2525// * C: The macro bit. We rotate it to the lowest bit so that we can save some
2626// space in case the index of the module file is 0.
2727//
28- // Specially, if the index of the module file is 0, we allow to encode a
29- // sequence of locations we store only differences between successive elements.
3028//
3129// ===----------------------------------------------------------------------===//
3230
3836#define LLVM_CLANG_SERIALIZATION_SOURCELOCATIONENCODING_H
3937
4038namespace clang {
41- class SourceLocationSequence ;
4239
4340// / Serialized encoding of SourceLocations without context.
4441// / Optimized to have small unsigned values (=> small after VBR encoding).
@@ -54,119 +51,22 @@ class SourceLocationEncoding {
5451 static UIntTy decodeRaw (UIntTy Raw) {
5552 return (Raw >> 1 ) | (Raw << (UIntBits - 1 ));
5653 }
57- friend SourceLocationSequence;
5854
5955public:
6056 using RawLocEncoding = uint64_t ;
6157
6258 static RawLocEncoding encode (SourceLocation Loc, UIntTy BaseOffset,
63- unsigned BaseModuleFileIndex,
64- SourceLocationSequence * = nullptr );
65- static std::pair<SourceLocation, unsigned >
66- decode (RawLocEncoding, SourceLocationSequence * = nullptr );
67- };
68-
69- // / Serialized encoding of a sequence of SourceLocations.
70- // /
71- // / Optimized to produce small values when locations with the sequence are
72- // / similar. Each element can be delta-encoded against the last nonzero element.
73- // /
74- // / Sequences should be started by creating a SourceLocationSequence::State,
75- // / and then passed around as SourceLocationSequence*. Example:
76- // /
77- // / // establishes a sequence
78- // / void EmitTopLevelThing() {
79- // / SourceLocationSequence::State Seq;
80- // / EmitContainedThing(Seq);
81- // / EmitRecursiveThing(Seq);
82- // / }
83- // /
84- // / // optionally part of a sequence
85- // / void EmitContainedThing(SourceLocationSequence *Seq = nullptr) {
86- // / Record.push_back(SourceLocationEncoding::encode(SomeLoc, Seq));
87- // / }
88- // /
89- // / // establishes a sequence if there isn't one already
90- // / void EmitRecursiveThing(SourceLocationSequence *ParentSeq = nullptr) {
91- // / SourceLocationSequence::State Seq(ParentSeq);
92- // / Record.push_back(SourceLocationEncoding::encode(SomeLoc, Seq));
93- // / EmitRecursiveThing(Seq);
94- // / }
95- // /
96- class SourceLocationSequence {
97- using UIntTy = SourceLocation::UIntTy;
98- using EncodedTy = uint64_t ;
99- constexpr static auto UIntBits = SourceLocationEncoding::UIntBits;
100- static_assert (sizeof (EncodedTy) > sizeof (UIntTy), " Need one extra bit!"
101-
102- // Prev stores the rotated last nonzero location.
103- UIntTy &Prev;
104-
105- // Zig-zag encoding turns small signed integers into small unsigned integers.
106- // 0 => 0, -1 => 1, 1 => 2, -2 => 3, ...
107- static UIntTy zigZag (UIntTy V) {
108- UIntTy Sign = (V & (1 << (UIntBits - 1 ))) ? UIntTy (-1 ) : UIntTy (0 );
109- return Sign ^ (V << 1 );
110- }
111- static UIntTy zagZig (UIntTy V) { return (V >> 1 ) ^ -(V & 1 ); }
112-
113- SourceLocationSequence (UIntTy &Prev) : Prev(Prev) {}
114-
115- EncodedTy encodeRaw (UIntTy Raw) {
116- if (Raw == 0 )
117- return 0 ;
118- UIntTy Rotated = SourceLocationEncoding::encodeRaw (Raw);
119- if (Prev == 0 )
120- return Prev = Rotated;
121- UIntTy Delta = Rotated - Prev;
122- Prev = Rotated;
123- // Exactly one 33 bit value is possible! (1 << 32).
124- // This is because we have two representations of zero: trivial & relative.
125- return 1 + EncodedTy{zigZag (Delta)};
126- }
127- UIntTy decodeRaw (EncodedTy Encoded) {
128- if (Encoded == 0 )
129- return 0 ;
130- if (Prev == 0 )
131- return SourceLocationEncoding::decodeRaw (Prev = Encoded);
132- return SourceLocationEncoding::decodeRaw (Prev += zagZig (Encoded - 1 ));
133- }
134-
135- public:
136- SourceLocation decode (EncodedTy Encoded) {
137- return SourceLocation::getFromRawEncoding (decodeRaw (Encoded));
138- }
139- EncodedTy encode (SourceLocation Loc) {
140- return encodeRaw (Loc.getRawEncoding ());
141- }
142-
143- class State ;
144- };
145-
146- // / This object establishes a SourceLocationSequence.
147- class SourceLocationSequence ::State {
148- UIntTy Prev = 0 ;
149- SourceLocationSequence Seq;
150-
151- public:
152- // If Parent is provided and non-null, then this root becomes part of that
153- // enclosing sequence instead of establishing a new one.
154- State (SourceLocationSequence *Parent = nullptr )
155- : Seq(Parent ? Parent->Prev : Prev) {}
156-
157- // Implicit conversion for uniform use of roots vs propagated sequences.
158- operator SourceLocationSequence *() { return &Seq; }
59+ unsigned BaseModuleFileIndex);
60+ static std::pair<SourceLocation, unsigned > decode (RawLocEncoding);
15961};
16062
16163inline SourceLocationEncoding::RawLocEncoding
16264SourceLocationEncoding::encode (SourceLocation Loc, UIntTy BaseOffset,
163- unsigned BaseModuleFileIndex,
164- SourceLocationSequence *Seq) {
65+ unsigned BaseModuleFileIndex) {
16566 // If the source location is a local source location, we can try to optimize
16667 // the similar sequences to only record the differences.
16768 if (!BaseOffset)
168- return Seq ? Seq->encode (Loc) : encodeRaw (Loc.getRawEncoding ());
169-
69+ return encodeRaw (Loc.getRawEncoding ());
17070 if (Loc.isInvalid ())
17171 return 0 ;
17272
@@ -183,13 +83,11 @@ SourceLocationEncoding::encode(SourceLocation Loc, UIntTy BaseOffset,
18383 return Encoded;
18484}
18585inline std::pair<SourceLocation, unsigned >
186- SourceLocationEncoding::decode (RawLocEncoding Encoded,
187- SourceLocationSequence *Seq) {
86+ SourceLocationEncoding::decode (RawLocEncoding Encoded) {
18887 unsigned ModuleFileIndex = Encoded >> 32 ;
18988
19089 if (!ModuleFileIndex)
191- return {Seq ? Seq->decode (Encoded)
192- : SourceLocation::getFromRawEncoding (decodeRaw (Encoded)),
90+ return {SourceLocation::getFromRawEncoding (decodeRaw (Encoded)),
19391 ModuleFileIndex};
19492
19593 Encoded &= llvm::maskTrailingOnes<RawLocEncoding>(32 );
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