[RISCV][RVV] Precommit a test case for D105684

Reviewed By: frasercrmck

Differential Revision: https://reviews.llvm.org/D105685

Author: arcbbb

llvm/test/CodeGen/RISCV/rvv/reg-coalescing.mir

@@ -0,0 +1,23 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc %s -mtriple=riscv64 -mattr=+experimental-v -run-pass=simple-register-coalescing -o - | FileCheck %s
+---
+# Make sure that SrcReg & DstReg of PseudoVRGATHER are not coalesced
+name:            test_earlyclobber
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $x10
+    ; CHECK-LABEL: name: test_earlyclobber
+    ; CHECK: liveins: $x10
+    ; CHECK: undef %2.sub_vrm2_0:vrn2m2 = PseudoVLE32_V_M2 $x10, 1, 5
+    ; CHECK: %2.sub_vrm2_1:vrn2m2 = PseudoVLE32_V_M2 $x10, 1, 5
+    ; CHECK: [[PseudoVLE32_V_M2_:%[0-9]+]]:vrm2 = PseudoVLE32_V_M2 $x10, 1, 5
+    ; CHECK: early-clobber %2.sub_vrm2_0:vrn2m2 = PseudoVRGATHER_VI_M2 %2.sub_vrm2_0, 0, 1, 5, implicit $vl, implicit $vtype
+    ; CHECK: PseudoVSUXSEG2EI32_V_M2_M2 %2, $x10, [[PseudoVLE32_V_M2_]], 1, 5, implicit $vl, implicit $vtype
+    undef %0.sub_vrm2_0:vrn2m2 = PseudoVLE32_V_M2 $x10, 1, 5
+    %0.sub_vrm2_1:vrn2m2 = PseudoVLE32_V_M2 $x10, 1, 5
+    %1:vrm2 = PseudoVLE32_V_M2 $x10, 1, 5
+    undef early-clobber %2.sub_vrm2_0:vrn2m2 = PseudoVRGATHER_VI_M2 %0.sub_vrm2_0:vrn2m2, 0, 1, 5, implicit $vl, implicit $vtype
+    %2.sub_vrm2_1:vrn2m2 = COPY %0.sub_vrm2_1:vrn2m2
+    PseudoVSUXSEG2EI32_V_M2_M2 %2:vrn2m2, $x10, %1:vrm2, 1, 5, implicit $vl, implicit $vtype
+...