AMDGPU: Cleanup and modernize limit-coalesce.mir test (#166465)

Author: arsenm

llvm/test/CodeGen/AMDGPU/limit-coalesce.mir

@@ -6,40 +6,12 @@
 # No more registers shall be defined
 ---
 name:            main
-alignment:       1
-exposesReturnsTwice: false
-legalized:       false
-regBankSelected: false
-selected:        false
 tracksRegLiveness: true
 registers:
-  - { id: 1, class: sreg_32_xm0, preferred-register: '%1' }
-  - { id: 2, class: vreg_64, preferred-register: '%2' }
-  - { id: 3, class: vreg_64 }
-  - { id: 4, class: vreg_64 }
-  - { id: 5, class: vreg_64 }
-  - { id: 6, class: vreg_96 }
-  - { id: 7, class: vreg_96 }
-  - { id: 8, class: vreg_128 }
-  - { id: 9, class: vreg_128 }
-liveins:
-  - { reg: '$sgpr6', virtual-reg: '%1' }
-frameInfo:
-  isFrameAddressTaken: false
-  isReturnAddressTaken: false
-  hasStackMap:     false
-  hasPatchPoint:   false
-  stackSize:       0
-  offsetAdjustment: 0
-  maxAlignment:    0
-  adjustsStack:    false
-  hasCalls:        false
-  maxCallFrameSize: 0
-  hasOpaqueSPAdjustment: false
-  hasVAStart:      false
-  hasMustTailInVarArgFunc: false
+  - { id: 0, class: sreg_32_xm0, preferred-register: '%0' }
+  - { id: 1, class: vreg_64, preferred-register: '%1' }
 body:             |
-  bb.0.entry:
+  bb.0:
     liveins: $sgpr0, $vgpr0_vgpr1
 
     ; CHECK-LABEL: name: main
@@ -59,20 +31,21 @@ body:             |
     ; CHECK-NEXT: undef [[COPY3:%[0-9]+]].sub0_sub1_sub2:vreg_128 = COPY [[DEF2]]
     ; CHECK-NEXT: [[COPY3:%[0-9]+]].sub3:vreg_128 = COPY [[DEF]].sub0
     ; CHECK-NEXT: FLAT_STORE_DWORDX4 $vgpr0_vgpr1, [[COPY3]], 0, 0, implicit $exec, implicit $flat_scr
-    %3 = IMPLICIT_DEF
-    undef %4.sub0 = COPY $sgpr0
-    %4.sub1 = COPY %3.sub0
-    undef %5.sub0 = COPY %4.sub1
-    %5.sub1 = COPY %4.sub0
-    FLAT_STORE_DWORDX2 $vgpr0_vgpr1, killed %5, 0, 0, implicit $exec, implicit $flat_scr
+    %2:vreg_64 = IMPLICIT_DEF
+    undef %3.sub0:vreg_64 = COPY $sgpr0
+    %3.sub1:vreg_64 = COPY %2.sub0
+    undef %4.sub0:vreg_64 = COPY %3.sub1
+    %4.sub1:vreg_64 = COPY %3.sub0
+    FLAT_STORE_DWORDX2 $vgpr0_vgpr1, killed %4, 0, 0, implicit $exec, implicit $flat_scr
 
-    %6 = IMPLICIT_DEF
-    undef %7.sub0_sub1 = COPY %6
-    %7.sub2 = COPY %3.sub0
-    FLAT_STORE_DWORDX3 $vgpr0_vgpr1, killed %7, 0, 0, implicit $exec, implicit $flat_scr
+    %5:vreg_96 = IMPLICIT_DEF
+    undef %6.sub0_sub1:vreg_96 = COPY %5
+    %6.sub2:vreg_96 = COPY %2.sub0
+    FLAT_STORE_DWORDX3 $vgpr0_vgpr1, killed %6, 0, 0, implicit $exec, implicit $flat_scr
+
+    %7:vreg_128 = IMPLICIT_DEF
+    undef %8.sub0_sub1_sub2:vreg_128 = COPY %7
+    %8.sub3:vreg_128 = COPY %2.sub0
+    FLAT_STORE_DWORDX4 $vgpr0_vgpr1, killed %8, 0, 0, implicit $exec, implicit $flat_scr
 
-    %8 = IMPLICIT_DEF
-    undef %9.sub0_sub1_sub2 = COPY %8
-    %9.sub3 = COPY %3.sub0
-    FLAT_STORE_DWORDX4 $vgpr0_vgpr1, killed %9, 0, 0, implicit $exec, implicit $flat_scr
 ...