[llvm] [ISel] Replace expensive move from wzr by two moves via floating point immediate (PR #146538)

[Julian Nagele via llvm-commits]

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@@ -8035,6 +8029,18 @@ def MOVIv2d_ns   : SIMDModifiedImmVectorNoShift<1, 1, 0, 0b1110, V128,
                                                 "movi", ".2d",
                    [(set (v2i64 V128:$Rd), (AArch64movi_edit imm0_255:$imm8))]>;
 
+def : Pat<(vector_insert (v8f16 V128:$Rn), (f16 fpimm0), (i64 VectorIndexH:$imm)),
+          (INSvi16lane V128:$Rn, VectorIndexH:$imm,
+          (v8f16 (MOVIv2d_ns (i32 0))), (i64 0))>;
+
+def : Pat<(vector_insert (v4f32 V128:$Rn), (f32 fpimm0), (i64 VectorIndexS:$imm)),
+          (INSvi32lane V128:$Rn, VectorIndexS:$imm,
+          (v4f32 (MOVIv2d_ns (i32 0))), (i64 0))>;
+
+def : Pat<(vector_insert (v2f64 V128:$Rn), (f64 fpimm0), (i64 VectorIndexD:$imm)),
+          (INSvi64lane V128:$Rn, VectorIndexD:$imm,
+          (v2f64 (MOVIv2d_ns (i32 0))), (i64 0))>;
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juliannagele wrote:

Hm, sorry not sure I understand, without those patterns we get the move from wzr (which we want to avoid).

https://github.com/llvm/llvm-project/pull/146538