Disable InstCombine unsafe folding bitcasts of calls w/ varargs.

Changing arguments from being passed as fixed to varargs is unsafe, as
the ABI may require they be handled differently (stack vs. register, for
example).

Remove two tests which rely on the bitcast being folded into the direct
call, which is exactly the transformation that's unsafe.

llvm-svn: 149457

1 files changed, 5 insertions, 14 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index a87fbbd9895..c3c13ae362f 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1105,21 +1105,12 @@ bool InstCombiner::transformConstExprCastCall(CallSite CS) {
     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
-    // won't be dropping them.  Check that these extra arguments have attributes
-    // that are compatible with being a vararg call argument.
-    for (unsigned i = CallerPAL.getNumSlots(); i; --i) {
-      if (CallerPAL.getSlot(i - 1).Index <= FT->getNumParams())
-        break;
-      Attributes PAttrs = CallerPAL.getSlot(i - 1).Attrs;
-      if (PAttrs & Attribute::VarArgsIncompatible)
-        return false;
-    }
 
-  
+  // If we're casting varargs to non-varargs, that may not be allowable
+  // under the ABI, so conservatively don't do anything.
+  if (FT->getNumParams() < NumActualArgs && FT->isVarArg())
+    return false;
+
   // Okay, we decided that this is a safe thing to do: go ahead and start
   // inserting cast instructions as necessary.
   std::vector<Value*> Args;