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//=-- MemProfCommon.cpp - MemProf common utilities ---------------=//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains MemProf common utilities.
//
//===----------------------------------------------------------------------===//
#include "llvm/ProfileData/MemProfCommon.h"
#include "llvm/ProfileData/MemProf.h"
#include "llvm/Support/BLAKE3.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/HashBuilder.h"
using namespace llvm;
using namespace llvm::memprof;
// Upper bound on lifetime access density (accesses per byte per lifetime sec)
// for marking an allocation cold.
LLVM_ABI cl::opt<float> MemProfLifetimeAccessDensityColdThreshold(
"memprof-lifetime-access-density-cold-threshold", cl::init(0.05),
cl::Hidden,
cl::desc("The threshold the lifetime access density (accesses per byte per "
"lifetime sec) must be under to consider an allocation cold"));
// Lower bound on lifetime to mark an allocation cold (in addition to accesses
// per byte per sec above). This is to avoid pessimizing short lived objects.
LLVM_ABI cl::opt<unsigned> MemProfAveLifetimeColdThreshold(
"memprof-ave-lifetime-cold-threshold", cl::init(200), cl::Hidden,
cl::desc("The average lifetime (s) for an allocation to be considered "
"cold"));
// Lower bound on average lifetime accesses density (total life time access
// density / alloc count) for marking an allocation hot.
LLVM_ABI cl::opt<unsigned> MemProfMinAveLifetimeAccessDensityHotThreshold(
"memprof-min-ave-lifetime-access-density-hot-threshold", cl::init(1000),
cl::Hidden,
cl::desc("The minimum TotalLifetimeAccessDensity / AllocCount for an "
"allocation to be considered hot"));
LLVM_ABI cl::opt<bool>
MemProfUseHotHints("memprof-use-hot-hints", cl::init(false), cl::Hidden,
cl::desc("Enable use of hot hints (only supported for "
"unambigously hot allocations)"));
AllocationType llvm::memprof::getAllocType(uint64_t TotalLifetimeAccessDensity,
uint64_t AllocCount,
uint64_t TotalLifetime) {
// The access densities are multiplied by 100 to hold 2 decimal places of
// precision, so need to divide by 100.
if (((float)TotalLifetimeAccessDensity) / AllocCount / 100 <
MemProfLifetimeAccessDensityColdThreshold
// Lifetime is expected to be in ms, so convert the threshold to ms.
&& ((float)TotalLifetime) / AllocCount >=
MemProfAveLifetimeColdThreshold * 1000)
return AllocationType::Cold;
// The access densities are multiplied by 100 to hold 2 decimal places of
// precision, so need to divide by 100.
if (MemProfUseHotHints &&
((float)TotalLifetimeAccessDensity) / AllocCount / 100 >
MemProfMinAveLifetimeAccessDensityHotThreshold)
return AllocationType::Hot;
return AllocationType::NotCold;
}
uint64_t llvm::memprof::computeFullStackId(ArrayRef<Frame> CallStack) {
llvm::HashBuilder<llvm::TruncatedBLAKE3<8>, llvm::endianness::little>
HashBuilder;
for (auto &F : CallStack)
HashBuilder.add(F.Function, F.LineOffset, F.Column);
llvm::BLAKE3Result<8> Hash = HashBuilder.final();
uint64_t Id;
std::memcpy(&Id, Hash.data(), sizeof(Hash));
return Id;
}
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