Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 9427bb870065f7ce29d7690a17ab359e70e178d5
https://github.com/WebKit/WebKit/commit/9427bb870065f7ce29d7690a17ab359e70e178d5
Author: Yusuke Suzuki <ysuz...@apple.com>
Date: 2025-04-11 (Fri, 11 Apr 2025)
Changed paths:
M Source/JavaScriptCore/dfg/DFGLoopUnrollingPhase.cpp
Log Message:
-----------
[JSC] Fix accidental partial unrolling enablement
https://bugs.webkit.org/show_bug.cgi?id=291427
rdar://149067411
Reviewed by Yijia Huang.
We accidentally enabled partial unrolling before. This patch fixes it by
reorganizing the code.
1. shouldFullyUnroll() was called before setting initialValue / operand.
In this case, since they are initialized with CheckedInt32 INT_MIN,
it always says "true". We should not call it before setting these
fields.
2. To make (1) more defensive, we add std::monostate to std::variant of
these fields and initialize them with std::monostate (1st variant).
So, it means "nothing is set".
3. Change shouldUnrollLoop to isLoopBodyUnrollable to make it more
explicit.
4. Explicitly checking partial / full unrolling after setting
initialValue / operand. And stop unrolling when partial unrolling is
disabled.
* Source/JavaScriptCore/dfg/DFGLoopUnrollingPhase.cpp:
(JSC::DFG::LoopUnrollingPhase::tryUnroll):
(JSC::DFG::LoopUnrollingPhase::identifyInductionVariable):
(JSC::DFG::LoopUnrollingPhase::isLoopBodyUnrollable):
(JSC::DFG::LoopUnrollingPhase::LoopData::dump const):
(JSC::DFG::LoopUnrollingPhase::shouldUnrollLoop): Deleted.
Canonical link: https://commits.webkit.org/293587@main
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