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

[Stepan Dyatkovskiy]

ping...
Stepan Dyatkovskiy wrote:
> 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.
>