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[Thumb-1] TBB generation: spot redefinitions of index register

Authored by jmolloy on Feb 13 2017, 6:07 AM.

Description

[Thumb-1] TBB generation: spot redefinitions of index register

We match a sequence of 3-4 instructions into a tTBB pseudo. One of our checks is that
a particular register in that sequence is killed (so it can be clobbered by the pseudo).

We weren't noticing if an errant MOV or other instruction had infiltrated the
sequence we were walking. If it had, and it defined the register we've already
identified as killed, it makes it live across the tBR_JT and thus unclobberable.

Notice this case and bail out.

llvm-svn: 294949

Details

Committed
jmolloyFeb 13 2017, 6:07 AM
Parents
rG9b3b89966966: [ARM] Register ConstantIslands with the pass manager
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