Eliminate support for the llvm.unwind intrinisic, using the Unwind instruction instead

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8411 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 24 insertions, 25 deletions

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index f47c840518..1d5e4ec8af 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -101,32 +101,31 @@ bool SimplifyCFG(BasicBlock *BB) {
   // 'llvm.unwind'.  If so, replace any invoke instructions which use this as an
   // exception destination with call instructions.
   //
-  if (CallInst *CI = dyn_cast<CallInst>(&BB->front()))
-    if (Function *F = CI->getCalledFunction())
-      if (F->getIntrinsicID() == LLVMIntrinsic::unwind) {
-        std::vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
-        while (!Preds.empty()) {
-          BasicBlock *Pred = Preds.back();
-          if (InvokeInst *II = dyn_cast<InvokeInst>(Pred->getTerminator()))
-            if (II->getExceptionalDest() == BB) {
-              // Insert a new branch instruction before the invoke, because this
-              // is now a fall through...
-              BranchInst *BI = new BranchInst(II->getNormalDest(), II);
-              Pred->getInstList().remove(II);   // Take out of symbol table
-              
-              // Insert the call now...
-              std::vector<Value*> Args(II->op_begin()+3, II->op_end());
-              CallInst *CI = new CallInst(II->getCalledValue(), Args,
-                                          II->getName(), BI);
-              // If the invoke produced a value, the Call now does instead
-              II->replaceAllUsesWith(CI);
-              delete II;
-              Changed = true;
-            }
-          
-          Preds.pop_back();
-        }
+  if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator()))
+    if (BB->begin() == BasicBlock::iterator(UI)) {  // Empty block?
+      std::vector<BasicBlock*> Preds(pred_begin(BB), pred_end(BB));
+      while (!Preds.empty()) {
+        BasicBlock *Pred = Preds.back();
+        if (InvokeInst *II = dyn_cast<InvokeInst>(Pred->getTerminator()))
+          if (II->getExceptionalDest() == BB) {
+            // Insert a new branch instruction before the invoke, because this
+            // is now a fall through...
+            BranchInst *BI = new BranchInst(II->getNormalDest(), II);
+            Pred->getInstList().remove(II);   // Take out of symbol table
+            
+            // Insert the call now...
+            std::vector<Value*> Args(II->op_begin()+3, II->op_end());
+            CallInst *CI = new CallInst(II->getCalledValue(), Args,
+                                        II->getName(), BI);
+            // If the invoke produced a value, the Call now does instead
+            II->replaceAllUsesWith(CI);
+            delete II;
+            Changed = true;
+          }
+        
+        Preds.pop_back();
       }
+    }
 
   // Remove basic blocks that have no predecessors... which are unreachable.
   if (pred_begin(BB) == pred_end(BB) &&