1 //===-- BPFTargetMachine.cpp - Define TargetMachine for BPF ---------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Implements the info about BPF target spec.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "BPFTargetMachine.h"
14 #include "BPF.h"
15 #include "BPFTargetTransformInfo.h"
16 #include "MCTargetDesc/BPFMCAsmInfo.h"
17 #include "TargetInfo/BPFTargetInfo.h"
18 #include "llvm/CodeGen/GlobalISel/IRTranslator.h"
19 #include "llvm/CodeGen/GlobalISel/InstructionSelect.h"
20 #include "llvm/CodeGen/GlobalISel/Legalizer.h"
21 #include "llvm/CodeGen/GlobalISel/RegBankSelect.h"
22 #include "llvm/CodeGen/Passes.h"
23 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
24 #include "llvm/CodeGen/TargetPassConfig.h"
25 #include "llvm/IR/PassManager.h"
26 #include "llvm/InitializePasses.h"
27 #include "llvm/MC/TargetRegistry.h"
28 #include "llvm/Passes/PassBuilder.h"
29 #include "llvm/Support/FormattedStream.h"
30 #include "llvm/Target/TargetOptions.h"
31 #include "llvm/Transforms/Scalar.h"
32 #include "llvm/Transforms/Scalar/SimplifyCFG.h"
33 #include "llvm/Transforms/Utils/SimplifyCFGOptions.h"
34 #include <optional>
35 using namespace llvm;
36
37 static cl::
38 opt<bool> DisableMIPeephole("disable-bpf-peephole", cl::Hidden,
39 cl::desc("Disable machine peepholes for BPF"));
40
LLVMInitializeBPFTarget()41 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeBPFTarget() {
42 // Register the target.
43 RegisterTargetMachine<BPFTargetMachine> X(getTheBPFleTarget());
44 RegisterTargetMachine<BPFTargetMachine> Y(getTheBPFbeTarget());
45 RegisterTargetMachine<BPFTargetMachine> Z(getTheBPFTarget());
46
47 PassRegistry &PR = *PassRegistry::getPassRegistry();
48 initializeGlobalISel(PR);
49 initializeBPFCheckAndAdjustIRPass(PR);
50 initializeBPFMIPeepholePass(PR);
51 initializeBPFDAGToDAGISelPass(PR);
52 }
53
54 // DataLayout: little or big endian
computeDataLayout(const Triple & TT)55 static std::string computeDataLayout(const Triple &TT) {
56 if (TT.getArch() == Triple::bpfeb)
57 return "E-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
58 else
59 return "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
60 }
61
getEffectiveRelocModel(std::optional<Reloc::Model> RM)62 static Reloc::Model getEffectiveRelocModel(std::optional<Reloc::Model> RM) {
63 return RM.value_or(Reloc::PIC_);
64 }
65
BPFTargetMachine(const Target & T,const Triple & TT,StringRef CPU,StringRef FS,const TargetOptions & Options,std::optional<Reloc::Model> RM,std::optional<CodeModel::Model> CM,CodeGenOptLevel OL,bool JIT)66 BPFTargetMachine::BPFTargetMachine(const Target &T, const Triple &TT,
67 StringRef CPU, StringRef FS,
68 const TargetOptions &Options,
69 std::optional<Reloc::Model> RM,
70 std::optional<CodeModel::Model> CM,
71 CodeGenOptLevel OL, bool JIT)
72 : LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS, Options,
73 getEffectiveRelocModel(RM),
74 getEffectiveCodeModel(CM, CodeModel::Small), OL),
75 TLOF(std::make_unique<TargetLoweringObjectFileELF>()),
76 Subtarget(TT, std::string(CPU), std::string(FS), *this) {
77 initAsmInfo();
78
79 BPFMCAsmInfo *MAI =
80 static_cast<BPFMCAsmInfo *>(const_cast<MCAsmInfo *>(AsmInfo.get()));
81 MAI->setDwarfUsesRelocationsAcrossSections(!Subtarget.getUseDwarfRIS());
82 }
83
84 namespace {
85 // BPF Code Generator Pass Configuration Options.
86 class BPFPassConfig : public TargetPassConfig {
87 public:
BPFPassConfig(BPFTargetMachine & TM,PassManagerBase & PM)88 BPFPassConfig(BPFTargetMachine &TM, PassManagerBase &PM)
89 : TargetPassConfig(TM, PM) {}
90
getBPFTargetMachine() const91 BPFTargetMachine &getBPFTargetMachine() const {
92 return getTM<BPFTargetMachine>();
93 }
94
95 void addIRPasses() override;
96 bool addInstSelector() override;
97 void addMachineSSAOptimization() override;
98 void addPreEmitPass() override;
99
100 bool addIRTranslator() override;
101 bool addLegalizeMachineIR() override;
102 bool addRegBankSelect() override;
103 bool addGlobalInstructionSelect() override;
104 };
105 }
106
createPassConfig(PassManagerBase & PM)107 TargetPassConfig *BPFTargetMachine::createPassConfig(PassManagerBase &PM) {
108 return new BPFPassConfig(*this, PM);
109 }
110
registerPassBuilderCallbacks(PassBuilder & PB,bool PopulateClassToPassNames)111 void BPFTargetMachine::registerPassBuilderCallbacks(
112 PassBuilder &PB, bool PopulateClassToPassNames) {
113 PB.registerPipelineParsingCallback(
114 [](StringRef PassName, FunctionPassManager &FPM,
115 ArrayRef<PassBuilder::PipelineElement>) {
116 if (PassName == "bpf-ir-peephole") {
117 FPM.addPass(BPFIRPeepholePass());
118 return true;
119 }
120 if (PassName == "bpf-preserve-static-offset") {
121 FPM.addPass(BPFPreserveStaticOffsetPass(false));
122 return true;
123 }
124 return false;
125 });
126 PB.registerPipelineStartEPCallback(
127 [=](ModulePassManager &MPM, OptimizationLevel) {
128 FunctionPassManager FPM;
129 FPM.addPass(BPFPreserveStaticOffsetPass(true));
130 FPM.addPass(BPFAbstractMemberAccessPass(this));
131 FPM.addPass(BPFPreserveDITypePass());
132 FPM.addPass(BPFIRPeepholePass());
133 MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
134 });
135 PB.registerPeepholeEPCallback([=](FunctionPassManager &FPM,
136 OptimizationLevel Level) {
137 FPM.addPass(SimplifyCFGPass(SimplifyCFGOptions().hoistCommonInsts(true)));
138 });
139 PB.registerScalarOptimizerLateEPCallback(
140 [=](FunctionPassManager &FPM, OptimizationLevel Level) {
141 // Run this after loop unrolling but before
142 // SimplifyCFGPass(... .sinkCommonInsts(true))
143 FPM.addPass(BPFPreserveStaticOffsetPass(false));
144 });
145 PB.registerPipelineEarlySimplificationEPCallback(
146 [=](ModulePassManager &MPM, OptimizationLevel) {
147 MPM.addPass(BPFAdjustOptPass());
148 });
149 }
150
addIRPasses()151 void BPFPassConfig::addIRPasses() {
152 addPass(createAtomicExpandPass());
153 addPass(createBPFCheckAndAdjustIR());
154
155 TargetPassConfig::addIRPasses();
156 }
157
158 TargetTransformInfo
getTargetTransformInfo(const Function & F) const159 BPFTargetMachine::getTargetTransformInfo(const Function &F) const {
160 return TargetTransformInfo(BPFTTIImpl(this, F));
161 }
162
163 // Install an instruction selector pass using
164 // the ISelDag to gen BPF code.
addInstSelector()165 bool BPFPassConfig::addInstSelector() {
166 addPass(createBPFISelDag(getBPFTargetMachine()));
167
168 return false;
169 }
170
addMachineSSAOptimization()171 void BPFPassConfig::addMachineSSAOptimization() {
172 addPass(createBPFMISimplifyPatchablePass());
173
174 // The default implementation must be called first as we want eBPF
175 // Peephole ran at last.
176 TargetPassConfig::addMachineSSAOptimization();
177
178 const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl();
179 if (!DisableMIPeephole) {
180 if (Subtarget->getHasAlu32())
181 addPass(createBPFMIPeepholePass());
182 }
183 }
184
addPreEmitPass()185 void BPFPassConfig::addPreEmitPass() {
186 addPass(createBPFMIPreEmitCheckingPass());
187 if (getOptLevel() != CodeGenOptLevel::None)
188 if (!DisableMIPeephole)
189 addPass(createBPFMIPreEmitPeepholePass());
190 }
191
addIRTranslator()192 bool BPFPassConfig::addIRTranslator() {
193 addPass(new IRTranslator());
194 return false;
195 }
196
addLegalizeMachineIR()197 bool BPFPassConfig::addLegalizeMachineIR() {
198 addPass(new Legalizer());
199 return false;
200 }
201
addRegBankSelect()202 bool BPFPassConfig::addRegBankSelect() {
203 addPass(new RegBankSelect());
204 return false;
205 }
206
addGlobalInstructionSelect()207 bool BPFPassConfig::addGlobalInstructionSelect() {
208 addPass(new InstructionSelect(getOptLevel()));
209 return false;
210 }
211