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Redo "[dart2js] Avoid premature interceptor optimizations"
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This reverts commit fc349bd.

Change-Id: Idb991651abdd8a60a1a2ef838f7396ad6c892223
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/194207
Reviewed-by: Stephen Adams <sra@google.com>
Commit-Queue: Stephen Adams <sra@google.com>
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@rakudrama
rakudrama authored and commit-bot@chromium.org committed Apr 8, 2021
1 parent 6af4987 commit 2f327a6
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Showing 6 changed files with 269 additions and 151 deletions.
3 changes: 1 addition & 2 deletions pkg/compiler/lib/src/ssa/codegen.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -414,8 +414,7 @@ class SsaCodeGenerator implements HVisitor, HBlockInformationVisitor {
assert(graph.isValid(), 'Graph not valid after ${phase.name}');
}

runPhase(
new SsaInstructionSelection(_options, _closedWorld, _interceptorData));
runPhase(new SsaInstructionSelection(_options, _closedWorld));
runPhase(new SsaTypeKnownRemover());
runPhase(new SsaTrustedCheckRemover(_options));
runPhase(new SsaAssignmentChaining(_closedWorld));
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132 changes: 1 addition & 131 deletions pkg/compiler/lib/src/ssa/codegen_helpers.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,6 @@
import '../constants/values.dart';
import '../elements/entities.dart';
import '../inferrer/abstract_value_domain.dart';
import '../js_backend/interceptor_data.dart';
import '../options.dart';
import '../universe/selector.dart' show Selector;
import '../world.dart' show JClosedWorld;
Expand All @@ -27,21 +26,14 @@ bool canUseAliasedSuperMember(MemberEntity member, Selector selector) {
///
/// - Remove NullChecks where the next instruction would fail on the operand.
///
/// - Dummy receiver optimization.
///
/// - One-shot interceptor optimization.
///
/// - Combine read/modify/write sequences into HReadModifyWrite instructions to
/// simplify codegen of expressions like `a.x += y`.
class SsaInstructionSelection extends HBaseVisitor with CodegenPhase {
final JClosedWorld _closedWorld;
final InterceptorData _interceptorData;
final CompilerOptions _options;
HGraph graph;

SsaInstructionSelection(
this._options, this._closedWorld, this._interceptorData);
SsaInstructionSelection(this._options, this._closedWorld);

AbstractValueDomain get _abstractValueDomain =>
_closedWorld.abstractValueDomain;
Expand Down Expand Up @@ -228,128 +220,6 @@ class SsaInstructionSelection extends HBaseVisitor with CodegenPhase {
.isInterceptor(_abstractValueDomain.excludeNull(type))
.isPotentiallyTrue;

@override
HInstruction visitInvokeDynamic(HInvokeDynamic node) {
if (!node.isInterceptedCall) return node;

tryReplaceExplicitReceiverWithDummy(
node, node.selector, node.element, node.receiverType);

// Try to replace
//
// getInterceptor(o).method(o, ...)
//
// with a 'one shot interceptor' which is a call to a synthesized static
// helper function that combines the two operations.
//
// oneShotMethod(o, 1, 2)
//
// This saves code size and makes the receiver of an intercepted call a
// candidate for being generated at use site.
//
// Avoid combining a hoisted interceptor back into a loop, and the faster
// almost-constant kind of interceptor.

HInstruction interceptor = node.inputs[0];
if (interceptor is HInterceptor &&
interceptor.usedBy.length == 1 &&
!interceptor.isConditionalConstantInterceptor &&
interceptor.hasSameLoopHeaderAs(node)) {
// Copy inputs and replace interceptor with `null`.
List<HInstruction> inputs = List.of(node.inputs);
inputs[0] = graph.addConstantNull(_closedWorld);

HOneShotInterceptor oneShot = HOneShotInterceptor(
node.selector,
node.receiverType,
inputs,
node.instructionType,
node.typeArguments,
interceptor.interceptedClasses);
oneShot.sourceInformation = node.sourceInformation;
oneShot.sourceElement = node.sourceElement;
oneShot.sideEffects.setTo(node.sideEffects);

HBasicBlock block = node.block;
block.addAfter(node, oneShot);
block.rewrite(node, oneShot);
block.remove(node);
interceptor.block.remove(interceptor);
return null;
}

return node;
}

@override
HInstruction visitInvokeSuper(HInvokeSuper node) {
tryReplaceExplicitReceiverWithDummy(
node, node.selector, node.element, null);
return node;
}

@override
HInstruction visitOneShotInterceptor(HOneShotInterceptor node) {
throw StateError('Should not see HOneShotInterceptor: $node');
}

void tryReplaceExplicitReceiverWithDummy(HInvoke node, Selector selector,
MemberEntity target, AbstractValue mask) {
// Calls of the form
//
// a.foo$1(a, x)
//
// where the interceptor calling convention is used come from recognizing
// that 'a' is a 'self-interceptor'. If the selector matches only methods
// that ignore the explicit receiver parameter, replace occurrences of the
// receiver argument with a dummy receiver '0':
//
// a.foo$1(a, x) ---> a.foo$1(0, x)
//
// This often reduces the number of references to 'a' to one, allowing 'a'
// to be generated at use to avoid a temporary, e.g.
//
// t1 = b.get$thing();
// t1.foo$1(t1, x)
// --->
// b.get$thing().foo$1(0, x)
//
assert(target != null || mask != null);

if (!node.isInterceptedCall) return;

// TODO(15933): Make automatically generated property extraction closures
// work with the dummy receiver optimization.
if (selector.isGetter) return;

// This assignment of inputs is uniform for HInvokeDynamic and HInvokeSuper.
HInstruction interceptor = node.inputs[0];
HInstruction receiverArgument = node.inputs[1];

// A 'self-interceptor'?
if (interceptor.nonCheck() != receiverArgument.nonCheck()) return;

// TODO(sra): Should this be an assert?
if (!_interceptorData.isInterceptedSelector(selector)) return;

if (target != null) {
// A call that resolves to a single instance method (element) requires the
// calling convention consistent with the method.
ClassEntity cls = target.enclosingClass;
assert(_interceptorData.isInterceptedMethod(target));
if (_interceptorData.isInterceptedClass(cls)) return;
} else if (_interceptorData.isInterceptedMixinSelector(
selector, mask, _closedWorld)) {
return;
}

ConstantValue constant = DummyInterceptorConstantValue();
HConstant dummy = graph.addConstant(constant, _closedWorld);
receiverArgument.usedBy.remove(node);
node.inputs[1] = dummy;
dummy.usedBy.add(node);
}

@override
HInstruction visitFieldSet(HFieldSet setter) {
// Pattern match
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