[lld] [lld-macho] Refactor BPSectionOrderer with CRTP. NFC (PR #124482)
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Sun Jan 26 13:06:51 PST 2025
https://github.com/MaskRay updated https://github.com/llvm/llvm-project/pull/124482
>From 4ba6a904cd250bf9f0e49af688f9d125cfaae176 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Sun, 26 Jan 2025 12:44:42 -0800
Subject: [PATCH 1/2] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20in?=
=?UTF-8?q?itial=20version?=
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Created using spr 1.3.5-bogner
---
lld/Common/CMakeLists.txt | 2 -
lld/MachO/BPSectionOrderer.cpp | 133 +++++++++++++++--
lld/MachO/BPSectionOrderer.h | 118 +--------------
lld/MachO/CMakeLists.txt | 1 +
lld/include/lld/Common/BPSectionOrdererBase.h | 70 ---------
.../lld/Common/BPSectionOrdererBase.inc} | 135 +++++++++++-------
6 files changed, 202 insertions(+), 257 deletions(-)
delete mode 100644 lld/include/lld/Common/BPSectionOrdererBase.h
rename lld/{Common/BPSectionOrdererBase.cpp => include/lld/Common/BPSectionOrdererBase.inc} (75%)
diff --git a/lld/Common/CMakeLists.txt b/lld/Common/CMakeLists.txt
index 43e91b85821dbf..4f503d04f7844f 100644
--- a/lld/Common/CMakeLists.txt
+++ b/lld/Common/CMakeLists.txt
@@ -24,7 +24,6 @@ set_source_files_properties("${version_inc}"
add_lld_library(lldCommon
Args.cpp
- BPSectionOrdererBase.cpp
CommonLinkerContext.cpp
DriverDispatcher.cpp
DWARF.cpp
@@ -48,7 +47,6 @@ add_lld_library(lldCommon
Demangle
MC
Option
- ProfileData
Support
Target
TargetParser
diff --git a/lld/MachO/BPSectionOrderer.cpp b/lld/MachO/BPSectionOrderer.cpp
index c2d03c968534e4..116daa1a2f6cbe 100644
--- a/lld/MachO/BPSectionOrderer.cpp
+++ b/lld/MachO/BPSectionOrderer.cpp
@@ -8,39 +8,142 @@
#include "BPSectionOrderer.h"
#include "InputSection.h"
+#include "Relocations.h"
+#include "Symbols.h"
+#include "lld/Common/BPSectionOrdererBase.inc"
#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StableHashing.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/xxhash.h"
#define DEBUG_TYPE "bp-section-orderer"
using namespace llvm;
using namespace lld::macho;
+namespace {
+struct BPOrdererMachO;
+}
+template <> struct lld::BPOrdererTraits<struct BPOrdererMachO> {
+ using Section = macho::InputSection;
+ using Symbol = macho::Symbol;
+};
+namespace {
+struct BPOrdererMachO : lld::BPOrderer<BPOrdererMachO> {
+ static uint64_t getSize(const Section &sec) { return sec.getSize(); }
+ static bool isCodeSection(const Section &sec) {
+ return macho::isCodeSection(&sec);
+ }
+ static SmallVector<Symbol *, 0> getSymbols(const Section &sec) {
+ SmallVector<Symbol *, 0> symbols;
+ for (auto *sym : sec.symbols)
+ if (auto *d = llvm::dyn_cast_or_null<Defined>(sym))
+ symbols.emplace_back(d);
+ return symbols;
+ }
+
+ // Linkage names can be prefixed with "_" or "l_" on Mach-O. See
+ // Mangler::getNameWithPrefix() for details.
+ std::optional<StringRef> static getResolvedLinkageName(llvm::StringRef name) {
+ if (name.consume_front("_") || name.consume_front("l_"))
+ return name;
+ return {};
+ }
+
+ static void
+ getSectionHashes(const Section &sec, llvm::SmallVectorImpl<uint64_t> &hashes,
+ const llvm::DenseMap<const void *, uint64_t> §ionToIdx) {
+ constexpr unsigned windowSize = 4;
+
+ // Calculate content hashes: k-mers and the last k-1 bytes.
+ ArrayRef<uint8_t> data = sec.data;
+ if (data.size() >= windowSize)
+ for (size_t i = 0; i <= data.size() - windowSize; ++i)
+ hashes.push_back(llvm::support::endian::read32le(data.data() + i));
+ for (uint8_t byte : data.take_back(windowSize - 1))
+ hashes.push_back(byte);
+
+ // Calculate relocation hashes
+ for (const auto &r : sec.relocs) {
+ if (r.length == 0 || r.referent.isNull() || r.offset >= data.size())
+ continue;
+
+ uint64_t relocHash = getRelocHash(r, sectionToIdx);
+ uint32_t start = (r.offset < windowSize) ? 0 : r.offset - windowSize + 1;
+ for (uint32_t i = start; i < r.offset + r.length; i++) {
+ auto window = data.drop_front(i).take_front(windowSize);
+ hashes.push_back(xxh3_64bits(window) ^ relocHash);
+ }
+ }
+
+ llvm::sort(hashes);
+ hashes.erase(std::unique(hashes.begin(), hashes.end()), hashes.end());
+ }
+
+ static llvm::StringRef getSymName(const Symbol &sym) { return sym.getName(); }
+ static uint64_t getSymValue(const Symbol &sym) {
+ if (auto *d = dyn_cast<Defined>(&sym))
+ return d->value;
+ return 0;
+ }
+ static uint64_t getSymSize(const Symbol &sym) {
+ if (auto *d = dyn_cast<Defined>(&sym))
+ return d->size;
+ return 0;
+ }
+
+private:
+ static uint64_t
+ getRelocHash(const Reloc &reloc,
+ const llvm::DenseMap<const void *, uint64_t> §ionToIdx) {
+ auto *isec = reloc.getReferentInputSection();
+ std::optional<uint64_t> sectionIdx;
+ if (auto it = sectionToIdx.find(isec); it != sectionToIdx.end())
+ sectionIdx = it->second;
+ uint64_t kind = -1, value = 0;
+ if (isec)
+ kind = uint64_t(isec->kind());
+
+ if (auto *sym = reloc.referent.dyn_cast<Symbol *>()) {
+ kind = (kind << 8) | uint8_t(sym->kind());
+ if (auto *d = llvm::dyn_cast<Defined>(sym))
+ value = d->value;
+ }
+ return llvm::stable_hash_combine(kind, sectionIdx.value_or(0), value,
+ reloc.addend);
+ }
+};
+} // namespace
+
DenseMap<const InputSection *, int> lld::macho::runBalancedPartitioning(
StringRef profilePath, bool forFunctionCompression, bool forDataCompression,
bool compressionSortStartupFunctions, bool verbose) {
-
- SmallVector<std::unique_ptr<BPSectionBase>> sections;
+ SmallVector<InputSection *> sections;
+ DenseMap<StringRef, DenseSet<unsigned>> symbolToSectionIdxs;
for (const auto *file : inputFiles) {
for (auto *sec : file->sections) {
for (auto &subsec : sec->subsections) {
auto *isec = subsec.isec;
- if (!isec || isec->data.empty() || !isec->data.data())
+ if (!isec || isec->data.empty())
continue;
- sections.emplace_back(std::make_unique<BPSectionMacho>(isec));
+ for (auto *sym : BPOrdererMachO::getSymbols(*isec))
+ symbolToSectionIdxs[sym->getName()].insert(sections.size());
+ sections.emplace_back(isec);
}
}
}
- auto reorderedSections = BPSectionBase::reorderSectionsByBalancedPartitioning(
- profilePath, forFunctionCompression, forDataCompression,
- compressionSortStartupFunctions, verbose, sections);
-
- DenseMap<const InputSection *, int> result;
- for (const auto &[sec, priority] : reorderedSections) {
- result.try_emplace(
- static_cast<const InputSection *>(
- static_cast<const BPSectionMacho *>(sec)->getSection()),
- priority);
+ DenseMap<CachedHashStringRef, DenseSet<unsigned>> rootSymbolToSectionIdxs;
+ for (auto &[name, sectionIdxs] : symbolToSectionIdxs) {
+ auto rootName = getRootSymbol(name);
+ rootSymbolToSectionIdxs[CachedHashStringRef(rootName)].insert(
+ sectionIdxs.begin(), sectionIdxs.end());
+ if (auto linkageName = BPOrdererMachO::getResolvedLinkageName(rootName))
+ rootSymbolToSectionIdxs[CachedHashStringRef(*linkageName)].insert(
+ sectionIdxs.begin(), sectionIdxs.end());
}
- return result;
+ return BPOrdererMachO::reorderSections(
+ profilePath, forFunctionCompression, forDataCompression,
+ compressionSortStartupFunctions, verbose, sections,
+ rootSymbolToSectionIdxs);
}
diff --git a/lld/MachO/BPSectionOrderer.h b/lld/MachO/BPSectionOrderer.h
index e3e6b12092e204..a27f605cb1180c 100644
--- a/lld/MachO/BPSectionOrderer.h
+++ b/lld/MachO/BPSectionOrderer.h
@@ -14,134 +14,18 @@
#ifndef LLD_MACHO_BPSECTION_ORDERER_H
#define LLD_MACHO_BPSECTION_ORDERER_H
-#include "InputSection.h"
-#include "Relocations.h"
-#include "Symbols.h"
-#include "lld/Common/BPSectionOrdererBase.h"
#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/StableHashing.h"
#include "llvm/ADT/StringRef.h"
-#include "llvm/Support/Endian.h"
-#include "llvm/Support/xxhash.h"
namespace lld::macho {
-
class InputSection;
-class BPSymbolMacho : public BPSymbol {
- const Symbol *sym;
-
-public:
- explicit BPSymbolMacho(const Symbol *s) : sym(s) {}
-
- llvm::StringRef getName() const override { return sym->getName(); }
-
- const Defined *asDefined() const {
- return llvm::dyn_cast_or_null<Defined>(sym);
- }
-
- std::optional<uint64_t> getValue() const override {
- if (auto *d = asDefined())
- return d->value;
- return {};
- }
-
- std::optional<uint64_t> getSize() const override {
- if (auto *d = asDefined())
- return d->size;
- return {};
- }
-
- const Symbol *getSymbol() const { return sym; }
-};
-
-class BPSectionMacho : public BPSectionBase {
- const InputSection *isec;
-
-public:
- explicit BPSectionMacho(const InputSection *sec) : isec(sec) {}
-
- const void *getSection() const override { return isec; }
-
- uint64_t getSize() const override { return isec->getSize(); }
-
- bool isCodeSection() const override { return macho::isCodeSection(isec); }
-
- SmallVector<std::unique_ptr<BPSymbol>> getSymbols() const override {
- SmallVector<std::unique_ptr<BPSymbol>> symbols;
- for (auto *sym : isec->symbols)
- if (auto *d = llvm::dyn_cast_or_null<Defined>(sym))
- symbols.emplace_back(std::make_unique<BPSymbolMacho>(d));
- return symbols;
- }
-
- // Linkage names can be prefixed with "_" or "l_" on Mach-O. See
- // Mangler::getNameWithPrefix() for details.
- std::optional<StringRef>
- getResolvedLinkageName(llvm::StringRef name) const override {
- if (name.consume_front("_") || name.consume_front("l_"))
- return name;
- return {};
- }
-
- void getSectionHashes(llvm::SmallVectorImpl<uint64_t> &hashes,
- const llvm::DenseMap<const void *, uint64_t>
- §ionToIdx) const override {
- constexpr unsigned windowSize = 4;
-
- // Calculate content hashes: k-mers and the last k-1 bytes.
- ArrayRef<uint8_t> data = isec->data;
- if (data.size() >= windowSize)
- for (size_t i = 0; i <= data.size() - windowSize; ++i)
- hashes.push_back(llvm::support::endian::read32le(data.data() + i));
- for (uint8_t byte : data.take_back(windowSize - 1))
- hashes.push_back(byte);
-
- // Calculate relocation hashes
- for (const auto &r : isec->relocs) {
- if (r.length == 0 || r.referent.isNull() || r.offset >= data.size())
- continue;
-
- uint64_t relocHash = getRelocHash(r, sectionToIdx);
- uint32_t start = (r.offset < windowSize) ? 0 : r.offset - windowSize + 1;
- for (uint32_t i = start; i < r.offset + r.length; i++) {
- auto window = data.drop_front(i).take_front(windowSize);
- hashes.push_back(xxh3_64bits(window) ^ relocHash);
- }
- }
-
- llvm::sort(hashes);
- hashes.erase(std::unique(hashes.begin(), hashes.end()), hashes.end());
- }
-
-private:
- static uint64_t
- getRelocHash(const Reloc &reloc,
- const llvm::DenseMap<const void *, uint64_t> §ionToIdx) {
- auto *isec = reloc.getReferentInputSection();
- std::optional<uint64_t> sectionIdx;
- if (auto it = sectionToIdx.find(isec); it != sectionToIdx.end())
- sectionIdx = it->second;
- uint64_t kind = -1, value = 0;
- if (isec)
- kind = uint64_t(isec->kind());
-
- if (auto *sym = reloc.referent.dyn_cast<Symbol *>()) {
- kind = (kind << 8) | uint8_t(sym->kind());
- if (auto *d = llvm::dyn_cast<Defined>(sym))
- value = d->value;
- }
- return llvm::stable_hash_combine(kind, sectionIdx.value_or(0), value,
- reloc.addend);
- }
-};
-
/// Run Balanced Partitioning to find the optimal function and data order to
/// improve startup time and compressed size.
///
/// It is important that .subsections_via_symbols is used to ensure functions
/// and data are in their own sections and thus can be reordered.
-llvm::DenseMap<const lld::macho::InputSection *, int>
+llvm::DenseMap<const InputSection *, int>
runBalancedPartitioning(llvm::StringRef profilePath,
bool forFunctionCompression, bool forDataCompression,
bool compressionSortStartupFunctions, bool verbose);
diff --git a/lld/MachO/CMakeLists.txt b/lld/MachO/CMakeLists.txt
index c778fcf7b6fff7..ecf6ce609e59f2 100644
--- a/lld/MachO/CMakeLists.txt
+++ b/lld/MachO/CMakeLists.txt
@@ -50,6 +50,7 @@ add_lld_library(lldMachO
Object
Option
Passes
+ ProfileData
Support
TargetParser
TextAPI
diff --git a/lld/include/lld/Common/BPSectionOrdererBase.h b/lld/include/lld/Common/BPSectionOrdererBase.h
deleted file mode 100644
index bbd05edc5e55ec..00000000000000
--- a/lld/include/lld/Common/BPSectionOrdererBase.h
+++ /dev/null
@@ -1,70 +0,0 @@
-//===- BPSectionOrdererBase.h ---------------------------------------------===//
-//
-// 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 defines the common interfaces which may be used by
-// BPSectionOrderer.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLD_COMMON_BP_SECTION_ORDERER_BASE_H
-#define LLD_COMMON_BP_SECTION_ORDERER_BASE_H
-
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/StringRef.h"
-#include "llvm/ADT/Twine.h"
-#include <memory>
-#include <optional>
-
-namespace lld {
-
-class BPSymbol {
-
-public:
- virtual ~BPSymbol() = default;
- virtual llvm::StringRef getName() const = 0;
- virtual std::optional<uint64_t> getValue() const = 0;
- virtual std::optional<uint64_t> getSize() const = 0;
-};
-
-class BPSectionBase {
-public:
- virtual ~BPSectionBase() = default;
- virtual uint64_t getSize() const = 0;
- virtual bool isCodeSection() const = 0;
- virtual llvm::SmallVector<std::unique_ptr<BPSymbol>> getSymbols() const = 0;
- virtual const void *getSection() const = 0;
- virtual void getSectionHashes(
- llvm::SmallVectorImpl<uint64_t> &hashes,
- const llvm::DenseMap<const void *, uint64_t> §ionToIdx) const = 0;
- virtual std::optional<llvm::StringRef>
- getResolvedLinkageName(llvm::StringRef name) const = 0;
-
- /// Symbols can be appended with "(.__uniq.xxxx)?.llvm.yyyy" where "xxxx" and
- /// "yyyy" are numbers that could change between builds. We need to use the
- /// root symbol name before this suffix so these symbols can be matched with
- /// profiles which may have different suffixes.
- static llvm::StringRef getRootSymbol(llvm::StringRef Name) {
- auto [P0, S0] = Name.rsplit(".llvm.");
- auto [P1, S1] = P0.rsplit(".__uniq.");
- return P1;
- }
-
- /// Reorders sections using balanced partitioning algorithm based on profile
- /// data.
- static llvm::DenseMap<const BPSectionBase *, int>
- reorderSectionsByBalancedPartitioning(
- llvm::StringRef profilePath, bool forFunctionCompression,
- bool forDataCompression, bool compressionSortStartupFunctions,
- bool verbose,
- llvm::SmallVector<std::unique_ptr<BPSectionBase>> &inputSections);
-};
-
-} // namespace lld
-
-#endif
diff --git a/lld/Common/BPSectionOrdererBase.cpp b/lld/include/lld/Common/BPSectionOrdererBase.inc
similarity index 75%
rename from lld/Common/BPSectionOrdererBase.cpp
rename to lld/include/lld/Common/BPSectionOrdererBase.inc
index 7d26a5fb844835..6c514e335f151d 100644
--- a/lld/Common/BPSectionOrdererBase.cpp
+++ b/lld/include/lld/Common/BPSectionOrdererBase.inc
@@ -1,31 +1,69 @@
-//===- BPSectionOrdererBase.cpp -------------------------------------------===//
+//===- BPSectionOrdererBase.inc ---------------------------------*- C++ -*-===//
//
// 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 defines the common BPSectionOrderer interface using the Curiously
+// Recurring Template Pattern and dispatches to the BalancedPartitioning
+// algorithm implemented in LLVMSupport. The optimized section layout attempts
+// to group similar sections together (resulting in a smaller compressed app
+// size) and utilize a temporal profile file to reduce page faults during
+// program startup.
+//
+// Clients should derive from BPOrderer, providing concrete implementations for
+// section and symbol representations. Include this file in a .cpp file to
+// specialize the template for the derived class.
+//
+//===----------------------------------------------------------------------===//
-#include "lld/Common/BPSectionOrdererBase.h"
#include "lld/Common/ErrorHandler.h"
+#include "llvm/ADT/CachedHashString.h"
+#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/Twine.h"
#include "llvm/ProfileData/InstrProfReader.h"
#include "llvm/Support/BalancedPartitioning.h"
#include "llvm/Support/TimeProfiler.h"
#include "llvm/Support/VirtualFileSystem.h"
+#include <memory>
+#include <optional>
#define DEBUG_TYPE "bp-section-orderer"
using namespace llvm;
using namespace lld;
+namespace lld {
+template <class D> struct BPOrdererTraits;
+
+template <class D> struct BPOrderer {
+ using Section = typename BPOrdererTraits<D>::Section;
+ using Symbol = typename BPOrdererTraits<D>::Symbol;
+
+ // Reorder sections using balanced partitioning algorithm based on profile.
+ static auto
+ reorderSections(llvm::StringRef profilePath, bool forFunctionCompression,
+ bool forDataCompression, bool compressionSortStartupFunctions,
+ bool verbose, llvm::ArrayRef<Section *> sections,
+ const DenseMap<CachedHashStringRef, DenseSet<unsigned>>
+ &rootSymbolToSectionIdxs)
+ -> llvm::DenseMap<const Section *, int>;
+};
+} // namespace lld
+
using UtilityNodes = SmallVector<BPFunctionNode::UtilityNodeT>;
+template <class D>
static SmallVector<std::pair<unsigned, UtilityNodes>> getUnsForCompression(
- ArrayRef<const BPSectionBase *> sections,
+ ArrayRef<const typename D::Section *> sections,
const DenseMap<const void *, uint64_t> §ionToIdx,
ArrayRef<unsigned> sectionIdxs,
DenseMap<unsigned, SmallVector<unsigned>> *duplicateSectionIdxs,
@@ -38,7 +76,7 @@ static SmallVector<std::pair<unsigned, UtilityNodes>> getUnsForCompression(
for (unsigned sectionIdx : sectionIdxs) {
const auto *isec = sections[sectionIdx];
- isec->getSectionHashes(hashes, sectionToIdx);
+ D::getSectionHashes(*isec, hashes, sectionToIdx);
sectionHashes.emplace_back(sectionIdx, std::move(hashes));
hashes.clear();
}
@@ -96,36 +134,27 @@ static SmallVector<std::pair<unsigned, UtilityNodes>> getUnsForCompression(
return sectionUns;
}
-llvm::DenseMap<const BPSectionBase *, int>
-BPSectionBase::reorderSectionsByBalancedPartitioning(
- llvm::StringRef profilePath, bool forFunctionCompression,
- bool forDataCompression, bool compressionSortStartupFunctions, bool verbose,
- SmallVector<std::unique_ptr<BPSectionBase>> &inputSections) {
+/// Symbols can be appended with "(.__uniq.xxxx)?.llvm.yyyy" where "xxxx" and
+/// "yyyy" are numbers that could change between builds. We need to use the
+/// root symbol name before this suffix so these symbols can be matched with
+/// profiles which may have different suffixes.
+inline StringRef getRootSymbol(StringRef name) {
+ auto [P0, S0] = name.rsplit(".llvm.");
+ auto [P1, S1] = P0.rsplit(".__uniq.");
+ return P1;
+}
+
+template <class D>
+auto BPOrderer<D>::reorderSections(
+ StringRef profilePath, bool forFunctionCompression, bool forDataCompression,
+ bool compressionSortStartupFunctions, bool verbose,
+ ArrayRef<Section *> sections,
+ const DenseMap<CachedHashStringRef, DenseSet<unsigned>>
+ &rootSymbolToSectionIdxs) -> DenseMap<const Section *, int> {
TimeTraceScope timeScope("Setup Balanced Partitioning");
- SmallVector<const BPSectionBase *> sections;
DenseMap<const void *, uint64_t> sectionToIdx;
- StringMap<DenseSet<unsigned>> symbolToSectionIdxs;
-
- // Process input sections
- for (const auto &isec : inputSections) {
- unsigned sectionIdx = sections.size();
- sectionToIdx.try_emplace(isec->getSection(), sectionIdx);
- sections.emplace_back(isec.get());
- for (auto &sym : isec->getSymbols())
- symbolToSectionIdxs[sym->getName()].insert(sectionIdx);
- }
- StringMap<DenseSet<unsigned>> rootSymbolToSectionIdxs;
- for (auto &entry : symbolToSectionIdxs) {
- StringRef name = entry.getKey();
- auto §ionIdxs = entry.getValue();
- name = BPSectionBase::getRootSymbol(name);
- rootSymbolToSectionIdxs[name].insert(sectionIdxs.begin(),
- sectionIdxs.end());
- if (auto resolvedLinkageName =
- sections[*sectionIdxs.begin()]->getResolvedLinkageName(name))
- rootSymbolToSectionIdxs[resolvedLinkageName.value()].insert(
- sectionIdxs.begin(), sectionIdxs.end());
- }
+ for (auto [i, isec] : llvm::enumerate(sections))
+ sectionToIdx.try_emplace(isec, i);
BPFunctionNode::UtilityNodeT maxUN = 0;
DenseMap<unsigned, UtilityNodes> startupSectionIdxUNs;
@@ -150,17 +179,18 @@ BPSectionBase::reorderSectionsByBalancedPartitioning(
size_t cutoffTimestamp = 1;
auto &trace = traces[traceIdx].FunctionNameRefs;
for (size_t timestamp = 0; timestamp < trace.size(); timestamp++) {
- auto [Filename, ParsedFuncName] = getParsedIRPGOName(
+ auto [_, parsedFuncName] = getParsedIRPGOName(
reader->getSymtab().getFuncOrVarName(trace[timestamp]));
- ParsedFuncName = BPSectionBase::getRootSymbol(ParsedFuncName);
+ parsedFuncName = getRootSymbol(parsedFuncName);
- auto sectionIdxsIt = rootSymbolToSectionIdxs.find(ParsedFuncName);
+ auto sectionIdxsIt =
+ rootSymbolToSectionIdxs.find(CachedHashStringRef(parsedFuncName));
if (sectionIdxsIt == rootSymbolToSectionIdxs.end())
continue;
- auto §ionIdxs = sectionIdxsIt->getValue();
+ auto §ionIdxs = sectionIdxsIt->second;
// If the same symbol is found in multiple sections, they might be
// identical, so we arbitrarily use the size from the first section.
- currentSize += sections[*sectionIdxs.begin()]->getSize();
+ currentSize += D::getSize(*sections[*sectionIdxs.begin()]);
// Since BalancedPartitioning is sensitive to the initial order, we need
// to explicitly define it to be ordered by earliest timestamp.
@@ -193,7 +223,7 @@ BPSectionBase::reorderSectionsByBalancedPartitioning(
if (startupSectionIdxUNs.count(sectionIdx))
continue;
const auto *isec = sections[sectionIdx];
- if (isec->isCodeSection()) {
+ if (D::isCodeSection(*isec)) {
if (forFunctionCompression)
sectionIdxsForFunctionCompression.push_back(sectionIdx);
} else {
@@ -207,8 +237,8 @@ BPSectionBase::reorderSectionsByBalancedPartitioning(
for (auto &[sectionIdx, uns] : startupSectionIdxUNs)
startupIdxs.push_back(sectionIdx);
auto unsForStartupFunctionCompression =
- getUnsForCompression(sections, sectionToIdx, startupIdxs,
- /*duplicateSectionIdxs=*/nullptr, maxUN);
+ getUnsForCompression<D>(sections, sectionToIdx, startupIdxs,
+ /*duplicateSectionIdxs=*/nullptr, maxUN);
for (auto &[sectionIdx, compressionUns] :
unsForStartupFunctionCompression) {
auto &uns = startupSectionIdxUNs[sectionIdx];
@@ -221,10 +251,10 @@ BPSectionBase::reorderSectionsByBalancedPartitioning(
// Map a section index (order directly) to a list of duplicate section indices
// (not ordered directly).
DenseMap<unsigned, SmallVector<unsigned>> duplicateSectionIdxs;
- auto unsForFunctionCompression = getUnsForCompression(
+ auto unsForFunctionCompression = getUnsForCompression<D>(
sections, sectionToIdx, sectionIdxsForFunctionCompression,
&duplicateSectionIdxs, maxUN);
- auto unsForDataCompression = getUnsForCompression(
+ auto unsForDataCompression = getUnsForCompression<D>(
sections, sectionToIdx, sectionIdxsForDataCompression,
&duplicateSectionIdxs, maxUN);
@@ -263,7 +293,7 @@ BPSectionBase::reorderSectionsByBalancedPartitioning(
unsigned numDuplicateCodeSections = 0;
unsigned numDataCompressionSections = 0;
unsigned numDuplicateDataSections = 0;
- SetVector<const BPSectionBase *> orderedSections;
+ SetVector<const Section *> orderedSections;
// Order startup functions,
for (auto &node : nodesForStartup) {
const auto *isec = sections[node.Id];
@@ -320,23 +350,22 @@ BPSectionBase::reorderSectionsByBalancedPartitioning(
const uint64_t pageSize = (1 << 14);
uint64_t currentAddress = 0;
for (const auto *isec : orderedSections) {
- for (auto &sym : isec->getSymbols()) {
- uint64_t startAddress = currentAddress + sym->getValue().value_or(0);
- uint64_t endAddress = startAddress + sym->getSize().value_or(0);
+ for (auto &sym : D::getSymbols(*isec)) {
+ uint64_t startAddress = currentAddress + D::getSymValue(*sym);
+ uint64_t endAddress = startAddress + D::getSymSize(*sym);
uint64_t firstPage = startAddress / pageSize;
// I think the kernel might pull in a few pages when one it touched,
// so it might be more accurate to force lastPage to be aligned by
// 4?
uint64_t lastPage = endAddress / pageSize;
- StringRef rootSymbol = sym->getName();
- rootSymbol = BPSectionBase::getRootSymbol(rootSymbol);
+ StringRef rootSymbol = D::getSymName(*sym);
+ rootSymbol = getRootSymbol(rootSymbol);
symbolToPageNumbers.try_emplace(rootSymbol, firstPage, lastPage);
- if (auto resolvedLinkageName =
- isec->getResolvedLinkageName(rootSymbol))
+ if (auto resolvedLinkageName = D::getResolvedLinkageName(rootSymbol))
symbolToPageNumbers.try_emplace(resolvedLinkageName.value(),
firstPage, lastPage);
}
- currentAddress += isec->getSize();
+ currentAddress += D::getSize(*isec);
}
// The area under the curve F where F(t) is the total number of page
@@ -348,7 +377,7 @@ BPSectionBase::reorderSectionsByBalancedPartitioning(
auto traceId = trace.FunctionNameRefs[step];
auto [Filename, ParsedFuncName] =
getParsedIRPGOName(reader->getSymtab().getFuncOrVarName(traceId));
- ParsedFuncName = BPSectionBase::getRootSymbol(ParsedFuncName);
+ ParsedFuncName = getRootSymbol(ParsedFuncName);
auto it = symbolToPageNumbers.find(ParsedFuncName);
if (it != symbolToPageNumbers.end()) {
auto &[firstPage, lastPage] = it->getValue();
@@ -363,7 +392,7 @@ BPSectionBase::reorderSectionsByBalancedPartitioning(
}
}
- DenseMap<const BPSectionBase *, int> sectionPriorities;
+ DenseMap<const Section *, int> sectionPriorities;
int prio = -orderedSections.size();
for (const auto *isec : orderedSections)
sectionPriorities[isec] = prio++;
>From 197ee8b29f98dbe187ec8c9c9131466b00d7b9d2 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Sun, 26 Jan 2025 13:06:41 -0800
Subject: [PATCH 2/2] more comment. optimize
Created using spr 1.3.5-bogner
---
lld/MachO/BPSectionOrderer.cpp | 31 +++++++++----------
.../lld/Common/BPSectionOrdererBase.inc | 21 ++++++++-----
2 files changed, 29 insertions(+), 23 deletions(-)
diff --git a/lld/MachO/BPSectionOrderer.cpp b/lld/MachO/BPSectionOrderer.cpp
index 116daa1a2f6cbe..e2f7a387deebc4 100644
--- a/lld/MachO/BPSectionOrderer.cpp
+++ b/lld/MachO/BPSectionOrderer.cpp
@@ -118,32 +118,31 @@ struct BPOrdererMachO : lld::BPOrderer<BPOrdererMachO> {
DenseMap<const InputSection *, int> lld::macho::runBalancedPartitioning(
StringRef profilePath, bool forFunctionCompression, bool forDataCompression,
bool compressionSortStartupFunctions, bool verbose) {
+ // Collect candidate sections and associated symbols.
SmallVector<InputSection *> sections;
- DenseMap<StringRef, DenseSet<unsigned>> symbolToSectionIdxs;
+ DenseMap<CachedHashStringRef, DenseSet<unsigned>> rootSymbolToSectionIdxs;
for (const auto *file : inputFiles) {
for (auto *sec : file->sections) {
for (auto &subsec : sec->subsections) {
auto *isec = subsec.isec;
if (!isec || isec->data.empty())
continue;
- for (auto *sym : BPOrdererMachO::getSymbols(*isec))
- symbolToSectionIdxs[sym->getName()].insert(sections.size());
+ size_t idx = sections.size();
sections.emplace_back(isec);
+ for (auto *sym : BPOrdererMachO::getSymbols(*isec)) {
+ auto rootName = getRootSymbol(sym->getName());
+ rootSymbolToSectionIdxs[CachedHashStringRef(rootName)].insert(idx);
+ if (auto linkageName =
+ BPOrdererMachO::getResolvedLinkageName(rootName))
+ rootSymbolToSectionIdxs[CachedHashStringRef(*linkageName)].insert(
+ idx);
+ }
}
}
}
- DenseMap<CachedHashStringRef, DenseSet<unsigned>> rootSymbolToSectionIdxs;
- for (auto &[name, sectionIdxs] : symbolToSectionIdxs) {
- auto rootName = getRootSymbol(name);
- rootSymbolToSectionIdxs[CachedHashStringRef(rootName)].insert(
- sectionIdxs.begin(), sectionIdxs.end());
- if (auto linkageName = BPOrdererMachO::getResolvedLinkageName(rootName))
- rootSymbolToSectionIdxs[CachedHashStringRef(*linkageName)].insert(
- sectionIdxs.begin(), sectionIdxs.end());
- }
- return BPOrdererMachO::reorderSections(
- profilePath, forFunctionCompression, forDataCompression,
- compressionSortStartupFunctions, verbose, sections,
- rootSymbolToSectionIdxs);
+ return BPOrdererMachO::computeOrder(profilePath, forFunctionCompression,
+ forDataCompression,
+ compressionSortStartupFunctions, verbose,
+ sections, rootSymbolToSectionIdxs);
}
diff --git a/lld/include/lld/Common/BPSectionOrdererBase.inc b/lld/include/lld/Common/BPSectionOrdererBase.inc
index 6c514e335f151d..6bdc6f1d3c1d1c 100644
--- a/lld/include/lld/Common/BPSectionOrdererBase.inc
+++ b/lld/include/lld/Common/BPSectionOrdererBase.inc
@@ -48,13 +48,20 @@ template <class D> struct BPOrderer {
using Section = typename BPOrdererTraits<D>::Section;
using Symbol = typename BPOrdererTraits<D>::Symbol;
- // Reorder sections using balanced partitioning algorithm based on profile.
+ // Compute a section order using the Balanced Partitioning algorithm.
+ //
+ // * for*Compresion: Improve Lempel-Ziv compression by grouping
+ // similar sections together.
+ // * profilePath: Utilize a temporal profile file to reduce page faults during
+ // program startup.
+ // * compressionSortStartupFunctions: if profilePath is specified, allocate
+ // extra utility vertices to prioritize nearby function similarity.
static auto
- reorderSections(llvm::StringRef profilePath, bool forFunctionCompression,
- bool forDataCompression, bool compressionSortStartupFunctions,
- bool verbose, llvm::ArrayRef<Section *> sections,
- const DenseMap<CachedHashStringRef, DenseSet<unsigned>>
- &rootSymbolToSectionIdxs)
+ computeOrder(llvm::StringRef profilePath, bool forFunctionCompression,
+ bool forDataCompression, bool compressionSortStartupFunctions,
+ bool verbose, llvm::ArrayRef<Section *> sections,
+ const DenseMap<CachedHashStringRef, DenseSet<unsigned>>
+ &rootSymbolToSectionIdxs)
-> llvm::DenseMap<const Section *, int>;
};
} // namespace lld
@@ -145,7 +152,7 @@ inline StringRef getRootSymbol(StringRef name) {
}
template <class D>
-auto BPOrderer<D>::reorderSections(
+auto BPOrderer<D>::computeOrder(
StringRef profilePath, bool forFunctionCompression, bool forDataCompression,
bool compressionSortStartupFunctions, bool verbose,
ArrayRef<Section *> sections,
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