[llvm] Fold SVE mul and mul_u to neg during isel (PR #160828)

[via llvm-commits]

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@@ -723,6 +723,16 @@ class SVE2p1_Cvt_VG2_Pat<string name, SDPatternOperator intrinsic, ValueType out
     : Pat<(out_vt (intrinsic in_vt:$Zn1, in_vt:$Zn2)),
                   (!cast<Instruction>(name) (REG_SEQUENCE ZPR2Mul2, in_vt:$Zn1, zsub0, in_vt:$Zn2, zsub1))>;
 
+class SVE_2_Op_Neg_One_Replace_Pat<ValueType vt, SDPatternOperator op,  ValueType pt,
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Lukacma wrote:

I wonder if these classes are necessary here. I think it would be okay to just define patterns directly in SVEInstrInfo instead of adding this layer of indirection. If not, a t least moving this classes into SVEInstrInfo would be good so its easier to see what these patterns are for.

https://github.com/llvm/llvm-project/pull/160828