Do not mark no-return calls tail calls. It'll screw up special calls like longjmp and it doesn't make much sense for performance reason. If my logic is faulty, please let me know.

llvm-svn: 94937

2 files changed, 17 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp b/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
index 162d902cfa4..913dd73cc17 100644
--- a/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/TailRecursionElimination.cpp
@@ -184,10 +184,11 @@ bool TailCallElim::runOnFunction(Function &F) {
   if (!FunctionContainsEscapingAllocas)
     for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
       for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
-        if (CallInst *CI = dyn_cast<CallInst>(I)) {
-          CI->setTailCall();
-          MadeChange = true;
-        }
+        if (CallInst *CI = dyn_cast<CallInst>(I))
+          if (!CI->doesNotReturn()) {
+            CI->setTailCall();
+            MadeChange = true;
+          }
 
   return MadeChange;
 }
diff --git a/llvm/test/Transforms/TailCallElim/no-return-calls.ll b/llvm/test/Transforms/TailCallElim/no-return-calls.ll
new file mode 100644
index 00000000000..f5643ae3330
--- /dev/null
+++ b/llvm/test/Transforms/TailCallElim/no-return-calls.ll
@@ -0,0 +1,12 @@
+; RUN: opt < %s -tailcallelim -S | FileCheck %s
+
+define void @t() nounwind ssp {
+entry:
+; CHECK: entry:
+; CHECK: %0 = call i32 @foo()
+; CHECK: ret void
+  %0 = call i32 @foo() nounwind noreturn
+  ret void
+}
+
+declare i32 @foo()