[llvm] [RISCV] Handle more cases when combining (vfmv.s.f (extract_subvector X, 0)) (PR #154175)

[Min-Yih Hsu via llvm-commits]

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@@ -0,0 +1,26 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple=riscv64 -mattr='+v,+zvl512b' < %s | FileCheck %s
+
+define <2 x float> @redundant_vfmv(<2 x float> %arg0, <64 x float> %arg1, <64 x float> %arg2) {
+; CHECK-LABEL: redundant_vfmv:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    li a0, 64
+; CHECK-NEXT:    vsetvli zero, a0, e32, m4, ta, ma
+; CHECK-NEXT:    vfredusum.vs v9, v12, v8
+; CHECK-NEXT:    vsetivli zero, 1, e32, mf2, ta, ma
+; CHECK-NEXT:    vslidedown.vi v8, v8, 1
+; CHECK-NEXT:    vsetvli zero, a0, e32, m4, ta, ma
+; CHECK-NEXT:    vfredusum.vs v8, v16, v8
+; CHECK-NEXT:    vfmv.f.s fa5, v8
+; CHECK-NEXT:    vsetivli zero, 2, e32, mf2, ta, ma
+; CHECK-NEXT:    vrgather.vi v8, v9, 0
+; CHECK-NEXT:    vfslide1down.vf v8, v8, fa5
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mshockwave wrote:

candidate PR: #154450 

https://github.com/llvm/llvm-project/pull/154175