[llvm] r191313 - MemoryBuiltins: Fix operator new bits.

[Benjamin Kramer]

On 24.09.2013, at 19:38, Hal Finkel <hfinkel at anl.gov> wrote:

> Ben,
> 
> Kind of off topic, but since you're looking at this code, can you see why posix_memalign is in this list:
> 
>  {LibFunc::posix_memalign,      MallocLike,  3, 2,  -1},
> 
> As far as I can tell, getAllocationData will always fail on it because of this check:
> 
> if (FTy->getReturnType() == Type::getInt8PtrTy(FTy->getContext()) && ...

Thanks for noticing this. posix_memalign doesn't make any sense there, the infrastructure isn't ready for it. Just fixing the check wouldn't work either because code calling isMallocLikeFn relies on the return value being a pointer. I'll replace the entry with a TODO for now.

- Ben

> 
> Thanks,
> Hal
> 
> 
> ----- Original Message -----
>> Author: d0k
>> Date: Tue Sep 24 12:15:14 2013
>> New Revision: 191313
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=191313&view=rev
>> Log:
>> MemoryBuiltins: Fix operator new bits.
>> 
>> We really don't want to optimize malloc return value checks away.
>> 
>> Modified:
>>    llvm/trunk/lib/Analysis/MemoryBuiltins.cpp
>>    llvm/trunk/test/Transforms/InstSimplify/call.ll
>> 
>> Modified: llvm/trunk/lib/Analysis/MemoryBuiltins.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/MemoryBuiltins.cpp?rev=191313&r1=191312&r2=191313&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Analysis/MemoryBuiltins.cpp (original)
>> +++ llvm/trunk/lib/Analysis/MemoryBuiltins.cpp Tue Sep 24 12:15:14
>> 2013
>> @@ -35,9 +35,9 @@ enum AllocType {
>>   CallocLike         = 1<<1, // allocates + bzero
>>   ReallocLike        = 1<<2, // reallocates
>>   StrDupLike         = 1<<3,
>> -  OpNewLike          = MallocLike | (1<<4), // allocates; never
>> returns null
>> -  AllocLike          = MallocLike | CallocLike | StrDupLike,
>> -  AnyAlloc           = MallocLike | CallocLike | ReallocLike |
>> StrDupLike
>> +  OpNewLike          = 1<<4, // allocates; never returns null
>> +  AllocLike          = MallocLike | CallocLike | StrDupLike |
>> OpNewLike,
>> +  AnyAlloc           = AllocLike | ReallocLike
>> };
>> 
>> struct AllocFnsTy {
>> 
>> Modified: llvm/trunk/test/Transforms/InstSimplify/call.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/call.ll?rev=191313&r1=191312&r2=191313&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/InstSimplify/call.ll (original)
>> +++ llvm/trunk/test/Transforms/InstSimplify/call.ll Tue Sep 24
>> 12:15:14 2013
>> @@ -121,3 +121,23 @@ cast.end:
>> }
>> 
>> declare noalias i8* @_Znwm(i64)
>> +
>> +define i8* @malloc_can_return_null() {
>> +entry:
>> +  %call = tail call noalias i8* @malloc(i64 8)
>> +  %cmp = icmp eq i8* %call, null
>> +  br i1 %cmp, label %cast.end, label %cast.notnull
>> +
>> +cast.notnull:                                     ; preds = %entry
>> +  %add.ptr = getelementptr inbounds i8* %call, i64 4
>> +  br label %cast.end
>> +
>> +cast.end:                                         ; preds =
>> %cast.notnull, %entry
>> +  %cast.result = phi i8* [ %add.ptr, %cast.notnull ], [ null, %entry
>> ]
>> +  ret i8* %cast.result
>> +
>> +; CHECK-LABEL: @malloc_can_return_null
>> +; CHECK: br i1 %cmp, label %cast.end, label %cast.notnull
>> +}
>> +
>> +declare noalias i8* @malloc(i64)
>> 
>> 
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>> 
> 
> -- 
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory