Take advantage of noreturn attribute to add unreachable instruction &
clear insertion point. The rest of IRgen should theoretically take
advantage of this to avoid emitting dead code. Theory != Practice.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@65141 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index d0122fa..02e0055 100644
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -1760,6 +1760,18 @@
if (const llvm::Function *F = dyn_cast<llvm::Function>(Callee))
CI->setCallingConv(F->getCallingConv());
+
+ // If the call doesn't return, finish the basic block and clear the
+ // insertion point; this allows the rest of IRgen to discard
+ // unreachable code.
+ if (CI->doesNotReturn()) {
+ Builder.CreateUnreachable();
+ Builder.ClearInsertionPoint();
+
+ // Return a reasonable RValue.
+ return GetUndefRValue(RetTy);
+ }
+
if (CI->getType() != llvm::Type::VoidTy)
CI->setName("call");