SWDEV-139118 fix missing s_waitcnt

The pass that adds s_waitcnt instructions where needed was prematurely ending
processing when traversing the blocks, with the result that required s_waitcnts
were sometimes not insterted resulting in incorrect shader behaviour.

Change-Id: I9f6e1d5affe5f7ea5d243bc697d1a77038551d86

lib/Target/AMDGPU/SIInsertWaitcnts.cpp

@@ -1271,7 +1271,7 @@ void SIInsertWaitcnts::mergeInputScoreBrackets(MachineBasicBlock &Block) {
         BlockWaitcntBracketsMap[pred].get();
     bool Visited = BlockVisitedSet.find(pred) != BlockVisitedSet.end();
     if (!Visited || PredScoreBrackets->getWaitAtBeginning()) {
-      break;
+      continue;
     }
     for (enum InstCounterType T = VM_CNT; T < NUM_INST_CNTS;
          T = (enum InstCounterType)(T + 1)) {
@@ -1310,7 +1310,7 @@ void SIInsertWaitcnts::mergeInputScoreBrackets(MachineBasicBlock &Block) {
         BlockWaitcntBracketsMap[Pred].get();
     bool Visited = BlockVisitedSet.find(Pred) != BlockVisitedSet.end();
     if (!Visited || PredScoreBrackets->getWaitAtBeginning()) {
-      break;
+      continue;
     }
 
     int GDSSpan = PredScoreBrackets->getEventUB(GDS_GPR_LOCK) -
@@ -1357,7 +1357,7 @@ void SIInsertWaitcnts::mergeInputScoreBrackets(MachineBasicBlock &Block) {
   // Set the register scoreboard.
   for (MachineBasicBlock *Pred : Block.predecessors()) {
     if (BlockVisitedSet.find(Pred) == BlockVisitedSet.end()) {
-      break;
+      continue;
     }
 
     BlockWaitcntBrackets *PredScoreBrackets =
@@ -1471,7 +1471,7 @@ void SIInsertWaitcnts::mergeInputScoreBrackets(MachineBasicBlock &Block) {
   // the delayed nature of these operations.
   for (MachineBasicBlock *Pred : Block.predecessors()) {
     if (BlockVisitedSet.find(Pred) == BlockVisitedSet.end()) {
-      break;
+      continue;
     }
 
     BlockWaitcntBrackets *PredScoreBrackets =