[IR] Don't treat callbr as indirect terminator

Callbr is no longer an indirect terminator in the sense that is
relevant here (that it's successors cannot be updated). The primary
effect of this change is that callbr no longer prevents formation
of loop simplify form.

I decided to drop the isIndirectTerminator() method entirely and
replace it with isa<IndirectBrInst>() checks. I assume this method
was added to abstract over indirectbr and callbr, but it never
really caught on, and there is nothing left to abstract anymore
at this point.

Differential Revision: https://reviews.llvm.org/D129849

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopSimplify.cpp b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
index 55d5c73..2ff8a3f7 100644
--- a/llvm/lib/Transforms/Utils/LoopSimplify.cpp
+++ b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
@@ -127,7 +127,7 @@ BasicBlock *llvm::InsertPreheaderForLoop(Loop *L, DominatorTree *DT,
       // If the loop is branched to from an indirect terminator, we won't
       // be able to fully transform the loop, because it prohibits
       // edge splitting.
-      if (P->getTerminator()->isIndirectTerminator())
+      if (isa<IndirectBrInst>(P->getTerminator()))
         return nullptr;
 
       // Keep track of it.
@@ -256,7 +256,7 @@ static Loop *separateNestedLoop(Loop *L, BasicBlock *Preheader,
     if (PN->getIncomingValue(i) != PN ||
         !L->contains(PN->getIncomingBlock(i))) {
       // We can't split indirect control flow edges.
-      if (PN->getIncomingBlock(i)->getTerminator()->isIndirectTerminator())
+      if (isa<IndirectBrInst>(PN->getIncomingBlock(i)->getTerminator()))
         return nullptr;
       OuterLoopPreds.push_back(PN->getIncomingBlock(i));
     }
@@ -375,7 +375,7 @@ static BasicBlock *insertUniqueBackedgeBlock(Loop *L, BasicBlock *Preheader,
   std::vector<BasicBlock*> BackedgeBlocks;
   for (BasicBlock *P : predecessors(Header)) {
     // Indirect edges cannot be split, so we must fail if we find one.
-    if (P->getTerminator()->isIndirectTerminator())
+    if (isa<IndirectBrInst>(P->getTerminator()))
       return nullptr;
 
     if (P != Preheader) BackedgeBlocks.push_back(P);