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Initial cleanups of the param-attribute code in the bitcode reader/writer.

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Rename the PARAMATTR_CODE_ENTRY to PARAMATTR_CODE_ENTRY_OLD. It will be replaced
by another encoding. Keep around the current LLVM attribute encoder/decoder
code, but move it to the bitcode directories so that no one's tempted to use
them.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174335 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling
2013-02-04 23:32:23 +00:00
parent 638c63ccf7
commit f9271ea159
5 changed files with 59 additions and 66 deletions
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42
lib/IR/Attributes.cpp
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@@ -927,6 +927,7 @@ bool AttrBuilder::operator==(const AttrBuilder &B) {
}
AttrBuilder &AttrBuilder::addRawValue(uint64_t Val) {
// FIXME: Remove this in 4.0.
if (!Val) return *this;
for (Attribute::AttrKind I = Attribute::None; I != Attribute::EndAttrKinds;
@@ -967,44 +968,3 @@ AttributeSet AttributeFuncs::typeIncompatible(Type *Ty, uint64_t Index) {
return AttributeSet::get(Ty->getContext(), Index, Incompatible);
}
/// \brief This returns an integer containing an encoding of all the LLVM
/// attributes found in the given attribute bitset. Any change to this encoding
/// is a breaking change to bitcode compatibility.
/// N.B. This should be used only by the bitcode reader!
uint64_t AttributeFuncs::encodeLLVMAttributesForBitcode(AttributeSet Attrs,
unsigned Index) {
// FIXME: It doesn't make sense to store the alignment information as an
// expanded out value, we should store it as a log2 value. However, we can't
// just change that here without breaking bitcode compatibility. If this ever
// becomes a problem in practice, we should introduce new tag numbers in the
// bitcode file and have those tags use a more efficiently encoded alignment
// field.
// Store the alignment in the bitcode as a 16-bit raw value instead of a 5-bit
// log2 encoded value. Shift the bits above the alignment up by 11 bits.
uint64_t EncodedAttrs = Attrs.Raw(Index) & 0xffff;
if (Attrs.hasAttribute(Index, Attribute::Alignment))
EncodedAttrs |= Attrs.getParamAlignment(Index) << 16;
EncodedAttrs |= (Attrs.Raw(Index) & (0xffffULL << 21)) << 11;
return EncodedAttrs;
}
/// \brief This fills an AttrBuilder object with the LLVM attributes that have
/// been decoded from the given integer. This function must stay in sync with
/// 'encodeLLVMAttributesForBitcode'.
/// N.B. This should be used only by the bitcode reader!
void AttributeFuncs::decodeLLVMAttributesForBitcode(LLVMContext &C,
AttrBuilder &B,
uint64_t EncodedAttrs) {
// The alignment is stored as a 16-bit raw value from bits 31--16. We shift
// the bits above 31 down by 11 bits.
unsigned Alignment = (EncodedAttrs & (0xffffULL << 16)) >> 16;
assert((!Alignment || isPowerOf2_32(Alignment)) &&
"Alignment must be a power of two.");
if (Alignment)
B.addAlignmentAttr(Alignment);
B.addRawValue(((EncodedAttrs & (0xffffULL << 32)) >> 11) |
(EncodedAttrs & 0xffff));
}