[llvm] r267708 - NFC. Introduce Value::getPointerDerferecnceableBytes

[David Blaikie via llvm-commits]

Right right - apparently 11am was still too early in the morning for me.
Carry on :)

On Wed, Apr 27, 2016 at 2:22 PM, Artur Pilipenko <apilipenko at azulsystems.com
> wrote:

> This is a non-functional refactoring of existing code, namely extracting a
> function out of existing code. This function is triggered by any
> dereferenceability test. Am I missing something?
>
> Artur
>
> On 27 Apr 2016, at 21:10, David Blaikie <dblaikie at gmail.com> wrote:
>
> It's generally good to not checkin entirely dead & untested code - could
> you include a unit test to demonstrate correctness, at least?
>
> On Wed, Apr 27, 2016 at 5:51 AM, Artur Pilipenko via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Author: apilipenko
>> Date: Wed Apr 27 07:51:01 2016
>> New Revision: 267708
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=267708&view=rev
>> Log:
>> NFC. Introduce Value::getPointerDerferecnceableBytes
>>
>> Extract a part of isDereferenceableAndAlignedPointer functionality to
>> Value::getPointerDerferecnceableBytes. Currently it's a NFC, but in future
>> I'm going to accumulate all the logic about value dereferenceability in
>> this function similarly to Value::getPointerAlignment function (D16144).
>>
>> Reviewed By: reames
>>
>> Differential Revision: http://reviews.llvm.org/D17572
>>
>> Modified:
>>     llvm/trunk/include/llvm/IR/Value.h
>>     llvm/trunk/lib/Analysis/Loads.cpp
>>     llvm/trunk/lib/IR/Value.cpp
>>
>> Modified: llvm/trunk/include/llvm/IR/Value.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/Value.h?rev=267708&r1=267707&r2=267708&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/include/llvm/IR/Value.h (original)
>> +++ llvm/trunk/include/llvm/IR/Value.h Wed Apr 27 07:51:01 2016
>> @@ -504,6 +504,13 @@ public:
>>      return const_cast<Value*>(this)->stripInBoundsOffsets();
>>    }
>>
>> +  /// \brief Returns the number of bytes known to be dereferenceable for
>> the
>> +  /// pointer value.
>> +  ///
>> +  /// If CanBeNull is set by this function the pointer can either be
>> null or be
>> +  /// dereferenceable up to the returned number of bytes.
>> +  unsigned getPointerDereferenceableBytes(bool &CanBeNull) const;
>> +
>>    /// \brief Returns an alignment of the pointer value.
>>    ///
>>    /// Returns an alignment which is either specified explicitly, e.g. via
>>
>> Modified: llvm/trunk/lib/Analysis/Loads.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/Loads.cpp?rev=267708&r1=267707&r2=267708&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Analysis/Loads.cpp (original)
>> +++ llvm/trunk/lib/Analysis/Loads.cpp Wed Apr 27 07:51:01 2016
>> @@ -33,34 +33,9 @@ static bool isDereferenceableFromAttribu
>>    assert(Offset.isNonNegative() && "offset can't be negative");
>>    assert(Ty->isSized() && "must be sized");
>>
>> -  APInt DerefBytes(Offset.getBitWidth(), 0);
>>    bool CheckForNonNull = false;
>> -  if (const Argument *A = dyn_cast<Argument>(BV)) {
>> -    DerefBytes = A->getDereferenceableBytes();
>> -    if (!DerefBytes.getBoolValue()) {
>> -      DerefBytes = A->getDereferenceableOrNullBytes();
>> -      CheckForNonNull = true;
>> -    }
>> -  } else if (auto CS = ImmutableCallSite(BV)) {
>> -    DerefBytes = CS.getDereferenceableBytes(0);
>> -    if (!DerefBytes.getBoolValue()) {
>> -      DerefBytes = CS.getDereferenceableOrNullBytes(0);
>> -      CheckForNonNull = true;
>> -    }
>> -  } else if (const LoadInst *LI = dyn_cast<LoadInst>(BV)) {
>> -    if (MDNode *MD = LI->getMetadata(LLVMContext::MD_dereferenceable)) {
>> -      ConstantInt *CI = mdconst::extract<ConstantInt>(MD->getOperand(0));
>> -      DerefBytes = CI->getLimitedValue();
>> -    }
>> -    if (!DerefBytes.getBoolValue()) {
>> -      if (MDNode *MD =
>> -              LI->getMetadata(LLVMContext::MD_dereferenceable_or_null)) {
>> -        ConstantInt *CI =
>> mdconst::extract<ConstantInt>(MD->getOperand(0));
>> -        DerefBytes = CI->getLimitedValue();
>> -      }
>> -      CheckForNonNull = true;
>> -    }
>> -  }
>> +  APInt DerefBytes(Offset.getBitWidth(),
>> +                   BV->getPointerDereferenceableBytes(CheckForNonNull));
>>
>>    if (DerefBytes.getBoolValue())
>>      if (DerefBytes.uge(Offset + DL.getTypeStoreSize(Ty)))
>>
>> Modified: llvm/trunk/lib/IR/Value.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Value.cpp?rev=267708&r1=267707&r2=267708&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/IR/Value.cpp (original)
>> +++ llvm/trunk/lib/IR/Value.cpp Wed Apr 27 07:51:01 2016
>> @@ -525,6 +525,40 @@ Value *Value::stripInBoundsOffsets() {
>>    return stripPointerCastsAndOffsets<PSK_InBounds>(this);
>>  }
>>
>> +unsigned Value::getPointerDereferenceableBytes(bool &CanBeNull) const {
>> +  assert(getType()->isPointerTy() && "must be pointer");
>> +
>> +  unsigned DerefBytes = 0;
>> +  CanBeNull = false;
>> +  if (const Argument *A = dyn_cast<Argument>(this)) {
>> +    DerefBytes = A->getDereferenceableBytes();
>> +    if (DerefBytes == 0) {
>> +      DerefBytes = A->getDereferenceableOrNullBytes();
>> +      CanBeNull = true;
>> +    }
>> +  } else if (auto CS = ImmutableCallSite(this)) {
>> +    DerefBytes = CS.getDereferenceableBytes(0);
>> +    if (DerefBytes == 0) {
>> +      DerefBytes = CS.getDereferenceableOrNullBytes(0);
>> +      CanBeNull = true;
>> +    }
>> +  } else if (const LoadInst *LI = dyn_cast<LoadInst>(this)) {
>> +    if (MDNode *MD = LI->getMetadata(LLVMContext::MD_dereferenceable)) {
>> +      ConstantInt *CI = mdconst::extract<ConstantInt>(MD->getOperand(0));
>> +      DerefBytes = CI->getLimitedValue();
>> +    }
>> +    if (DerefBytes == 0) {
>> +      if (MDNode *MD =
>> +              LI->getMetadata(LLVMContext::MD_dereferenceable_or_null)) {
>> +        ConstantInt *CI =
>> mdconst::extract<ConstantInt>(MD->getOperand(0));
>> +        DerefBytes = CI->getLimitedValue();
>> +      }
>> +      CanBeNull = true;
>> +    }
>> +  }
>> +  return DerefBytes;
>> +}
>> +
>>  unsigned Value::getPointerAlignment(const DataLayout &DL) const {
>>    assert(getType()->isPointerTy() && "must be pointer");
>>
>>
>>
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>
>
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