Implement a minor space optimization for the PCH identifier table,
which eliminates the storage for IdentifierInfo in the "uninteresting
identifier" cases. Sadly, this only brought back 7k of the 500k we
lost :(
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@70325 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/PCHWriter.cpp b/lib/Frontend/PCHWriter.cpp
index 11f6202..4870b49 100644
--- a/lib/Frontend/PCHWriter.cpp
+++ b/lib/Frontend/PCHWriter.cpp
@@ -1291,6 +1291,17 @@
PCHWriter &Writer;
Preprocessor &PP;
+ /// \brief Determines whether this is an "interesting" identifier
+ /// that needs a full IdentifierInfo structure written into the hash
+ /// table.
+ static bool isInterestingIdentifier(const IdentifierInfo *II) {
+ return II->isPoisoned() ||
+ II->isExtensionToken() ||
+ II->hasMacroDefinition() ||
+ II->getObjCOrBuiltinID() ||
+ II->getFETokenInfo<void>();
+ }
+
public:
typedef const IdentifierInfo* key_type;
typedef key_type key_type_ref;
@@ -1309,15 +1320,17 @@
EmitKeyDataLength(llvm::raw_ostream& Out, const IdentifierInfo* II,
pch::IdentID ID) {
unsigned KeyLen = strlen(II->getName()) + 1;
- unsigned DataLen = 4 + 4; // 4 bytes for token ID, builtin, flags
- // 4 bytes for the persistent ID
- if (II->hasMacroDefinition() &&
- !PP.getMacroInfo(const_cast<IdentifierInfo *>(II))->isBuiltinMacro())
- DataLen += 8;
- for (IdentifierResolver::iterator D = IdentifierResolver::begin(II),
- DEnd = IdentifierResolver::end();
- D != DEnd; ++D)
- DataLen += sizeof(pch::DeclID);
+ unsigned DataLen = 4; // 4 bytes for the persistent ID << 1
+ if (isInterestingIdentifier(II)) {
+ DataLen += 4; // 4 bytes for token ID, builtin, flags
+ if (II->hasMacroDefinition() &&
+ !PP.getMacroInfo(const_cast<IdentifierInfo *>(II))->isBuiltinMacro())
+ DataLen += 8;
+ for (IdentifierResolver::iterator D = IdentifierResolver::begin(II),
+ DEnd = IdentifierResolver::end();
+ D != DEnd; ++D)
+ DataLen += sizeof(pch::DeclID);
+ }
clang::io::Emit16(Out, DataLen);
// We emit the key length after the data length so that every
// string is preceded by a 16-bit length. This matches the PTH
@@ -1336,6 +1349,11 @@
void EmitData(llvm::raw_ostream& Out, const IdentifierInfo* II,
pch::IdentID ID, unsigned) {
+ if (!isInterestingIdentifier(II)) {
+ clang::io::Emit32(Out, ID << 1);
+ return;
+ }
+ clang::io::Emit32(Out, (ID << 1) | 0x01);
uint32_t Bits = 0;
bool hasMacroDefinition =
II->hasMacroDefinition() &&
@@ -1347,7 +1365,6 @@
Bits = (Bits << 1) | II->isPoisoned();
Bits = (Bits << 1) | II->isCPlusPlusOperatorKeyword();
clang::io::Emit32(Out, Bits);
- clang::io::Emit32(Out, ID);
if (hasMacroDefinition)
clang::io::Emit64(Out, Writer.getMacroOffset(II));