caio/clang-p2996
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[BOLT] Delta-encode offsets in BAT (#76900)

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This change further reduces the size of BAT:
- large binary: to 13073904 bytes (0.34x original),
- medium binary: to 1703116 bytes (0.29x original),
- small binary: to 436 bytes (0.30x original).

Test Plan: Updated bolt/test/X86/bolt-address-translation.test
This commit is contained in:
Amir Ayupov
2024-01-11 14:29:46 -08:00
committed by GitHub
parent b3981edb51
commit bbe07989d7
3 changed files with 19 additions and 10 deletions
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21
bolt/lib/Profile/BoltAddressTranslation.cpp
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@@ -114,9 +114,12 @@ void BoltAddressTranslation::write(const BinaryContext &BC, raw_ostream &OS) {
<< Twine::utohexstr(Address) << ".\n");
encodeULEB128(Address, OS);
encodeULEB128(NumEntries, OS);
uint64_t InOffset = 0, OutOffset = 0;
// Output and Input addresses and delta-encoded
for (std::pair<const uint32_t, uint32_t> &KeyVal : Map) {
encodeULEB128(KeyVal.first, OS);
encodeULEB128(KeyVal.second, OS);
encodeULEB128(KeyVal.first - OutOffset, OS);
encodeSLEB128(KeyVal.second - InOffset, OS);
std::tie(OutOffset, InOffset) = KeyVal;
}
}
const uint32_t NumColdEntries = ColdPartSource.size();
@@ -164,12 +167,16 @@ std::error_code BoltAddressTranslation::parse(StringRef Buf) {
LLVM_DEBUG(dbgs() << "Parsing " << NumEntries << " entries for 0x"
<< Twine::utohexstr(Address) << "\n");
uint64_t InputOffset = 0, OutputOffset = 0;
for (uint32_t J = 0; J < NumEntries; ++J) {
const uint32_t OutputAddr = DE.getULEB128(&Offset, &Err);
const uint32_t InputAddr = DE.getULEB128(&Offset, &Err);
Map.insert(std::pair<uint32_t, uint32_t>(OutputAddr, InputAddr));
LLVM_DEBUG(dbgs() << Twine::utohexstr(OutputAddr) << " -> "
<< Twine::utohexstr(InputAddr) << "\n");
const uint64_t OutputDelta = DE.getULEB128(&Offset, &Err);
const int64_t InputDelta = DE.getSLEB128(&Offset, &Err);
OutputOffset += OutputDelta;
InputOffset += InputDelta;
Map.insert(std::pair<uint32_t, uint32_t>(OutputOffset, InputOffset));
LLVM_DEBUG(dbgs() << Twine::utohexstr(OutputOffset) << " -> "
<< Twine::utohexstr(InputOffset) << " (" << OutputDelta
<< ", " << InputDelta << ")\n");
}
Maps.insert(std::pair<uint64_t, MapTy>(Address, Map));
}