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Add CreateAlignmentAssumption to IRBuilder

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Clang CodeGen had a utility function for creating pointer alignment assumptions
using the @llvm.assume intrinsic. This functionality will also be needed by the
inliner (to preserve function-argument alignment attributes when inlining), so
this moves the utility function into IRBuilder where it can be used both by
Clang CodeGen and also other LLVM-level code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219875 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel 2014-10-15 23:44:22 +00:00
parent fb9d61a8d6
commit 76ce614af7
2 changed files with 53 additions and 0 deletions
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42
include/llvm/IR/IRBuilder.h
View File

@ -429,6 +429,10 @@ public:
/// If the pointer isn't i8* it will be converted.
CallInst *CreateLifetimeEnd(Value *Ptr, ConstantInt *Size = nullptr);
/// \brief Create an assume intrinsic call that allows the optimizer to
/// assume that the provided condition will be true.
CallInst *CreateAssumption(Value *Cond);
private:
Value *getCastedInt8PtrValue(Value *Ptr);
};
@ -1524,6 +1528,44 @@ public:
}
return V;
}
/// \brief Create an assume intrinsic call that represents an alignment
/// assumption on the provided pointer.
///
/// An optional offset can be provided, and if it is provided, the offset
/// must be subtracted from the provided pointer to get the pointer with the
/// specified alignment.
CallInst *CreateAlignmentAssumption(const DataLayout &DL, Value *PtrValue,
unsigned Alignment,
Value *OffsetValue = nullptr) {
assert(isa<PointerType>(PtrValue->getType()) &&
"trying to create an alignment assumption on a non-pointer?");
PointerType *PtrTy = cast<PointerType>(PtrValue->getType());
Type *IntPtrTy = getIntPtrTy(&DL, PtrTy->getAddressSpace());
Value *PtrIntValue = CreatePtrToInt(PtrValue, IntPtrTy, "ptrint");
Value *Mask = ConstantInt::get(IntPtrTy,
Alignment > 0 ? Alignment - 1 : 0);
if (OffsetValue) {
bool IsOffsetZero = false;
if (ConstantInt *CI = dyn_cast<ConstantInt>(OffsetValue))
IsOffsetZero = CI->isZero();
if (!IsOffsetZero) {
if (OffsetValue->getType() != IntPtrTy)
OffsetValue = CreateIntCast(OffsetValue, IntPtrTy, /*isSigned*/ true,
"offsetcast");
PtrIntValue = CreateSub(PtrIntValue, OffsetValue, "offsetptr");
}
}
Value *Zero = ConstantInt::get(IntPtrTy, 0);
Value *MaskedPtr = CreateAnd(PtrIntValue, Mask, "maskedptr");
Value *InvCond = CreateICmpEQ(MaskedPtr, Zero, "maskcond");
return CreateAssumption(InvCond);
}
};
// Create wrappers for C Binding types (see CBindingWrapping.h).

11
lib/IR/IRBuilder.cpp
View File

@ -172,3 +172,14 @@ CallInst *IRBuilderBase::CreateLifetimeEnd(Value *Ptr, ConstantInt *Size) {
Value *TheFn = Intrinsic::getDeclaration(M, Intrinsic::lifetime_end);
return createCallHelper(TheFn, Ops, this);
}
CallInst *IRBuilderBase::CreateAssumption(Value *Cond) {
assert(Cond->getType() == getInt1Ty() &&
"an assumption condition must be of type i1");
Value *Ops[] = { Cond };
Module *M = BB->getParent()->getParent();
Value *FnAssume = Intrinsic::getDeclaration(M, Intrinsic::assume);
return createCallHelper(FnAssume, Ops, this);
}