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[TurboFan] Add DCHECK to FunctionBlueprint equality

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A slow dcheck can verify that hints are equal for the same
SharedFunctionInfo+FeedbackVector combo.

Bug: v8:7790
Change-Id: I43dcacf19c857770b609d13c310835a873c814fe
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1835952
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64109}
This commit is contained in:
Mike Stanton 2019-10-04 13:41:20 +02:00 committed by Commit Bot
parent 1200f3c95b
commit 18a8548d2f
1 changed files with 13 additions and 2 deletions
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15
src/compiler/serializer-for-background-compilation.cc
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@ -339,10 +339,21 @@ class FunctionBlueprint {
const Hints& context_hints() const { return context_hints_; }
bool operator==(const FunctionBlueprint& other) const {
// A feedback vector is never used for more than one SFI, so it can
// be used for equality of blueprints.
// A feedback vector is never used for more than one SFI. Moreover, we can
// never have two blueprints with identical feedback vector (and SFI) but
// different hints, because:
// (1) A blueprint originates either (i) from the data associated with a
// CreateClosure bytecode, in which case two different CreateClosure
// bytecodes never have the same feedback vector, or (ii) from a
// JSFunction, in which case the hints are determined by the closure.
// (2) We never extend a blueprint's hints after construction.
//
// It is therefore sufficient to look at the feedback vector in order to
// decide equality.
DCHECK_IMPLIES(feedback_vector_.equals(other.feedback_vector_),
shared_.equals(other.shared_));
SLOW_DCHECK(!feedback_vector_.equals(other.feedback_vector_) ||
context_hints_.Equals(other.context_hints_));
return feedback_vector_.equals(other.feedback_vector_);
}