Do not codegen dummy block.
Dummy block is an empty block with no predecessors.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@42451 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CodeGen/CodeGenFunction.cpp b/CodeGen/CodeGenFunction.cpp
index d540ea7..363d299 100644
--- a/CodeGen/CodeGenFunction.cpp
+++ b/CodeGen/CodeGenFunction.cpp
@@ -19,6 +19,7 @@
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Analysis/Verifier.h"
+#include "llvm/Support/CFG.h"
using namespace clang;
using namespace CodeGen;
@@ -87,13 +88,18 @@
// Emit the function body.
EmitStmt(FD->getBody());
- // Emit a return for code that falls off the end.
- // FIXME: if this is C++ main, this should return 0.
- if (CurFn->getReturnType() == llvm::Type::VoidTy)
- Builder.CreateRetVoid();
- else
- Builder.CreateRet(llvm::UndefValue::get(CurFn->getReturnType()));
-
+ // Emit a return for code that falls off the end. If insert point
+ // is a dummy block with no predecessors then remove the block itself.
+ llvm::BasicBlock *BB = Builder.GetInsertBlock();
+ if (isDummyBlock(BB))
+ BB->eraseFromParent();
+ else {
+ // FIXME: if this is C++ main, this should return 0.
+ if (CurFn->getReturnType() == llvm::Type::VoidTy)
+ Builder.CreateRetVoid();
+ else
+ Builder.CreateRet(llvm::UndefValue::get(CurFn->getReturnType()));
+ }
assert(BreakContinueStack.empty() &&
"mismatched push/pop in break/continue stack!");
@@ -101,3 +107,11 @@
assert(!verifyFunction(*CurFn));
}
+/// isDummyBlock - Return true if BB is an empty basic block
+/// with no predecessors.
+bool CodeGenFunction::isDummyBlock(const llvm::BasicBlock *BB) {
+ if (BB->empty() && pred_begin(BB) == pred_end(BB))
+ return true;
+ return false;
+}
+