[InlineCost] Mark functions accessing varargs as not viable.

This prevents functions accessing varargs from being inlined if they
have the alwaysinline attribute.

Reviewers: efriedma, rnk, davide

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D42556

llvm-svn: 323619

1 files changed, 12 insertions, 6 deletions

diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index 0e7be52cae7..b0e0acd3629 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -2040,12 +2040,18 @@ bool llvm::isInlineViable(Function &F) {
           cast<CallInst>(CS.getInstruction())->canReturnTwice())
         return false;
 
-      // Disallow inlining functions that call @llvm.localescape. Doing this
-      // correctly would require major changes to the inliner.
-      if (CS.getCalledFunction() &&
-          CS.getCalledFunction()->getIntrinsicID() ==
-              llvm::Intrinsic::localescape)
-        return false;
+      if (CS.getCalledFunction())
+        switch (CS.getCalledFunction()->getIntrinsicID()) {
+        default:
+          break;
+        // Disallow inlining functions that call @llvm.localescape. Doing this
+        // correctly would require major changes to the inliner.
+        case llvm::Intrinsic::localescape:
+        // Disallow inlining of functions that access VarArgs.
+        case llvm::Intrinsic::vastart:
+        case llvm::Intrinsic::vaend:
+          return false;
+        }
     }
   }