[llvm-commits] [FIX+regression-test] PR13617: LLVM+Clang emits movw instrucionts with -march=armv6zk

[Stepan Dyatkovskiy]

ping.
Stepan Dyatkovskiy wrote:
> Hi all!
>
> The bug is fired when dag-to-dag isel meets 'add' instruction with
> second operand that is negative number less than -256. E.g.:
> add %var, -1000
>
> ARM dag-to-dag instruction selector matches the pattern that emits
> (sub %var (MOVi16 Rd, 1000))
>
> After fast TableGen learning, I found that it ignores instruction
> predicates for patterns (ARMPat, ARMV6Pat and so on) while generating
> MatcherTable. So it ignores restrictions defined for MOVi16 instruction
> (ARMv6t2 and higher).
>
> I also found that for several patterns this behaviour compensated by
> adding 'Requires' predicate explicitly. So, I did the same in this
> patch. Please find the patch in attachment for review.
>
> -Stepan.