[llvm] [CodeGen][StaticDataPartitioning]Place local-linkage global variables in hot or unlikely prefixed sections based on profile information (PR #125756)
Mingming Liu via llvm-commits
llvm-commits at lists.llvm.org
Fri Feb 7 17:45:18 PST 2025
https://github.com/mingmingl-llvm updated https://github.com/llvm/llvm-project/pull/125756
>From 8eea1ea0109f07d590d189bc17d5f5411556d77a Mon Sep 17 00:00:00 2001
From: mingmingl <mingmingl at google.com>
Date: Tue, 4 Feb 2025 11:19:44 -0800
Subject: [PATCH 1/4] [CodeGen][StaticDataPartitioning]Place module-internal
global variables based on profile information
---
llvm/include/llvm/IR/Function.h | 6 -
llvm/include/llvm/IR/GlobalObject.h | 11 +
llvm/include/llvm/IR/MDBuilder.h | 4 +-
llvm/lib/CodeGen/StaticDataSplitter.cpp | 201 +++++++++++++-----
.../CodeGen/TargetLoweringObjectFileImpl.cpp | 6 +
llvm/lib/IR/Function.cpp | 16 --
llvm/lib/IR/Globals.cpp | 30 +++
llvm/lib/IR/MDBuilder.cpp | 6 +-
llvm/test/CodeGen/X86/data-section-prefix.ll | 27 +++
.../CodeGen/X86/global-variable-partition.ll | 159 ++++++++++++++
.../CodeGenPrepare/X86/section-samplepgo.ll | 4 +-
.../Transforms/CodeGenPrepare/X86/section.ll | 4 +-
.../Transforms/HotColdSplit/coldentrycount.ll | 4 +-
.../section-accurate-samplepgo.ll | 6 +-
14 files changed, 396 insertions(+), 88 deletions(-)
create mode 100644 llvm/test/CodeGen/X86/data-section-prefix.ll
create mode 100644 llvm/test/CodeGen/X86/global-variable-partition.ll
diff --git a/llvm/include/llvm/IR/Function.h b/llvm/include/llvm/IR/Function.h
index fcd5396ccfdbc87..29041688124bc29 100644
--- a/llvm/include/llvm/IR/Function.h
+++ b/llvm/include/llvm/IR/Function.h
@@ -346,12 +346,6 @@ class LLVM_ABI Function : public GlobalObject, public ilist_node<Function> {
/// sample PGO, to enable the same inlines as the profiled optimized binary.
DenseSet<GlobalValue::GUID> getImportGUIDs() const;
- /// Set the section prefix for this function.
- void setSectionPrefix(StringRef Prefix);
-
- /// Get the section prefix for this function.
- std::optional<StringRef> getSectionPrefix() const;
-
/// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
/// to use during code generation.
bool hasGC() const {
diff --git a/llvm/include/llvm/IR/GlobalObject.h b/llvm/include/llvm/IR/GlobalObject.h
index 08edc13d81f880a..bb50c39813e1407 100644
--- a/llvm/include/llvm/IR/GlobalObject.h
+++ b/llvm/include/llvm/IR/GlobalObject.h
@@ -124,6 +124,17 @@ class GlobalObject : public GlobalValue {
/// appropriate default object file section.
void setSection(StringRef S);
+ /// Set the section prefix for this global object.
+ void setSectionPrefix(StringRef Prefix);
+
+ /// Update the section prefix, unless the existing prefix is the same as
+ /// `KeepPrefix`.
+ void updateSectionPrefix(StringRef Prefix,
+ std::optional<StringRef> KeepPrefix = std::nullopt);
+
+ /// Get the section prefix for this global object.
+ std::optional<StringRef> getSectionPrefix() const;
+
bool hasComdat() const { return getComdat() != nullptr; }
const Comdat *getComdat() const { return ObjComdat; }
Comdat *getComdat() { return ObjComdat; }
diff --git a/llvm/include/llvm/IR/MDBuilder.h b/llvm/include/llvm/IR/MDBuilder.h
index e02ec8f5a3d8bb1..ce4e1da656049d1 100644
--- a/llvm/include/llvm/IR/MDBuilder.h
+++ b/llvm/include/llvm/IR/MDBuilder.h
@@ -89,8 +89,8 @@ class MDBuilder {
MDNode *createFunctionEntryCount(uint64_t Count, bool Synthetic,
const DenseSet<GlobalValue::GUID> *Imports);
- /// Return metadata containing the section prefix for a function.
- MDNode *createFunctionSectionPrefix(StringRef Prefix);
+ /// Return metadata containing the section prefix for a global object.
+ MDNode *createGlobalObjectSectionPrefix(StringRef Prefix);
/// Return metadata containing the pseudo probe descriptor for a function.
MDNode *createPseudoProbeDesc(uint64_t GUID, uint64_t Hash, StringRef FName);
diff --git a/llvm/lib/CodeGen/StaticDataSplitter.cpp b/llvm/lib/CodeGen/StaticDataSplitter.cpp
index e5bf0a5a3a255f6..f09e3b41e0723e6 100644
--- a/llvm/lib/CodeGen/StaticDataSplitter.cpp
+++ b/llvm/lib/CodeGen/StaticDataSplitter.cpp
@@ -9,13 +9,13 @@
// The pass uses branch profile data to assign hotness based section qualifiers
// for the following types of static data:
// - Jump tables
+// - Module-internal global variables
// - Constant pools (TODO)
-// - Other module-internal data (TODO)
//
// For the original RFC of this pass please see
// https://discourse.llvm.org/t/rfc-profile-guided-static-data-partitioning/83744
-#include "llvm/ADT/ScopeExit.h"
+#include "llvm/ADT/APInt.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/CodeGen/MBFIWrapper.h"
@@ -27,9 +27,12 @@
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/Passes.h"
+#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/Module.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
using namespace llvm;
@@ -46,12 +49,27 @@ class StaticDataSplitter : public MachineFunctionPass {
const MachineBlockFrequencyInfo *MBFI = nullptr;
const ProfileSummaryInfo *PSI = nullptr;
- // Returns true iff any jump table is hot-cold categorized.
- bool splitJumpTables(MachineFunction &MF);
+ void updateStats(bool ProfileAvailable, const MachineJumpTableInfo *MJTI);
+ void updateJumpTableStats(bool ProfileAvailable,
+ const MachineJumpTableInfo &MJTI);
- // Same as above but works on functions with profile information.
- bool splitJumpTablesWithProfiles(const MachineFunction &MF,
- MachineJumpTableInfo &MJTI);
+ // Use profiles to partition static data.
+ bool partitionStaticDataWithProfiles(MachineFunction &MF);
+
+ // If the global value is a local linkage global variable, return it.
+ // Otherwise, return nullptr.
+ const GlobalVariable *getLocalLinkageGlobalVariable(const GlobalValue *GV);
+
+ // Returns true if the global variable is in one of {.rodata, .bss, .data,
+ // .data.rel.ro} sections
+ bool inStaticDataSection(const GlobalVariable *GV, const TargetMachine &TM);
+
+ // Iterate all global variables in the module and update the section prefix
+ // of the module-internal data.
+ void updateGlobalVariableSectionPrefix(MachineFunction &MF);
+
+ // Accummulated data profile count across machine functions in the module.
+ DenseMap<const GlobalVariable *, APInt> DataProfileCounts;
public:
static char ID;
@@ -77,13 +95,24 @@ bool StaticDataSplitter::runOnMachineFunction(MachineFunction &MF) {
MBFI = &getAnalysis<MachineBlockFrequencyInfoWrapperPass>().getMBFI();
PSI = &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
- return splitJumpTables(MF);
+ const bool ProfileAvailable = PSI && PSI->hasProfileSummary() && MBFI &&
+ MF.getFunction().hasProfileData();
+ bool Changed = false;
+
+ if (ProfileAvailable)
+ Changed |= partitionStaticDataWithProfiles(MF);
+
+ updateGlobalVariableSectionPrefix(MF);
+ updateStats(ProfileAvailable, MF.getJumpTableInfo());
+ return Changed;
}
-bool StaticDataSplitter::splitJumpTablesWithProfiles(
- const MachineFunction &MF, MachineJumpTableInfo &MJTI) {
+bool StaticDataSplitter::partitionStaticDataWithProfiles(MachineFunction &MF) {
int NumChangedJumpTables = 0;
+ const TargetMachine &TM = MF.getTarget();
+ MachineJumpTableInfo *MJTI = MF.getJumpTableInfo();
+
// Jump table could be used by either terminating instructions or
// non-terminating ones, so we walk all instructions and use
// `MachineOperand::isJTI()` to identify jump table operands.
@@ -92,63 +121,131 @@ bool StaticDataSplitter::splitJumpTablesWithProfiles(
for (const auto &MBB : MF) {
for (const MachineInstr &I : MBB) {
for (const MachineOperand &Op : I.operands()) {
- if (!Op.isJTI())
- continue;
- const int JTI = Op.getIndex();
- // This is not a source block of jump table.
- if (JTI == -1)
+ std::optional<uint64_t> Count = std::nullopt;
+ if (!Op.isJTI() && !Op.isGlobal())
continue;
- auto Hotness = MachineFunctionDataHotness::Hot;
+ Count = MBFI->getBlockProfileCount(&MBB);
+
+ if (Op.isJTI()) {
+ assert(MJTI != nullptr && "Jump table info is not available.");
+ const int JTI = Op.getIndex();
+ // This is not a source block of jump table.
+ if (JTI == -1)
+ continue;
+
+ auto Hotness = MachineFunctionDataHotness::Hot;
+
+ // Hotness is based on source basic block hotness.
+ // TODO: PSI APIs are about instruction hotness. Introduce API for
+ // data access hotness.
+ if (Count && PSI->isColdCount(*Count))
+ Hotness = MachineFunctionDataHotness::Cold;
- // Hotness is based on source basic block hotness.
- // TODO: PSI APIs are about instruction hotness. Introduce API for data
- // access hotness.
- if (PSI->isColdBlock(&MBB, MBFI))
- Hotness = MachineFunctionDataHotness::Cold;
+ if (MJTI->updateJumpTableEntryHotness(JTI, Hotness))
+ ++NumChangedJumpTables;
+ } else if (Op.isGlobal()) {
+ // Find global variables with local linkage
+ const GlobalVariable *GV =
+ getLocalLinkageGlobalVariable(Op.getGlobal());
+ if (!GV || !inStaticDataSection(GV, TM))
+ continue;
- if (MJTI.updateJumpTableEntryHotness(JTI, Hotness))
- ++NumChangedJumpTables;
+ // Acccumulate data profile count across machine function
+ // instructions.
+ // TODO: Analyze global variable's initializers.
+ if (Count) {
+ auto [It, Inserted] =
+ DataProfileCounts.try_emplace(GV, APInt(128, 0));
+ It->second += *Count;
+ }
+ }
}
}
}
return NumChangedJumpTables > 0;
}
-bool StaticDataSplitter::splitJumpTables(MachineFunction &MF) {
- MachineJumpTableInfo *MJTI = MF.getJumpTableInfo();
- if (!MJTI || MJTI->getJumpTables().empty())
- return false;
-
- const bool ProfileAvailable = PSI && PSI->hasProfileSummary() && MBFI &&
- MF.getFunction().hasProfileData();
- auto statOnExit = llvm::make_scope_exit([&] {
- if (!AreStatisticsEnabled())
- return;
+void StaticDataSplitter::updateJumpTableStats(
+ bool ProfileAvailable, const MachineJumpTableInfo &MJTI) {
+ if (!ProfileAvailable) {
+ NumUnknownJumpTables += MJTI.getJumpTables().size();
+ return;
+ }
- if (!ProfileAvailable) {
- NumUnknownJumpTables += MJTI->getJumpTables().size();
- return;
+ for (size_t JTI = 0; JTI < MJTI.getJumpTables().size(); JTI++) {
+ auto Hotness = MJTI.getJumpTables()[JTI].Hotness;
+ if (Hotness == MachineFunctionDataHotness::Hot) {
+ ++NumHotJumpTables;
+ } else {
+ assert(Hotness == MachineFunctionDataHotness::Cold &&
+ "A jump table is either hot or cold when profile information is "
+ "available.");
+ ++NumColdJumpTables;
}
+ }
+}
- for (size_t JTI = 0; JTI < MJTI->getJumpTables().size(); JTI++) {
- auto Hotness = MJTI->getJumpTables()[JTI].Hotness;
- if (Hotness == MachineFunctionDataHotness::Hot) {
- ++NumHotJumpTables;
- } else {
- assert(Hotness == MachineFunctionDataHotness::Cold &&
- "A jump table is either hot or cold when profile information is "
- "available.");
- ++NumColdJumpTables;
- }
- }
- });
+void StaticDataSplitter::updateStats(bool ProfileAvailable,
+ const MachineJumpTableInfo *MJTI) {
+ if (!AreStatisticsEnabled())
+ return;
- // Place jump tables according to block hotness if function has profile data.
- if (ProfileAvailable)
- return splitJumpTablesWithProfiles(MF, *MJTI);
+ if (MJTI)
+ updateJumpTableStats(ProfileAvailable, *MJTI);
+}
- return true;
+const GlobalVariable *
+StaticDataSplitter::getLocalLinkageGlobalVariable(const GlobalValue *GV) {
+ if (!GV || GV->isDeclarationForLinker())
+ return nullptr;
+
+ return GV->hasLocalLinkage() ? dyn_cast<GlobalVariable>(GV) : nullptr;
+}
+
+bool StaticDataSplitter::inStaticDataSection(const GlobalVariable *GV,
+ const TargetMachine &TM) {
+ assert(GV && "Caller guaranteed");
+
+ // Skip LLVM reserved symbols.
+ if (GV->getName().starts_with("llvm."))
+ return false;
+
+ SectionKind Kind = TargetLoweringObjectFile::getKindForGlobal(GV, TM);
+ return Kind.isData() || Kind.isReadOnly() || Kind.isReadOnlyWithRel() ||
+ Kind.isBSS();
+}
+
+void StaticDataSplitter::updateGlobalVariableSectionPrefix(
+ MachineFunction &MF) {
+ for (GlobalVariable &GV : MF.getFunction().getParent()->globals()) {
+ if (GV.isDeclarationForLinker())
+ continue;
+ // DataProfileCounts accumulates data profile count across all machine
+ // function instructions, and it can't model the indirect accesses through
+ // other global variables' initializers.
+ // TODO: Analyze the users of module-internal global variables and see
+ // through the users' initializers. Do not place a global variable into
+ // unlikely section if any of its users are potentially hot.
+ auto Iter = DataProfileCounts.find(&GV);
+ if (Iter == DataProfileCounts.end())
+ continue;
+
+ // StaticDataSplitter is made a machine function pass rather than a module
+ // pass because (Lazy)MachineBlockFrequencyInfo is a machine-function
+ // analysis pass and cannot be used for a legacy module pass.
+ // As a result, we use `DataProfileCounts` to accumulate data
+ // profile count across machine functions and update global variable section
+ // prefix once per machine function.
+ // FIXME: Make StaticDataSplitter a module pass under new pass manager
+ // framework, and set global variable section prefix once per module after
+ // analyzing all machine functions.
+ if (PSI->isColdCount(Iter->second.getZExtValue())) {
+ GV.updateSectionPrefix("unlikely", std::make_optional(StringRef("hot")));
+ } else if (PSI->isHotCount(Iter->second.getZExtValue())) {
+ GV.updateSectionPrefix("hot");
+ }
+ }
}
char StaticDataSplitter::ID = 0;
diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 3c2c7c8c9fed69a..d20ab29cc197974 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -670,6 +670,7 @@ getELFSectionNameForGlobal(const GlobalObject *GO, SectionKind Kind,
}
bool HasPrefix = false;
+
if (const auto *F = dyn_cast<Function>(GO)) {
// Jump table hotness takes precedence over its enclosing function's hotness
// if it's known. The function's section prefix is used if jump table entry
@@ -687,6 +688,11 @@ getELFSectionNameForGlobal(const GlobalObject *GO, SectionKind Kind,
raw_svector_ostream(Name) << '.' << *Prefix;
HasPrefix = true;
}
+ } else if (const auto *GV = dyn_cast<GlobalVariable>(GO)) {
+ if (std::optional<StringRef> Prefix = GV->getSectionPrefix()) {
+ raw_svector_ostream(Name) << '.' << *Prefix;
+ HasPrefix = true;
+ }
}
if (UniqueSectionName) {
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index e6f0d64d071ba67..5666f0a53866fda 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -1164,22 +1164,6 @@ DenseSet<GlobalValue::GUID> Function::getImportGUIDs() const {
return R;
}
-void Function::setSectionPrefix(StringRef Prefix) {
- MDBuilder MDB(getContext());
- setMetadata(LLVMContext::MD_section_prefix,
- MDB.createFunctionSectionPrefix(Prefix));
-}
-
-std::optional<StringRef> Function::getSectionPrefix() const {
- if (MDNode *MD = getMetadata(LLVMContext::MD_section_prefix)) {
- assert(cast<MDString>(MD->getOperand(0))->getString() ==
- "function_section_prefix" &&
- "Metadata not match");
- return cast<MDString>(MD->getOperand(1))->getString();
- }
- return std::nullopt;
-}
-
bool Function::nullPointerIsDefined() const {
return hasFnAttribute(Attribute::NullPointerIsValid);
}
diff --git a/llvm/lib/IR/Globals.cpp b/llvm/lib/IR/Globals.cpp
index db5e1cb57b1bab8..884089262e4659d 100644
--- a/llvm/lib/IR/Globals.cpp
+++ b/llvm/lib/IR/Globals.cpp
@@ -18,6 +18,7 @@
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/ErrorHandling.h"
@@ -286,6 +287,35 @@ void GlobalObject::setSection(StringRef S) {
setGlobalObjectFlag(HasSectionHashEntryBit, !S.empty());
}
+void GlobalObject::setSectionPrefix(StringRef Prefix) {
+ MDBuilder MDB(getContext());
+ setMetadata(LLVMContext::MD_section_prefix,
+ MDB.createGlobalObjectSectionPrefix(Prefix));
+}
+
+void GlobalObject::updateSectionPrefix(StringRef Prefix,
+ std::optional<StringRef> KeepPrefix) {
+ auto SectionPrefix = getSectionPrefix();
+ if (SectionPrefix && (*SectionPrefix == Prefix ||
+ (KeepPrefix && *SectionPrefix == *KeepPrefix)))
+ return;
+
+ setSectionPrefix(Prefix);
+ return;
+}
+
+std::optional<StringRef> GlobalObject::getSectionPrefix() const {
+ if (MDNode *MD = getMetadata(LLVMContext::MD_section_prefix)) {
+ [[maybe_unused]] StringRef MDName =
+ cast<MDString>(MD->getOperand(0))->getString();
+ assert((MDName == "section_prefix" ||
+ (isa<Function>(this) && MDName == "function_section_prefix")) &&
+ "Metadata not match");
+ return cast<MDString>(MD->getOperand(1))->getString();
+ }
+ return std::nullopt;
+}
+
bool GlobalValue::isNobuiltinFnDef() const {
const Function *F = dyn_cast<Function>(this);
if (!F || F->empty())
diff --git a/llvm/lib/IR/MDBuilder.cpp b/llvm/lib/IR/MDBuilder.cpp
index 26c8ab9fc36c850..b6aa8844a7eafa7 100644
--- a/llvm/lib/IR/MDBuilder.cpp
+++ b/llvm/lib/IR/MDBuilder.cpp
@@ -87,9 +87,9 @@ MDNode *MDBuilder::createFunctionEntryCount(
return MDNode::get(Context, Ops);
}
-MDNode *MDBuilder::createFunctionSectionPrefix(StringRef Prefix) {
- return MDNode::get(
- Context, {createString("function_section_prefix"), createString(Prefix)});
+MDNode *MDBuilder::createGlobalObjectSectionPrefix(StringRef Prefix) {
+ return MDNode::get(Context,
+ {createString("section_prefix"), createString(Prefix)});
}
MDNode *MDBuilder::createRange(const APInt &Lo, const APInt &Hi) {
diff --git a/llvm/test/CodeGen/X86/data-section-prefix.ll b/llvm/test/CodeGen/X86/data-section-prefix.ll
new file mode 100644
index 000000000000000..4812fc70758fbce
--- /dev/null
+++ b/llvm/test/CodeGen/X86/data-section-prefix.ll
@@ -0,0 +1,27 @@
+; RUN: llc -mtriple x86_64-linux-gnu -data-sections %s -o - | FileCheck %s --check-prefix=ELF
+; RUN: llc -mtriple x86_64-linux-gnu -unique-section-names=0 -data-sections %s -o - | FileCheck %s --check-prefix=ELF-NOUNIQ
+
+; RUN: llc -mtriple x86_64-windows-msvc -data-sections %s -o - | FileCheck %s --check-prefix=COFF-MSVC
+
+; ELF: .section .data.hot.foo,
+; ELF: .section .data.bar,
+; ELF: .section .bss.unlikely.baz,
+; ELF: .section .bss.quz,
+
+; ELF-NOUNIQ: .section .data.hot.,"aw", at progbits,unique,1
+; ELF-NOUNIQ: .section .data,"aw", at progbits,unique,2
+; ELF-NOUNIQ: .section .bss.unlikely.,"aw", at nobits,unique,3
+; ELF-NOUNIQ: .section .bss,"aw", at nobits,unique,4
+
+; COFF-MSVC: .section .data,"dw",one_only,foo
+; COFF-MSVC: .section .data,"dw",one_only,bar
+; COFF-MSVC: .section .bss,"bw",one_only,baz
+; COFF-MSVC: .section .bss,"bw",one_only,quz
+
+ at foo = global i32 1, !section_prefix !0
+ at bar = global i32 2
+ at baz = global i32 0, !section_prefix !1
+ at quz = global i32 0
+
+!0 = !{!"section_prefix", !"hot"}
+!1 = !{!"section_prefix", !"unlikely"}
diff --git a/llvm/test/CodeGen/X86/global-variable-partition.ll b/llvm/test/CodeGen/X86/global-variable-partition.ll
new file mode 100644
index 000000000000000..d457d766999e246
--- /dev/null
+++ b/llvm/test/CodeGen/X86/global-variable-partition.ll
@@ -0,0 +1,159 @@
+
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; RUN: llc -mtriple=x86_64-unknown-linux-gnu -enable-split-machine-functions \
+; RUN: -partition-static-data-sections=true -data-sections=true \
+; RUN: -unique-section-names=true -relocation-model=pic \
+; RUN: %s -o - 2>&1 | FileCheck %s --check-prefixes=SYM,DATA
+
+; RUN: llc -mtriple=x86_64-unknown-linux-gnu -enable-split-machine-functions \
+; RUN: -partition-static-data-sections=true -data-sections=true \
+; RUN: -unique-section-names=false -relocation-model=pic \
+; RUN: %s -o - 2>&1 | FileCheck %s --check-prefixes=UNIQ,DATA
+
+; RUN: llc -mtriple=x86_64-unknown-linux-gnu -enable-split-machine-functions \
+; RUN: -partition-static-data-sections=true -data-sections=false \
+; RUN: -unique-section-names=false -relocation-model=pic \
+; RUN: %s -o - 2>&1 | FileCheck %s --check-prefixes=AGG,DATA
+
+; SYM: .section .rodata.str1.1.hot.
+; UNIQ: .section .rodata.str1.1.hot.,"aMS", at progbits,1
+; AGG: .section .rodata.str1.1.hot
+; DATA: .L.str
+; DATA: "hot\t"
+; DATA: .L.str.1
+; DATA: "%d\t%d\t%d\n"
+
+
+; SYM: .section .data.rel.ro.hot.hot_relro_array
+; SYM: .section .data.hot.hot_data,"aw", at progbits
+; SYM: .section .bss.hot.hot_bss,"aw", at nobits
+
+; UNIQ: .section .data.rel.ro.hot.,"aw", at progbits,unique,3
+; UNIQ: .section .data.hot.,"aw", at progbits,unique,4
+; UNIQ: .section .bss.hot.,"aw", at nobits,unique,5
+
+; AGG: .section .data.rel.ro.hot.,"aw", at progbits
+; AGG: .section .data.hot.,"aw", at progbits
+; AGG: .section .bss.hot.,"aw", at nobits
+
+
+; SYM: .section .rodata.str1.1.unlikely.,"aMS", at progbits,1
+; UNIQ: section .rodata.str1.1.unlikely.,"aMS", at progbits,1
+; AGG: .section .rodata.str1.1.unlikely.,"aMS", at progbits,1
+; DATA: .L.str.2:
+; DATA: "cold%d\t%d\t%d\n"
+
+
+; SYM: .section .bss.unlikely.cold_bss,"aw", at nobits
+; SYM: .section .data.unlikely.cold_data,"aw", at progbits
+; SYM: .section .data.rel.ro.unlikely.cold_relro_array,"aw", at progbits
+; SYM: .section .bss.unlikely._ZL4bss2,"aw", at nobits
+; SYM: .section .data.unlikely._ZL5data3,"aw", at progbits
+
+; UNIQ: .section .bss.unlikely.,"aw", at nobits,unique,6
+; UNIQ: .section .data.unlikely.,"aw", at progbits,unique,7
+; UNIQ: .section .data.rel.ro.unlikely.,"aw", at progbits,unique,8
+; UNIQ: .section .bss.unlikely.,"aw", at nobits,unique,9
+; UNIQ: .section .data.unlikely.,"aw", at progbits,unique,10
+
+; AGG: .section .bss.unlikely.,"aw", at nobits
+; AGG: .section .data.unlikely.,"aw", at progbits
+; AGG: .section .data.rel.ro.unlikely.,"aw", at progbits
+; AGG: .section .bss.unlikely.,"aw", at nobits
+; AGG: .section .data.unlikely.,"aw", at progbits
+
+ at .str = private unnamed_addr constant [5 x i8] c"hot\09\00", align 1
+ at .str.1 = private unnamed_addr constant [10 x i8] c"%d\09%d\09%d\0A\00", align 1
+ at hot_relro_array = internal constant [2 x ptr] [ptr @_ZL4bss2, ptr @_ZL5data3]
+ at hot_data = internal global i32 5
+ at hot_bss = internal global i32 0
+ at .str.2 = private unnamed_addr constant [14 x i8] c"cold%d\09%d\09%d\0A\00", align 1
+ at cold_bss = internal global i32 0
+ at cold_data = internal global i32 4
+ at cold_relro_array = internal constant [2 x ptr] [ptr @_ZL5data3, ptr @_ZL4bss2]
+ at _ZL4bss2 = internal global i32 0
+ at _ZL5data3 = internal global i32 3
+
+define void @hot_callee(i32 %0) !prof !51 {
+ %2 = call i32 (ptr, ...) @printf(ptr @.str)
+ %3 = srem i32 %0, 2
+ %4 = sext i32 %3 to i64
+ %5 = getelementptr inbounds [2 x ptr], ptr @hot_relro_array, i64 0, i64 %4
+ %6 = load ptr, ptr %5
+ %7 = load i32, ptr %6
+ %8 = load i32, ptr @hot_data
+ %9 = load i32, ptr @hot_bss
+ %10 = call i32 (ptr, ...) @printf(ptr @.str.1, i32 %7, i32 %8, i32 %9)
+ ret void
+}
+
+define void @cold_callee(i32 %0) !prof !52 {
+ %2 = load i32, ptr @cold_bss
+ %3 = load i32, ptr @cold_data
+ %4 = srem i32 %0, 2
+ %5 = sext i32 %4 to i64
+ %6 = getelementptr inbounds [2 x ptr], ptr @cold_relro_array, i64 0, i64 %5
+ %7 = load ptr, ptr %6
+ %8 = load i32, ptr %7
+ %9 = call i32 (ptr, ...) @printf(ptr @.str.2, i32 %2, i32 %3, i32 %8)
+ ret void
+}
+
+define i32 @main(i32 %0, ptr %1) !prof !52 {
+ %3 = call i64 @time(ptr null)
+ %4 = trunc i64 %3 to i32
+ call void @srand(i32 %4)
+ br label %11
+
+5: ; preds = %11
+ %6 = call i32 @rand()
+ store i32 %6, ptr @cold_bss
+ store i32 %6, ptr @cold_data
+ store i32 %6, ptr @_ZL4bss2
+ store i32 %6, ptr @_ZL5data3
+ call void @cold_callee(i32 %6)
+ ret i32 0
+
+11: ; preds = %11, %2
+ %12 = phi i32 [ 0, %2 ], [ %19, %11 ]
+ %13 = call i32 @rand()
+ %14 = srem i32 %13, 2
+ %15 = sext i32 %14 to i64
+ %16 = getelementptr inbounds [2 x ptr], ptr @hot_relro_array, i64 0, i64 %15
+ %17 = load ptr, ptr %16
+ store i32 %13, ptr %17
+ store i32 %13, ptr @hot_data
+ %18 = add i32 %13, 1
+ store i32 %18, ptr @hot_bss
+ call void @hot_callee(i32 %12)
+ %19 = add i32 %12, 1
+ %20 = icmp eq i32 %19, 100000
+ br i1 %20, label %5, label %11, !prof !53
+}
+
+declare void @srand(i32)
+declare i64 @time(ptr)
+declare i32 @rand()
+declare i32 @printf(ptr, ...)
+
+!llvm.module.flags = !{!12}
+
+!12 = !{i32 1, !"ProfileSummary", !13}
+!13 = !{!14, !15, !16, !17, !18, !19, !20, !23}
+!14 = !{!"ProfileFormat", !"InstrProf"}
+!15 = !{!"TotalCount", i64 1460183}
+!16 = !{!"MaxCount", i64 849024}
+!17 = !{!"MaxInternalCount", i64 32769}
+!18 = !{!"MaxFunctionCount", i64 849024}
+!19 = !{!"NumCounts", i64 23627}
+!20 = !{!"NumFunctions", i64 3271}
+!23 = !{!"DetailedSummary", !24}
+!24 = !{!36, !40}
+!36 = !{i32 990000, i64 166, i32 73}
+!40 = !{i32 999999, i64 1, i32 1443}
+!51 = !{!"function_entry_count", i64 100000}
+!52 = !{!"function_entry_count", i64 1}
+!53 = !{!"branch_weights", i32 1, i32 99999}
diff --git a/llvm/test/Transforms/CodeGenPrepare/X86/section-samplepgo.ll b/llvm/test/Transforms/CodeGenPrepare/X86/section-samplepgo.ll
index 58af88d8cf3653d..48d02e5cebc69c8 100644
--- a/llvm/test/Transforms/CodeGenPrepare/X86/section-samplepgo.ll
+++ b/llvm/test/Transforms/CodeGenPrepare/X86/section-samplepgo.ll
@@ -34,8 +34,8 @@ define void @cold_func() !prof !16 {
ret void
}
-; CHECK: ![[HOT_ID]] = !{!"function_section_prefix", !"hot"}
-; CHECK: ![[COLD_ID]] = !{!"function_section_prefix", !"unlikely"}
+; CHECK: ![[HOT_ID]] = !{!"section_prefix", !"hot"}
+; CHECK: ![[COLD_ID]] = !{!"section_prefix", !"unlikely"}
!llvm.module.flags = !{!1}
!1 = !{i32 1, !"ProfileSummary", !2}
!2 = !{!3, !4, !5, !6, !7, !8, !9, !10}
diff --git a/llvm/test/Transforms/CodeGenPrepare/X86/section.ll b/llvm/test/Transforms/CodeGenPrepare/X86/section.ll
index 6dad1122e429455..4baa0b5baa4be5d 100644
--- a/llvm/test/Transforms/CodeGenPrepare/X86/section.ll
+++ b/llvm/test/Transforms/CodeGenPrepare/X86/section.ll
@@ -66,8 +66,8 @@ define void @cold_func3() !prof !16 {
ret void
}
-; CHECK: ![[HOT_ID]] = !{!"function_section_prefix", !"hot"}
-; CHECK: ![[COLD_ID]] = !{!"function_section_prefix", !"unlikely"}
+; CHECK: ![[HOT_ID]] = !{!"section_prefix", !"hot"}
+; CHECK: ![[COLD_ID]] = !{!"section_prefix", !"unlikely"}
!llvm.module.flags = !{!1}
!1 = !{i32 1, !"ProfileSummary", !2}
!2 = !{!3, !4, !5, !6, !7, !8, !9, !10}
diff --git a/llvm/test/Transforms/HotColdSplit/coldentrycount.ll b/llvm/test/Transforms/HotColdSplit/coldentrycount.ll
index 6e5ef1aa253921f..1e8825e651ec4c8 100644
--- a/llvm/test/Transforms/HotColdSplit/coldentrycount.ll
+++ b/llvm/test/Transforms/HotColdSplit/coldentrycount.ll
@@ -27,9 +27,9 @@ declare void @sink() cold
; CHECK: define {{.*}} @fun.cold.1{{.*}} ![[PROF:[0-9]+]] {{.*}}section_prefix ![[UNLIKELY:[0-9]+]]
; CHECK: ![[HOTPROF]] = !{!"function_entry_count", i64 100}
-; CHECK: ![[LIKELY]] = !{!"function_section_prefix", !"hot"}
+; CHECK: ![[LIKELY]] = !{!"section_prefix", !"hot"}
; CHECK: ![[PROF]] = !{!"function_entry_count", i64 0}
-; CHECK: ![[UNLIKELY]] = !{!"function_section_prefix", !"unlikely"}
+; CHECK: ![[UNLIKELY]] = !{!"section_prefix", !"unlikely"}
!llvm.module.flags = !{!0}
!0 = !{i32 1, !"ProfileSummary", !1}
diff --git a/llvm/test/Transforms/SampleProfile/section-accurate-samplepgo.ll b/llvm/test/Transforms/SampleProfile/section-accurate-samplepgo.ll
index ef2ddbc33cee4c5..af4b875818f6fed 100644
--- a/llvm/test/Transforms/SampleProfile/section-accurate-samplepgo.ll
+++ b/llvm/test/Transforms/SampleProfile/section-accurate-samplepgo.ll
@@ -36,11 +36,11 @@ attributes #1 = { "use-sample-profile" }
; CHECK: ![[NOPROFILE_ID]] = !{!"function_entry_count", i64 -1}
; CHECK: ![[ZERO_ID]] = !{!"function_entry_count", i64 0}
-; CHECK: ![[COLD_ID]] = !{!"function_section_prefix", !"unlikely"}
+; CHECK: ![[COLD_ID]] = !{!"section_prefix", !"unlikely"}
; UNKNOWN: ![[NOPROFILE_ID]] = !{!"function_entry_count", i64 -1}
-; UNKNOWN: ![[UNKNOWN_ID]] = !{!"function_section_prefix", !"unknown"}
+; UNKNOWN: ![[UNKNOWN_ID]] = !{!"section_prefix", !"unknown"}
; ACCURATE: ![[ZERO_ID]] = !{!"function_entry_count", i64 0}
-; ACCURATE: ![[COLD_ID]] = !{!"function_section_prefix", !"unlikely"}
+; ACCURATE: ![[COLD_ID]] = !{!"section_prefix", !"unlikely"}
!llvm.module.flags = !{!1}
!1 = !{i32 1, !"ProfileSummary", !2}
!2 = !{!3, !4, !5, !6, !7, !8, !9, !10}
>From 93d9881754b4713a6202011a2e1ffe520cf80367 Mon Sep 17 00:00:00 2001
From: mingmingl <mingmingl at google.com>
Date: Tue, 4 Feb 2025 12:13:52 -0800
Subject: [PATCH 2/4] add comment for bss22 and data3
---
.../CodeGen/X86/global-variable-partition.ll | 22 ++++++++++++-------
1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/llvm/test/CodeGen/X86/global-variable-partition.ll b/llvm/test/CodeGen/X86/global-variable-partition.ll
index d457d766999e246..bb77f3362406bdc 100644
--- a/llvm/test/CodeGen/X86/global-variable-partition.ll
+++ b/llvm/test/CodeGen/X86/global-variable-partition.ll
@@ -50,8 +50,8 @@ target triple = "x86_64-unknown-linux-gnu"
; SYM: .section .bss.unlikely.cold_bss,"aw", at nobits
; SYM: .section .data.unlikely.cold_data,"aw", at progbits
; SYM: .section .data.rel.ro.unlikely.cold_relro_array,"aw", at progbits
-; SYM: .section .bss.unlikely._ZL4bss2,"aw", at nobits
-; SYM: .section .data.unlikely._ZL5data3,"aw", at progbits
+; SYM: .section .bss.unlikely.bss2,"aw", at nobits
+; SYM: .section .data.unlikely.data3,"aw", at progbits
; UNIQ: .section .bss.unlikely.,"aw", at nobits,unique,6
; UNIQ: .section .data.unlikely.,"aw", at progbits,unique,7
@@ -67,15 +67,21 @@ target triple = "x86_64-unknown-linux-gnu"
@.str = private unnamed_addr constant [5 x i8] c"hot\09\00", align 1
@.str.1 = private unnamed_addr constant [10 x i8] c"%d\09%d\09%d\0A\00", align 1
- at hot_relro_array = internal constant [2 x ptr] [ptr @_ZL4bss2, ptr @_ZL5data3]
+ at hot_relro_array = internal constant [2 x ptr] [ptr @bss2, ptr @data3]
@hot_data = internal global i32 5
@hot_bss = internal global i32 0
@.str.2 = private unnamed_addr constant [14 x i8] c"cold%d\09%d\09%d\0A\00", align 1
@cold_bss = internal global i32 0
@cold_data = internal global i32 4
- at cold_relro_array = internal constant [2 x ptr] [ptr @_ZL5data3, ptr @_ZL4bss2]
- at _ZL4bss2 = internal global i32 0
- at _ZL5data3 = internal global i32 3
+ at cold_relro_array = internal constant [2 x ptr] [ptr @data3, ptr @bss2]
+
+; COM: Currently static-data-splitter only analyzes access from code.
+; COM: @bss2 and @data3 are indirectly accessed by code through @hot_relro_array
+; COM: and @cold_relro_array.
+; COM: A follow-up item is to analyze access from data and prune the unlikely
+; COM: list.
+ at bss2 = internal global i32 0
+ at data3 = internal global i32 3
define void @hot_callee(i32 %0) !prof !51 {
%2 = call i32 (ptr, ...) @printf(ptr @.str)
@@ -112,8 +118,8 @@ define i32 @main(i32 %0, ptr %1) !prof !52 {
%6 = call i32 @rand()
store i32 %6, ptr @cold_bss
store i32 %6, ptr @cold_data
- store i32 %6, ptr @_ZL4bss2
- store i32 %6, ptr @_ZL5data3
+ store i32 %6, ptr @bss2
+ store i32 %6, ptr @data3
call void @cold_callee(i32 %6)
ret i32 0
>From 8f21570c7d9dd528ad56ff2eefe85af8125ba99c Mon Sep 17 00:00:00 2001
From: mingmingl <mingmingl at google.com>
Date: Wed, 5 Feb 2025 14:20:12 -0800
Subject: [PATCH 3/4] apply code review suggestions
---
llvm/lib/CodeGen/StaticDataSplitter.cpp | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/llvm/lib/CodeGen/StaticDataSplitter.cpp b/llvm/lib/CodeGen/StaticDataSplitter.cpp
index e6e20db0724a57a..0716f6dac27f1d2 100644
--- a/llvm/lib/CodeGen/StaticDataSplitter.cpp
+++ b/llvm/lib/CodeGen/StaticDataSplitter.cpp
@@ -123,11 +123,10 @@ bool StaticDataSplitter::partitionStaticDataWithProfiles(MachineFunction &MF) {
for (const auto &MBB : MF) {
for (const MachineInstr &I : MBB) {
for (const MachineOperand &Op : I.operands()) {
- std::optional<uint64_t> Count = std::nullopt;
if (!Op.isJTI() && !Op.isGlobal())
continue;
- Count = MBFI->getBlockProfileCount(&MBB);
+ std::optional<uint64_t> Count = MBFI->getBlockProfileCount(&MBB);
if (Op.isJTI()) {
assert(MJTI != nullptr && "Jump table info is not available.");
>From f07d34d0d02bf9a8c46364cf4e1e605d3b626b92 Mon Sep 17 00:00:00 2001
From: mingmingl <mingmingl at google.com>
Date: Wed, 5 Feb 2025 14:48:39 -0800
Subject: [PATCH 4/4] record global variable section prefix updates as module
updates
---
llvm/include/llvm/IR/GlobalObject.h | 2 +-
llvm/lib/CodeGen/StaticDataSplitter.cpp | 13 +++++++++----
llvm/lib/IR/Globals.cpp | 6 +++---
3 files changed, 13 insertions(+), 8 deletions(-)
diff --git a/llvm/include/llvm/IR/GlobalObject.h b/llvm/include/llvm/IR/GlobalObject.h
index bb50c39813e1407..400ea6a1a7fca5b 100644
--- a/llvm/include/llvm/IR/GlobalObject.h
+++ b/llvm/include/llvm/IR/GlobalObject.h
@@ -129,7 +129,7 @@ class GlobalObject : public GlobalValue {
/// Update the section prefix, unless the existing prefix is the same as
/// `KeepPrefix`.
- void updateSectionPrefix(StringRef Prefix,
+ bool updateSectionPrefix(StringRef Prefix,
std::optional<StringRef> KeepPrefix = std::nullopt);
/// Get the section prefix for this global object.
diff --git a/llvm/lib/CodeGen/StaticDataSplitter.cpp b/llvm/lib/CodeGen/StaticDataSplitter.cpp
index 0716f6dac27f1d2..bbe3f9ff8cbd36a 100644
--- a/llvm/lib/CodeGen/StaticDataSplitter.cpp
+++ b/llvm/lib/CodeGen/StaticDataSplitter.cpp
@@ -59,7 +59,7 @@ class StaticDataSplitter : public MachineFunctionPass {
// Iterate all global variables in the module and update the section prefix
// of the module-internal data.
- void updateGlobalVariableSectionPrefix(MachineFunction &MF);
+ bool updateGlobalVariableSectionPrefix(MachineFunction &MF);
// Accummulated data profile count across machine functions in the module.
DenseMap<const GlobalVariable *, APInt> DataProfileCounts;
@@ -105,6 +105,8 @@ bool StaticDataSplitter::runOnMachineFunction(MachineFunction &MF) {
bool Changed = partitionStaticDataWithProfiles(MF);
+ Changed |= updateGlobalVariableSectionPrefix(MF);
+
updateStatsWithProfiles(MF);
return Changed;
}
@@ -188,8 +190,9 @@ bool StaticDataSplitter::inStaticDataSection(const GlobalVariable *GV,
Kind.isBSS();
}
-void StaticDataSplitter::updateGlobalVariableSectionPrefix(
+bool StaticDataSplitter::updateGlobalVariableSectionPrefix(
MachineFunction &MF) {
+ bool Changed = false;
for (GlobalVariable &GV : MF.getFunction().getParent()->globals()) {
if (GV.isDeclarationForLinker())
continue;
@@ -213,11 +216,13 @@ void StaticDataSplitter::updateGlobalVariableSectionPrefix(
// framework, and set global variable section prefix once per module after
// analyzing all machine functions.
if (PSI->isColdCount(Iter->second.getZExtValue())) {
- GV.updateSectionPrefix("unlikely", std::make_optional(StringRef("hot")));
+ Changed |= GV.updateSectionPrefix("unlikely",
+ std::make_optional(StringRef("hot")));
} else if (PSI->isHotCount(Iter->second.getZExtValue())) {
- GV.updateSectionPrefix("hot");
+ Changed |= GV.updateSectionPrefix("hot");
}
}
+ return Changed;
}
void StaticDataSplitter::updateStatsWithProfiles(const MachineFunction &MF) {
diff --git a/llvm/lib/IR/Globals.cpp b/llvm/lib/IR/Globals.cpp
index 884089262e4659d..5baf854cd552ba3 100644
--- a/llvm/lib/IR/Globals.cpp
+++ b/llvm/lib/IR/Globals.cpp
@@ -293,15 +293,15 @@ void GlobalObject::setSectionPrefix(StringRef Prefix) {
MDB.createGlobalObjectSectionPrefix(Prefix));
}
-void GlobalObject::updateSectionPrefix(StringRef Prefix,
+bool GlobalObject::updateSectionPrefix(StringRef Prefix,
std::optional<StringRef> KeepPrefix) {
auto SectionPrefix = getSectionPrefix();
if (SectionPrefix && (*SectionPrefix == Prefix ||
(KeepPrefix && *SectionPrefix == *KeepPrefix)))
- return;
+ return false;
setSectionPrefix(Prefix);
- return;
+ return true;
}
std::optional<StringRef> GlobalObject::getSectionPrefix() const {
More information about the llvm-commits
mailing list