The code was written by adjusting sp down by 8 bytes. ARM64 hardware asserts that sp is 16 byte align when used as the destination of the load/store. The fix is to keep the stack aligned.
Created attachment 335371 [details] Patch for landing
Committed r229446: <https://trac.webkit.org/changeset/229446>
<rdar://problem/38285026>
Reverted r229446 for reason: This change relies on changes that have been rolled out. Committed r229464: <https://trac.webkit.org/changeset/229464>
This looks to have broke The High Sierra LLINT CLoop build when it was re-landed in https://trac.webkit.org/changeset/229476/webkit https://build.webkit.org/builders/Apple%20High%20Sierra%20LLINT%20CLoop%20%28BuildAndTest%29/builds/4330 https://build.webkit.org/builders/Apple%20High%20Sierra%20LLINT%20CLoop%20%28BuildAndTest%29/builds/4330/steps/compile-webkit/logs/stdio /Volumes/Data/slave/highsierra-cloop-debug/build/Source/JavaScriptCore/runtime/StackAlignment.h:45:80: error: use of undeclared identifier 'CallFrame' /Volumes/Data/slave/highsierra-cloop-debug/build/Source/JavaScriptCore/runtime/StackAlignment.h:45:116: error: use of undeclared identifier 'CallFrame' /Volumes/Data/slave/highsierra-cloop-debug/build/Source/JavaScriptCore/runtime/StackAlignment.h:52:85: error: use of undeclared identifier 'CallerFrameAndPC' /Volumes/Data/slave/highsierra-cloop-debug/build/Source/JavaScriptCore/runtime/StackAlignment.h:52:122: error: use of undeclared identifier 'CallerFrameAndPC'
Michael relanded the patch in r229476: <http://trac.webkit.org/r229476>.
Build fix landed in r229486: <http://trac.webkit.org/r229486>.