[llvm] 1076b6c - [Analysis] use better version of getLibFunc to check for alloc/free calls

[Sanjay Patel via llvm-commits]

Author: Sanjay Patel
Date: 2021-06-25T12:14:07-04:00
New Revision: 1076b6c4f022a024a54af9e6a0e9997472cb89ef

URL: https://github.com/llvm/llvm-project/commit/1076b6c4f022a024a54af9e6a0e9997472cb89ef
DIFF: https://github.com/llvm/llvm-project/commit/1076b6c4f022a024a54af9e6a0e9997472cb89ef.diff

LOG: [Analysis] use better version of getLibFunc to check for alloc/free calls

There's no reason to use the weaker name-only analysis when we
have a function prototype to check (in fact, we probably should
not even have that name-only function exposed for general use,
but removing it requires auditing all of the callers).

The version of getLibFunc that takes a Function argument also
does some prototype checking to make sure the arguments/return
type match the expected signature of a real library call.

This is NFC-intended because the code in MemoryBuiltins does its
own function signature checking. For now, that means there may
be some redundancy in the checking, but that should not be above
the noise for compile-time. Ideally, we can move the checks to
a single location.

There's still a hole in the logic that allows the example in
https://llvm.org/PR50846 to cause a compiler crash.

Added: 
    

Modified: 
    llvm/lib/Analysis/MemoryBuiltins.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/MemoryBuiltins.cpp b/llvm/lib/Analysis/MemoryBuiltins.cpp
index cf7ee0f5fdeb..e3d197c482bd 100644
--- a/llvm/lib/Analysis/MemoryBuiltins.cpp
+++ b/llvm/lib/Analysis/MemoryBuiltins.cpp
@@ -142,9 +142,8 @@ static Optional<AllocFnsTy>
 getAllocationDataForFunction(const Function *Callee, AllocType AllocTy,
                              const TargetLibraryInfo *TLI) {
   // Make sure that the function is available.
-  StringRef FnName = Callee->getName();
   LibFunc TLIFn;
-  if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
+  if (!TLI || !TLI->getLibFunc(*Callee, TLIFn) || !TLI->has(TLIFn))
     return None;
 
   const auto *Iter = find_if(
@@ -492,9 +491,8 @@ const CallInst *llvm::isFreeCall(const Value *I, const TargetLibraryInfo *TLI) {
   if (Callee == nullptr || IsNoBuiltinCall)
     return nullptr;
 
-  StringRef FnName = Callee->getName();
   LibFunc TLIFn;
-  if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
+  if (!TLI || !TLI->getLibFunc(*Callee, TLIFn) || !TLI->has(TLIFn))
     return nullptr;
 
   return isLibFreeFunction(Callee, TLIFn) ? dyn_cast<CallInst>(I) : nullptr;