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/Passes.h"
19 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
20 #include "llvm/CodeGen/TargetPassConfig.h"
21 #include "llvm/IR/LegacyPassManager.h"
22 #include "llvm/IR/PassManager.h"
23 #include "llvm/MC/TargetRegistry.h"
24 #include "llvm/Passes/PassBuilder.h"
25 #include "llvm/Support/FormattedStream.h"
26 #include "llvm/Target/TargetOptions.h"
27 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
28 #include "llvm/Transforms/Scalar.h"
29 #include "llvm/Transforms/Scalar/SimplifyCFG.h"
30 #include "llvm/Transforms/Utils/SimplifyCFGOptions.h"
31 using namespace llvm;
32
33 static cl::
34 opt<bool> DisableMIPeephole("disable-bpf-peephole", cl::Hidden,
35 cl::desc("Disable machine peepholes for BPF"));
36
LLVMInitializeBPFTarget()37 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeBPFTarget() {
38 // Register the target.
39 RegisterTargetMachine<BPFTargetMachine> X(getTheBPFleTarget());
40 RegisterTargetMachine<BPFTargetMachine> Y(getTheBPFbeTarget());
41 RegisterTargetMachine<BPFTargetMachine> Z(getTheBPFTarget());
42
43 PassRegistry &PR = *PassRegistry::getPassRegistry();
44 initializeBPFAbstractMemberAccessLegacyPassPass(PR);
45 initializeBPFPreserveDITypePass(PR);
46 initializeBPFIRPeepholePass(PR);
47 initializeBPFAdjustOptPass(PR);
48 initializeBPFCheckAndAdjustIRPass(PR);
49 initializeBPFMIPeepholePass(PR);
50 initializeBPFMIPeepholeTruncElimPass(PR);
51 }
52
53 // DataLayout: little or big endian
computeDataLayout(const Triple & TT)54 static std::string computeDataLayout(const Triple &TT) {
55 if (TT.getArch() == Triple::bpfeb)
56 return "E-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
57 else
58 return "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
59 }
60
getEffectiveRelocModel(Optional<Reloc::Model> RM)61 static Reloc::Model getEffectiveRelocModel(Optional<Reloc::Model> RM) {
62 return RM.value_or(Reloc::PIC_);
63 }
64
BPFTargetMachine(const Target & T,const Triple & TT,StringRef CPU,StringRef FS,const TargetOptions & Options,Optional<Reloc::Model> RM,Optional<CodeModel::Model> CM,CodeGenOpt::Level OL,bool JIT)65 BPFTargetMachine::BPFTargetMachine(const Target &T, const Triple &TT,
66 StringRef CPU, StringRef FS,
67 const TargetOptions &Options,
68 Optional<Reloc::Model> RM,
69 Optional<CodeModel::Model> CM,
70 CodeGenOpt::Level OL, bool JIT)
71 : LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS, Options,
72 getEffectiveRelocModel(RM),
73 getEffectiveCodeModel(CM, CodeModel::Small), OL),
74 TLOF(std::make_unique<TargetLoweringObjectFileELF>()),
75 Subtarget(TT, std::string(CPU), std::string(FS), *this) {
76 initAsmInfo();
77
78 BPFMCAsmInfo *MAI =
79 static_cast<BPFMCAsmInfo *>(const_cast<MCAsmInfo *>(AsmInfo.get()));
80 MAI->setDwarfUsesRelocationsAcrossSections(!Subtarget.getUseDwarfRIS());
81 }
82
83 namespace {
84 // BPF Code Generator Pass Configuration Options.
85 class BPFPassConfig : public TargetPassConfig {
86 public:
BPFPassConfig(BPFTargetMachine & TM,PassManagerBase & PM)87 BPFPassConfig(BPFTargetMachine &TM, PassManagerBase &PM)
88 : TargetPassConfig(TM, PM) {}
89
getBPFTargetMachine() const90 BPFTargetMachine &getBPFTargetMachine() const {
91 return getTM<BPFTargetMachine>();
92 }
93
94 void addIRPasses() override;
95 bool addInstSelector() override;
96 void addMachineSSAOptimization() override;
97 void addPreEmitPass() override;
98 };
99 }
100
createPassConfig(PassManagerBase & PM)101 TargetPassConfig *BPFTargetMachine::createPassConfig(PassManagerBase &PM) {
102 return new BPFPassConfig(*this, PM);
103 }
104
adjustPassManager(PassManagerBuilder & Builder)105 void BPFTargetMachine::adjustPassManager(PassManagerBuilder &Builder) {
106 Builder.addExtension(
107 PassManagerBuilder::EP_EarlyAsPossible,
108 [&](const PassManagerBuilder &, legacy::PassManagerBase &PM) {
109 PM.add(createBPFAbstractMemberAccess(this));
110 PM.add(createBPFPreserveDIType());
111 PM.add(createBPFIRPeephole());
112 });
113
114 Builder.addExtension(
115 PassManagerBuilder::EP_Peephole,
116 [&](const PassManagerBuilder &, legacy::PassManagerBase &PM) {
117 PM.add(createCFGSimplificationPass(
118 SimplifyCFGOptions().hoistCommonInsts(true)));
119 });
120 Builder.addExtension(
121 PassManagerBuilder::EP_ModuleOptimizerEarly,
122 [&](const PassManagerBuilder &, legacy::PassManagerBase &PM) {
123 PM.add(createBPFAdjustOpt());
124 });
125 }
126
registerPassBuilderCallbacks(PassBuilder & PB)127 void BPFTargetMachine::registerPassBuilderCallbacks(PassBuilder &PB) {
128 PB.registerPipelineStartEPCallback(
129 [=](ModulePassManager &MPM, OptimizationLevel) {
130 FunctionPassManager FPM;
131 FPM.addPass(BPFAbstractMemberAccessPass(this));
132 FPM.addPass(BPFPreserveDITypePass());
133 FPM.addPass(BPFIRPeepholePass());
134 MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
135 });
136 PB.registerPeepholeEPCallback([=](FunctionPassManager &FPM,
137 OptimizationLevel Level) {
138 FPM.addPass(SimplifyCFGPass(SimplifyCFGOptions().hoistCommonInsts(true)));
139 });
140 PB.registerPipelineEarlySimplificationEPCallback(
141 [=](ModulePassManager &MPM, OptimizationLevel) {
142 MPM.addPass(BPFAdjustOptPass());
143 });
144 }
145
addIRPasses()146 void BPFPassConfig::addIRPasses() {
147 addPass(createBPFCheckAndAdjustIR());
148 TargetPassConfig::addIRPasses();
149 }
150
151 TargetTransformInfo
getTargetTransformInfo(const Function & F) const152 BPFTargetMachine::getTargetTransformInfo(const Function &F) const {
153 return TargetTransformInfo(BPFTTIImpl(this, F));
154 }
155
156 // Install an instruction selector pass using
157 // the ISelDag to gen BPF code.
addInstSelector()158 bool BPFPassConfig::addInstSelector() {
159 addPass(createBPFISelDag(getBPFTargetMachine()));
160
161 return false;
162 }
163
addMachineSSAOptimization()164 void BPFPassConfig::addMachineSSAOptimization() {
165 addPass(createBPFMISimplifyPatchablePass());
166
167 // The default implementation must be called first as we want eBPF
168 // Peephole ran at last.
169 TargetPassConfig::addMachineSSAOptimization();
170
171 const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl();
172 if (!DisableMIPeephole) {
173 if (Subtarget->getHasAlu32())
174 addPass(createBPFMIPeepholePass());
175 addPass(createBPFMIPeepholeTruncElimPass());
176 }
177 }
178
addPreEmitPass()179 void BPFPassConfig::addPreEmitPass() {
180 addPass(createBPFMIPreEmitCheckingPass());
181 if (getOptLevel() != CodeGenOpt::None)
182 if (!DisableMIPeephole)
183 addPass(createBPFMIPreEmitPeepholePass());
184 }
185