Fix a miscompilation I introduced in r129652, thanks for Eli for tracking
it down. we effectively were compile the testcase into:
void test14(int x) {
switch (x) {
case 11: break;
case 42: test14(97); // fallthrough
default: test14(42); break;
which is not the same thing at all. This fixes a miscompilation of
MallocBench/gs seen on the clang-x86_64-linux-fnt buildbot.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@129679 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp
index b8b2cd9..8bb4534 100644
--- a/lib/CodeGen/CGStmt.cpp
+++ b/lib/CodeGen/CGStmt.cpp
@@ -873,7 +873,8 @@
return;
}
- // If the body of the case is just a 'break', try to not emit an empty block.
+ // If the body of the case is just a 'break', and if there was no fallthrough,
+ // try to not emit an empty block.
if (isa<BreakStmt>(S.getSubStmt())) {
JumpDest Block = BreakContinueStack.back().BreakBlock;
@@ -882,6 +883,13 @@
llvm::APSInt CaseVal = S.getLHS()->EvaluateAsInt(getContext());
SwitchInsn->addCase(llvm::ConstantInt::get(getLLVMContext(), CaseVal),
Block.getBlock());
+
+ // If there was a fallthrough into this case, make sure to redirect it to
+ // the end of the switch as well.
+ if (Builder.GetInsertBlock()) {
+ Builder.CreateBr(Block.getBlock());
+ Builder.ClearInsertionPoint();
+ }
return;
}
}