sammccall created this revision.
sammccall added a reviewer: ilya-biryukov.
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Macro expansion SLocEntries are significant to PCH size (7-10% in my tests).
These store the expansion end location as vbr8. However it's highly predictable:
- for macro arg expansion it's zero
- for object macros it equals the expansion start
- for function macros it's usually shortly after the expansion start
Instead, this change stores (bool relative, unsigned value).
If relative is true, ExpEnd is ExpBegin+value, otherwise it's just value.
We define abbreviations to cover the common cases above.
This saves ~15% of SM_SLOC_EXPANSION, which is 1-1.5% of overall PCH size.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D124420
Files:
clang/lib/Serialization/ASTReader.cpp
clang/lib/Serialization/ASTWriter.cpp
Index: clang/lib/Serialization/ASTWriter.cpp
===================================================================
--- clang/lib/Serialization/ASTWriter.cpp
+++ clang/lib/Serialization/ASTWriter.cpp
@@ -1689,19 +1689,47 @@
return Stream.EmitAbbrev(std::move(Abbrev));
}
-/// Create an abbreviation for the SLocEntry that refers to a macro
-/// expansion.
-static unsigned CreateSLocExpansionAbbrev(llvm::BitstreamWriter &Stream) {
+/// We use a family of abbreviations for common cases of expansion SLocEntrys.
+static std::shared_ptr<llvm::BitCodeAbbrev> SLocExpansionAbbrevCommon() {
using namespace llvm;
-
auto Abbrev = std::make_shared<BitCodeAbbrev>();
Abbrev->Add(BitCodeAbbrevOp(SM_SLOC_EXPANSION_ENTRY));
Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Offset
- Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Spelling location
- Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Start location
- Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // End location
- Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Is token range
- Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Token length
+ Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Spelling start
+ Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Spelling length
+ Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Expansion start
+ Abbrev->Add(BitCodeAbbrevOp(1)); // ExpEnd is token
+ return Abbrev;
+}
+
+/// Create an abbreviation for the SLocEntry that refers to a macro
+/// argument expansion.
+static unsigned CreateSLocArgExpansionAbbrev(llvm::BitstreamWriter &Stream) {
+ using namespace llvm;
+ auto Abbrev = SLocExpansionAbbrevCommon();
+ Abbrev->Add(BitCodeAbbrevOp(0)); // ExpEnd is relative
+ Abbrev->Add(BitCodeAbbrevOp(0)); // ExpEnd
+ return Stream.EmitAbbrev(std::move(Abbrev));
+}
+
+/// Create an abbreviation for the SLocEntry that refers to a macro
+/// expansion.
+static unsigned CreateSLocObjectExpansionAbbrev(llvm::BitstreamWriter &Stream) {
+ using namespace llvm;
+ auto Abbrev = SLocExpansionAbbrevCommon();
+ Abbrev->Add(BitCodeAbbrevOp(1)); // ExpEnd is relative
+ Abbrev->Add(BitCodeAbbrevOp(0)); // ExpEnd
+ return Stream.EmitAbbrev(std::move(Abbrev));
+}
+
+/// Create an abbreviation for the SLocEntry that refers to a function-like
+/// macro expansion.
+static unsigned
+CreateSLocFunctionExpansionAbbrev(llvm::BitstreamWriter &Stream) {
+ using namespace llvm;
+ auto Abbrev = SLocExpansionAbbrevCommon();
+ Abbrev->Add(BitCodeAbbrevOp(1)); // ExpEnd is relative
+ Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // End
return Stream.EmitAbbrev(std::move(Abbrev));
}
@@ -2018,7 +2046,10 @@
unsigned SLocBufferBlobAbbrv = CreateSLocBufferBlobAbbrev(Stream, false);
unsigned SLocBufferBlobCompressedAbbrv =
CreateSLocBufferBlobAbbrev(Stream, true);
- unsigned SLocExpansionAbbrv = CreateSLocExpansionAbbrev(Stream);
+ unsigned SLocArgExpansionAbbrv = CreateSLocArgExpansionAbbrev(Stream);
+ unsigned SLocObjectExpansionAbbrv = CreateSLocObjectExpansionAbbrev(Stream);
+ unsigned SLocFunctionExpansionAbbrv =
+ CreateSLocFunctionExpansionAbbrev(Stream);
// Write out the source location entry table. We skip the first
// entry, which is always the same dummy entry.
@@ -2123,19 +2154,47 @@
// The source location entry is a macro expansion.
const SrcMgr::ExpansionInfo &Expansion = SLoc->getExpansion();
AddSourceLocation(Expansion.getSpellingLoc(), Record);
- AddSourceLocation(Expansion.getExpansionLocStart(), Record);
- AddSourceLocation(Expansion.isMacroArgExpansion()
- ? SourceLocation()
- : Expansion.getExpansionLocEnd(),
- Record);
- Record.push_back(Expansion.isExpansionTokenRange());
-
- // Compute the token length for this macro expansion.
+ // Compute the length for this macro expansion.
SourceLocation::UIntTy NextOffset = SourceMgr.getNextLocalOffset();
if (I + 1 != N)
NextOffset = SourceMgr.getLocalSLocEntry(I + 1).getOffset();
Record.push_back(NextOffset - SLoc->getOffset() - 1);
- Stream.EmitRecordWithAbbrev(SLocExpansionAbbrv, Record);
+
+ // ExpStart, ExpEndIsToken, ExpEndIsRelative, ExpEnd
+ AddSourceLocation(Expansion.getExpansionLocStart(), Record);
+ Record.push_back(Expansion.isExpansionTokenRange());
+ SourceLocation ExpEnd = Expansion.isMacroArgExpansion()
+ ? SourceLocation()
+ : Expansion.getExpansionLocEnd();
+ SourceLocation::IntTy Delta;
+ bool EndIsRelative =
+ SourceMgr.isInSameSLocAddrSpace(Expansion.getExpansionLocStart(),
+ ExpEnd, &Delta) &&
+ Delta >= 0;
+ Record.push_back(EndIsRelative);
+ if (EndIsRelative)
+ Record.push_back(Delta);
+ else
+ AddSourceLocation(ExpEnd, Record);
+
+ // Common cases are covered by abbreviations.
+ unsigned Abbrev = [&]() -> unsigned {
+ if (!Expansion.isExpansionTokenRange()) // Token splits.
+ return 0;
+ if (Expansion.isMacroArgExpansion())
+ return SLocArgExpansionAbbrv;
+ if (!EndIsRelative) // Expansion start/end in different FileIDs.
+ return 0;
+ if (Expansion.isFunctionMacroExpansion())
+ return SLocFunctionExpansionAbbrv;
+ return SLocObjectExpansionAbbrv;
+ }();
+ if (Abbrev)
+ Stream.EmitRecordWithAbbrev(Abbrev, Record);
+ else
+ Stream.EmitRecord(SM_SLOC_EXPANSION_ENTRY,
+ // To emit without abbrev, we must omit the code.
+ llvm::makeArrayRef(Record).drop_front(1));
}
}
Index: clang/lib/Serialization/ASTReader.cpp
===================================================================
--- clang/lib/Serialization/ASTReader.cpp
+++ clang/lib/Serialization/ASTReader.cpp
@@ -1588,13 +1588,16 @@
case SM_SLOC_EXPANSION_ENTRY: {
SourceLocation SpellingLoc = ReadSourceLocation(*F, Record[1]);
- SourceMgr.createExpansionLoc(SpellingLoc,
- ReadSourceLocation(*F, Record[2]),
- ReadSourceLocation(*F, Record[3]),
- Record[5],
- Record[4],
- ID,
- BaseOffset + Record[0]);
+ unsigned SpellingLength = Record[2];
+ SourceLocation ExpansionStart = ReadSourceLocation(*F, Record[3]);
+ bool EndIsToken = Record[4];
+ bool EndIsRelative = Record[5];
+ SourceLocation ExpansionEnd =
+ EndIsRelative ? ExpansionStart.getLocWithOffset(Record[6])
+ : ReadSourceLocation(*F, Record[6]);
+ SourceMgr.createExpansionLoc(SpellingLoc, ExpansionStart, ExpansionEnd,
+ SpellingLength, EndIsToken, ID,
+ BaseOffset + Record[0]);
break;
}
}
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