[RISCV] Test for D155140. NFC

[craig.topper]

Summary

The vmv1r.v v8, v9 in the last block can be removed by late
copy propagation.

[wangpc]

LGTM

llvm/test/CodeGen/RISCV/rvv/copyprop.mir

+# NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
+# RUN: llc %s -o - -mtriple=riscv64 -mattr=+v -start-after=finalize-isel | FileCheck %s
+
+--- |
+  define void @foo() {
+  ; CHECK-LABEL: foo:
+  ; CHECK:       # %bb.0: # %entry
+  ; CHECK-NEXT:    vsetivli zero, 1, e64, m1, ta, ma
+  ; CHECK-NEXT:    vmsne.vi v0, v8, 0
+  ; CHECK-NEXT:    vsll.vi v9, v8, 5
+  ; CHECK-NEXT:    vmerge.vim v9, v9, -1, v0
+  ; CHECK-NEXT:    csrwi vxrm, 0
+  ; CHECK-NEXT:    vssra.vi v8, v8, 2
+  ; CHECK-NEXT:    bgeu a0, zero, .LBB0_3
+  ; CHECK-NEXT:  # %bb.1: # %entry
+  ; CHECK-NEXT:    li a2, 128
+  ; CHECK-NEXT:    bltu a0, a2, .LBB0_4
+  ; CHECK-NEXT:  .LBB0_2: # %entry
+  ; CHECK-NEXT:    vse64.v v8, (a1)
+  ; CHECK-NEXT:    ret
+  ; CHECK-NEXT:  .LBB0_3:
+  ; CHECK-NEXT:    vmv.v.i v8, 0
+  ; CHECK-NEXT:    li a2, 128
+  ; CHECK-NEXT:    bgeu a0, a2, .LBB0_2
+  ; CHECK-NEXT:  .LBB0_4: # %entry
+  ; CHECK-NEXT:    vmv1r.v v8, v9
+  ; CHECK-NEXT:    vse64.v v8, (a1)
+  ; CHECK-NEXT:    ret
+  entry:
+    ret void
+  }
+...
+---
+name:            foo
+tracksRegLiveness: true
+liveins:
+  - { reg: '$x10', virtual-reg: '%1' }
+  - { reg: '$x11', virtual-reg: '%2' }
+  - { reg: '$v8', virtual-reg: '%2' }
+body:             |
+  bb.0.entry:
+    successors: %bb.1, %bb.2
+    liveins: $x10, $x11, $x12, $v8
+
+    %2:gpr = COPY $x11
+    %1:gpr = COPY $x10
+    %3:vr = COPY $v8
+    %pt5:vr = IMPLICIT_DEF
+    %17:vr = PseudoVSLL_VI_M1 %pt5, %3, 5, 1, 6 /* e64 */, 0
+    %22:vr = PseudoVMSNE_VI_M1 %3, 0, 1, 6 /* e64 */
+    $v0 = COPY %22
+    %26:vrnov0 = IMPLICIT_DEF
+    %25:vrnov0 = PseudoVMERGE_VIM_M1 %26, %17, -1, $v0, 1, 6 /* e64 */
+    %pt8:vr = IMPLICIT_DEF
+    %29:vr = PseudoVSSRA_VI_M1 %pt8, %3, 2, 0, 1, 6 /* e64 */, 0
+    %pt9:vr = IMPLICIT_DEF
+    %30:vr = PseudoVMV_V_I_M1 %pt9, 0, 1, 6 /* e64 */, 0
+    BGEU %1, $x0, %bb.2
+
+  bb.1.entry:
+
+  bb.2.entry:
+    successors: %bb.3, %bb.4
+
+    %31:vr = PHI %30, %bb.0, %29, %bb.1
+    %32:gpr = ADDI $x0, 128
+    BGEU %1, %32, %bb.4
+
+  bb.3.entry:
+
+  bb.4.entry:
+    %33:vr = PHI %31, %bb.2, %25, %bb.3
+    PseudoVSE64_V_M1 killed %33, %2, 1, 6 /* e64 */
+    PseudoRET
+
+...