Revision: 15240
Author: [email protected]
Date: Thu Jun 20 05:59:45 2013
Log: Generators: Avoid calling into runtime if operand stack is empty
This patch makes yield sites save the resume continuation and context
inline. If the operand stack is empty, we can avoid a call into the
runtime. This also makes the SuspendJSGeneratorObject runtime function
less magical: it just has to save the operand stack and stack handlers.
This speeds up the following case by a factor of 3 or so:
function* until(n) {
for (var i = 0; i < n; i++)
yield i;
}
function sum(iter) {
var sum = 0;
for (var x of iter) sum += x;
return sum;
}
for (var i = 0; i < 10000; i++) sum(until(1000))
Also, there is no more sentinel value as the generators will resume in
the right place already, allowing me to remove the hack added to the
--debug-code check in r14437.
[email protected]
BUG=
Review URL: https://codereview.chromium.org/15990004
http://code.google.com/p/v8/source/detail?r=15240
Modified:
/branches/bleeding_edge/src/arm/full-codegen-arm.cc
/branches/bleeding_edge/src/ia32/code-stubs-ia32.cc
/branches/bleeding_edge/src/ia32/full-codegen-ia32.cc
/branches/bleeding_edge/src/runtime.cc
/branches/bleeding_edge/src/x64/full-codegen-x64.cc
=======================================
--- /branches/bleeding_edge/src/arm/full-codegen-arm.cc Thu Jun 20 03:48:34
2013
+++ /branches/bleeding_edge/src/arm/full-codegen-arm.cc Thu Jun 20 05:59:45
2013
@@ -1994,14 +1994,29 @@
__ push(result_register());
// Fall through.
case Yield::INITIAL: {
- VisitForStackValue(expr->generator_object());
+ Label suspend, continuation, post_runtime, resume;
+
+ __ jmp(&suspend);
+
+ __ bind(&continuation);
+ __ jmp(&resume);
+
+ __ bind(&suspend);
+ VisitForAccumulatorValue(expr->generator_object());
+ ASSERT(continuation.pos() > 0 && Smi::IsValid(continuation.pos()));
+ __ mov(r1, Operand(Smi::FromInt(continuation.pos())));
+ __ str(r1, FieldMemOperand(r0,
JSGeneratorObject::kContinuationOffset));
+ __ str(cp, FieldMemOperand(r0, JSGeneratorObject::kContextOffset));
+ __ mov(r1, cp);
+ __ RecordWriteField(r0, JSGeneratorObject::kContextOffset, r1, r2,
+ kLRHasBeenSaved, kDontSaveFPRegs);
+ __ add(r1, fp, Operand(StandardFrameConstants::kExpressionsOffset));
+ __ cmp(sp, r1);
+ __ b(eq, &post_runtime);
+ __ push(r0); // generator object
__ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
- __ ldr(context_register(),
- MemOperand(fp, StandardFrameConstants::kContextOffset));
-
- Label resume;
- __ CompareRoot(result_register(), Heap::kTheHoleValueRootIndex);
- __ b(ne, &resume);
+ __ ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
+ __ bind(&post_runtime);
__ pop(result_register());
EmitReturnSequence();
@@ -2029,7 +2044,8 @@
// [sp + 1 * kPointerSize] iter
// [sp + 0 * kPointerSize] g
- Label l_catch, l_try, l_resume, l_next, l_call, l_loop;
+ Label l_catch, l_try, l_suspend, l_continuation, l_resume;
+ Label l_next, l_call, l_loop;
// Initial send value is undefined.
__ LoadRoot(r0, Heap::kUndefinedValueRootIndex);
__ b(&l_next);
@@ -2051,13 +2067,22 @@
__ PushTryHandler(StackHandler::CATCH, expr->index());
const int handler_size = StackHandlerConstants::kSize;
__ push(r0); // result
- __ ldr(r3, MemOperand(sp, (0 + 1) * kPointerSize + handler_size));
// g
- __ push(r3); // g
+ __ jmp(&l_suspend);
+ __ bind(&l_continuation);
+ __ jmp(&l_resume);
+ __ bind(&l_suspend);
+ const int generator_object_depth = kPointerSize + handler_size;
+ __ ldr(r0, MemOperand(sp, generator_object_depth));
+ __ push(r0); // g
+ ASSERT(l_continuation.pos() > 0 &&
Smi::IsValid(l_continuation.pos()));
+ __ mov(r1, Operand(Smi::FromInt(l_continuation.pos())));
+ __ str(r1, FieldMemOperand(r0,
JSGeneratorObject::kContinuationOffset));
+ __ str(cp, FieldMemOperand(r0, JSGeneratorObject::kContextOffset));
+ __ mov(r1, cp);
+ __ RecordWriteField(r0, JSGeneratorObject::kContextOffset, r1, r2,
+ kLRHasBeenSaved, kDontSaveFPRegs);
__ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
- __ ldr(context_register(),
- MemOperand(fp, StandardFrameConstants::kContextOffset));
- __ CompareRoot(r0, Heap::kTheHoleValueRootIndex);
- __ b(ne, &l_resume);
+ __ ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
__ pop(r0); // result
EmitReturnSequence();
__ bind(&l_resume); // received in r0
=======================================
--- /branches/bleeding_edge/src/ia32/code-stubs-ia32.cc Fri Jun 14 09:06:12
2013
+++ /branches/bleeding_edge/src/ia32/code-stubs-ia32.cc Thu Jun 20 05:59:45
2013
@@ -5050,11 +5050,6 @@
Label okay;
__ cmp(eax, masm->isolate()->factory()->the_hole_value());
__ j(not_equal, &okay, Label::kNear);
- // TODO(wingo): Currently SuspendJSGeneratorObject returns the hole.
Change
- // to return another sentinel like a harmony symbol.
- __ cmp(ebx, Immediate(ExternalReference(
- Runtime::kSuspendJSGeneratorObject, masm->isolate())));
- __ j(equal, &okay, Label::kNear);
__ int3();
__ bind(&okay);
}
=======================================
--- /branches/bleeding_edge/src/ia32/full-codegen-ia32.cc Thu Jun 20
03:48:34 2013
+++ /branches/bleeding_edge/src/ia32/full-codegen-ia32.cc Thu Jun 20
05:59:45 2013
@@ -1953,14 +1953,30 @@
__ push(result_register());
// Fall through.
case Yield::INITIAL: {
- VisitForStackValue(expr->generator_object());
+ Label suspend, continuation, post_runtime, resume;
+
+ __ jmp(&suspend);
+
+ __ bind(&continuation);
+ __ jmp(&resume);
+
+ __ bind(&suspend);
+ VisitForAccumulatorValue(expr->generator_object());
+ ASSERT(continuation.pos() > 0 && Smi::IsValid(continuation.pos()));
+ __ mov(FieldOperand(eax, JSGeneratorObject::kContinuationOffset),
+ Immediate(Smi::FromInt(continuation.pos())));
+ __ mov(FieldOperand(eax, JSGeneratorObject::kContextOffset), esi);
+ __ mov(ecx, esi);
+ __ RecordWriteField(eax, JSGeneratorObject::kContextOffset, ecx, edx,
+ kDontSaveFPRegs);
+ __ lea(ebx, Operand(ebp,
StandardFrameConstants::kExpressionsOffset));
+ __ cmp(esp, ebx);
+ __ j(equal, &post_runtime);
+ __ push(eax); // generator object
__ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
__ mov(context_register(),
Operand(ebp, StandardFrameConstants::kContextOffset));
-
- Label resume;
- __ CompareRoot(result_register(), Heap::kTheHoleValueRootIndex);
- __ j(not_equal, &resume);
+ __ bind(&post_runtime);
__ pop(result_register());
EmitReturnSequence();
@@ -1988,7 +2004,8 @@
// [sp + 1 * kPointerSize] iter
// [sp + 0 * kPointerSize] g
- Label l_catch, l_try, l_resume, l_next, l_call, l_loop;
+ Label l_catch, l_try, l_suspend, l_continuation, l_resume;
+ Label l_next, l_call, l_loop;
// Initial send value is undefined.
__ mov(eax, isolate()->factory()->undefined_value());
__ jmp(&l_next);
@@ -2010,12 +2027,23 @@
__ PushTryHandler(StackHandler::CATCH, expr->index());
const int handler_size = StackHandlerConstants::kSize;
__ push(eax); // result
- __ push(Operand(esp, (0 + 1) * kPointerSize + handler_size)); // g
+ __ jmp(&l_suspend);
+ __ bind(&l_continuation);
+ __ jmp(&l_resume);
+ __ bind(&l_suspend);
+ const int generator_object_depth = kPointerSize + handler_size;
+ __ mov(eax, Operand(esp, generator_object_depth));
+ __ push(eax); // g
+ ASSERT(l_continuation.pos() > 0 &&
Smi::IsValid(l_continuation.pos()));
+ __ mov(FieldOperand(eax, JSGeneratorObject::kContinuationOffset),
+ Immediate(Smi::FromInt(l_continuation.pos())));
+ __ mov(FieldOperand(eax, JSGeneratorObject::kContextOffset), esi);
+ __ mov(ecx, esi);
+ __ RecordWriteField(eax, JSGeneratorObject::kContextOffset, ecx, edx,
+ kDontSaveFPRegs);
__ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
__ mov(context_register(),
Operand(ebp, StandardFrameConstants::kContextOffset));
- __ CompareRoot(eax, Heap::kTheHoleValueRootIndex);
- __ j(not_equal, &l_resume);
__ pop(eax); // result
EmitReturnSequence();
__ bind(&l_resume); // received in eax
=======================================
--- /branches/bleeding_edge/src/runtime.cc Wed Jun 19 04:53:30 2013
+++ /branches/bleeding_edge/src/runtime.cc Thu Jun 20 05:59:45 2013
@@ -2583,18 +2583,23 @@
JavaScriptFrameIterator stack_iterator(isolate);
JavaScriptFrame* frame = stack_iterator.frame();
- JSFunction* function = JSFunction::cast(frame->function());
- RUNTIME_ASSERT(function->shared()->is_generator());
- ASSERT_EQ(function, generator_object->function());
+
RUNTIME_ASSERT(JSFunction::cast(frame->function())->shared()->is_generator());
+ ASSERT_EQ(JSFunction::cast(frame->function()),
generator_object->function());
+
+ // The caller should have saved the context and continuation already.
+ ASSERT_EQ(generator_object->context(), Context::cast(frame->context()));
+ ASSERT_LT(0, generator_object->continuation());
// We expect there to be at least two values on the operand stack: the
return
// value of the yield expression, and the argument to this runtime call.
// Neither of those should be saved.
int operands_count = frame->ComputeOperandsCount();
- ASSERT(operands_count >= 2);
+ ASSERT_GE(operands_count, 2);
operands_count -= 2;
if (operands_count == 0) {
+ // Although it's semantically harmless to call this function with an
+ // operands_count of zero, it is also unnecessary.
ASSERT_EQ(generator_object->operand_stack(),
isolate->heap()->empty_fixed_array());
ASSERT_EQ(generator_object->stack_handler_index(), -1);
@@ -2611,20 +2616,7 @@
generator_object->set_stack_handler_index(stack_handler_index);
}
- // Set continuation down here to avoid side effects if the operand stack
- // allocation fails.
- intptr_t offset = frame->pc() - function->code()->instruction_start();
- ASSERT(offset > 0 && Smi::IsValid(offset));
- generator_object->set_continuation(static_cast<int>(offset));
-
- // It's possible for the context to be other than the initial context
even if
- // there is no stack handler active. For example, this is the case in
the
- // body of a "with" statement. Therefore we always save the context.
- generator_object->set_context(Context::cast(frame->context()));
-
- // The return value is the hole for a suspend return, and anything else
for a
- // resume return.
- return isolate->heap()->the_hole_value();
+ return isolate->heap()->undefined_value();
}
=======================================
--- /branches/bleeding_edge/src/x64/full-codegen-x64.cc Fri Jun 14 04:35:00
2013
+++ /branches/bleeding_edge/src/x64/full-codegen-x64.cc Thu Jun 20 05:59:45
2013
@@ -1976,14 +1976,31 @@
__ push(result_register());
// Fall through.
case Yield::INITIAL: {
- VisitForStackValue(expr->generator_object());
+ Label suspend, continuation, post_runtime, resume;
+
+ __ jmp(&suspend);
+
+ __ bind(&continuation);
+ __ jmp(&resume);
+
+ __ bind(&suspend);
+ VisitForAccumulatorValue(expr->generator_object());
+ ASSERT(continuation.pos() > 0 && Smi::IsValid(continuation.pos()));
+ __ Move(FieldOperand(rax, JSGeneratorObject::kContinuationOffset),
+ Smi::FromInt(continuation.pos()));
+ __ movq(FieldOperand(rax, JSGeneratorObject::kContextOffset), rsi);
+ __ movq(rcx, rsi);
+ __ RecordWriteField(rax, JSGeneratorObject::kContextOffset, rcx, rdx,
+ kDontSaveFPRegs);
+ __ lea(rbx, Operand(rbp,
StandardFrameConstants::kExpressionsOffset));
+ __ cmpq(rsp, rbx);
+ __ j(equal, &post_runtime);
+ __ push(rax); // generator object
__ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
__ movq(context_register(),
Operand(rbp, StandardFrameConstants::kContextOffset));
+ __ bind(&post_runtime);
- Label resume;
- __ CompareRoot(result_register(), Heap::kTheHoleValueRootIndex);
- __ j(not_equal, &resume);
__ pop(result_register());
EmitReturnSequence();
@@ -2011,7 +2028,8 @@
// [sp + 1 * kPointerSize] iter
// [sp + 0 * kPointerSize] g
- Label l_catch, l_try, l_resume, l_next, l_call, l_loop;
+ Label l_catch, l_try, l_suspend, l_continuation, l_resume;
+ Label l_next, l_call, l_loop;
// Initial send value is undefined.
__ LoadRoot(rax, Heap::kUndefinedValueRootIndex);
__ jmp(&l_next);
@@ -2033,12 +2051,23 @@
__ PushTryHandler(StackHandler::CATCH, expr->index());
const int handler_size = StackHandlerConstants::kSize;
__ push(rax); // result
- __ push(Operand(rsp, (0 + 1) * kPointerSize + handler_size)); // g
+ __ jmp(&l_suspend);
+ __ bind(&l_continuation);
+ __ jmp(&l_resume);
+ __ bind(&l_suspend);
+ const int generator_object_depth = kPointerSize + handler_size;
+ __ movq(rax, Operand(rsp, generator_object_depth));
+ __ push(rax); // g
+ ASSERT(l_continuation.pos() > 0 &&
Smi::IsValid(l_continuation.pos()));
+ __ Move(FieldOperand(rax, JSGeneratorObject::kContinuationOffset),
+ Smi::FromInt(l_continuation.pos()));
+ __ movq(FieldOperand(rax, JSGeneratorObject::kContextOffset), rsi);
+ __ movq(rcx, rsi);
+ __ RecordWriteField(rax, JSGeneratorObject::kContextOffset, rcx, rdx,
+ kDontSaveFPRegs);
__ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
__ movq(context_register(),
Operand(rbp, StandardFrameConstants::kContextOffset));
- __ CompareRoot(rax, Heap::kTheHoleValueRootIndex);
- __ j(not_equal, &l_resume);
__ pop(rax); // result
EmitReturnSequence();
__ bind(&l_resume); // received in rax
--
--
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