[AMDGPU] Add test for VALU hoisiting from WWM region. NFC.

The test demonstraits a suboptimal VALU hoisting from a WWM
region. As a result we have 2 WWM regions instead of one.

Author: rampitec

llvm/test/CodeGen/AMDGPU/licm-wwm.mir

@@ -0,0 +1,43 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx1100 -run-pass=early-machinelicm,si-wqm -o - %s | FileCheck -check-prefix=GCN %s
+
+---
+name: licm_move_wwm
+tracksRegLiveness: true
+body:             |
+  ; GCN-LABEL: name: licm_move_wwm
+  ; GCN: bb.0:
+  ; GCN-NEXT:   successors: %bb.1(0x80000000)
+  ; GCN-NEXT: {{  $}}
+  ; GCN-NEXT:   [[ENTER_STRICT_WWM:%[0-9]+]]:sreg_32 = ENTER_STRICT_WWM -1, implicit-def $exec, implicit-def $scc, implicit $exec
+  ; GCN-NEXT:   [[V_MOV_B32_e32_:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 1, implicit $exec
+  ; GCN-NEXT:   $exec_lo = EXIT_STRICT_WWM [[ENTER_STRICT_WWM]]
+  ; GCN-NEXT:   S_BRANCH %bb.1
+  ; GCN-NEXT: {{  $}}
+  ; GCN-NEXT: bb.1:
+  ; GCN-NEXT:   successors: %bb.1(0x40000000), %bb.2(0x40000000)
+  ; GCN-NEXT: {{  $}}
+  ; GCN-NEXT:   [[ENTER_STRICT_WWM1:%[0-9]+]]:sreg_32 = ENTER_STRICT_WWM -1, implicit-def $exec, implicit-def $scc, implicit $exec
+  ; GCN-NEXT:   [[V_READFIRSTLANE_B32_:%[0-9]+]]:sreg_32 = V_READFIRSTLANE_B32 [[V_MOV_B32_e32_]], implicit $exec
+  ; GCN-NEXT:   $exec_lo = EXIT_STRICT_WWM [[ENTER_STRICT_WWM1]]
+  ; GCN-NEXT:   [[COPY:%[0-9]+]]:sreg_32 = COPY [[V_READFIRSTLANE_B32_]]
+  ; GCN-NEXT:   $exec_lo = S_OR_B32 $exec_lo, [[COPY]], implicit-def $scc
+  ; GCN-NEXT:   S_CBRANCH_EXECNZ %bb.1, implicit $exec
+  ; GCN-NEXT:   S_BRANCH %bb.2
+  ; GCN-NEXT: {{  $}}
+  ; GCN-NEXT: bb.2:
+  ; GCN-NEXT:   S_ENDPGM 0
+  bb.0:
+    S_BRANCH %bb.1
+
+  bb.1:
+    %0:vgpr_32 = V_MOV_B32_e32 1, implicit $exec
+    %1:sreg_32 = V_READFIRSTLANE_B32 killed %0:vgpr_32, implicit $exec
+    early-clobber %2:sreg_32 = STRICT_WWM killed %1:sreg_32, implicit $exec
+    $exec_lo = S_OR_B32 $exec_lo, %2, implicit-def $scc
+    S_CBRANCH_EXECNZ %bb.1, implicit $exec
+    S_BRANCH %bb.2
+
+  bb.2:
+    S_ENDPGM 0
+...