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 initializeBPFDAGToDAGISelLegacyPass(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
parseBPFPreserveStaticOffsetOptions(StringRef Params)111 static Expected<bool> parseBPFPreserveStaticOffsetOptions(StringRef Params) {
112 return PassBuilder::parseSinglePassOption(Params, "allow-partial",
113 "BPFPreserveStaticOffsetPass");
114 }
115
registerPassBuilderCallbacks(PassBuilder & PB)116 void BPFTargetMachine::registerPassBuilderCallbacks(PassBuilder &PB) {
117 #define GET_PASS_REGISTRY "BPFPassRegistry.def"
118 #include "llvm/Passes/TargetPassRegistry.inc"
119
120 PB.registerPipelineStartEPCallback(
121 [=](ModulePassManager &MPM, OptimizationLevel) {
122 FunctionPassManager FPM;
123 FPM.addPass(BPFPreserveStaticOffsetPass(true));
124 FPM.addPass(BPFAbstractMemberAccessPass(this));
125 FPM.addPass(BPFPreserveDITypePass());
126 FPM.addPass(BPFIRPeepholePass());
127 MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
128 });
129 PB.registerPeepholeEPCallback([=](FunctionPassManager &FPM,
130 OptimizationLevel Level) {
131 FPM.addPass(SimplifyCFGPass(SimplifyCFGOptions().hoistCommonInsts(true)));
132 FPM.addPass(BPFASpaceCastSimplifyPass());
133 });
134 PB.registerScalarOptimizerLateEPCallback(
135 [=](FunctionPassManager &FPM, OptimizationLevel Level) {
136 // Run this after loop unrolling but before
137 // SimplifyCFGPass(... .sinkCommonInsts(true))
138 FPM.addPass(BPFPreserveStaticOffsetPass(false));
139 });
140 PB.registerPipelineEarlySimplificationEPCallback(
141 [=](ModulePassManager &MPM, OptimizationLevel) {
142 MPM.addPass(BPFAdjustOptPass());
143 });
144 }
145
addIRPasses()146 void BPFPassConfig::addIRPasses() {
147 addPass(createAtomicExpandLegacyPass());
148 addPass(createBPFCheckAndAdjustIR());
149
150 TargetPassConfig::addIRPasses();
151 }
152
153 TargetTransformInfo
getTargetTransformInfo(const Function & F) const154 BPFTargetMachine::getTargetTransformInfo(const Function &F) const {
155 return TargetTransformInfo(BPFTTIImpl(this, F));
156 }
157
158 // Install an instruction selector pass using
159 // the ISelDag to gen BPF code.
addInstSelector()160 bool BPFPassConfig::addInstSelector() {
161 addPass(createBPFISelDag(getBPFTargetMachine()));
162
163 return false;
164 }
165
addMachineSSAOptimization()166 void BPFPassConfig::addMachineSSAOptimization() {
167 addPass(createBPFMISimplifyPatchablePass());
168
169 // The default implementation must be called first as we want eBPF
170 // Peephole ran at last.
171 TargetPassConfig::addMachineSSAOptimization();
172
173 const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl();
174 if (!DisableMIPeephole) {
175 if (Subtarget->getHasAlu32())
176 addPass(createBPFMIPeepholePass());
177 }
178 }
179
addPreEmitPass()180 void BPFPassConfig::addPreEmitPass() {
181 addPass(createBPFMIPreEmitCheckingPass());
182 if (getOptLevel() != CodeGenOptLevel::None)
183 if (!DisableMIPeephole)
184 addPass(createBPFMIPreEmitPeepholePass());
185 }
186
addIRTranslator()187 bool BPFPassConfig::addIRTranslator() {
188 addPass(new IRTranslator());
189 return false;
190 }
191
addLegalizeMachineIR()192 bool BPFPassConfig::addLegalizeMachineIR() {
193 addPass(new Legalizer());
194 return false;
195 }
196
addRegBankSelect()197 bool BPFPassConfig::addRegBankSelect() {
198 addPass(new RegBankSelect());
199 return false;
200 }
201
addGlobalInstructionSelect()202 bool BPFPassConfig::addGlobalInstructionSelect() {
203 addPass(new InstructionSelect(getOptLevel()));
204 return false;
205 }
206