Add ToBoolean-conversion of constants in Crankshaft and use it when generating...

Add ToBoolean-conversion of constants in Crankshaft and use it when generating a branch based on a constant.
Review URL: http://codereview.chromium.org/6801050

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7552 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/lithium-arm.cc

@@ -1114,9 +1114,9 @@ LInstruction* LChunkBuilder::DoTest(HTest* instr) {
       return new LIsConstructCallAndBranch(TempRegister());
     } else {
       if (v->IsConstant()) {
-        if (HConstant::cast(v)->handle()->IsTrue()) {
+        if (HConstant::cast(v)->ToBoolean()) {
           return new LGoto(instr->FirstSuccessor()->block_id());
-        } else if (HConstant::cast(v)->handle()->IsFalse()) {
+        } else {
           return new LGoto(instr->SecondSuccessor()->block_id());
         }
       }

src/hydrogen-instructions.cc

@@ -1050,6 +1050,23 @@ HConstant* HConstant::CopyToTruncatedInt32() const {
 }
 
 
+bool HConstant::ToBoolean() const {
+  // Converts the constant's boolean value according to
+  // ECMAScript section 9.2 ToBoolean conversion.
+  if (HasInteger32Value()) return Integer32Value() != 0;
+  if (HasDoubleValue()) {
+    double v = DoubleValue();
+    return v != 0 && !isnan(v);
+  }
+  if (handle()->IsTrue()) return true;
+  if (handle()->IsFalse()) return false;
+  if (handle()->IsUndefined()) return false;
+  if (handle()->IsNull()) return false;
+  if (handle()->IsString() &&
+      String::cast(*handle())->length() == 0) return false;
+  return true;
+}
+
 void HConstant::PrintDataTo(StringStream* stream) {
   handle()->ShortPrint(stream);
 }

src/hydrogen-instructions.h

@@ -1961,6 +1961,8 @@ class HConstant: public HTemplateInstruction<0> {
   }
   bool HasStringValue() const { return handle_->IsString(); }
 
+  bool ToBoolean() const;
+
   virtual intptr_t Hashcode() {
     ASSERT(!HEAP->allow_allocation(false));
     return reinterpret_cast<intptr_t>(*handle());

src/ia32/lithium-ia32.cc

@@ -1120,9 +1120,9 @@ LInstruction* LChunkBuilder::DoTest(HTest* instr) {
       return new LIsConstructCallAndBranch(TempRegister());
     } else {
       if (v->IsConstant()) {
-        if (HConstant::cast(v)->handle()->IsTrue()) {
+        if (HConstant::cast(v)->ToBoolean()) {
           return new LGoto(instr->FirstSuccessor()->block_id());
-        } else if (HConstant::cast(v)->handle()->IsFalse()) {
+        } else {
           return new LGoto(instr->SecondSuccessor()->block_id());
         }
       }

src/x64/lithium-x64.cc

@@ -1114,9 +1114,9 @@ LInstruction* LChunkBuilder::DoTest(HTest* instr) {
       return new LIsConstructCallAndBranch(TempRegister());
     } else {
       if (v->IsConstant()) {
-        if (HConstant::cast(v)->handle()->IsTrue()) {
+        if (HConstant::cast(v)->ToBoolean()) {
           return new LGoto(instr->FirstSuccessor()->block_id());
-        } else if (HConstant::cast(v)->handle()->IsFalse()) {
+        } else {
           return new LGoto(instr->SecondSuccessor()->block_id());
         }
       }