Add tests and comments

Author: jofrn

llvm/test/CodeGen/AMDGPU/livevars-implicitdef.mir

@@ -1,6 +1,7 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
 # RUN: llc -mtriple=amdgcn --run-pass=livevars -o - %s | FileCheck %s
 ---
+# Check that super register is implicitly defined for an sgpr copy.
 name:            sgpr_copy
 tracksRegLiveness: true
 body:             |
@@ -23,6 +24,7 @@ body:             |
 
 ...
 ---
+# Check that super register is implicitly defined for a vgpr vector copy.
 name:            vgpr_copy
 tracksRegLiveness: true
 body:             |
@@ -44,3 +46,45 @@ body:             |
     %0:vgpr_32 = COPY $vgpr0_vgpr1_vgpr2_vgpr3
 
 ...
+---
+# Check that super register is implicitly defined when there is a hole.
+name:            sgpr_copy_hole
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    ; CHECK-LABEL: name: sgpr_copy_hole
+    ; CHECK: %sval:sreg_32 = S_MOV_B32 0
+    ; CHECK-NEXT: $sgpr0 = COPY %sval
+    ; CHECK-NEXT: $sgpr2 = COPY %sval
+    ; CHECK-NEXT: $sgpr3 = COPY killed %sval, implicit-def $sgpr0_sgpr1_sgpr2_sgpr3
+    ; CHECK-NEXT: dead $sgpr30_sgpr31 = COPY killed $sgpr0_sgpr1_sgpr2_sgpr3
+    %sval:sreg_32 = S_MOV_B32 0
+
+    $sgpr0 = COPY %sval
+    $sgpr2 = COPY %sval
+    $sgpr3 = COPY %sval
+    $sgpr30_sgpr31 = COPY $sgpr0_sgpr1_sgpr2_sgpr3
+
+...
+---
+# Check that super register is imp-def when a pair interrupts the sequence.
+name:            vgpr_copy_pair
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    ; CHECK-LABEL: name: vgpr_copy_pair
+    ; CHECK: %vval:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
+    ; CHECK-NEXT: $vgpr0 = COPY %vval
+    ; CHECK-NEXT: $vgpr1 = COPY %vval
+    ; CHECK-NEXT: $vgpr2 = COPY %vval, implicit-def $vgpr1_vgpr2
+    ; CHECK-NEXT: $vgpr3 = COPY killed %vval, implicit-def $vgpr0_vgpr1_vgpr2_vgpr3
+    ; CHECK-NEXT: dead [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr1_vgpr2
+    ; CHECK-NEXT: dead [[COPY1:%[0-9]+]]:vgpr_32 = COPY killed $vgpr0_vgpr1_vgpr2_vgpr3
+    %vval:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
+
+    $vgpr0 = COPY %vval
+    $vgpr1 = COPY %vval
+    $vgpr2 = COPY %vval
+    $vgpr3 = COPY %vval
+    %0:vgpr_32 = COPY $vgpr1_vgpr2
+    %1:vgpr_32 = COPY $vgpr0_vgpr1_vgpr2_vgpr3