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 "MCTargetDesc/BPFMCAsmInfo.h"
16 #include "TargetInfo/BPFTargetInfo.h"
17 #include "llvm/CodeGen/Passes.h"
18 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
19 #include "llvm/CodeGen/TargetPassConfig.h"
20 #include "llvm/IR/LegacyPassManager.h"
21 #include "llvm/Support/FormattedStream.h"
22 #include "llvm/Support/TargetRegistry.h"
23 #include "llvm/Target/TargetOptions.h"
24 using namespace llvm;
25
26 static cl::
27 opt<bool> DisableMIPeephole("disable-bpf-peephole", cl::Hidden,
28 cl::desc("Disable machine peepholes for BPF"));
29
LLVMInitializeBPFTarget()30 extern "C" void LLVMInitializeBPFTarget() {
31 // Register the target.
32 RegisterTargetMachine<BPFTargetMachine> X(getTheBPFleTarget());
33 RegisterTargetMachine<BPFTargetMachine> Y(getTheBPFbeTarget());
34 RegisterTargetMachine<BPFTargetMachine> Z(getTheBPFTarget());
35
36 PassRegistry &PR = *PassRegistry::getPassRegistry();
37 initializeBPFAbstractMemberAccessPass(PR);
38 initializeBPFMIPeepholePass(PR);
39 }
40
41 // DataLayout: little or big endian
computeDataLayout(const Triple & TT)42 static std::string computeDataLayout(const Triple &TT) {
43 if (TT.getArch() == Triple::bpfeb)
44 return "E-m:e-p:64:64-i64:64-n32:64-S128";
45 else
46 return "e-m:e-p:64:64-i64:64-n32:64-S128";
47 }
48
getEffectiveRelocModel(Optional<Reloc::Model> RM)49 static Reloc::Model getEffectiveRelocModel(Optional<Reloc::Model> RM) {
50 if (!RM.hasValue())
51 return Reloc::PIC_;
52 return *RM;
53 }
54
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)55 BPFTargetMachine::BPFTargetMachine(const Target &T, const Triple &TT,
56 StringRef CPU, StringRef FS,
57 const TargetOptions &Options,
58 Optional<Reloc::Model> RM,
59 Optional<CodeModel::Model> CM,
60 CodeGenOpt::Level OL, bool JIT)
61 : LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS, Options,
62 getEffectiveRelocModel(RM),
63 getEffectiveCodeModel(CM, CodeModel::Small), OL),
64 TLOF(make_unique<TargetLoweringObjectFileELF>()),
65 Subtarget(TT, CPU, FS, *this) {
66 initAsmInfo();
67
68 BPFMCAsmInfo *MAI =
69 static_cast<BPFMCAsmInfo *>(const_cast<MCAsmInfo *>(AsmInfo.get()));
70 MAI->setDwarfUsesRelocationsAcrossSections(!Subtarget.getUseDwarfRIS());
71 }
72
73 namespace {
74 // BPF Code Generator Pass Configuration Options.
75 class BPFPassConfig : public TargetPassConfig {
76 public:
BPFPassConfig(BPFTargetMachine & TM,PassManagerBase & PM)77 BPFPassConfig(BPFTargetMachine &TM, PassManagerBase &PM)
78 : TargetPassConfig(TM, PM) {}
79
getBPFTargetMachine() const80 BPFTargetMachine &getBPFTargetMachine() const {
81 return getTM<BPFTargetMachine>();
82 }
83
84 void addIRPasses() override;
85 bool addInstSelector() override;
86 void addMachineSSAOptimization() override;
87 void addPreEmitPass() override;
88 };
89 }
90
createPassConfig(PassManagerBase & PM)91 TargetPassConfig *BPFTargetMachine::createPassConfig(PassManagerBase &PM) {
92 return new BPFPassConfig(*this, PM);
93 }
94
addIRPasses()95 void BPFPassConfig::addIRPasses() {
96
97 addPass(createBPFAbstractMemberAccess());
98
99 TargetPassConfig::addIRPasses();
100 }
101
102 // Install an instruction selector pass using
103 // the ISelDag to gen BPF code.
addInstSelector()104 bool BPFPassConfig::addInstSelector() {
105 addPass(createBPFISelDag(getBPFTargetMachine()));
106
107 return false;
108 }
109
addMachineSSAOptimization()110 void BPFPassConfig::addMachineSSAOptimization() {
111 addPass(createBPFMISimplifyPatchablePass());
112
113 // The default implementation must be called first as we want eBPF
114 // Peephole ran at last.
115 TargetPassConfig::addMachineSSAOptimization();
116
117 const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl();
118 if (Subtarget->getHasAlu32() && !DisableMIPeephole)
119 addPass(createBPFMIPeepholePass());
120 }
121
addPreEmitPass()122 void BPFPassConfig::addPreEmitPass() {
123 const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl();
124
125 addPass(createBPFMIPreEmitCheckingPass());
126 if (getOptLevel() != CodeGenOpt::None)
127 if (Subtarget->getHasAlu32() && !DisableMIPeephole)
128 addPass(createBPFMIPreEmitPeepholePass());
129 }
130