RESOLVED FIXED 263660
REGRESSION(269608@main): 32-bit shifts are used to zero out upper 32-bits after all. 
https://bugs.webkit.org/show_bug.cgi?id=263660
Summary REGRESSION(269608@main): 32-bit shifts are used to zero out upper 32-bits aft...
Mark Lam
Reported 2023-10-25 08:22:37 PDT
In https://commits.webkit.org/269608@main, we added a peephole optimization to reduce shifts to moves if the shift amount is 0. However, this is only correct if shift instructions are never used indirectly to zero out the upper 32-bits of the register. It turns out that the JIT backends do rely on shifts to zero out the upper 32-bits.
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Radar WebKit Bug Importer
Comment 1 2023-10-25 08:22:56 PDT
<rdar://problem/117475957>
Mark Lam
Comment 2 2023-10-25 09:25:51 PDT
Pull request: https://github.com/WebKit/WebKit/pull/19543
EWS
Comment 3 2023-10-25 14:39:02 PDT
Committed 269785@main (748f4d4620ab): <https://commits.webkit.org/269785@main> Reviewed commits have been landed. Closing PR #19543 and removing active labels.
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