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Add a dereferenceable attribute

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This attribute indicates that the parameter or return pointer is
dereferenceable. Practically speaking, loads from such a pointer within the
associated byte range are safe to speculatively execute. Such pointer
parameters are common in source languages (C++ references, for example).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213385 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel
2014-07-18 15:51:28 +00:00
parent a11bf68f6c
commit 11af4b49b2
22 changed files with 388 additions and 18 deletions
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18
lib/IR/Function.cpp
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@@ -77,11 +77,17 @@ unsigned Argument::getArgNo() const {
}
/// hasNonNullAttr - Return true if this argument has the nonnull attribute on
/// it in its containing function.
/// it in its containing function. Also returns true if at least one byte is
/// known to be dereferenceable and the pointer is in addrspace(0).
bool Argument::hasNonNullAttr() const {
if (!getType()->isPointerTy()) return false;
return getParent()->getAttributes().
hasAttribute(getArgNo()+1, Attribute::NonNull);
if (getParent()->getAttributes().
hasAttribute(getArgNo()+1, Attribute::NonNull))
return true;
else if (getDereferenceableBytes() > 0 &&
getType()->getPointerAddressSpace() == 0)
return true;
return false;
}
/// hasByValAttr - Return true if this argument has the byval attribute on it
@@ -113,6 +119,12 @@ unsigned Argument::getParamAlignment() const {
}
uint64_t Argument::getDereferenceableBytes() const {
assert(getType()->isPointerTy() &&
"Only pointers have dereferenceable bytes");
return getParent()->getDereferenceableBytes(getArgNo()+1);
}
/// hasNestAttr - Return true if this argument has the nest attribute on
/// it in its containing function.
bool Argument::hasNestAttr() const {