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/Scalar.h"
28 #include "llvm/Transforms/Scalar/SimplifyCFG.h"
29 #include "llvm/Transforms/Utils/SimplifyCFGOptions.h"
30 #include <optional>
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 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,CodeGenOpt::Level 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 CodeGenOpt::Level 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 }
101
createPassConfig(PassManagerBase & PM)102 TargetPassConfig *BPFTargetMachine::createPassConfig(PassManagerBase &PM) {
103 return new BPFPassConfig(*this, PM);
104 }
105
registerPassBuilderCallbacks(PassBuilder & PB)106 void BPFTargetMachine::registerPassBuilderCallbacks(PassBuilder &PB) {
107 PB.registerPipelineStartEPCallback(
108 [=](ModulePassManager &MPM, OptimizationLevel) {
109 FunctionPassManager FPM;
110 FPM.addPass(BPFAbstractMemberAccessPass(this));
111 FPM.addPass(BPFPreserveDITypePass());
112 FPM.addPass(BPFIRPeepholePass());
113 MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
114 });
115 PB.registerPeepholeEPCallback([=](FunctionPassManager &FPM,
116 OptimizationLevel Level) {
117 FPM.addPass(SimplifyCFGPass(SimplifyCFGOptions().hoistCommonInsts(true)));
118 });
119 PB.registerPipelineEarlySimplificationEPCallback(
120 [=](ModulePassManager &MPM, OptimizationLevel) {
121 MPM.addPass(BPFAdjustOptPass());
122 });
123 }
124
addIRPasses()125 void BPFPassConfig::addIRPasses() {
126 addPass(createBPFCheckAndAdjustIR());
127 TargetPassConfig::addIRPasses();
128 }
129
130 TargetTransformInfo
getTargetTransformInfo(const Function & F) const131 BPFTargetMachine::getTargetTransformInfo(const Function &F) const {
132 return TargetTransformInfo(BPFTTIImpl(this, F));
133 }
134
135 // Install an instruction selector pass using
136 // the ISelDag to gen BPF code.
addInstSelector()137 bool BPFPassConfig::addInstSelector() {
138 addPass(createBPFISelDag(getBPFTargetMachine()));
139
140 return false;
141 }
142
addMachineSSAOptimization()143 void BPFPassConfig::addMachineSSAOptimization() {
144 addPass(createBPFMISimplifyPatchablePass());
145
146 // The default implementation must be called first as we want eBPF
147 // Peephole ran at last.
148 TargetPassConfig::addMachineSSAOptimization();
149
150 const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl();
151 if (!DisableMIPeephole) {
152 if (Subtarget->getHasAlu32())
153 addPass(createBPFMIPeepholePass());
154 addPass(createBPFMIPeepholeTruncElimPass());
155 }
156 }
157
addPreEmitPass()158 void BPFPassConfig::addPreEmitPass() {
159 addPass(createBPFMIPreEmitCheckingPass());
160 if (getOptLevel() != CodeGenOpt::None)
161 if (!DisableMIPeephole)
162 addPass(createBPFMIPreEmitPeepholePass());
163 }
164