Bug 263660
| Summary: | REGRESSION(269608@main): 32-bit shifts are used to zero out upper 32-bits after all. | ||
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| Product: | WebKit | Reporter: | Mark Lam <mark.lam> |
| Component: | JavaScriptCore | Assignee: | Mark Lam <mark.lam> |
| Status: | RESOLVED FIXED | ||
| Severity: | Normal | CC: | webkit-bug-importer |
| Priority: | P2 | Keywords: | InRadar |
| Version: | WebKit Nightly Build | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
Mark Lam
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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| Add attachment proposed patch, testcase, etc. |
Radar WebKit Bug Importer
<rdar://problem/117475957>
Mark Lam
Pull request: https://github.com/WebKit/WebKit/pull/19543
EWS
Committed 269785@main (748f4d4620ab): <https://commits.webkit.org/269785@main>
Reviewed commits have been landed. Closing PR #19543 and removing active labels.