change instcombine to not turn a call to non-varargs bitcast of
function prototype into a call to a varargs prototype. We do
allow the xform if we have a definition, but otherwise we don't
want to risk that we're changing the abi in a subtle way. On
X86-64, for example, varargs require passing stuff in %al.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126363 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 8449f7b..0e46450 100644
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -953,10 +953,19 @@
if (Callee->isDeclaration() && !isConvertible) return false;
}
- if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
- Callee->isDeclaration())
- return false; // Do not delete arguments unless we have a function body.
+ if (Callee->isDeclaration()) {
+ // Do not delete arguments unless we have a function body.
+ if (FT->getNumParams() < NumActualArgs && !FT->isVarArg())
+ return false;
+ // If the callee is just a declaration, don't change the varargsness of the
+ // call. We don't want to introduce a varargs call where one doesn't
+ // already exist.
+ const PointerType *APTy = cast<PointerType>(CS.getCalledValue()->getType());
+ if (FT->isVarArg()!=cast<FunctionType>(APTy->getElementType())->isVarArg())
+ return false;
+ }
+
if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
!CallerPAL.isEmpty())
// In this case we have more arguments than the new function type, but we
@@ -970,8 +979,9 @@
return false;
}
+
// Okay, we decided that this is a safe thing to do: go ahead and start
- // inserting cast instructions as necessary...
+ // inserting cast instructions as necessary.
std::vector<Value*> Args;
Args.reserve(NumActualArgs);
SmallVector<AttributeWithIndex, 8> attrVec;