[llvm] [LV][VPlan] Extract the implementation of transform Recipe to EVLRecipe into a small function. NFC (PR #119510)

[Elvis Wang via llvm-commits]

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@@ -1727,7 +1727,7 @@ define float @fmuladd(ptr %a, ptr %b, i64 %n, float %start) {
 ; IF-EVL-NEXT:    [[TMP14:%.*]] = getelementptr inbounds float, ptr [[B:%.*]], i64 [[TMP11]]
 ; IF-EVL-NEXT:    [[TMP15:%.*]] = getelementptr inbounds float, ptr [[TMP14]], i32 0
 ; IF-EVL-NEXT:    [[VP_OP_LOAD1:%.*]] = call <vscale x 4 x float> @llvm.vp.load.nxv4f32.p0(ptr align 4 [[TMP15]], <vscale x 4 x i1> splat (i1 true), i32 [[TMP10]])
-; IF-EVL-NEXT:    [[TMP16:%.*]] = call reassoc <vscale x 4 x float> @llvm.vp.fmuladd.nxv4f32(<vscale x 4 x float> [[VP_OP_LOAD]], <vscale x 4 x float> [[VP_OP_LOAD1]], <vscale x 4 x float> [[VEC_PHI]], <vscale x 4 x i1> splat (i1 true), i32 [[TMP10]])
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ElvisWang123 wrote:

I think we should preserve `reassoc` flag after EVL transformation. 

Perhaps add/modify a constructor of VPWidenInstrinsicRecipe with flags independent from underlying instruction.

https://github.com/llvm/llvm-project/pull/119510