← WebKit — 2026-W41
c5cb0e0f45e4a389cc7074b23e036d4da6af7b39 [JSC] Do some micro-optimization about bit-ops in MacroAssembler
not a security fix
confidence 0.1
signal score 10.22
Source/JavaScriptCore/assembler
Classified as not security-relevant.
Triage note: Adds peephole fast paths to MacroAssemblerARM64 and/or/lshift with immediates (imm==0, imm==-1, 0xffffffff, shift masking) and a large unit-test harness (checkRegisterImmediateOp, aliasing cases, expectedBranchArithTaken). The old slow fallback already produced correct results (0/-1 are non-encodable logical immediates and fell through); this is optimization plus tests, no miscompile fixed.
This commit was flagged by the signal scorer and reviewed by AI (not a human). It is listed only so the triage is auditable; there is no root-cause analysis because this is not a vulnerability fix.
Triage note: Adds peephole fast paths to MacroAssemblerARM64 and/or/lshift with immediates (imm==0, imm==-1, 0xffffffff, shift masking) and a large unit-test harness (checkRegisterImmediateOp, aliasing cases, expectedBranchArithTaken). The old slow fallback already produced correct results (0/-1 are non-encodable logical immediates and fell through); this is optimization plus tests, no miscompile fixed.
This commit was flagged by the signal scorer and reviewed by AI (not a human). It is listed only so the triage is auditable; there is no root-cause analysis because this is not a vulnerability fix.
Structural signals: checked_int (+5.39), security_assert (+4.87), null_guard (+1.95), large_churn (-2.0)
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