[llvm] [AMDGPU][FixIrreducible][UnifyLoopExits] Support callbr with inline-asm (PR #149308)

[Sameer Sahasrabuddhe via llvm-commits]

================
@@ -150,25 +154,51 @@ static bool unifyLoopExits(DominatorTree &DT, LoopInfo &LI, Loop *L) {
   SmallVector<BasicBlock *, 8> ExitingBlocks;
   L->getExitingBlocks(ExitingBlocks);
 
+  DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
+  SmallVector<BasicBlock *, 8> CallBrTargetBlocks;
   // Redirect exiting edges through a control flow hub.
   ControlFlowHub CHub;
-  for (auto *BB : ExitingBlocks) {
-    auto *Branch = cast<BranchInst>(BB->getTerminator());
-    BasicBlock *Succ0 = Branch->getSuccessor(0);
-    Succ0 = L->contains(Succ0) ? nullptr : Succ0;
-
-    BasicBlock *Succ1 =
-        Branch->isUnconditional() ? nullptr : Branch->getSuccessor(1);
-    Succ1 = L->contains(Succ1) ? nullptr : Succ1;
-    CHub.addBranch(BB, Succ0, Succ1);
-
-    LLVM_DEBUG(dbgs() << "Added exiting branch: " << BB->getName() << " -> {"
-                      << (Succ0 ? Succ0->getName() : "<none>") << ", "
-                      << (Succ1 ? Succ1->getName() : "<none>") << "}\n");
+
+  for (unsigned I = 0; I < ExitingBlocks.size(); ++I) {
+    BasicBlock *BB = ExitingBlocks[I];
+    if (BranchInst *Branch = dyn_cast<BranchInst>(BB->getTerminator())) {
+      BasicBlock *Succ0 = Branch->getSuccessor(0);
+      Succ0 = L->contains(Succ0) ? nullptr : Succ0;
+
+      BasicBlock *Succ1 =
+          Branch->isUnconditional() ? nullptr : Branch->getSuccessor(1);
+      Succ1 = L->contains(Succ1) ? nullptr : Succ1;
+      CHub.addBranch(BB, Succ0, Succ1);
+
+      LLVM_DEBUG(dbgs() << "Added extiting branch: " << printBBPtr(BB) << " -> "
+                        << printBBPtr(Succ0) << (Succ0 && Succ1 ? " " : "")
+                        << printBBPtr(Succ1) << "\n");
+    } else if (CallBrInst *CallBr = dyn_cast<CallBrInst>(BB->getTerminator())) {
+      for (unsigned J = 0; J < CallBr->getNumSuccessors(); ++J) {
+        BasicBlock *Succ = CallBr->getSuccessor(J);
+        if (L->contains(Succ))
+          continue;
+        BasicBlock *NewSucc = ControlFlowHub::createCallBrTarget(
+            CallBr, Succ, J, false, nullptr, &DTU, &LI);
----------------
ssahasra wrote:

```suggestion
            CallBr, Succ, J, /* AttachToCallBr = */ false, nullptr, &DTU, &LI);
```

https://github.com/llvm/llvm-project/pull/149308