[BreakCritEdges] Check whether IndirectBr is the terminator of the block

Critical edges with an IndirectBr terminator cannot be split.
We have already handled it with Assertion, but change it to checking
whether block has IndirectBr terminator.

Fixes : #150229

Author: ParkHanbum

llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp

@@ -111,15 +111,14 @@ BasicBlock *
 llvm::SplitKnownCriticalEdge(Instruction *TI, unsigned SuccNum,
                              const CriticalEdgeSplittingOptions &Options,
                              const Twine &BBName) {
-  assert(!isa<IndirectBrInst>(TI) &&
-         "Cannot split critical edge from IndirectBrInst");
-
   BasicBlock *TIBB = TI->getParent();
   BasicBlock *DestBB = TI->getSuccessor(SuccNum);
 
-  // Splitting the critical edge to a pad block is non-trivial. Don't do
-  // it in this generic function.
-  if (DestBB->isEHPad()) return nullptr;
+  // Splitting the critical edge to a pad block is non-trivial.
+  // And we cannot split block with IndirectBr as a terminator.
+  // Don't do it in this generic function.
+  if (DestBB->isEHPad() || isa<IndirectBrInst>(TI))
+    return nullptr;
 
   if (Options.IgnoreUnreachableDests &&
       isa<UnreachableInst>(DestBB->getFirstNonPHIOrDbgOrLifetime()))

llvm/test/Transforms/GVN/cond_br.ll

@@ -53,3 +53,22 @@ if.end:                                           ; preds = %if.else, %if.then
 }
 
 declare void @bar(i32)
+
+define void @indirectbr_could_not_split() {
+; CHECK-LABEL: define void @indirectbr_could_not_split() {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    br i1 false, label %[[IBR:.*]], label %[[EXIT:.*]]
+; CHECK:       [[IBR]]:
+; CHECK-NEXT:    indirectbr ptr null, [label %[[EXIT]], label %exit]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br i1 false, label %ibr, label %exit
+
+ibr:
+  indirectbr ptr null, [label %exit, label %exit]
+
+exit:
+  ret void
+}