[PATCH] D80485: [DAGCombiner][PowerPC] Remove isMulhCheaperThanMulShift TLI hook. Use isOperationLegalOrCustom directly instead.

[Piotr Sobczak via Phabricator via llvm-commits]

piotr added a comment.

Hi! This commit causes problems for AMDGPU backend - see attached file F13392080: repro.ll <https://reviews.llvm.org/F13392080>. Any ideas before I start investigating this in detail?

LLVM ERROR: Cannot select: t56: i16 = mulhs t42, Constant:i16<-32509>

  t42: i16 = truncate t67
    t67: i32 = add t66, t28
      t66: i32 = add t37, t34
        t37: i32 = shl nuw nsw t12, Constant:i32<13>
          t12: i32,ch = CopyFromReg t0, Register:i32 %5
            t11: i32 = Register %5
          t36: i32 = Constant<13>
        t34: i32 = shl nuw nsw t10, Constant:i32<7>
          t10: i32,ch = CopyFromReg t0, Register:i32 %4
            t9: i32 = Register %4
          t26: i32 = Constant<7>
      t28: i32 = add t16, t27
        t16: i32,ch = CopyFromReg t0, Register:i32 %7
          t15: i32 = Register %7
        t27: i32 = shl t8, Constant:i32<7>
          t8: i32,ch = CopyFromReg t0, Register:i32 %3
            t7: i32 = Register %3
          t26: i32 = Constant<7>
  t52: i16 = Constant<-32509>


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D80485/new/

https://reviews.llvm.org/D80485