RESOLVED FIXED 189758
Packed Variant violates alignment on ARM and MIPS 
https://bugs.webkit.org/show_bug.cgi?id=189758
Summary Packed Variant violates alignment on ARM and MIPS
Dominik Inführ
Reported 2018-09-19 11:26:15 PDT
Hi, recent patch https://bugs.webkit.org/show_bug.cgi?id=188559 broke tests in JSC on ARM and MIPS because data isn't aligned anymore. Not sure what's the best way to fix that: if we should just disable pack'ing on at least ARM and MIPS.
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Dominik Inführ
Comment 1 2018-09-20 06:05:00 PDT
Some more additional information: JSC has now 26k test failures due to this change on ARM: https://build.webkit.org/builders/JSCOnly%20Linux%20ARMv7%20Thumb2%20Release. Reason for that is the lexer uses a type std::optional<Variant<double,int*>> which breaks probably all tests (see Source/JavaScriptCore/parser/Lexer.(h|cpp)).
Fujii Hironori
Comment 2 2018-09-20 07:34:57 PDT
How do you know Lexer is the crash point? Did you get the coredump and the backtrace?
Dominik Inführ
Comment 3 2018-09-21 00:35:34 PDT
I got the backtrace from testing it locally on my board. It also makes sense since the Lexer uses a Variant in an std::optional and the corresponding assembly code fails on storing a floating point register to a memory location that's not 8-byte aligned.
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