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Shrink the asm matcher tables. 

- Shrink the opcode field to 16 bits.
- Shrink the AsmVariantID field to 8 bits.
- Store the mnemonic string in a string table, store a 16 bit index.
- Store a pascal-style length byte in the string instead of a null terminator,
  so we can avoid calling strlen on every entry we visit during mnemonic search.

Shrinks X86AsmParser.o from 434k to 201k on x86_64 and eliminates relocs from the table.

llvm-svn: 151984
This commit is contained in:
Benjamin Kramer 2012-03-03 19:13:26 +00:00
parent dbe7f3bf2e
commit 5aeee5f854
1 changed files with 23 additions and 8 deletions
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31
llvm/utils/TableGen/AsmMatcherEmitter.cpp
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@ -99,6 +99,7 @@
#include "AsmMatcherEmitter.h"
#include "CodeGenTarget.h"
#include "StringMatcher.h"
#include "StringToOffsetTable.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/PointerUnion.h"
#include "llvm/ADT/SmallPtrSet.h"
@ -2302,32 +2303,39 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
// following the mnemonic.
OS << "namespace {\n";
OS << " struct MatchEntry {\n";
OS << " unsigned Opcode;\n";
OS << " const char *Mnemonic;\n";
OS << " static const char *MnemonicTable;\n";
OS << " uint16_t Opcode;\n";
OS << " uint16_t Mnemonic;\n";
OS << " " << getMinimalTypeForRange(Info.Matchables.size())
<< " ConvertFn;\n";
OS << " " << getMinimalTypeForRange(Info.Classes.size())
<< " Classes[" << MaxNumOperands << "];\n";
OS << " " << getMinimalTypeForRange(1ULL << Info.SubtargetFeatures.size())
<< " RequiredFeatures;\n";
OS << " unsigned AsmVariantID;\n";
OS << " uint8_t AsmVariantID;\n\n";
OS << " StringRef getMnemonic() const {\n";
OS << " return StringRef(MnemonicTable + Mnemonic + 1,\n";
OS << " MnemonicTable[Mnemonic]);\n";
OS << " }\n";
OS << " };\n\n";
OS << " // Predicate for searching for an opcode.\n";
OS << " struct LessOpcode {\n";
OS << " bool operator()(const MatchEntry &LHS, StringRef RHS) {\n";
OS << " return StringRef(LHS.Mnemonic) < RHS;\n";
OS << " return LHS.getMnemonic() < RHS;\n";
OS << " }\n";
OS << " bool operator()(StringRef LHS, const MatchEntry &RHS) {\n";
OS << " return LHS < StringRef(RHS.Mnemonic);\n";
OS << " return LHS < RHS.getMnemonic();\n";
OS << " }\n";
OS << " bool operator()(const MatchEntry &LHS, const MatchEntry &RHS) {\n";
OS << " return StringRef(LHS.Mnemonic) < StringRef(RHS.Mnemonic);\n";
OS << " return LHS.getMnemonic() < RHS.getMnemonic();\n";
OS << " }\n";
OS << " };\n";
OS << "} // end anonymous namespace.\n\n";
StringToOffsetTable StringTable;
OS << "static const MatchEntry MatchTable["
<< Info.Matchables.size() << "] = {\n";
@ -2336,8 +2344,11 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
it != ie; ++it) {
MatchableInfo &II = **it;
// Store a pascal-style length byte in the mnemonic.
std::string LenMnemonic = char(II.Mnemonic.size()) + II.Mnemonic.str();
OS << " { " << Target.getName() << "::"
<< II.getResultInst()->TheDef->getName() << ", \"" << II.Mnemonic << "\""
<< II.getResultInst()->TheDef->getName() << ", "
<< StringTable.GetOrAddStringOffset(LenMnemonic, false)
<< ", " << II.ConversionFnKind << ", { ";
for (unsigned i = 0, e = II.AsmOperands.size(); i != e; ++i) {
MatchableInfo::AsmOperand &Op = II.AsmOperands[i];
@ -2361,6 +2372,10 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
OS << "};\n\n";
OS << "const char *MatchEntry::MnemonicTable =\n";
StringTable.EmitString(OS);
OS << ";\n\n";
// A method to determine if a mnemonic is in the list.
OS << "bool " << Target.getName() << ClassName << "::\n"
<< "MnemonicIsValid(StringRef Mnemonic) {\n";
@ -2424,7 +2439,7 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
OS << " it != ie; ++it) {\n";
OS << " // equal_range guarantees that instruction mnemonic matches.\n";
OS << " assert(Mnemonic == it->Mnemonic);\n";
OS << " assert(Mnemonic == it->getMnemonic());\n";
// Emit check that the subclasses match.
OS << " if (VariantID != it->AsmVariantID) continue;\n";