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[AArch64] Fix disassembly of SXTL and UXTL aliases
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Authored by olista01 on Nov 21 2018, 5:32 AM.

Details

Summary

These instructions are aliases of SSHLL and USHLL, and should be
preferred for disassembly.

We did already have aliases for these in the tablegen, but they were
not being used. The problem was that we actually had two aliases for
each, one each for the "generic" and "apple-neon" syntaxes. This made
the disassembly ambiguous, so tablegen was not emitting either of them.
The fix was to use one alias with both syntaxes in the string, so that
the correct one can be picked by the disassembler.

This fixes https://bugs.llvm.org/show_bug.cgi?id=39721

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olista01 created this revision.Nov 21 2018, 5:32 AM

I'm not sure what's the supposed behaviour on Apple syntax, but the tests show both apple and eabi syntax changing to the recommended encoding, so this LGTM.

Adding Tim to confirm the behaviour on Apple mode.

Herald added a project: Restricted Project. · View Herald TranscriptFeb 18 2019, 3:11 AM
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@t.p.northover Is this the correct behaviour for Apple's syntax?