot(ip, Heap::kTrueValueRootIndex);
-  __ cmp(r0, ip);
-  __ b(eq, true_label);
-  __ jmp(false_label);
-}
-
-
 void FastCodeGenerator::VisitDeclaration(Declaration* decl) {
   Comment cmnt(masm_, "[ Declaration");
   Variable* var = decl->proxy()->var();
@@ -402,9 +552,8 @@
           __ LoadRoot(ip, Heap::kTheHoleValueRootIndex);
           __ str(ip, MemOperand(fp, SlotOffset(slot)));
         } else if (decl->fun() != NULL) {
-          Visit(decl->fun());
-          __ pop(ip);
-          __ str(ip, MemOperand(fp, SlotOffset(slot)));
+          VisitForValue(decl->fun(), kAccumulator);
+          __ str(result_register(), MemOperand(fp, SlotOffset(slot)));
         }
         break;
 
@@ -426,13 +575,13 @@
           __ str(ip, CodeGenerator::ContextOperand(cp, slot->index()));
           // No write barrier since the_hole_value is in old space.
         } else if (decl->fun() != NULL) {
-          Visit(decl->fun());
-          __ pop(r0);
-          __ str(r0, CodeGenerator::ContextOperand(cp, slot->index()));
+          VisitForValue(decl->fun(), kAccumulator);
+          __ str(result_register(),
+                 CodeGenerator::ContextOperand(cp, slot->index()));
           int offset = Context::SlotOffset(slot->index());
           __ mov(r2, Operand(offset));
           // We know that we have written a function, which is not a smi.
-          __ RecordWrite(cp, r2, r0);
+          __ RecordWrite(cp, r2, result_register());
         }
         break;
 
@@ -453,7 +602,8 @@
           __ stm(db_w, sp, cp.bit() | r2.bit() | r1.bit() | r0.bit());
         } else if (decl->fun() != NULL) {
           __ stm(db_w, sp, cp.bit() | r2.bit() | r1.bit());
-          Visit(decl->fun());  // Initial value for function decl.
+          // Push initial value for function declaration.
+          VisitForValue(decl->fun(), kStack);
         } else {
           __ mov(r0, Operand(Smi::FromInt(0)));  // No initial value!
           __ stm(db_w, sp, cp.bit() | r2.bit() | r1.bit() | r0.bit());
@@ -467,17 +617,13 @@
     if (decl->fun() != NULL || decl->mode() == Variable::CONST) {
       // We are declaring a function or constant that rewrites to a
       // property.  Use (keyed) IC to set the initial value.
-      ASSERT_EQ(Expression::kValue, prop->obj()->context());
-      Visit(prop->obj());
-      ASSERT_EQ(Expression::kValue, prop->key()->context());
-      Visit(prop->key());
+      VisitForValue(prop->obj(), kStack);
+      VisitForValue(prop->key(), kStack);
 
       if (decl->fun() != NULL) {
-        ASSERT_EQ(Expression::kValue, decl->fun()->context());
-        Visit(decl->fun());
-        __ pop(r0);
+        VisitForValue(decl->fun(), kAccumulator);
       } else {
-        __ LoadRoot(r0, Heap::kTheHoleValueRootIndex);
+        __ LoadRoot(result_register(), Heap::kTheHoleValueRootIndex);
       }
 
       Handle<Code> ic(Builtins::builtin(Builtins::KeyedStoreIC_Initialize));
@@ -558,7 +704,7 @@
           break;
       }
     }
-    Apply(context, slot, r0);
+    Apply(context, slot);
   } else {
     Comment cmnt(masm_, "Variable rewritten to property");
     // A variable has been rewritten into an explicit access to an object
@@ -639,9 +785,8 @@
     __ CallRuntime(Runtime::kCreateObjectLiteralShallow, 3);
   }
 
-  // If result_saved == true: The result is saved on top of the
-  //  stack and in r0.
-  // If result_saved == false: The result not on the stack, just in r0.
+  // If result_saved is true the result is on top of the stack.  If
+  // result_saved is false the result is in r0.
   bool result_saved = false;
 
   for (int i = 0; i < expr->properties()->length(); i++) {
@@ -657,80 +802,47 @@
     switch (property->kind()) {
       case ObjectLiteral::Property::CONSTANT:
         UNREACHABLE();
-
-      case ObjectLiteral::Property::MATERIALIZED_LITERAL:   // Fall through.
+      case ObjectLiteral::Property::MATERIALIZED_LITERAL:
         ASSERT(!CompileTimeValue::IsCompileTimeValue(property->value()));
+        // Fall through.
       case ObjectLiteral::Property::COMPUTED:
         if (key->handle()->IsSymbol()) {
-          Visit(value);
-          ASSERT_EQ(Expression::kValue, value->context());
-          __ pop(r0);
+          VisitForValue(value, kAccumulator);
           __ mov(r2, Operand(key->handle()));
           Handle<Code> ic(Builtins::builtin(Builtins::StoreIC_Initialize));
           __ Call(ic, RelocInfo::CODE_TARGET);
           // StoreIC leaves the receiver on the stack.
-          __ ldr(r0, MemOperand(sp));  // Restore result into r0.
           break;
         }
         // Fall through.
-
       case ObjectLiteral::Property::PROTOTYPE:
+        // Duplicate receiver on stack.
+        __ ldr(r0, MemOperand(sp));
         __ push(r0);
-        Visit(key);
-        ASSERT_EQ(Expression::kValue, key->context());
-        Visit(value);
-        ASSERT_EQ(Expression::kValue, value->context());
+        VisitForValue(key, kStack);
+        VisitForValue(value, kStack);
         __ CallRuntime(Runtime::kSetProperty, 3);
-        __ ldr(r0, MemOperand(sp));  // Restore result into r0.
         break;
-
       case ObjectLiteral::Property::GETTER:
       case ObjectLiteral::Property::SETTER:
+        // Duplicate receiver on stack.
+        __ ldr(r0, MemOperand(sp));
         __ push(r0);
-        Visit(key);
-        ASSERT_EQ(Expression::kValue, key->context());
+        VisitForValue(key, kStack);
         __ mov(r1, Operand(property->kind() == ObjectLiteral::Property::SETTER ?
                            Smi::FromInt(1) :
                            Smi::FromInt(0)));
         __ push(r1);
-        Visit(value);
-        ASSERT_EQ(Expression::kValue, value->context());
+        VisitForValue(value, kStack);
         __ CallRuntime(Runtime::kDefineAccessor, 4);
-        __ ldr(r0, MemOperand(sp));  // Restore result into r0
         break;
     }
   }
-  switch (expr->context()) {
-    case Expression::kUninitialized:
-      UNREACHABLE();
-    case Expression::kEffect:
-      if (result_saved) __ Drop(1);
-      break;
-    case Expression::kValue:
-      if (!result_saved) __ push(r0);
-      break;
-    case Expression::kTest:
-      if (result_saved) __ pop(r0);
-      TestAndBranch(r0, true_label_, false_label_);
-      break;
-    case Expression::kValueTest: {
-      Label discard;
-      if (!result_saved) __ push(r0);
-      TestAndBranch(r0, true_label_, &discard);
-      __ bind(&discard);
-      __ Drop(1);
-      __ jmp(false_label_);
-      break;
-    }
-    case Expression::kTestValue: {
-      Label discard;
-      if (!result_saved) __ push(r0);
-      TestAndBranch(r0, &discard, false_label_);
-      __ bind(&discard);
-      __ Drop(1);
-      __ jmp(true_label_);
-      break;
-    }
+
+  if (result_saved) {
+    ApplyTOS(expr->context());
+  } else {
+    Apply(expr->context(), r0);
   }
 }
 
@@ -766,53 +878,24 @@
       __ push(r0);
       result_saved = true;
     }
-    Visit(subexpr);
-    ASSERT_EQ(Expression::kValue, subexpr->context());
+    VisitForValue(subexpr, kAccumulator);
 
     // Store the subexpression value in the array's elements.
-    __ pop(r0);  // Subexpression value.
     __ ldr(r1, MemOperand(sp));  // Copy of array literal.
     __ ldr(r1, FieldMemOperand(r1, JSObject::kElementsOffset));
     int offset = FixedArray::kHeaderSize + (i * kPointerSize);
-    __ str(r0, FieldMemOperand(r1, offset));
+    __ str(result_register(), FieldMemOperand(r1, offset));
 
     // Update the write barrier for the array store with r0 as the scratch
     // register.
     __ mov(r2, Operand(offset));
-    __ RecordWrite(r1, r2, r0);
+    __ RecordWrite(r1, r2, result_register());
   }
 
-  switch (expr->context()) {
-    case Expression::kUninitialized:
-      UNREACHABLE();
-    case Expression::kEffect:
-      if (result_saved) __ Drop(1);
-      break;
-    case Expression::kValue:
-      if (!result_saved) __ push(r0);
-      break;
-    case Expression::kTest:
-      if (result_saved) __ pop(r0);
-      TestAndBranch(r0, true_label_, false_label_);
-      break;
-    case Expression::kValueTest: {
-      Label discard;
-      if (!result_saved) __ push(r0);
-      TestAndBranch(r0, true_label_, &discard);
-      __ bind(&discard);
-      __ Drop(1);
-      __ jmp(false_label_);
-      break;
-    }
-    case Expression::kTestValue: {
-      Label discard;
-      if (!result_saved) __ push(r0);
-      TestAndBranch(r0, &discard, false_label_);
-      __ bind(&discard);
-      __ Drop(1);
-      __ jmp(true_label_);
-      break;
-    }
+  if (result_saved) {
+    ApplyTOS(expr->context());
+  } else {
+    Apply(expr->context(), r0);
   }
 }
 
@@ -833,12 +916,10 @@
 }
 
 
-void FastCodeGenerator::EmitCompoundAssignmentOp(Token::Value op,
-                                                 Expression::Context context) {
-  __ pop(r0);
+void FastCodeGenerator::EmitBinaryOp(Token::Value op,
+                                     Expression::Context context) {
   __ pop(r1);
-  GenericBinaryOpStub stub(op,
-                           NO_OVERWRITE);
+  GenericBinaryOpStub stub(op, NO_OVERWRITE);
   __ CallStub(&stub);
   Apply(context, r0);
 }
@@ -852,7 +933,6 @@
     // Assignment to a global variable.  Use inline caching for the
     // assignment.  Right-hand-side value is passed in r0, variable name in
     // r2, and the global object on the stack.
-    __ pop(r0);
     __ mov(r2, Operand(var->name()));
     __ ldr(ip, CodeGenerator::GlobalObject());
     __ push(ip);
@@ -865,77 +945,20 @@
     Slot* slot = var->slot();
     switch (slot->type()) {
       case Slot::LOCAL:
-      case Slot::PARAMETER: {
-        MemOperand target = MemOperand(fp, SlotOffset(slot));
-        switch (context) {
-          case Expression::kUninitialized:
-            UNREACHABLE();
-          case Expression::kEffect:
-            // Perform assignment and discard value.
-            __ pop(r0);
-            __ str(r0, target);
-            break;
-          case Expression::kValue:
-            // Perform assignment and preserve value.
-            __ ldr(r0, MemOperand(sp));
-            __ str(r0, target);
-            break;
-          case Expression::kTest:
-            // Perform assignment and test (and discard) value.
-            __ pop(r0);
-            __ str(r0, target);
-            TestAndBranch(r0, true_label_, false_label_);
-            break;
-          case Expression::kValueTest: {
-            Label discard;
-            __ ldr(r0, MemOperand(sp));
-            __ str(r0, target);
-            TestAndBranch(r0, true_label_, &discard);
-            __ bind(&discard);
-            __ Drop(1);
-            __ jmp(false_label_);
-            break;
-          }
-          case Expression::kTestValue: {
-            Label discard;
-            __ ldr(r0, MemOperand(sp));
-            __ str(r0, target);
-            TestAndBranch(r0, &discard, false_label_);
-            __ bind(&discard);
-            __ Drop(1);
-            __ jmp(true_label_);
-            break;
-          }
-        }
+      case Slot::PARAMETER:
+        __ str(result_register(), MemOperand(fp, SlotOffset(slot)));
         break;
-      }
 
       case Slot::CONTEXT: {
         MemOperand target = EmitSlotSearch(slot, r1);
-        __ pop(r0);
-        __ str(r0, target);
+        __ str(result_register(), target);
 
         // RecordWrite may destroy all its register arguments.
-        if (context == Expression::kValue) {
-          __ push(r0);
-        } else if (context != Expression::kEffect) {
-          __ mov(r3, r0);
-        }
+        __ mov(r3, result_register());
         int offset = FixedArray::kHeaderSize + slot->index() * kPointerSize;
 
-        // Update the write barrier for the array store with r0 as the scratch
-        // register.  Skip the write barrier if the value written (r1) is a smi.
-        // The smi test is part of RecordWrite on other platforms, not on arm.
-        Label exit;
-        __ tst(r0, Operand(kSmiTagMask));
-        __ b(eq, &exit);
-
         __ mov(r2, Operand(offset));
-        __ RecordWrite(r1, r2, r0);
-        __ bind(&exit);
-        if (context != Expression::kEffect && context != Expression::kValue) {
-          Apply(context, r3);
-        }
+        __ RecordWrite(r1, r2, r3);
         break;
       }
 
@@ -943,6 +966,7 @@
         UNREACHABLE();
         break;
     }
+    Apply(context, result_register());
   } else {
     // Variables rewritten as properties are not treated as variables in
     // assignments.
@@ -961,15 +985,15 @@
   // change to slow case to avoid the quadratic behavior of repeatedly
   // adding fast properties.
   if (expr->starts_initialization_block()) {
-    __ ldr(ip, MemOperand(sp, kPointerSize));  // Receiver is under value.
+    __ push(result_register());
+    __ ldr(ip, MemOperand(sp, kPointerSize));  // Receiver is now under value.
     __ push(ip);
     __ CallRuntime(Runtime::kToSlowProperties, 1);
+    __ pop(result_register());
   }
 
   // Record source code position before IC call.
   SetSourcePosition(expr->position());
-
-  __ pop(r0);
   __ mov(r2, Operand(prop->key()->AsLiteral()->handle()));
   Handle<Code> ic(Builtins::builtin(Builtins::StoreIC_Initialize));
   __ Call(ic, RelocInfo::CODE_TARGET);
@@ -994,23 +1018,23 @@
   // change to slow case to avoid the quadratic behavior of repeatedly
   // adding fast properties.
   if (expr->starts_initialization_block()) {
-    // Receiver is under the key and value.
+    __ push(result_register());
+    // Receiver is now under the key and value.
     __ ldr(ip, MemOperand(sp, 2 * kPointerSize));
     __ push(ip);
     __ CallRuntime(Runtime::kToSlowProperties, 1);
+    __ pop(result_register());
   }
 
   // Record source code position before IC call.
   SetSourcePosition(expr->position());
-
-  __ pop(r0);
   Handle<Code> ic(Builtins::builtin(Builtins::KeyedStoreIC_Initialize));
   __ Call(ic, RelocInfo::CODE_TARGET);
 
   // If the assignment ends an initialization block, revert to fast case.
   if (expr->ends_initialization_block()) {
     __ push(r0);  // Result of assignment, saved even if not needed.
-    // Reciever is under the key and value.
+    // Receiver is under the key and value.
     __ ldr(ip, MemOperand(sp, 2 * kPointerSize));
     __ push(ip);
     __ CallRuntime(Runtime::kToFastProperties, 1);
@@ -1027,14 +1051,14 @@
   Expression* key = expr->key();
 
   // Evaluate receiver.
-  Visit(expr->obj());
+  VisitForValue(expr->obj(), kStack);
 
   if (key->IsPropertyName()) {
     EmitNamedPropertyLoad(expr);
     // Drop receiver left on the stack by IC.
     DropAndApply(1, expr->context(), r0);
   } else {
-    Visit(expr->key());
+    VisitForValue(expr->key(), kStack);
     EmitKeyedPropertyLoad(expr);
     // Drop key and receiver left on the stack by IC.
     DropAndApply(2, expr->context(), r0);
@@ -1048,8 +1072,7 @@
   ZoneList<Expression*>* args = expr->arguments();
   int arg_count = args->length();
   for (int i = 0; i < arg_count; i++) {
-    Visit(args->at(i));
-    ASSERT_EQ(Expression::kValue, args->at(i)->context());
+    VisitForValue(args->at(i), kStack);
   }
   // Record source position for debugger.
   SetSourcePosition(expr->position());
@@ -1069,7 +1092,7 @@
   ZoneList<Expression*>* args = expr->arguments();
   int arg_count = args->length();
   for (int i = 0; i < arg_count; i++) {
-    Visit(args->at(i));
+    VisitForValue(args->at(i), kStack);
   }
   // Record source position for debugger.
   SetSourcePosition(expr->position());
@@ -1109,13 +1132,13 @@
       // Call to a named property, use call IC.
       __ mov(r0, Operand(key->handle()));
       __ push(r0);
-      Visit(prop->obj());
+      VisitForValue(prop->obj(), kStack);
       EmitCallWithIC(expr, key->handle(), RelocInfo::CODE_TARGET);
     } else {
       // Call to a keyed property, use keyed load IC followed by function
       // call.
-      Visit(prop->obj());
-      Visit(prop->key());
+      VisitForValue(prop->obj(), kStack);
+      VisitForValue(prop->key(), kStack);
       // Record source code position for IC call.
       SetSourcePosition(prop->position());
       Handle<Code> ic(Builtins::builtin(Builtins::KeyedLoadIC_Initialize));
@@ -1142,7 +1165,7 @@
         loop_depth() == 0) {
       lit->set_try_fast_codegen(true);
     }
-    Visit(fun);
+    VisitForValue(fun, kStack);
     // Load global receiver object.
     __ ldr(r1, CodeGenerator::GlobalObject());
     __ ldr(r1, FieldMemOperand(r1, GlobalObject::kGlobalReceiverOffset));
@@ -1159,8 +1182,7 @@
   // expression in new calls must be evaluated before the
   // arguments.
   // Push function on the stack.
-  Visit(expr->expression());
-  ASSERT_EQ(Expression::kValue, expr->expression()->context());
+  VisitForValue(expr->expression(), kStack);
 
   // Push global object (receiver).
   __ ldr(r0, CodeGenerator::GlobalObject());
@@ -1169,10 +1191,7 @@
   ZoneList<Expression*>* args = expr->arguments();
   int arg_count = args->length();
   for (int i = 0; i < arg_count; i++) {
-    Visit(args->at(i));
-    ASSERT_EQ(Expression::kValue, args->at(i)->context());
-    // If location is value, it is already on the stack,
-    // so nothing to do here.
+    VisitForValue(args->at(i), kStack);
   }
 
   // Call the construct call builtin that handles allocation and
@@ -1207,8 +1226,7 @@
   // Push the arguments ("left-to-right").
   int arg_count = args->length();
   for (int i = 0; i < arg_count; i++) {
-    Visit(args->at(i));
-    ASSERT_EQ(Expression::kValue, args->at(i)->context());
+    VisitForValue(args->at(i), kStack);
   }
 
   if (expr->is_jsruntime()) {
@@ -1232,8 +1250,8 @@
   switch (expr->op()) {
     case Token::VOID: {
       Comment cmnt(masm_, "[ UnaryOperation (VOID)");
-      Visit(expr->expression());
       ASSERT_EQ(Expression::kEffect, expr->expression()->context());
+      Visit(expr->expression());
       switch (expr->context()) {
         case Expression::kUninitialized:
           UNREACHABLE();
@@ -1241,13 +1259,26 @@
         case Expression::kEffect:
           break;
         case Expression::kValue:
-          __ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
-          __ push(ip);
+          __ LoadRoot(result_register(), Heap::kUndefinedValueRootIndex);
+          switch (location_) {
+            case kAccumulator:
+              break;
+            case kStack:
+              __ push(result_register());
+              break;
+          }
           break;
         case Expression::kTestValue:
           // Value is false so it's needed.
-          __ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
-          __ push(ip);
+          __ LoadRoot(result_register(), Heap::kUndefinedValueRootIndex);
+          switch (location_) {
+            case kAccumulator:
+              break;
+            case kStack:
+              __ push(result_register());
+              break;
+          }
+          // Fall through.
         case Expression::kTest:
         case Expression::kValueTest:
           __ jmp(false_label_);
@@ -1260,49 +1291,34 @@
       Comment cmnt(masm_, "[ UnaryOperation (NOT)");
       ASSERT_EQ(Expression::kTest, expr->expression()->context());
 
-      Label push_true, push_false, done;
+      Label materialize_true, materialize_false, done;
+      // Initially assume a pure test context.  Notice that the labels are
+      // swapped.
+      Label* if_true = false_label_;
+      Label* if_false = true_label_;
       switch (expr->context()) {
         case Expression::kUninitialized:
           UNREACHABLE();
           break;
-
         case Expression::kEffect:
-          VisitForControl(expr->expression(), &done, &done);
-          __ bind(&done);
+          if_true = &done;
+          if_false = &done;
           break;
-
         case Expression::kValue:
-          VisitForControl(expr->expression(), &push_false, &push_true);
-          __ bind(&push_true);
-          __ LoadRoot(ip, Heap::kTrueValueRootIndex);
-          __ push(ip);
-          __ jmp(&done);
-          __ bind(&push_false);
-          __ LoadRoot(ip, Heap::kFalseValueRootIndex);
-          __ push(ip);
-          __ bind(&done);
+          if_true = &materialize_false;
+          if_false = &materialize_true;
           break;
-
         case Expression::kTest:
-          VisitForControl(expr->expression(), false_label_, true_label_);
           break;
-
         case Expression::kValueTest:
-          VisitForControl(expr->expression(), false_label_, &push_true);
-          __ bind(&push_true);
-          __ LoadRoot(ip, Heap::kTrueValueRootIndex);
-          __ push(ip);
-          __ jmp(true_label_);
+          if_false = &materialize_true;
           break;
-
         case Expression::kTestValue:
-          VisitForControl(expr->expression(), &push_false, true_label_);
-          __ bind(&push_false);
-          __ LoadRoot(ip, Heap::kFalseValueRootIndex);
-          __ push(ip);
-          __ jmp(false_label_);
+          if_true = &materialize_false;
           break;
       }
+      VisitForControl(expr->expression(), if_true, if_false);
+      Apply(expr->context(), if_false, if_true);  // Labels swapped.
       break;
     }
 
@@ -1332,7 +1348,7 @@
         __ push(r0);
       } else {
         // This expression cannot throw a reference error at the top level.
-        Visit(expr->expression());
+        VisitForValue(expr->expression(), kStack);
       }
 
       __ CallRuntime(Runtime::kTypeof, 1);
@@ -1365,8 +1381,11 @@
   // Evaluate expression and get value.
   if (assign_type == VARIABLE) {
     ASSERT(expr->expression()->AsVariableProxy()->var() != NULL);
+    Location saved_location = location_;
+    location_ = kStack;
     EmitVariableLoad(expr->expression()->AsVariableProxy()->var(),
                      Expression::kValue);
+    location_ = saved_location;
   } else {
     // Reserve space for result of postfix operation.
     if (expr->is_postfix() && expr->context() != Expression::kEffect) {
@@ -1374,13 +1393,11 @@
       __ mov(ip, Operand(Smi::FromInt(0)));
       __ push(ip);
     }
-    Visit(prop->obj());
-    ASSERT_EQ(Expression::kValue, prop->obj()->context());
+    VisitForValue(prop->obj(), kStack);
     if (assign_type == NAMED_PROPERTY) {
       EmitNamedPropertyLoad(prop);
     } else {
-      Visit(prop->key());
-      ASSERT_EQ(Expression::kValue, prop->key()->context());
+      VisitForValue(prop->key(), kStack);
       EmitKeyedPropertyLoad(prop);
     }
     __ push(r0);
@@ -1399,8 +1416,8 @@
         break;
       case Expression::kValue:
       case Expression::kTest:
-      case Expression::kTestValue:
       case Expression::kValueTest:
+      case Expression::kTestValue:
         // Save the result on the stack. If we have a named or keyed property
         // we store the result under the receiver that is currently on top
         // of the stack.
@@ -1429,7 +1446,6 @@
   // Store the value returned in r0.
   switch (assign_type) {
     case VARIABLE:
-      __ push(r0);
       if (expr->is_postfix()) {
         EmitVariableAssignment(expr->expression()->AsVariableProxy()->var(),
                                Expression::kEffect);
@@ -1499,21 +1515,12 @@
     case Token::BIT_XOR:
     case Token::SHL:
     case Token::SHR:
-    case Token::SAR: {
-      ASSERT_EQ(Expression::kValue, expr->left()->context());
-      ASSERT_EQ(Expression::kValue, expr->right()->context());
-
-      Visit(expr->left());
-      Visit(expr->right());
-      __ pop(r0);
-      __ pop(r1);
-      GenericBinaryOpStub stub(expr->op(),
-                               NO_OVERWRITE);
-      __ CallStub(&stub);
-      Apply(expr->context(), r0);
-
+    case Token::SAR:
+      VisitForValue(expr->left(), kStack);
+      VisitForValue(expr->right(), kAccumulator);
+      EmitBinaryOp(expr->op(), expr->context());
       break;
-    }
+
     default:
       UNREACHABLE();
   }
@@ -1522,14 +1529,10 @@
 
 void FastCodeGenerator::VisitCompareOperation(CompareOperation* expr) {
   Comment cmnt(masm_, "[ CompareOperation");
-  ASSERT_EQ(Expression::kValue, expr->left()->context());
-  ASSERT_EQ(Expression::kValue, expr->right()->context());
-  Visit(expr->left());
-  Visit(expr->right());
 
   // Always perform the comparison for its control flow.  Pack the result
   // into the expression's context after the comparison is performed.
-  Label push_true, push_false, done;
+  Label materialize_true, materialize_false, done;
   // Initially assume we are in a test context.
   Label* if_true = true_label_;
   Label* if_false = false_label_;
@@ -1542,30 +1545,32 @@
       if_false = &done;
       break;
     case Expression::kValue:
-      if_true = &push_true;
-      if_false = &push_false;
+      if_true = &materialize_true;
+      if_false = &materialize_false;
       break;
     case Expression::kTest:
       break;
     case Expression::kValueTest:
-      if_true = &push_true;
+      if_true = &materialize_true;
       break;
     case Expression::kTestValue:
-      if_false = &push_false;
+      if_false = &materialize_false;
       break;
   }
 
+  VisitForValue(expr->left(), kStack);
   switch (expr->op()) {
-    case Token::IN: {
+    case Token::IN:
+      VisitForValue(expr->right(), kStack);
       __ InvokeBuiltin(Builtins::IN, CALL_JS);
       __ LoadRoot(ip, Heap::kTrueValueRootIndex);
       __ cmp(r0, ip);
       __ b(eq, if_true);
       __ jmp(if_false);
       break;
-    }
 
     case Token::INSTANCEOF: {
+      VisitForValue(expr->right(), kStack);
       InstanceofStub stub;
       __ CallStub(&stub);
       __ tst(r0, r0);
@@ -1575,6 +1580,7 @@
     }
 
     default: {
+      VisitForValue(expr->right(), kAccumulator);
       Condition cc = eq;
       bool strict = false;
       switch (expr->op()) {
@@ -1583,29 +1589,26 @@
           // Fall through
         case Token::EQ:
           cc = eq;
-          __ pop(r0);
           __ pop(r1);
           break;
         case Token::LT:
           cc = lt;
-          __ pop(r0);
           __ pop(r1);
           break;
         case Token::GT:
           // Reverse left and right sides to obtain ECMA-262 conversion order.
           cc = lt;
-          __ pop(r1);
+          __ mov(r1, result_register());
           __ pop(r0);
          break;
         case Token::LTE:
           // Reverse left and right sides to obtain ECMA-262 conversion order.
           cc = ge;
-          __ pop(r1);
+          __ mov(r1, result_register());
           __ pop(r0);
           break;
         case Token::GTE:
           cc = ge;
-          __ pop(r0);
           __ pop(r1);
           break;
         case Token::IN:
@@ -1635,43 +1638,7 @@
 
   // Convert the result of the comparison into one expected for this
   // expression's context.
-  switch (expr->context()) {
-    case Expression::kUninitialized:
-      UNREACHABLE();
-      break;
-
-    case Expression::kEffect:
-      __ bind(&done);
-      break;
-
-    case Expression::kValue:
-      __ bind(&push_true);
-      __ LoadRoot(ip, Heap::kTrueValueRootIndex);
-      __ push(ip);
-      __ jmp(&done);
-      __ bind(&push_false);
-      __ LoadRoot(ip, Heap::kFalseValueRootIndex);
-      __ push(ip);
-      __ bind(&done);
-      break;
-
-    case Expression::kTest:
-      break;
-
-    case Expression::kValueTest:
-      __ bind(&push_true);
-      __ LoadRoot(ip, Heap::kTrueValueRootIndex);
-      __ push(ip);
-      __ jmp(true_label_);
-      break;
-
-    case Expression::kTestValue:
-      __ bind(&push_false);
-      __ LoadRoot(ip, Heap::kFalseValueRootIndex);
-      __ push(ip);
-      __ jmp(false_label_);
-      break;
-  }
+  Apply(expr->context(), if_true, if_false);
 }