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[BOLT] Add number of basic blocks to BAT #86045

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Merged
merged 7 commits into from
Mar 22, 2024
Merged

[BOLT] Add number of basic blocks to BAT #86045

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fd9071c
[𝘀𝗽𝗿] changes to main this commit is based on
aaupov Mar 20, 2024
f7f38a7
[𝘀𝗽𝗿] initial version
aaupov Mar 20, 2024
d54237d
[𝘀𝗽𝗿] changes introduced through rebase
aaupov Mar 21, 2024
515de33
update test
aaupov Mar 21, 2024
361e9ed
[𝘀𝗽𝗿] changes introduced through rebase
aaupov Mar 21, 2024
b00132e
rebase
aaupov Mar 21, 2024
25fdf36
rebase
aaupov Mar 22, 2024
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1 change: 1 addition & 0 deletions bolt/docs/BAT.md
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Expand Up @@ -79,6 +79,7 @@ Hot indices are delta encoded, implicitly starting at zero.
| `Address` | Continuous, Delta, ULEB128 | Function address in the output binary |
| `HotIndex` | Delta, ULEB128 | Cold functions only: index of corresponding hot function in hot functions table |
| `FuncHash` | 8b | Hot functions only: function hash for input function |
| `NumBlocks` | ULEB128 | Hot functions only: number of basic blocks in the original function |
| `NumEntries` | ULEB128 | Number of address translation entries for a function |
| `EqualElems` | ULEB128 | Hot functions only: number of equal offsets in the beginning of a function |
| `BranchEntries` | Bitmask, `alignTo(EqualElems, 8)` bits | Hot functions only: if `EqualElems` is non-zero, bitmask denoting entries with `BRANCHENTRY` bit |
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3 changes: 3 additions & 0 deletions bolt/include/bolt/Profile/BoltAddressTranslation.h
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Expand Up @@ -162,6 +162,9 @@ class BoltAddressTranslation {
using BBHashMap = std::unordered_map<uint32_t, std::pair<unsigned, size_t>>;
std::unordered_map<uint64_t, std::pair<size_t, BBHashMap>> FuncHashes;

/// Map a function to its basic blocks count
std::unordered_map<uint64_t, size_t> NumBasicBlocksMap;

/// Links outlined cold bocks to their original function
std::map<uint64_t, uint64_t> ColdPartSource;

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10 changes: 10 additions & 0 deletions bolt/lib/Profile/BoltAddressTranslation.cpp
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Expand Up @@ -196,6 +196,10 @@ void BoltAddressTranslation::writeMaps(std::map<uint64_t, MapTy> &Maps,
// Function hash
LLVM_DEBUG(dbgs() << "Hash: " << formatv("{0:x}\n", FuncHashPair.first));
OS.write(reinterpret_cast<char *>(&FuncHashPair.first), 8);
// Number of basic blocks
size_t NumBasicBlocks = FuncHashPair.second.size();
LLVM_DEBUG(dbgs() << "Basic blocks: " << NumBasicBlocks << '\n');
encodeULEB128(NumBasicBlocks, OS);
}
encodeULEB128(NumEntries, OS);
// For hot fragments only: encode the number of equal offsets
Expand Down Expand Up @@ -293,6 +297,12 @@ void BoltAddressTranslation::parseMaps(std::vector<uint64_t> &HotFuncs,
const size_t FuncHash = DE.getU64(&Offset, &Err);
FuncHashes[Address].first = FuncHash;
LLVM_DEBUG(dbgs() << formatv("{0:x}: hash {1:x}\n", Address, FuncHash));
// Number of basic blocks
const size_t NumBasicBlocks = DE.getULEB128(&Offset, &Err);
NumBasicBlocksMap.emplace(Address, NumBasicBlocks);
LLVM_DEBUG(dbgs() << formatv("{0:x}: #bbs {1}, {2} bytes\n", Address,
NumBasicBlocks,
getULEB128Size(NumBasicBlocks)));
}
const uint32_t NumEntries = DE.getULEB128(&Offset, &Err);
// Equal offsets, hot fragments only.
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2 changes: 1 addition & 1 deletion bolt/test/X86/bolt-address-translation-yaml.test
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Expand Up @@ -18,7 +18,7 @@ RUN: | FileCheck --check-prefix CHECK-BOLT-YAML %s

WRITE-BAT-CHECK: BOLT-INFO: Wrote 5 BAT maps
WRITE-BAT-CHECK: BOLT-INFO: Wrote 4 function and 22 basic block hashes
WRITE-BAT-CHECK: BOLT-INFO: BAT section size (bytes): 376
WRITE-BAT-CHECK: BOLT-INFO: BAT section size (bytes): 380

READ-BAT-CHECK-NOT: BOLT-ERROR: unable to save profile in YAML format for input file processed by BOLT
READ-BAT-CHECK: BOLT-INFO: Parsed 5 BAT entries
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