270971 2024-03-14 05:26:29 -0700 Unpredictable temporary selection in offlineasm 2024-05-16 01:53:34 -0700 1 1 1 Unclassified WebKit JavaScriptCore WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 1 maximilian webkit-unassigned justin_michaud keith_miller mark.lam webkit-bug-importer oldest_to_newest 2020988 0 maximilian 2024-03-14 05:26:29 -0700 assignRegistersToTemporaries reverses its freeRegisters stack in each iteration, leading to somewhat unpredictable assignment of scratch registers. This goes against the inline documentation for scratch register allocation: # These are allocated from the end. Use the low order r6 first, ast it's often # cheaper to encode. r12 and r9 are equivalent, but r9 conflicts with t7, so r9 # only as last resort. So for example the following unstable expansions occur (on armv7): leap (x), t7 -> globaladdr x, r9, r12 leap (x), t7 -> globaladdr x, r9, r9 leap (x), t7 -> globaladdr x, r9, r12 We should maintain the freeRegisters stack order across iterations to ensure temp/scratch priority is respected. 2021110 1 mark.lam 2024-03-14 13:32:58 -0700 FWIW, the "inline documentation" that Max quoted is specific to 32-bit arm i.e. armv7 only. 2022712 2 webkit-bug-importer 2024-03-21 05:27:13 -0700 <rdar://problem/125161316> 2035731 3 ews-feeder 2024-05-16 01:53:32 -0700 Committed 278856@main (4a07711b9554): <https://commits.webkit.org/278856@main> Reviewed commits have been landed. Closing PR #25882 and removing active labels.