Fast-codegen: Implementing try/finally on top of nesting context.

Review URL: http://codereview.chromium.org/492002


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3461 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
lrn@chromium.org 2009-12-14 11:09:25 +00:00
parent d225baa2b5
commit 9ff5f9daed
9 changed files with 226 additions and 6 deletions

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@ -1681,6 +1681,7 @@ void FastCodeGenerator::VisitCompareOperation(CompareOperation* expr) {
// Convert current context to test context: End post-test code. // Convert current context to test context: End post-test code.
} }
void FastCodeGenerator::VisitThisFunction(ThisFunction* expr) { void FastCodeGenerator::VisitThisFunction(ThisFunction* expr) {
__ ldr(r0, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset)); __ ldr(r0, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
Move(expr->context(), r0); Move(expr->context(), r0);
@ -1689,7 +1690,40 @@ void FastCodeGenerator::VisitThisFunction(ThisFunction* expr) {
Register FastCodeGenerator::result_register() { return r0; } Register FastCodeGenerator::result_register() { return r0; }
// ----------------------------------------------------------------------------
// Non-local control flow support.
void FastCodeGenerator::EnterFinallyBlock() {
ASSERT(!result_register().is(r1));
// Cook return address in link register to stack (smi encoded Code* delta)
__ sub(r1, lr, Operand(masm_->CodeObject()));
ASSERT_EQ(1, kSmiTagSize + kSmiShiftSize);
ASSERT_EQ(0, kSmiTag);
__ add(r1, r1, Operand(r1)); // Convert to smi.
__ push(r1);
// Store result register while executing finally block.
__ push(result_register());
}
void FastCodeGenerator::ExitFinallyBlock() {
ASSERT(!result_register().is(r1));
// Restore result register from stack.
__ pop(result_register());
// Uncook return address and return.
__ pop(r1);
ASSERT_EQ(1, kSmiTagSize + kSmiShiftSize);
__ mov(r1, Operand(r1, ASR, 1)); // Un-smi-tag value.
__ add(pc, r1, Operand(masm_->CodeObject()));
}
void FastCodeGenerator::ThrowException() {
__ push(result_register());
__ CallRuntime(Runtime::kThrow, 1);
}
#undef __ #undef __
} } // namespace v8::internal } } // namespace v8::internal

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@ -751,7 +751,9 @@ void CodeGenSelector::VisitTryCatchStatement(TryCatchStatement* stmt) {
void CodeGenSelector::VisitTryFinallyStatement(TryFinallyStatement* stmt) { void CodeGenSelector::VisitTryFinallyStatement(TryFinallyStatement* stmt) {
BAILOUT("TryFinallyStatement"); Visit(stmt->try_block());
CHECK_BAILOUT;
Visit(stmt->finally_block());
} }

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@ -443,7 +443,63 @@ void FastCodeGenerator::VisitTryCatchStatement(TryCatchStatement* stmt) {
void FastCodeGenerator::VisitTryFinallyStatement(TryFinallyStatement* stmt) { void FastCodeGenerator::VisitTryFinallyStatement(TryFinallyStatement* stmt) {
UNREACHABLE(); // Try finally is compiled by setting up a try-handler on the stack while
// executing the try body, and removing it again afterwards.
//
// The try-finally construct can enter the finally block in three ways:
// 1. By exiting the try-block normally. This removes the try-handler and
// calls the finally block code before continuing.
// 2. By exiting the try-block with a function-local control flow transfer
// (break/continue/return). The site of the, e.g., break removes the
// try handler and calls the finally block code before continuing
// its outward control transfer.
// 3. by exiting the try-block with a thrown exception.
// This can happen in nested function calls. It traverses the try-handler
// chaing and consumes the try-handler entry before jumping to the
// handler code. The handler code then calls the finally-block before
// rethrowing the exception.
//
// The finally block must assume a return address on top of the stack
// (or in the link register on ARM chips) and a value (return value or
// exception) in the result register (rax/eax/r0), both of which must
// be preserved. The return address isn't GC-safe, so it should be
// cooked before GC.
Label finally_entry;
Label try_handler_setup;
// Setup the try-handler chain. Use a call to
// Jump to try-handler setup and try-block code. Use call to put try-handler
// address on stack.
__ Call(&try_handler_setup);
// Try handler code. Return address of call is pushed on handler stack.
{
// This code is only executed during stack-handler traversal when an
// exception is thrown. The execption is in the result register, which
// is retained by the finally block.
// Call the finally block and then rethrow the exception.
__ Call(&finally_entry);
ThrowException();
}
__ bind(&finally_entry);
{
// Finally block implementation.
EnterFinallyBlock();
Finally finally_block(this);
Visit(stmt->finally_block());
ExitFinallyBlock(); // Return to the calling code.
}
__ bind(&try_handler_setup);
{
// Setup try handler (stack pointer registers).
__ PushTryHandler(IN_JAVASCRIPT, TRY_FINALLY_HANDLER);
TryFinally try_block(this, &finally_entry);
VisitStatements(stmt->try_block()->statements());
__ PopTryHandler();
}
// Execute the finally block on the way out.
__ Call(&finally_entry);
} }

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@ -276,6 +276,12 @@ class FastCodeGenerator: public AstVisitor {
void SetStatementPosition(Statement* stmt); void SetStatementPosition(Statement* stmt);
void SetSourcePosition(int pos); void SetSourcePosition(int pos);
// Non-local control flow support.
void EnterFinallyBlock();
void ExitFinallyBlock();
void ThrowException();
// Loop nesting counter.
int loop_depth() { return loop_depth_; } int loop_depth() { return loop_depth_; }
void increment_loop_depth() { loop_depth_++; } void increment_loop_depth() { loop_depth_++; }
void decrement_loop_depth() { void decrement_loop_depth() {

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@ -1656,14 +1656,51 @@ void FastCodeGenerator::VisitCompareOperation(CompareOperation* expr) {
// Convert current context to test context: End post-test code. // Convert current context to test context: End post-test code.
} }
Register FastCodeGenerator::result_register() { return eax; }
void FastCodeGenerator::VisitThisFunction(ThisFunction* expr) { void FastCodeGenerator::VisitThisFunction(ThisFunction* expr) {
__ mov(eax, Operand(ebp, JavaScriptFrameConstants::kFunctionOffset)); __ mov(eax, Operand(ebp, JavaScriptFrameConstants::kFunctionOffset));
Move(expr->context(), eax); Move(expr->context(), eax);
} }
Register FastCodeGenerator::result_register() { return eax; }
// ----------------------------------------------------------------------------
// Non-local control flow support.
void FastCodeGenerator::EnterFinallyBlock() {
// Cook return address on top of stack (smi encoded Code* delta)
ASSERT(!result_register().is(edx));
__ mov(edx, Operand(esp, 0));
__ sub(Operand(edx), Immediate(masm_->CodeObject()));
ASSERT_EQ(1, kSmiTagSize + kSmiShiftSize);
ASSERT_EQ(0, kSmiTag);
__ add(edx, Operand(edx)); // Convert to smi.
__ mov(Operand(esp, 0), edx);
// Store result register while executing finally block.
__ push(result_register());
}
void FastCodeGenerator::ExitFinallyBlock() {
ASSERT(!result_register().is(edx));
// Restore result register from stack.
__ pop(result_register());
// Uncook return address.
__ mov(edx, Operand(esp, 0));
__ sar(edx, 1); // Convert smi to int.
__ add(Operand(edx), Immediate(masm_->CodeObject()));
__ mov(Operand(esp, 0), edx);
// And return.
__ ret(0);
}
void FastCodeGenerator::ThrowException() {
__ push(result_register());
__ CallRuntime(Runtime::kThrow, 1);
}
#undef __ #undef __
} } // namespace v8::internal } } // namespace v8::internal

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@ -152,7 +152,6 @@ class MacroAssembler: public Assembler {
// Unlink the stack handler on top of the stack from the try handler chain. // Unlink the stack handler on top of the stack from the try handler chain.
void PopTryHandler(); void PopTryHandler();
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
// Inline caching support // Inline caching support

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@ -1671,6 +1671,45 @@ void FastCodeGenerator::VisitThisFunction(ThisFunction* expr) {
Register FastCodeGenerator::result_register() { return rax; } Register FastCodeGenerator::result_register() { return rax; }
// ----------------------------------------------------------------------------
// Non-local control flow support.
void FastCodeGenerator::EnterFinallyBlock() {
ASSERT(!result_register().is(rdx));
ASSERT(!result_register().is(rcx));
// Cook return address on top of stack (smi encoded Code* delta)
__ movq(rdx, Operand(rsp, 0));
__ Move(rcx, masm_->CodeObject());
__ subq(rdx, rcx);
__ Integer32ToSmi(rdx, rdx);
__ movq(Operand(rsp, 0), rdx);
// Store result register while executing finally block.
__ push(result_register());
}
void FastCodeGenerator::ExitFinallyBlock() {
ASSERT(!result_register().is(rdx));
ASSERT(!result_register().is(rcx));
// Restore result register from stack.
__ pop(result_register());
// Uncook return address.
__ movq(rdx, Operand(rsp, 0));
__ SmiToInteger32(rdx, rdx);
__ Move(rcx, masm_->CodeObject());
__ addq(rdx, rcx);
__ movq(Operand(rsp, 0), rdx);
// And return.
__ ret(0);
}
void FastCodeGenerator::ThrowException() {
__ push(result_register());
__ CallRuntime(Runtime::kThrow, 1);
}
#undef __ #undef __

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@ -1440,8 +1440,10 @@ void MacroAssembler::PushTryHandler(CodeLocation try_location,
void MacroAssembler::PopTryHandler() { void MacroAssembler::PopTryHandler() {
ASSERT_EQ(0, StackHandlerConstants::kNextOffset); ASSERT_EQ(0, StackHandlerConstants::kNextOffset);
// Unlink this handler.
movq(kScratchRegister, ExternalReference(Top::k_handler_address)); movq(kScratchRegister, ExternalReference(Top::k_handler_address));
pop(Operand(kScratchRegister, 0)); pop(Operand(kScratchRegister, 0));
// Remove the remaining fields.
addq(rsp, Immediate(StackHandlerConstants::kSize - kPointerSize)); addq(rsp, Immediate(StackHandlerConstants::kSize - kPointerSize));
} }

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@ -347,3 +347,48 @@ assertTrue(broke);
assertFalse(caught); assertFalse(caught);
assertTrue(finalized); assertTrue(finalized);
function return_from_nested_finally_in_finally() {
try {
return 1;
} finally {
try {
return 2;
} finally {
return 42;
}
}
}
assertEquals(42, return_from_nested_finally_in_finally());
function break_from_nested_finally_in_finally() {
L: try {
return 1;
} finally {
try {
return 2;
} finally {
break L;
}
}
return 42;
}
assertEquals(42, break_from_nested_finally_in_finally());
function continue_from_nested_finally_in_finally() {
do {
try {
return 1;
} finally {
try {
return 2;
} finally {
continue;
}
}
} while (false);
return 42;
}
assertEquals(42, continue_from_nested_finally_in_finally());