[CFL-AA] CFL-AA should not assert on an va_arg instruction
The CFL-AA implementation was missing a visit* routine for va_arg instructions,
causing it to assert when run on a function that had one. For now, handle these
in a conservative way.
Fixes PR20954.
llvm-svn: 219718
diff --git a/llvm/lib/Analysis/CFLAliasAnalysis.cpp b/llvm/lib/Analysis/CFLAliasAnalysis.cpp
index 0386afe..20bd286 100644
--- a/llvm/lib/Analysis/CFLAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/CFLAliasAnalysis.cpp
@@ -317,6 +317,17 @@
Output.push_back(Edge(Ptr, Val, EdgeType::Dereference, AttrNone));
}
+ void visitVAArgInst(VAArgInst &Inst) {
+ // We can't fully model va_arg here. For *Ptr = Inst.getOperand(0), it does
+ // two things:
+ // 1. Loads a value from *((T*)*Ptr).
+ // 2. Increments (stores to) *Ptr by some target-specific amount.
+ // For now, we'll handle this like a landingpad instruction (by placing the
+ // result in its own group, and having that group alias externals).
+ auto *Val = &Inst;
+ Output.push_back(Edge(Val, Val, EdgeType::Assign, AttrAll));
+ }
+
static bool isFunctionExternal(Function *Fn) {
return Fn->isDeclaration() || !Fn->hasLocalLinkage();
}