https://github.com/amy-kwan updated
https://github.com/llvm/llvm-project/pull/101224
>From 7a0a6ba50edda592bf3acc1b5ae0d8d2272fc8f2 Mon Sep 17 00:00:00 2001
From: Amy Kwan <amy.kw...@ibm.com>
Date: Tue, 30 Jul 2024 12:53:15 -0500
Subject: [PATCH 1/2] [PowerPC][GlobalMerge] Reduce TOC usage by merging
internal and private global data
This patch aims to reduce TOC usage by merging internal and private global data.
Moreover, we also add the GlobalMerge pass within the PPCTargetMachine pipeline,
which is disabled by default. This transformation can be enabled by
-ppc-global-merge.
---
llvm/include/llvm/CodeGen/GlobalMerge.h | 4 +++
llvm/include/llvm/CodeGen/Passes.h | 4 ++-
llvm/lib/CodeGen/GlobalMerge.cpp | 27 ++++++++++++++++----
llvm/lib/Target/PowerPC/PPCTargetMachine.cpp | 13 ++++++++++
llvm/test/CodeGen/PowerPC/merge-private.ll | 20 +++++++--------
5 files changed, 52 insertions(+), 16 deletions(-)
diff --git a/llvm/include/llvm/CodeGen/GlobalMerge.h
b/llvm/include/llvm/CodeGen/GlobalMerge.h
index 13ad67d4544bc..ef767d548dc6e 100644
--- a/llvm/include/llvm/CodeGen/GlobalMerge.h
+++ b/llvm/include/llvm/CodeGen/GlobalMerge.h
@@ -28,6 +28,10 @@ struct GlobalMergeOptions {
bool MergeConst = false;
/// Whether we should merge global variables that have external linkage.
bool MergeExternal = true;
+ /// Whether we should merge global variables that have private linkage.
+ bool MergePrivateGlobals = false;
+ /// Whether we should merge constant global variables.
+ bool MergeConstantGlobals = false;
/// Whether we should try to optimize for size only.
/// Currently, this applies a dead simple heuristic: only consider globals
/// used in minsize functions for merging.
diff --git a/llvm/include/llvm/CodeGen/Passes.h
b/llvm/include/llvm/CodeGen/Passes.h
index cafb9781698a2..b401a8d9f10fd 100644
--- a/llvm/include/llvm/CodeGen/Passes.h
+++ b/llvm/include/llvm/CodeGen/Passes.h
@@ -476,7 +476,9 @@ namespace llvm {
///
Pass *createGlobalMergePass(const TargetMachine *TM, unsigned MaximalOffset,
bool OnlyOptimizeForSize = false,
- bool MergeExternalByDefault = false);
+ bool MergeExternalByDefault = false,
+ bool MergePrivateByDefault = false,
+ bool MergeConstantByDefault = false);
/// This pass splits the stack into a safe stack and an unsafe stack to
/// protect against stack-based overflow vulnerabilities.
diff --git a/llvm/lib/CodeGen/GlobalMerge.cpp b/llvm/lib/CodeGen/GlobalMerge.cpp
index 8aa4345cfd6df..46bda37ea45a5 100644
--- a/llvm/lib/CodeGen/GlobalMerge.cpp
+++ b/llvm/lib/CodeGen/GlobalMerge.cpp
@@ -196,11 +196,14 @@ class GlobalMerge : public FunctionPass {
}
explicit GlobalMerge(const TargetMachine *TM, unsigned MaximalOffset,
- bool OnlyOptimizeForSize, bool MergeExternalGlobals)
+ bool OnlyOptimizeForSize, bool MergeExternalGlobals,
+ bool MergePrivateGlobals, bool MergeConstantGlobals)
: FunctionPass(ID), TM(TM) {
Opt.MaxOffset = MaximalOffset;
Opt.SizeOnly = OnlyOptimizeForSize;
Opt.MergeExternal = MergeExternalGlobals;
+ Opt.MergePrivateGlobals = MergePrivateGlobals;
+ Opt.MergeConstantGlobals = MergeConstantGlobals;
initializeGlobalMergePass(*PassRegistry::getPassRegistry());
}
@@ -475,7 +478,8 @@ bool GlobalMergeImpl::doMerge(const
SmallVectorImpl<GlobalVariable *> &Globals,
auto &DL = M.getDataLayout();
LLVM_DEBUG(dbgs() << " Trying to merge set, starts with #"
- << GlobalSet.find_first() << "\n");
+ << GlobalSet.find_first() << ", total of " <<
Globals.size()
+ << "\n");
bool Changed = false;
ssize_t i = GlobalSet.find_first();
@@ -551,6 +555,8 @@ bool GlobalMergeImpl::doMerge(const
SmallVectorImpl<GlobalVariable *> &Globals,
MergedGV->setAlignment(MaxAlign);
MergedGV->setSection(Globals[i]->getSection());
+ LLVM_DEBUG(dbgs() << "MergedGV: " << *MergedGV << "\n");
+
const StructLayout *MergedLayout = DL.getStructLayout(MergedTy);
for (ssize_t k = i, idx = 0; k != j; k = GlobalSet.find_next(k), ++idx) {
GlobalValue::LinkageTypes Linkage = Globals[k]->getLinkage();
@@ -700,6 +706,11 @@ bool GlobalMergeImpl::run(Module &M) {
else
Globals[{AddressSpace, Section}].push_back(&GV);
}
+ LLVM_DEBUG(dbgs() << "GV "
+ << ((DL.getTypeAllocSize(Ty) < Opt.MaxOffset)
+ ? "to merge: "
+ : "not to merge: ")
+ << GV << "\n");
}
for (auto &P : Globals)
@@ -710,7 +721,7 @@ bool GlobalMergeImpl::run(Module &M) {
if (P.second.size() > 1)
Changed |= doMerge(P.second, M, false, P.first.first);
- if (EnableGlobalMergeOnConst)
+ if (Opt.MergeConstantGlobals)
for (auto &P : ConstGlobals)
if (P.second.size() > 1)
Changed |= doMerge(P.second, M, true, P.first.first);
@@ -720,8 +731,14 @@ bool GlobalMergeImpl::run(Module &M) {
Pass *llvm::createGlobalMergePass(const TargetMachine *TM, unsigned Offset,
bool OnlyOptimizeForSize,
- bool MergeExternalByDefault) {
+ bool MergeExternalByDefault,
+ bool MergePrivateByDefault,
+ bool MergeConstantByDefault) {
bool MergeExternal = (EnableGlobalMergeOnExternal == cl::BOU_UNSET) ?
MergeExternalByDefault : (EnableGlobalMergeOnExternal == cl::BOU_TRUE);
- return new GlobalMerge(TM, Offset, OnlyOptimizeForSize, MergeExternal);
+ bool MergeConstant = EnableGlobalMergeOnConst.getNumOccurrences() > 0
+ ? EnableGlobalMergeOnConst
+ : MergeConstantByDefault;
+ return new GlobalMerge(TM, Offset, OnlyOptimizeForSize, MergeExternal,
+ MergePrivateByDefault, MergeConstant);
}
diff --git a/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
b/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
index 1ef891d1b677a..e4045ec304435 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
+++ b/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
@@ -111,6 +111,15 @@ static cl::opt<bool> EnablePPCGenScalarMASSEntries(
"(scalar) entries"),
cl::Hidden);
+static cl::opt<bool>
+ EnableGlobalMerge("ppc-global-merge", cl::Hidden, cl::init(false),
+ cl::desc("Enable the global merge pass"));
+
+static cl::opt<unsigned>
+ GlobalMergeMaxOffset("ppc-global-merge-max-offset", cl::Hidden,
+ cl::init(0x7fff),
+ cl::desc("Maximum global merge offset"));
+
extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializePowerPCTarget() {
// Register the targets
RegisterTargetMachine<PPCTargetMachine> A(getThePPC32Target());
@@ -491,6 +500,10 @@ void PPCPassConfig::addIRPasses() {
}
bool PPCPassConfig::addPreISel() {
+ if (EnableGlobalMerge)
+ addPass(createGlobalMergePass(TM, GlobalMergeMaxOffset, false, false, true,
+ true));
+
if (MergeStringPool && getOptLevel() != CodeGenOptLevel::None)
addPass(createPPCMergeStringPoolPass());
diff --git a/llvm/test/CodeGen/PowerPC/merge-private.ll
b/llvm/test/CodeGen/PowerPC/merge-private.ll
index 6cf276990d7ea..6ed2d6dfc542b 100644
--- a/llvm/test/CodeGen/PowerPC/merge-private.ll
+++ b/llvm/test/CodeGen/PowerPC/merge-private.ll
@@ -1,15 +1,15 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
UTC_ARGS: --version 5
; RUN: llc -verify-machineinstrs -mtriple powerpc64-ibm-aix-xcoff -mcpu=pwr8 \
-; RUN: -ppc-asm-full-reg-names < %s | FileCheck %s \
+; RUN: -ppc-asm-full-reg-names -ppc-global-merge=true < %s | FileCheck %s \
; RUN: --check-prefix=AIX64
; RUN: llc -verify-machineinstrs -mtriple powerpc-ibm-aix-xcoff -mcpu=pwr8 \
-; RUN: -ppc-asm-full-reg-names < %s | FileCheck %s \
+; RUN: -ppc-asm-full-reg-names -ppc-global-merge=true < %s | FileCheck %s \
; RUN: --check-prefix=AIX32
; RUN: llc -verify-machineinstrs -mtriple powerpc64le-unknown-linux -mcpu=pwr8
\
-; RUN: -ppc-asm-full-reg-names < %s | FileCheck %s \
+; RUN: -ppc-asm-full-reg-names -ppc-global-merge=true < %s | FileCheck %s \
; RUN: --check-prefix=LINUX64LE
; RUN: llc -verify-machineinstrs -mtriple powerpc64-unknown-linux -mcpu=pwr8 \
-; RUN: -ppc-asm-full-reg-names < %s | FileCheck %s \
+; RUN: -ppc-asm-full-reg-names -ppc-global-merge=true < %s | FileCheck %s \
; RUN: --check-prefix=LINUX64BE
@.str = private unnamed_addr constant [15 x i8] c"Private global\00", align 1
@@ -24,7 +24,7 @@ define dso_local void @print_func() {
; AIX64-NEXT: stdu r1, -128(r1)
; AIX64-NEXT: std r0, 144(r1)
; AIX64-NEXT: std r31, 120(r1) # 8-byte Folded Spill
-; AIX64-NEXT: ld r31, L..C0(r2) # @__ModuleStringPool
+; AIX64-NEXT: ld r31, L..C0(r2) # @_MergedGlobals
; AIX64-NEXT: mr r3, r31
; AIX64-NEXT: bl .puts[PR]
; AIX64-NEXT: nop
@@ -43,7 +43,7 @@ define dso_local void @print_func() {
; AIX32-NEXT: stwu r1, -64(r1)
; AIX32-NEXT: stw r0, 72(r1)
; AIX32-NEXT: stw r31, 60(r1) # 4-byte Folded Spill
-; AIX32-NEXT: lwz r31, L..C0(r2) # @__ModuleStringPool
+; AIX32-NEXT: lwz r31, L..C0(r2) # @_MergedGlobals
; AIX32-NEXT: mr r3, r31
; AIX32-NEXT: bl .puts[PR]
; AIX32-NEXT: nop
@@ -64,9 +64,9 @@ define dso_local void @print_func() {
; LINUX64LE-NEXT: .cfi_offset r30, -16
; LINUX64LE-NEXT: std r30, -16(r1) # 8-byte Folded Spill
; LINUX64LE-NEXT: stdu r1, -48(r1)
-; LINUX64LE-NEXT: addis r3, r2, .L__ModuleStringPool@toc@ha
+; LINUX64LE-NEXT: addis r3, r2, .L_MergedGlobals@toc@ha
; LINUX64LE-NEXT: std r0, 64(r1)
-; LINUX64LE-NEXT: addi r30, r3, .L__ModuleStringPool@toc@l
+; LINUX64LE-NEXT: addi r30, r3, .L_MergedGlobals@toc@l
; LINUX64LE-NEXT: mr r3, r30
; LINUX64LE-NEXT: bl puts
; LINUX64LE-NEXT: nop
@@ -87,9 +87,9 @@ define dso_local void @print_func() {
; LINUX64BE-NEXT: .cfi_def_cfa_offset 128
; LINUX64BE-NEXT: .cfi_offset lr, 16
; LINUX64BE-NEXT: .cfi_offset r30, -16
-; LINUX64BE-NEXT: addis r3, r2, .L__ModuleStringPool@toc@ha
+; LINUX64BE-NEXT: addis r3, r2, .L_MergedGlobals@toc@ha
; LINUX64BE-NEXT: std r30, 112(r1) # 8-byte Folded Spill
-; LINUX64BE-NEXT: addi r30, r3, .L__ModuleStringPool@toc@l
+; LINUX64BE-NEXT: addi r30, r3, .L_MergedGlobals@toc@l
; LINUX64BE-NEXT: mr r3, r30
; LINUX64BE-NEXT: bl puts
; LINUX64BE-NEXT: nop
>From d14bd7c6adb86f5fbd75591d480aa50f5feb3c96 Mon Sep 17 00:00:00 2001
From: Amy Kwan <amy.kw...@ibm.com>
Date: Thu, 1 Aug 2024 12:58:44 -0500
Subject: [PATCH 2/2] Remove unused MergePrivateGlobals
---
llvm/include/llvm/CodeGen/GlobalMerge.h | 2 --
llvm/include/llvm/CodeGen/Passes.h | 1 -
llvm/lib/CodeGen/GlobalMerge.cpp | 10 +++-------
llvm/lib/Target/PowerPC/PPCTargetMachine.cpp | 2 +-
4 files changed, 4 insertions(+), 11 deletions(-)
diff --git a/llvm/include/llvm/CodeGen/GlobalMerge.h
b/llvm/include/llvm/CodeGen/GlobalMerge.h
index ef767d548dc6e..1577bcf8903f5 100644
--- a/llvm/include/llvm/CodeGen/GlobalMerge.h
+++ b/llvm/include/llvm/CodeGen/GlobalMerge.h
@@ -28,8 +28,6 @@ struct GlobalMergeOptions {
bool MergeConst = false;
/// Whether we should merge global variables that have external linkage.
bool MergeExternal = true;
- /// Whether we should merge global variables that have private linkage.
- bool MergePrivateGlobals = false;
/// Whether we should merge constant global variables.
bool MergeConstantGlobals = false;
/// Whether we should try to optimize for size only.
diff --git a/llvm/include/llvm/CodeGen/Passes.h
b/llvm/include/llvm/CodeGen/Passes.h
index b401a8d9f10fd..597bfbe69be23 100644
--- a/llvm/include/llvm/CodeGen/Passes.h
+++ b/llvm/include/llvm/CodeGen/Passes.h
@@ -477,7 +477,6 @@ namespace llvm {
Pass *createGlobalMergePass(const TargetMachine *TM, unsigned MaximalOffset,
bool OnlyOptimizeForSize = false,
bool MergeExternalByDefault = false,
- bool MergePrivateByDefault = false,
bool MergeConstantByDefault = false);
/// This pass splits the stack into a safe stack and an unsafe stack to
diff --git a/llvm/lib/CodeGen/GlobalMerge.cpp b/llvm/lib/CodeGen/GlobalMerge.cpp
index 46bda37ea45a5..c31ba6b31ad9a 100644
--- a/llvm/lib/CodeGen/GlobalMerge.cpp
+++ b/llvm/lib/CodeGen/GlobalMerge.cpp
@@ -197,12 +197,11 @@ class GlobalMerge : public FunctionPass {
explicit GlobalMerge(const TargetMachine *TM, unsigned MaximalOffset,
bool OnlyOptimizeForSize, bool MergeExternalGlobals,
- bool MergePrivateGlobals, bool MergeConstantGlobals)
+ bool MergeConstantGlobals)
: FunctionPass(ID), TM(TM) {
Opt.MaxOffset = MaximalOffset;
Opt.SizeOnly = OnlyOptimizeForSize;
Opt.MergeExternal = MergeExternalGlobals;
- Opt.MergePrivateGlobals = MergePrivateGlobals;
Opt.MergeConstantGlobals = MergeConstantGlobals;
initializeGlobalMergePass(*PassRegistry::getPassRegistry());
}
@@ -732,13 +731,10 @@ bool GlobalMergeImpl::run(Module &M) {
Pass *llvm::createGlobalMergePass(const TargetMachine *TM, unsigned Offset,
bool OnlyOptimizeForSize,
bool MergeExternalByDefault,
- bool MergePrivateByDefault,
bool MergeConstantByDefault) {
bool MergeExternal = (EnableGlobalMergeOnExternal == cl::BOU_UNSET) ?
MergeExternalByDefault : (EnableGlobalMergeOnExternal == cl::BOU_TRUE);
- bool MergeConstant = EnableGlobalMergeOnConst.getNumOccurrences() > 0
- ? EnableGlobalMergeOnConst
- : MergeConstantByDefault;
+ bool MergeConstant = EnableGlobalMergeOnConst || MergeConstantByDefault;
return new GlobalMerge(TM, Offset, OnlyOptimizeForSize, MergeExternal,
- MergePrivateByDefault, MergeConstant);
+ MergeConstant);
}
diff --git a/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
b/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
index e4045ec304435..6a50223048281 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
+++ b/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
@@ -501,7 +501,7 @@ void PPCPassConfig::addIRPasses() {
bool PPCPassConfig::addPreISel() {
if (EnableGlobalMerge)
- addPass(createGlobalMergePass(TM, GlobalMergeMaxOffset, false, false, true,
+ addPass(createGlobalMergePass(TM, GlobalMergeMaxOffset, false, false,
true));
if (MergeStringPool && getOptLevel() != CodeGenOptLevel::None)
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