Eliminate the constant location used for literals in the AST....

src/x64/fast-codegen-x64.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 126 matching lines @@
   Comment cmnt(masm_, "[ ExpressionStatement");
   SetStatementPosition(stmt);
   Visit(stmt->expression());
 }
 
 
 void FastCodeGenerator::VisitReturnStatement(ReturnStatement* stmt) {
   Comment cmnt(masm_, "[ ReturnStatement");
   SetStatementPosition(stmt);
   Expression* expr = stmt->expression();
-  Visit(expr);
+  // Complete the statement based on the type of the subexpression.
+  if (expr->AsLiteral() != NULL) {
+    __ Move(rax, expr->AsLiteral()->handle());
+  } else {
+    Visit(expr);
+    ASSERT(expr->location().is_temporary());
+    __ pop(rax);
+  }
 
-  // Complete the statement based on the location of the subexpression.
-  Location source = expr->location();
-  ASSERT(!source.is_nowhere());
-  if (source.is_temporary()) {
-    __ pop(rax);
-  } else {
-    ASSERT(source.is_constant());
-    ASSERT(expr->AsLiteral() != NULL);
-    __ Move(rax, expr->AsLiteral()->handle());
-  }
   if (FLAG_trace) {
     __ push(rax);
     __ CallRuntime(Runtime::kTraceExit, 1);
   }
 
   __ RecordJSReturn();
   // Do not use the leave instruction here because it is too short to
   // patch with the code required by the debugger.
   __ movq(rsp, rbp);
   __ pop(rbp);
@@ skipping 61 matching lines @@
     ASSERT(slot != NULL);
     if (expr->location().is_temporary()) {
       __ push(Operand(rbp, SlotOffset(slot)));
     } else {
       ASSERT(expr->location().is_nowhere());
     }
   }
 }
 
 
+void FastCodeGenerator::VisitLiteral(Literal* expr) {
+  if (expr->location().is_temporary()) {
+    __ Push(expr->handle());
+  } else {
+    ASSERT(expr->location().is_nowhere());
+  }
+}
+
+
 void FastCodeGenerator::VisitObjectLiteral(ObjectLiteral* expr) {
   Comment cmnt(masm_, "[ ObjectLiteral");
   Label boilerplate_exists;
 
   __ movq(rdi, Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
   __ movq(rbx, FieldOperand(rdi, JSFunction::kLiteralsOffset));
   int literal_offset =
     FixedArray::kHeaderSize + expr->literal_index() * kPointerSize;
   __ movq(rax, FieldOperand(rbx, literal_offset));
   __ CompareRoot(rax, Heap::kUndefinedValueRootIndex);
@@ skipping 44 matching lines @@
           __ Move(rcx, key->handle());
           Handle<Code> ic(Builtins::builtin(Builtins::StoreIC_Initialize));
           __ call(ic, RelocInfo::CODE_TARGET);
           // StoreIC leaves the receiver on the stack.
           break;
         }
         // fall through
       case ObjectLiteral::Property::PROTOTYPE:
         __ push(rax);
         Visit(key);
-        if (key->location().is_constant()) {
-          __ Push(key->handle());
-        }
+        ASSERT(key->location().is_temporary());
         Visit(value);
         ASSERT(value->location().is_temporary());
         __ CallRuntime(Runtime::kSetProperty, 3);
         __ movq(rax, Operand(rsp, 0));  // Restore result into rax.
         break;
       case ObjectLiteral::Property::SETTER:  // fall through
       case ObjectLiteral::Property::GETTER:
         __ push(rax);
         Visit(key);
-        if (key->location().is_constant()) {
-          __ Push(key->handle());
-        }
+        ASSERT(key->location.is_temporary());
         __ Push(property->kind() == ObjectLiteral::Property::SETTER ?
                 Smi::FromInt(1) :
                 Smi::FromInt(0));
         Visit(value);
         ASSERT(value->location().is_temporary());
         __ CallRuntime(Runtime::kDefineAccessor, 4);
         __ movq(rax, Operand(rsp, 0));  // Restore result into rax.
         break;
       default: UNREACHABLE();
     }
@@ skipping 103 matching lines @@
     __ addq(rsp, Immediate(kPointerSize));
   } else if (destination.is_temporary() && !result_saved) {
     __ push(rax);
   }
 }
 
 
 void FastCodeGenerator::VisitAssignment(Assignment* expr) {
   Comment cmnt(masm_, "[ Assignment");
   ASSERT(expr->op() == Token::ASSIGN || expr->op() == Token::INIT_VAR);
-  Expression* rhs = expr->value();
-  Visit(rhs);
 
   // Left-hand side can only be a global or a (parameter or local) slot.
   Variable* var = expr->target()->AsVariableProxy()->AsVariable();
   ASSERT(var != NULL);
   ASSERT(var->is_global() || var->slot() != NULL);
 
-  // Complete the assignment based on the location of the right-hand-side
-  // value and the desired location of the assignment value.
+  Expression* rhs = expr->value();
   Location destination = expr->location();
-  Location source = rhs->location();
-  ASSERT(!destination.is_constant());
-  ASSERT(!source.is_nowhere());
-
   if (var->is_global()) {
     // Assignment to a global variable, use inline caching.  Right-hand-side
     // value is passed in rax, variable name in rcx, and the global object
     // on the stack.
-    if (source.is_temporary()) {
+
+    // Code for the right-hand-side expression depends on its type.
+    if (rhs->AsLiteral() != NULL) {
+      __ Move(rax, rhs->AsLiteral()->handle());
+    } else {
+      ASSERT(rhs->location().is_temporary());
+      Visit(rhs);
       __ pop(rax);
-    } else {
-      ASSERT(source.is_constant());
-      ASSERT(rhs->AsLiteral() != NULL);
-      __ Move(rax, rhs->AsLiteral()->handle());
     }
     __ Move(rcx, var->name());
     __ push(CodeGenerator::GlobalObject());
     Handle<Code> ic(Builtins::builtin(Builtins::StoreIC_Initialize));
     __ Call(ic, RelocInfo::CODE_TARGET);
     // Overwrite the global object on the stack with the result if needed.
     if (destination.is_temporary()) {
       __ movq(Operand(rsp, 0), rax);
     } else {
       __ addq(rsp, Immediate(kPointerSize));
     }
   } else {
-    if (source.is_temporary()) {
+    // Local or parameter assignment.
+
+    // Code for the right-hand-side expression depends on its type.
+    if (rhs->AsLiteral() != NULL) {
+      // Two cases: 'temp <- (var = constant)', or 'var = constant' with a
+      // discarded result.  Always perform the assignment.
+      __ Move(kScratchRegister, rhs->AsLiteral()->handle());
+      __ movq(Operand(rbp, SlotOffset(var->slot())), kScratchRegister);
+      if (destination.is_temporary()) {
+        // Case 'temp <- (var = constant)'.  Save result.
+        __ push(kScratchRegister);
+      }

[fschneider, 2009/10/26 17:57:20]

Add an assert here to be consistent with the rest of the code:

else { ASSERT(destination.is_nowhere()); }

+    } else {
+      ASSERT(rhs->location().is_temporary());
+      Visit(rhs);
       if (destination.is_temporary()) {
         // Case 'temp1 <- (var = temp0)'.  Preserve right-hand-side temporary
         // on the stack.
         __ movq(kScratchRegister, Operand(rsp, 0));
         __ movq(Operand(rbp, SlotOffset(var->slot())), kScratchRegister);
       } else {
         ASSERT(destination.is_nowhere());
         // Case 'var = temp'.  Discard right-hand-side temporary.
         __ pop(Operand(rbp, SlotOffset(var->slot())));
       }
-    } else {
-      ASSERT(source.is_constant());
-      ASSERT(rhs->AsLiteral() != NULL);
-      // Two cases: 'temp <- (var = constant)', or 'var = constant' with a
-      // discarded result.  Always perform the assignment.
-      __ Move(kScratchRegister, rhs->AsLiteral()->handle());
-      __ movq(Operand(rbp, SlotOffset(var->slot())), kScratchRegister);
-      if (destination.is_temporary()) {
-        // Case 'temp <- (var = constant)'.  Save result.
-        __ push(kScratchRegister);
-      }
     }
   }
 }
 
 
 void FastCodeGenerator::VisitCall(Call* expr) {
   Expression* fun = expr->expression();
   ZoneList<Expression*>* args = expr->arguments();
   Variable* var = fun->AsVariableProxy()->AsVariable();
   ASSERT(var != NULL && !var->is_this() && var->is_global());
   ASSERT(!var->is_possibly_eval());
 
   __ Push(var->name());
   // Push global object (receiver).
   __ push(CodeGenerator::GlobalObject());
   int arg_count = args->length();
   for (int i = 0; i < arg_count; i++) {
     Visit(args->at(i));
-    ASSERT(!args->at(i)->location().is_nowhere());
-    if (args->at(i)->location().is_constant()) {
-      ASSERT(args->at(i)->AsLiteral() != NULL);
-      __ Push(args->at(i)->AsLiteral()->handle());
-    }
+    ASSERT(args->at(i)->location().is_temporary());
   }
   // Record source position for debugger
   SetSourcePosition(expr->position());
   // Call the IC initialization code.
   Handle<Code> ic = CodeGenerator::ComputeCallInitialize(arg_count,
                                                          NOT_IN_LOOP);
   __ call(ic, RelocInfo::CODE_TARGET_CONTEXT);
   // Restore context register.
   __ movq(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
   // Discard the function left on TOS.
@@ skipping 10 matching lines @@
   Comment cmnt(masm_, "[ CallRuntime");
   ZoneList<Expression*>* args = expr->arguments();
   Runtime::Function* function = expr->function();
 
   ASSERT(function != NULL);
 
   // Push the arguments ("left-to-right").
   int arg_count = args->length();
   for (int i = 0; i < arg_count; i++) {
     Visit(args->at(i));
-    ASSERT(!args->at(i)->location().is_nowhere());
-    if (args->at(i)->location().is_constant()) {
-      ASSERT(args->at(i)->AsLiteral() != NULL);
-      __ Push(args->at(i)->AsLiteral()->handle());
-    } else {
-      ASSERT(args->at(i)->location().is_temporary());
-      // If location is temporary, it is already on the stack,
-      // so nothing to do here.
-    }
+    ASSERT(args->at(i)->location().is_temporary());
   }
 
   __ CallRuntime(function, arg_count);
   if (expr->location().is_temporary()) {
     __ push(rax);
   } else {
     ASSERT(expr->location().is_nowhere());
   }
 }
 
 
 void FastCodeGenerator::VisitBinaryOperation(BinaryOperation* expr) {
   // Compile a short-circuited boolean or operation in a non-test
   // context.
   ASSERT(expr->op() == Token::OR);
   // Compile (e0 || e1) as if it were
   // (let (temp = e0) temp ? temp : e1).
 
   Label eval_right, done;
   Location destination = expr->location();
-  ASSERT(!destination.is_constant());
+  Expression* left = expr->left();
+  Expression* right = expr->right();
 
-  Expression* left = expr->left();
-  Location left_source = left->location();
-  ASSERT(!left_source.is_nowhere());
-
-  Expression* right = expr->right();
-  Location right_source = right->location();
-  ASSERT(!right_source.is_nowhere());
-
-  Visit(left);
   // Use the shared ToBoolean stub to find the boolean value of the
   // left-hand subexpression.  Load the value into rax to perform some
   // inlined checks assumed by the stub.
-  if (left_source.is_temporary()) {
+
+  // Compile the left-hand value into rax.  Put it on the stack if we may
+  // need it as the value of the whole expression.
+  if (left->AsLiteral() != NULL) {
+    __ Move(rax, left->AsLiteral()->handle());
+    if (destination.is_temporary()) __ push(rax);

[fschneider, 2009/10/26 17:57:20]

May want to add an assert here to be consistent with the rest of the code:

else ASSERT(destination.is_nowhere());

+  } else {
+    Visit(left);
+    ASSERT(left->location().is_temporary());
     if (destination.is_temporary()) {
       // Copy the left-hand value into rax because we may need it as the
       // final result.
       __ movq(rax, Operand(rsp, 0));
     } else {
       // Pop the left-hand value into rax because we will not need it as the
       // final result.
       __ pop(rax);

[fschneider, 2009/10/26 17:57:20]

Adding an assert to be consistent on all platforms:

ASSERT(destination.is_nowhere());

     }
-  } else {
-    // Load the left-hand value into rax.  Put it on the stack if we may
-    // need it.
-    ASSERT(left->AsLiteral() != NULL);
-    __ Move(rax, left->AsLiteral()->handle());
-    if (destination.is_temporary()) __ push(rax);
   }
   // The left-hand value is in rax.  It is also on the stack iff the
   // destination location is temporary.
 
   // Perform fast checks assumed by the stub.
   // The undefined value is false.
   __ CompareRoot(rax, Heap::kUndefinedValueRootIndex);
   __ j(equal, &eval_right);
   __ CompareRoot(rax, Heap::kTrueValueRootIndex);  // True is true.
   __ j(equal, &done);
@@ skipping 10 matching lines @@
   ToBooleanStub stub;
   __ CallStub(&stub);
   __ testq(rax, rax);  // The stub returns nonzero for true.
   __ j(not_zero, &done);
 
   __ bind(&eval_right);
   // Discard the left-hand value if present on the stack.
   if (destination.is_temporary()) {
     __ addq(rsp, Immediate(kPointerSize));
   }
-  Visit(right);
-
   // Save or discard the right-hand value as needed.
-  if (destination.is_temporary() && right_source.is_constant()) {
-    ASSERT(right->AsLiteral() != NULL);
-    __ Push(right->AsLiteral()->handle());
-  } else if (destination.is_nowhere() && right_source.is_temporary()) {
-    __ addq(rsp, Immediate(kPointerSize));
+  if (right->AsLiteral() != NULL) {
+    if (destination.is_temporary()) {
+      __ Push(right->AsLiteral()->handle());
+    } else {
+      ASSERT(destination.is_nowhere());
+    }
+  } else {
+    Visit(right);
+    ASSERT(right->location().is_temporary());
+    if (destination.is_nowhere()) {
+      __ addq(rsp, Immediate(kPointerSize));
+    } else {
+      ASSERT(destination.is_temporary());
+    }
   }
 
   __ bind(&done);
 }
 
 
 } }  // namespace v8::internal