Reviewers: Paul Lind, kisg, wingo, danno, kilvadyb,
Description:
MIPS: Generators: Avoid calling into runtime if operand stack is empty
Port r15240 (909f716e)
Original commit message:
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.
BUG=
Please review this at https://codereview.chromium.org/17291016/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/mips/full-codegen-mips.cc
Index: src/mips/full-codegen-mips.cc
diff --git a/src/mips/full-codegen-mips.cc b/src/mips/full-codegen-mips.cc
index
06226ca671d0372a2068bbe055fc7d80c3ace75e..7ef9fd6c04031719d2826791f308a264815b44fd
100644
--- a/src/mips/full-codegen-mips.cc
+++ b/src/mips/full-codegen-mips.cc
@@ -2001,14 +2001,28 @@ void FullCodeGenerator::VisitYield(Yield* expr) {
__ push(result_register());
// Fall through.
case Yield::INITIAL: {
- VisitForStackValue(expr->generator_object());
- __ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
- __ lw(context_register(),
- MemOperand(fp, StandardFrameConstants::kContextOffset));
+ Label suspend, continuation, post_runtime, resume;
- Label resume;
- __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
- __ Branch(&resume, ne, result_register(), Operand(at));
+ __ jmp(&suspend);
+
+ __ bind(&continuation);
+ __ jmp(&resume);
+
+ __ bind(&suspend);
+ VisitForAccumulatorValue(expr->generator_object());
+ ASSERT(continuation.pos() > 0 && Smi::IsValid(continuation.pos()));
+ __ li(a1, Operand(Smi::FromInt(continuation.pos())));
+ __ sw(a1, FieldMemOperand(v0,
JSGeneratorObject::kContinuationOffset));
+ __ sw(cp, FieldMemOperand(v0, JSGeneratorObject::kContextOffset));
+ __ mov(a1, cp);
+ __ RecordWriteField(v0, JSGeneratorObject::kContextOffset, a1, a2,
+ kRAHasBeenSaved, kDontSaveFPRegs);
+ __ Addu(a1, fp, Operand(StandardFrameConstants::kExpressionsOffset));
+ __ Branch(&post_runtime, eq, sp, Operand(a1));
+ __ push(v0); // generator object
+ __ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
+ __ lw(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
+ __ bind(&post_runtime);
__ pop(result_register());
EmitReturnSequence();
@@ -2036,7 +2050,8 @@ void FullCodeGenerator::VisitYield(Yield* expr) {
// [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(a0, Heap::kUndefinedValueRootIndex);
__ Branch(&l_next);
@@ -2059,14 +2074,23 @@ void FullCodeGenerator::VisitYield(Yield* expr) {
__ PushTryHandler(StackHandler::CATCH, expr->index());
const int handler_size = StackHandlerConstants::kSize;
__ push(a0); // result
- __ lw(a3, MemOperand(sp, (0 + 1) * kPointerSize + handler_size));
// g
- __ push(a3); // g
- __ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
+ __ jmp(&l_suspend);
+ __ bind(&l_continuation);
__ mov(a0, v0);
- __ lw(context_register(),
- MemOperand(fp, StandardFrameConstants::kContextOffset));
- __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
- __ Branch(&l_resume, ne, a0, Operand(at));
+ __ jmp(&l_resume);
+ __ bind(&l_suspend);
+ const int generator_object_depth = kPointerSize + handler_size;
+ __ lw(a0, MemOperand(sp, generator_object_depth));
+ __ push(a0); // g
+ ASSERT(l_continuation.pos() > 0 &&
Smi::IsValid(l_continuation.pos()));
+ __ li(a1, Operand(Smi::FromInt(l_continuation.pos())));
+ __ sw(a1, FieldMemOperand(a0,
JSGeneratorObject::kContinuationOffset));
+ __ sw(cp, FieldMemOperand(a0, JSGeneratorObject::kContextOffset));
+ __ mov(a1, cp);
+ __ RecordWriteField(a0, JSGeneratorObject::kContextOffset, a1, a2,
+ kRAHasBeenSaved, kDontSaveFPRegs);
+ __ CallRuntime(Runtime::kSuspendJSGeneratorObject, 1);
+ __ lw(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
__ pop(v0); // result
EmitReturnSequence();
__ mov(a0, v0);
--
--
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