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[Serialization] Fix source location data loss during decoding. #145529

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[Serialization] Fix source location data loss during decoding. #145529

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9 changes: 6 additions & 3 deletions clang/include/clang/Serialization/SourceLocationEncoding.h
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,9 @@ class SourceLocationEncoding {
using UIntTy = SourceLocation::UIntTy;
constexpr static unsigned UIntBits = CHAR_BIT * sizeof(UIntTy);

// The maximum number of bits we use for the encoding.
constexpr static unsigned EncodingBits = UIntBits + 1;

static UIntTy encodeRaw(UIntTy Raw) {
return (Raw << 1) | (Raw >> (UIntBits - 1));
}
Expand Down Expand Up @@ -179,20 +182,20 @@ SourceLocationEncoding::encode(SourceLocation Loc, UIntTy BaseOffset,

// 16 bits should be sufficient to store the module file index.
assert(BaseModuleFileIndex < (1 << 16));
Encoded |= (RawLocEncoding)BaseModuleFileIndex << 32;
Encoded |= (RawLocEncoding)BaseModuleFileIndex << EncodingBits;
return Encoded;
}
inline std::pair<SourceLocation, unsigned>
SourceLocationEncoding::decode(RawLocEncoding Encoded,
SourceLocationSequence *Seq) {
unsigned ModuleFileIndex = Encoded >> 32;
unsigned ModuleFileIndex = Encoded >> EncodingBits;

if (!ModuleFileIndex)
return {Seq ? Seq->decode(Encoded)
: SourceLocation::getFromRawEncoding(decodeRaw(Encoded)),
ModuleFileIndex};

Encoded &= llvm::maskTrailingOnes<RawLocEncoding>(32);
Encoded &= llvm::maskTrailingOnes<RawLocEncoding>(EncodingBits);
SourceLocation Loc = SourceLocation::getFromRawEncoding(decodeRaw(Encoded));

return {Loc, ModuleFileIndex};
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2 changes: 2 additions & 0 deletions clang/unittests/Serialization/SourceLocationEncodingTest.cpp
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Expand Up @@ -104,6 +104,8 @@ TEST(SourceLocationEncoding, Sequence) {

roundTrip(
{123 | MacroBit, 1, 9, Biggest, Big, Big + 1, 0, MacroBit | Big, 0});

roundTrip({1, (1u << 30) + 1});
}

} // namespace
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