[llvm] 5e990b0 - [PowerPC][GlobalMerge] Reduce TOC usage by merging internal and private global data (#101224)
via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 14 07:14:36 PDT 2024
Author: Amy Kwan
Date: 2024-08-14T10:14:33-04:00
New Revision: 5e990b0b7f4cf60e6b700ba4f7c76005c0d53086
URL: https://github.com/llvm/llvm-project/commit/5e990b0b7f4cf60e6b700ba4f7c76005c0d53086
DIFF: https://github.com/llvm/llvm-project/commit/5e990b0b7f4cf60e6b700ba4f7c76005c0d53086.diff
LOG: [PowerPC][GlobalMerge] Reduce TOC usage by merging internal and private global data (#101224)
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.
Added:
Modified:
llvm/include/llvm/CodeGen/GlobalMerge.h
llvm/include/llvm/CodeGen/Passes.h
llvm/lib/CodeGen/GlobalMerge.cpp
llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
llvm/test/CodeGen/PowerPC/merge-private.ll
Removed:
################################################################################
diff --git a/llvm/include/llvm/CodeGen/GlobalMerge.h b/llvm/include/llvm/CodeGen/GlobalMerge.h
index 13ad67d4544bc7..1577bcf8903f52 100644
--- a/llvm/include/llvm/CodeGen/GlobalMerge.h
+++ b/llvm/include/llvm/CodeGen/GlobalMerge.h
@@ -28,6 +28,8 @@ struct GlobalMergeOptions {
bool MergeConst = false;
/// Whether we should merge global variables that have external linkage.
bool MergeExternal = true;
+ /// 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 20273d069bf053..c7c2178571215b 100644
--- a/llvm/include/llvm/CodeGen/Passes.h
+++ b/llvm/include/llvm/CodeGen/Passes.h
@@ -476,7 +476,8 @@ namespace llvm {
///
Pass *createGlobalMergePass(const TargetMachine *TM, unsigned MaximalOffset,
bool OnlyOptimizeForSize = false,
- bool MergeExternalByDefault = false);
+ bool MergeExternalByDefault = 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 8aa4345cfd6df6..c31ba6b31ad9ac 100644
--- a/llvm/lib/CodeGen/GlobalMerge.cpp
+++ b/llvm/lib/CodeGen/GlobalMerge.cpp
@@ -196,11 +196,13 @@ class GlobalMerge : public FunctionPass {
}
explicit GlobalMerge(const TargetMachine *TM, unsigned MaximalOffset,
- bool OnlyOptimizeForSize, bool MergeExternalGlobals)
+ bool OnlyOptimizeForSize, bool MergeExternalGlobals,
+ bool MergeConstantGlobals)
: FunctionPass(ID), TM(TM) {
Opt.MaxOffset = MaximalOffset;
Opt.SizeOnly = OnlyOptimizeForSize;
Opt.MergeExternal = MergeExternalGlobals;
+ Opt.MergeConstantGlobals = MergeConstantGlobals;
initializeGlobalMergePass(*PassRegistry::getPassRegistry());
}
@@ -475,7 +477,8 @@ 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 +554,8 @@ 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 +705,11 @@ 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 +720,7 @@ 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 +730,11 @@ bool GlobalMergeImpl::run(Module &M) {
Pass *llvm::createGlobalMergePass(const TargetMachine *TM, unsigned Offset,
bool OnlyOptimizeForSize,
- bool MergeExternalByDefault) {
+ bool MergeExternalByDefault,
+ bool MergeConstantByDefault) {
bool MergeExternal = (EnableGlobalMergeOnExternal == cl::BOU_UNSET) ?
MergeExternalByDefault : (EnableGlobalMergeOnExternal == cl::BOU_TRUE);
- return new GlobalMerge(TM, Offset, OnlyOptimizeForSize, MergeExternal);
+ bool MergeConstant = EnableGlobalMergeOnConst || MergeConstantByDefault;
+ return new GlobalMerge(TM, Offset, OnlyOptimizeForSize, MergeExternal,
+ MergeConstant);
}
diff --git a/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp b/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
index 1ef891d1b677a2..763b6edb1c09fb 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));
+
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 6cf276990d7ea2..6ed2d6dfc542b7 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 at toc@ha
+; LINUX64LE-NEXT: addis r3, r2, .L_MergedGlobals at toc@ha
; LINUX64LE-NEXT: std r0, 64(r1)
-; LINUX64LE-NEXT: addi r30, r3, .L__ModuleStringPool at toc@l
+; LINUX64LE-NEXT: addi r30, r3, .L_MergedGlobals at 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 at toc@ha
+; LINUX64BE-NEXT: addis r3, r2, .L_MergedGlobals at toc@ha
; LINUX64BE-NEXT: std r30, 112(r1) # 8-byte Folded Spill
-; LINUX64BE-NEXT: addi r30, r3, .L__ModuleStringPool at toc@l
+; LINUX64BE-NEXT: addi r30, r3, .L_MergedGlobals at toc@l
; LINUX64BE-NEXT: mr r3, r30
; LINUX64BE-NEXT: bl puts
; LINUX64BE-NEXT: nop
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