xref: /freebsd/contrib/llvm-project/llvm/lib/Target/BPF/BPFTargetMachine.cpp (revision 9e5787d2284e187abb5b654d924394a65772e004)
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 
30 extern "C" LLVM_EXTERNAL_VISIBILITY 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   initializeBPFPreserveDITypePass(PR);
39   initializeBPFMIPeepholePass(PR);
40   initializeBPFMIPeepholeTruncElimPass(PR);
41 }
42 
43 // DataLayout: little or big endian
44 static std::string computeDataLayout(const Triple &TT) {
45   if (TT.getArch() == Triple::bpfeb)
46     return "E-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
47   else
48     return "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
49 }
50 
51 static Reloc::Model getEffectiveRelocModel(Optional<Reloc::Model> RM) {
52   if (!RM.hasValue())
53     return Reloc::PIC_;
54   return *RM;
55 }
56 
57 BPFTargetMachine::BPFTargetMachine(const Target &T, const Triple &TT,
58                                    StringRef CPU, StringRef FS,
59                                    const TargetOptions &Options,
60                                    Optional<Reloc::Model> RM,
61                                    Optional<CodeModel::Model> CM,
62                                    CodeGenOpt::Level OL, bool JIT)
63     : LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS, Options,
64                         getEffectiveRelocModel(RM),
65                         getEffectiveCodeModel(CM, CodeModel::Small), OL),
66       TLOF(std::make_unique<TargetLoweringObjectFileELF>()),
67       Subtarget(TT, std::string(CPU), std::string(FS), *this) {
68   initAsmInfo();
69 
70   BPFMCAsmInfo *MAI =
71       static_cast<BPFMCAsmInfo *>(const_cast<MCAsmInfo *>(AsmInfo.get()));
72   MAI->setDwarfUsesRelocationsAcrossSections(!Subtarget.getUseDwarfRIS());
73 }
74 
75 namespace {
76 // BPF Code Generator Pass Configuration Options.
77 class BPFPassConfig : public TargetPassConfig {
78 public:
79   BPFPassConfig(BPFTargetMachine &TM, PassManagerBase &PM)
80       : TargetPassConfig(TM, PM) {}
81 
82   BPFTargetMachine &getBPFTargetMachine() const {
83     return getTM<BPFTargetMachine>();
84   }
85 
86   void addIRPasses() override;
87   bool addInstSelector() override;
88   void addMachineSSAOptimization() override;
89   void addPreEmitPass() override;
90 };
91 }
92 
93 TargetPassConfig *BPFTargetMachine::createPassConfig(PassManagerBase &PM) {
94   return new BPFPassConfig(*this, PM);
95 }
96 
97 void BPFPassConfig::addIRPasses() {
98 
99   addPass(createBPFAbstractMemberAccess(&getBPFTargetMachine()));
100   addPass(createBPFPreserveDIType());
101 
102   TargetPassConfig::addIRPasses();
103 }
104 
105 // Install an instruction selector pass using
106 // the ISelDag to gen BPF code.
107 bool BPFPassConfig::addInstSelector() {
108   addPass(createBPFISelDag(getBPFTargetMachine()));
109 
110   return false;
111 }
112 
113 void BPFPassConfig::addMachineSSAOptimization() {
114   addPass(createBPFMISimplifyPatchablePass());
115 
116   // The default implementation must be called first as we want eBPF
117   // Peephole ran at last.
118   TargetPassConfig::addMachineSSAOptimization();
119 
120   const BPFSubtarget *Subtarget = getBPFTargetMachine().getSubtargetImpl();
121   if (!DisableMIPeephole) {
122     if (Subtarget->getHasAlu32())
123       addPass(createBPFMIPeepholePass());
124     addPass(createBPFMIPeepholeTruncElimPass());
125   }
126 }
127 
128 void BPFPassConfig::addPreEmitPass() {
129   addPass(createBPFMIPreEmitCheckingPass());
130   if (getOptLevel() != CodeGenOpt::None)
131     if (!DisableMIPeephole)
132       addPass(createBPFMIPreEmitPeepholePass());
133 }
134