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

[Matt Arsenault via llvm-commits]

================
@@ -242,18 +290,33 @@ static bool fixIrreducible(Cycle &C, CycleInfo &CI, DominatorTree &DT,
   }
 
   for (BasicBlock *P : Predecessors) {
-    auto *Branch = cast<BranchInst>(P->getTerminator());
-    // Exactly one of the two successors is the header.
-    BasicBlock *Succ0 = Branch->getSuccessor(0) == Header ? Header : nullptr;
-    BasicBlock *Succ1 = Succ0 ? nullptr : Header;
-    if (!Succ0)
-      assert(Branch->getSuccessor(1) == Header);
-    assert(Succ0 || Succ1);
-    CHub.addBranch(P, Succ0, Succ1);
-
-    LLVM_DEBUG(dbgs() << "Added internal branch: " << P->getName() << " -> "
-                      << (Succ0 ? Succ0->getName() : "") << " "
-                      << (Succ1 ? Succ1->getName() : "") << "\n");
+    if (BranchInst *Branch = dyn_cast<BranchInst>(P->getTerminator()); Branch) {
+      // Exactly one of the two successors is the header.
+      BasicBlock *Succ0 = Branch->getSuccessor(0) == Header ? Header : nullptr;
+      BasicBlock *Succ1 = Succ0 ? nullptr : Header;
+      if (!Succ0)
+        assert(Branch->getSuccessor(1) == Header);
+      assert(Succ0 || Succ1);
+      CHub.addBranch(P, Succ0, Succ1);
+
+      LLVM_DEBUG(dbgs() << "Added internal branch: " << P->getName() << " -> "
+                        << (Succ0 ? Succ0->getName() : "") << " "
+                        << (Succ1 ? Succ1->getName() : "") << "\n");
+    } else if (CallBrInst *CallBr = dyn_cast<CallBrInst>(P->getTerminator());
+               CallBr) {
+      for (unsigned I = 0; I < CallBr->getNumSuccessors(); ++I) {
+        BasicBlock *Succ = CallBr->getSuccessor(I);
+        if (Succ != Header)
+          continue;
+        BasicBlock *NewSucc = llvm::ControlFlowHub::createCallBrTarget(
----------------
arsenm wrote:

```suggestion
        BasicBlock *NewSucc = ControlFlowHub::createCallBrTarget(
```

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