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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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30
lib/Bitcode/Writer/BitcodeWriter.cpp
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@ -161,7 +161,30 @@ static void WriteStringRecord(unsigned Code, StringRef Str,
Stream.EmitRecord(Code, Vals, AbbrevToUse);
}
// Emit information about parameter attributes.
/// \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 writer!
static uint64_t encodeLLVMAttributesForBitcode(AttributeSet Attrs,
unsigned Index) {
// FIXME: Remove in 4.0!
// 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;
}
static void WriteAttributeTable(const ValueEnumerator &VE,
BitstreamWriter &Stream) {
const std::vector<AttributeSet> &Attrs = VE.getAttributes();
@ -175,12 +198,11 @@ static void WriteAttributeTable(const ValueEnumerator &VE,
for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i) {
unsigned Index = A.getSlotIndex(i);
Record.push_back(Index);
Record.push_back(AttributeFuncs::
encodeLLVMAttributesForBitcode(A.getSlotAttributes(i),
Record.push_back(encodeLLVMAttributesForBitcode(A.getSlotAttributes(i),
Index));
}
Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY_OLD, Record);
Record.clear();
}