[PATCH] D66805: [MIPS] For vectors, select `add %x, C` as `sub %x, -C` if it results in inline immediate

Wed Sep 18 12:32:45 PDT 2019

atanasyan added inline comments.

================
Comment at: llvm/test/CodeGen/Mips/msa/arithmetic.ll:220-241
 define void @sub_v2i64_i(<2 x i64>* %c, <2 x i64>* %a) nounwind {
 ; MIPS-LABEL: sub_v2i64_i:
 ; MIPS:       # %bb.0:
 ; MIPS-NEXT:    ldi.b $w0, -1
 ; MIPS-NEXT:    shf.w $w0, $w0, 177
 ; MIPS-NEXT:    ld.d $w1, 0($5)
 ; MIPS-NEXT:    addv.d $w0, $w1, $w0
----------------
lebedev.ri wrote:
> Hm, this one didn't get recovered by the patch.
I saw this regression. Unfortunately I could not quickly create a fix for it. As far as I remember, the problem is in this statement `auto *BVN = dyn_cast<BuildVectorSDNode>(C)`. In `@sub_v2i64_i` the second operand (i.e. `C`) is a bitcast and `dyn_cast<BuildVectorSDNode>` returns zero. Right now I do not have a time to dig it. Maybe next week.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D66805/new/

https://reviews.llvm.org/D66805