[LLVMdev] How to test isDereferenceablePointer?

[Nick Lewycky]

Philip Reames wrote:
> T.M.K., there's no direct way to test it.

There is. See the 'unittests/' directory which contains the C++ unit 
tests. See unittests/IR/UserTest.cpp for an example that builds up IR 
from a .ll-in-a-C-string then queries C++ API operations on it.

Nick

  You have to construct a
> transformation which happens with the information you added and not
> otherwise.
>
> The easiest case might be LICM.
>
> Philip
>
> On 01/17/2015 11:25 AM, Ramkumar Ramachandra wrote:
>> I'm have a
>> [PATCH] isDereferenceablePointer: look through gc.relocates
>>
>> and I want to know how to test this patch. So far, I've found one
>> candiate: speculative execution in SimplifyCFG
>> (test/Transforms/SimplifyCFG/SpeculativeExec.ll). However, it's
>> somewhat involved to show that SimplifyCFG does kick in for
>> gc.relocate. Is there a better way to directly test it?
>>
>> Signed-off-by: Ramkumar Ramachandra <artagnon at gmail.com>
>> ---
>> lib/IR/Value.cpp | 9 +++++++++
>> 1 file changed, 9 insertions(+)
>>
>> diff --git a/lib/IR/Value.cpp b/lib/IR/Value.cpp
>> index 5f7e258..aa701d5 100644
>> --- a/lib/IR/Value.cpp
>> +++ b/lib/IR/Value.cpp
>> @@ -23,8 +23,10 @@
>> #include "llvm/IR/GetElementPtrTypeIterator.h"
>> #include "llvm/IR/InstrTypes.h"
>> #include "llvm/IR/Instructions.h"
>> +#include "llvm/IR/IntrinsicInst.h"
>> #include "llvm/IR/Module.h"
>> #include "llvm/IR/Operator.h"
>> +#include "llvm/IR/Statepoint.h"
>> #include "llvm/IR/ValueHandle.h"
>> #include "llvm/IR/ValueSymbolTable.h"
>> #include "llvm/Support/Debug.h"
>> @@ -570,6 +572,13 @@ static bool isDereferenceablePointer(const Value
>> *V, const DataLayout *DL,
>> return true;
>> }
>> + // For gc.relocate, look through relocations
>> + if (const IntrinsicInst *I = dyn_cast<IntrinsicInst>(V))
>> + if (I->getIntrinsicID() == Intrinsic::experimental_gc_relocate) {
>> + GCRelocateOperands RelocateInst(I);
>> + return isDereferenceablePointer(RelocateInst.derivedPtr(), DL,
>> Visited);
>> + }
>> +
>> if (const AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(V))
>> return isDereferenceablePointer(ASC->getOperand(0), DL, Visited);
>
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