[MergeFunc] Prevent silent miscompile of vararg functions
The function merging pass miscompiles identical vararg functions. The
forwarding thunk it emits doesn't forward the full variable-length list
of arguments. Disable merging for vararg functions for now.
I've filed llvm.org/PR40345 to track the issue.
rdar://47326238
llvm-svn: 351411
diff --git a/llvm/lib/Transforms/IPO/MergeFunctions.cpp b/llvm/lib/Transforms/IPO/MergeFunctions.cpp
index 11efe95..26b204f 100644
--- a/llvm/lib/Transforms/IPO/MergeFunctions.cpp
+++ b/llvm/lib/Transforms/IPO/MergeFunctions.cpp
@@ -383,6 +383,12 @@
}
#endif
+/// Check whether \p F is eligible for function merging.
+static bool isEligibleForMerging(Function &F) {
+ return !F.isDeclaration() && !F.hasAvailableExternallyLinkage() &&
+ !F.isVarArg();
+}
+
bool MergeFunctions::runOnModule(Module &M) {
if (skipModule(M))
return false;
@@ -394,7 +400,7 @@
std::vector<std::pair<FunctionComparator::FunctionHash, Function *>>
HashedFuncs;
for (Function &Func : M) {
- if (!Func.isDeclaration() && !Func.hasAvailableExternallyLinkage()) {
+ if (isEligibleForMerging(Func)) {
HashedFuncs.push_back({FunctionComparator::functionHash(Func), &Func});
}
}