implement rdar://9289524 - case followed immediately by break results in empty IR block,
a -O0 code quality issue.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@129652 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp
index 7a1ce19..b8b2cd9 100644
--- a/lib/CodeGen/CGStmt.cpp
+++ b/lib/CodeGen/CGStmt.cpp
@@ -867,11 +867,25 @@
}
void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) {
+ // Handle case ranges.
if (S.getRHS()) {
EmitCaseStmtRange(S);
return;
}
+ // If the body of the case is just a 'break', try to not emit an empty block.
+ if (isa<BreakStmt>(S.getSubStmt())) {
+ JumpDest Block = BreakContinueStack.back().BreakBlock;
+
+ // Only do this optimization if there are no cleanups that need emitting.
+ if (isObviouslyBranchWithoutCleanups(Block)) {
+ llvm::APSInt CaseVal = S.getLHS()->EvaluateAsInt(getContext());
+ SwitchInsn->addCase(llvm::ConstantInt::get(getLLVMContext(), CaseVal),
+ Block.getBlock());
+ return;
+ }
+ }
+
EmitBlock(createBasicBlock("sw.bb"));
llvm::BasicBlock *CaseDest = Builder.GetInsertBlock();
llvm::APSInt CaseVal = S.getLHS()->EvaluateAsInt(getContext());