[llvm] r340807 - Fix in getAllocationDataForFunction

[Kaylor, Andrew via llvm-commits]

I believe this change is incorrect. It causes us to report that malloc is a new-like function.

The way that the allocation kinds are defined, each allocation kind has a unique bit except for malloc-like which shares a bit with new-like. With the old implementation, this allowed us to recognize new-like functions as also being malloc-like, but not the other way around. The other combination masks in the AllocType enum allow for matching any of multiple types, but no function will be defined as being, for instance, MallocOrCallocLike.

So the old logic in getAllocationDataForFunction was applying the incoming AllocTy as a mask, and if the FnData->AllocTy was unchanged after applying that mask, then it matched.  That is, if all of the bits in the FnData->AllocTy were in the callers mask, then it matched. Otherwise, it did not. I think that's the behavior we want.

Can this change be reverted?

-Andy

-----Original Message-----
From: llvm-commits [mailto:llvm-commits-bounces at lists.llvm.org] On Behalf Of David Chisnall via llvm-commits
Sent: Tuesday, August 28, 2018 1:59 AM
To: llvm-commits at lists.llvm.org
Subject: [llvm] r340807 - Fix in getAllocationDataForFunction

Author: theraven
Date: Tue Aug 28 01:59:06 2018
New Revision: 340807

URL: http://llvm.org/viewvc/llvm-project?rev=340807&view=rev
Log:
Fix in getAllocationDataForFunction

Summary:
Correct to use set like behaviour of AllocType.  Should check for subset, not precise value.

Reviewers: theraven

Reviewed By: theraven

Subscribers: hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D50959

Modified:
    llvm/trunk/lib/Analysis/MemoryBuiltins.cpp

Modified: llvm/trunk/lib/Analysis/MemoryBuiltins.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MemoryBuiltins.cpp?rev=340807&r1=340806&r2=340807&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/MemoryBuiltins.cpp (original)
+++ llvm/trunk/lib/Analysis/MemoryBuiltins.cpp Tue Aug 28 01:59:06 2018
@@ -150,7 +150,7 @@ getAllocationDataForFunction(const Funct
     return None;
 
   const AllocFnsTy *FnData = &Iter->second;
-  if ((FnData->AllocTy & AllocTy) != FnData->AllocTy)
+  if ((FnData->AllocTy & AllocTy) == 0)
     return None;
 
   // Check function prototype.


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