Improve the code generated by the full codegen by keeping...

src/arm/full-codegen-arm.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 251 matching lines @@
           break;
         case kStack:
           __ push(reg);
           break;
       }
       break;
 
     case Expression::kTest:
       // For simplicity we always test the accumulator register.
       if (!reg.is(result_register())) __ mov(result_register(), reg);
-      DoTest(true_label_, false_label_, NULL);
+      DoTest(true_label_, false_label_, fall_through_);
       break;
   }
 }
 
 
 void FullCodeGenerator::Apply(Expression::Context context, Slot* slot) {
   switch (context) {
     case Expression::kUninitialized:
       UNREACHABLE();
     case Expression::kEffect:
@@ skipping 42 matching lines @@
         case kAccumulator:
           __ pop(result_register());
           break;
         case kStack:
           break;
       }
       break;
 
     case Expression::kTest:
       __ pop(result_register());
-      DoTest(true_label_, false_label_, NULL);
+      DoTest(true_label_, false_label_, fall_through_);
       break;
   }
 }
 
 
 void FullCodeGenerator::DropAndApply(int count,
                                      Expression::Context context,
                                      Register reg) {
   ASSERT(count > 0);
   ASSERT(!reg.is(sp));
@@ skipping 14 matching lines @@
         case kStack:
           if (count > 1) __ Drop(count - 1);
           __ str(reg, MemOperand(sp));
           break;
       }
       break;
 
     case Expression::kTest:
       __ Drop(count);
       if (!reg.is(result_register())) __ mov(result_register(), reg);
-      DoTest(true_label_, false_label_, NULL);
-      break;
-  }
-}
-
-void FullCodeGenerator::PrepareTest(Label* materialize_true,
-                                    Label* materialize_false,
-                                    Label** if_true,
-                                    Label** if_false) {
-  switch (context_) {
-    case Expression::kUninitialized:
-      UNREACHABLE();
-      break;
-    case Expression::kEffect:
-      // In an effect context, the true and the false case branch to the
-      // same label.
-      *if_true = *if_false = materialize_true;
-      break;
-    case Expression::kValue:
-      *if_true = materialize_true;
-      *if_false = materialize_false;
-      break;
-    case Expression::kTest:
-      *if_true = true_label_;
-      *if_false = false_label_;
+      DoTest(true_label_, false_label_, fall_through_);
       break;
   }
 }
 
 
 void FullCodeGenerator::Apply(Expression::Context context,
                               Label* materialize_true,
                               Label* materialize_false) {
   switch (context) {
     case Expression::kUninitialized:
@@ skipping 50 matching lines @@
           __ LoadRoot(result_register(), value_root_index);
           break;
         case kStack:
           __ LoadRoot(ip, value_root_index);
           __ push(ip);
           break;
       }
       break;
     }
     case Expression::kTest:
-      __ b(flag ? true_label_ : false_label_);
+      if (flag) {
+        if (true_label_ != fall_through_) __ b(true_label_);
+      } else {
+        if (false_label_ != fall_through_) __ b(false_label_);
+      }
       break;
   }
 }
 
 
 void FullCodeGenerator::DoTest(Label* if_true,
                                Label* if_false,
                                Label* fall_through) {
   // Call the runtime to find the boolean value of the source and then
   // translate it into control flow to the pair of labels.
@@ skipping 1252 matching lines @@
 
 
 void FullCodeGenerator::EmitIsSmi(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
   VisitForValue(args->at(0), kAccumulator);
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
 
   __ BranchOnSmi(r0, if_true);
   __ b(if_false);
 
   Apply(context_, if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsNonNegativeSmi(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
   VisitForValue(args->at(0), kAccumulator);
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
 
   __ tst(r0, Operand(kSmiTagMask | 0x80000000));
-  Split(eq, if_true, if_false, NULL);
+  Split(eq, if_true, if_false, fall_through);
 
   Apply(context_, if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsObject(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
   VisitForValue(args->at(0), kAccumulator);
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
+
   __ BranchOnSmi(r0, if_false);
   __ LoadRoot(ip, Heap::kNullValueRootIndex);
   __ cmp(r0, ip);
   __ b(eq, if_true);
   __ ldr(r2, FieldMemOperand(r0, HeapObject::kMapOffset));
   // Undetectable objects behave like undefined when tested with typeof.
   __ ldrb(r1, FieldMemOperand(r2, Map::kBitFieldOffset));
   __ tst(r1, Operand(1 << Map::kIsUndetectable));
   __ b(ne, if_false);
   __ ldrb(r1, FieldMemOperand(r2, Map::kInstanceTypeOffset));
   __ cmp(r1, Operand(FIRST_JS_OBJECT_TYPE));
   __ b(lt, if_false);
   __ cmp(r1, Operand(LAST_JS_OBJECT_TYPE));
-  Split(le, if_true, if_false, NULL);
+  Split(le, if_true, if_false, fall_through);
 
   Apply(context_, if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsSpecObject(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
   VisitForValue(args->at(0), kAccumulator);
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
 
   __ BranchOnSmi(r0, if_false);
   __ CompareObjectType(r0, r1, r1, FIRST_JS_OBJECT_TYPE);
-  Split(ge, if_true, if_false, NULL);
+  Split(ge, if_true, if_false, fall_through);
 
   Apply(context_, if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsUndetectableObject(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
   VisitForValue(args->at(0), kAccumulator);
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
 
   __ BranchOnSmi(r0, if_false);
   __ ldr(r1, FieldMemOperand(r0, HeapObject::kMapOffset));
   __ ldrb(r1, FieldMemOperand(r1, Map::kBitFieldOffset));
   __ tst(r1, Operand(1 << Map::kIsUndetectable));
-  Split(ne, if_true, if_false, NULL);
+  Split(ne, if_true, if_false, fall_through);
 
   Apply(context_, if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsStringWrapperSafeForDefaultValueOf(
     ZoneList<Expression*>* args) {
 
   ASSERT(args->length() == 1);
 
   VisitForValue(args->at(0), kAccumulator);
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
 
   // Just indicate false, as %_IsStringWrapperSafeForDefaultValueOf() is only
   // used in a few functions in runtime.js which should not normally be hit by
   // this compiler.
   __ jmp(if_false);
   Apply(context_, if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsFunction(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
   VisitForValue(args->at(0), kAccumulator);
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
 
   __ BranchOnSmi(r0, if_false);
   __ CompareObjectType(r0, r1, r1, JS_FUNCTION_TYPE);
-  Split(eq, if_true, if_false, NULL);
+  Split(eq, if_true, if_false, fall_through);
 
   Apply(context_, if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsArray(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
   VisitForValue(args->at(0), kAccumulator);
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
 
   __ BranchOnSmi(r0, if_false);
   __ CompareObjectType(r0, r1, r1, JS_ARRAY_TYPE);
-  Split(eq, if_true, if_false, NULL);
+  Split(eq, if_true, if_false, fall_through);
 
   Apply(context_, if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitIsRegExp(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
   VisitForValue(args->at(0), kAccumulator);
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
 
   __ BranchOnSmi(r0, if_false);
   __ CompareObjectType(r0, r1, r1, JS_REGEXP_TYPE);
-  Split(eq, if_true, if_false, NULL);
+  Split(eq, if_true, if_false, fall_through);
 
   Apply(context_, if_true, if_false);
 }
 
 
 
 void FullCodeGenerator::EmitIsConstructCall(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 0);
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
 
   // Get the frame pointer for the calling frame.
   __ ldr(r2, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
 
   // Skip the arguments adaptor frame if it exists.
   Label check_frame_marker;
   __ ldr(r1, MemOperand(r2, StandardFrameConstants::kContextOffset));
   __ cmp(r1, Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
   __ b(ne, &check_frame_marker);
   __ ldr(r2, MemOperand(r2, StandardFrameConstants::kCallerFPOffset));
 
   // Check the marker in the calling frame.
   __ bind(&check_frame_marker);
   __ ldr(r1, MemOperand(r2, StandardFrameConstants::kMarkerOffset));
   __ cmp(r1, Operand(Smi::FromInt(StackFrame::CONSTRUCT)));
-  Split(eq, if_true, if_false, NULL);
+  Split(eq, if_true, if_false, fall_through);
 
   Apply(context_, if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitObjectEquals(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 2);
 
   // Load the two objects into registers and perform the comparison.
   VisitForValue(args->at(0), kStack);
   VisitForValue(args->at(1), kAccumulator);
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
 
   __ pop(r1);
   __ cmp(r0, r1);
-  Split(eq, if_true, if_false, NULL);
+  Split(eq, if_true, if_false, fall_through);
 
   Apply(context_, if_true, if_false);
 }
 
 
 void FullCodeGenerator::EmitArguments(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
   // ArgumentsAccessStub expects the key in edx and the formal
   // parameter count in eax.
@@ skipping 652 matching lines @@
           break;
       }
       break;
     }
 
     case Token::NOT: {
       Comment cmnt(masm_, "[ UnaryOperation (NOT)");
       Label materialize_true, materialize_false;
       Label* if_true = NULL;
       Label* if_false = NULL;
+      Label* fall_through = NULL;
 
       // Notice that the labels are swapped.
-      PrepareTest(&materialize_true, &materialize_false, &if_false, &if_true);
-
-      VisitForControl(expr->expression(), if_true, if_false);
-
+      PrepareTest(&materialize_true, &materialize_false,
+                  &if_false, &if_true, &fall_through);
+      VisitForControl(expr->expression(), if_true, if_false, fall_through);
       Apply(context_, if_false, if_true);  // Labels swapped.
       break;
     }
 
     case Token::TYPEOF: {
       Comment cmnt(masm_, "[ UnaryOperation (TYPEOF)");
       VisitForTypeofValue(expr->expression(), kStack);
       __ CallRuntime(Runtime::kTypeof, 1);
       Apply(context_, r0);
       break;
@@ skipping 336 matching lines @@
 void FullCodeGenerator::VisitCompareOperation(CompareOperation* expr) {
   Comment cmnt(masm_, "[ CompareOperation");
   SetSourcePosition(expr->position());
 
   // Always perform the comparison for its control flow.  Pack the result
   // into the expression's context after the comparison is performed.
 
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
 
   // First we try a fast inlined version of the compare when one of
   // the operands is a literal.
   Token::Value op = expr->op();
   Expression* left = expr->left();
   Expression* right = expr->right();
-  if (TryLiteralCompare(op, left, right, if_true, if_false, NULL)) {
+  if (TryLiteralCompare(op, left, right, if_true, if_false, fall_through)) {
     Apply(context_, if_true, if_false);
     return;
   }
 
   VisitForValue(expr->left(), kStack);
   switch (expr->op()) {
     case Token::IN:
       VisitForValue(expr->right(), kStack);
       __ InvokeBuiltin(Builtins::IN, CALL_JS);
       __ LoadRoot(ip, Heap::kTrueValueRootIndex);
       __ cmp(r0, ip);
-      Split(eq, if_true, if_false, NULL);
+      Split(eq, if_true, if_false, fall_through);
       break;
 
     case Token::INSTANCEOF: {
       VisitForValue(expr->right(), kStack);
       InstanceofStub stub;
       __ CallStub(&stub);
       // The stub returns 0 for true.
       __ tst(r0, r0);
-      Split(eq, if_true, if_false, NULL);
+      Split(eq, if_true, if_false, fall_through);
       break;
     }
 
     default: {
       VisitForValue(expr->right(), kAccumulator);
       Condition cc = eq;
       bool strict = false;
       switch (expr->op()) {
         case Token::EQ_STRICT:
           strict = true;
@@ skipping 34 matching lines @@
       __ orr(r2, r0, Operand(r1));
       __ BranchOnNotSmi(r2, &slow_case);
       __ cmp(r1, r0);
       __ b(cc, if_true);
       __ jmp(if_false);
 
       __ bind(&slow_case);
       CompareStub stub(cc, strict, kBothCouldBeNaN, true, r1, r0);
       __ CallStub(&stub);
       __ cmp(r0, Operand(0));
-      Split(cc, if_true, if_false, NULL);
+      Split(cc, if_true, if_false, fall_through);
     }
   }
 
   // Convert the result of the comparison into one expected for this
   // expression's context.
   Apply(context_, if_true, if_false);
 }
 
 
 void FullCodeGenerator::VisitCompareToNull(CompareToNull* expr) {
   Comment cmnt(masm_, "[ CompareToNull");
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
-  PrepareTest(&materialize_true, &materialize_false, &if_true, &if_false);
+  Label* fall_through = NULL;
+  PrepareTest(&materialize_true, &materialize_false,
+              &if_true, &if_false, &fall_through);
 
   VisitForValue(expr->expression(), kAccumulator);
   __ LoadRoot(r1, Heap::kNullValueRootIndex);
   __ cmp(r0, r1);
   if (expr->is_strict()) {
-    Split(eq, if_true, if_false, NULL);
+    Split(eq, if_true, if_false, fall_through);
   } else {
     __ b(eq, if_true);
     __ LoadRoot(r1, Heap::kUndefinedValueRootIndex);
     __ cmp(r0, r1);
     __ b(eq, if_true);
     __ tst(r0, Operand(kSmiTagMask));
     __ b(eq, if_false);
     // It can be an undetectable object.
     __ ldr(r1, FieldMemOperand(r0, HeapObject::kMapOffset));
     __ ldrb(r1, FieldMemOperand(r1, Map::kBitFieldOffset));
     __ and_(r1, r1, Operand(1 << Map::kIsUndetectable));
     __ cmp(r1, Operand(1 << Map::kIsUndetectable));
-    Split(eq, if_true, if_false, NULL);
+    Split(eq, if_true, if_false, fall_through);
   }
   Apply(context_, if_true, if_false);
 }
 
 
 void FullCodeGenerator::VisitThisFunction(ThisFunction* expr) {
   __ ldr(r0, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
   Apply(context_, r0);
 }
 
@@ skipping 41 matching lines @@
   __ mov(r1, Operand(r1, ASR, 1));  // Un-smi-tag value.
   __ add(pc, r1, Operand(masm_->CodeObject()));
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM