1 //===-- LLVMTargetMachine.cpp - Implement the LLVMTargetMachine class -----===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the LLVMTargetMachine class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Target/TargetMachine.h"
15 #include "llvm/Analysis/Passes.h"
16 #include "llvm/CodeGen/AsmPrinter.h"
17 #include "llvm/CodeGen/BasicTTIImpl.h"
18 #include "llvm/CodeGen/MachineFunctionAnalysis.h"
19 #include "llvm/CodeGen/MachineModuleInfo.h"
20 #include "llvm/CodeGen/Passes.h"
21 #include "llvm/IR/IRPrintingPasses.h"
22 #include "llvm/IR/LegacyPassManager.h"
23 #include "llvm/IR/Verifier.h"
24 #include "llvm/MC/MCAsmInfo.h"
25 #include "llvm/MC/MCContext.h"
26 #include "llvm/MC/MCInstrInfo.h"
27 #include "llvm/MC/MCStreamer.h"
28 #include "llvm/MC/MCSubtargetInfo.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/ErrorHandling.h"
31 #include "llvm/Support/FormattedStream.h"
32 #include "llvm/Support/TargetRegistry.h"
33 #include "llvm/Target/TargetLoweringObjectFile.h"
34 #include "llvm/Target/TargetOptions.h"
35 #include "llvm/Transforms/Scalar.h"
36 using namespace llvm;
37 
38 // Enable or disable FastISel. Both options are needed, because
39 // FastISel is enabled by default with -fast, and we wish to be
40 // able to enable or disable fast-isel independently from -O0.
41 static cl::opt<cl::boolOrDefault>
42 EnableFastISelOption("fast-isel", cl::Hidden,
43   cl::desc("Enable the \"fast\" instruction selector"));
44 
45 void LLVMTargetMachine::initAsmInfo() {
46   MRI = TheTarget.createMCRegInfo(getTargetTriple().str());
47   MII = TheTarget.createMCInstrInfo();
48   // FIXME: Having an MCSubtargetInfo on the target machine is a hack due
49   // to some backends having subtarget feature dependent module level
50   // code generation. This is similar to the hack in the AsmPrinter for
51   // module level assembly etc.
52   STI = TheTarget.createMCSubtargetInfo(getTargetTriple().str(), getTargetCPU(),
53                                         getTargetFeatureString());
54 
55   MCAsmInfo *TmpAsmInfo =
56       TheTarget.createMCAsmInfo(*MRI, getTargetTriple().str());
57   // TargetSelect.h moved to a different directory between LLVM 2.9 and 3.0,
58   // and if the old one gets included then MCAsmInfo will be NULL and
59   // we'll crash later.
60   // Provide the user with a useful error message about what's wrong.
61   assert(TmpAsmInfo && "MCAsmInfo not initialized. "
62          "Make sure you include the correct TargetSelect.h"
63          "and that InitializeAllTargetMCs() is being invoked!");
64 
65   if (Options.DisableIntegratedAS)
66     TmpAsmInfo->setUseIntegratedAssembler(false);
67 
68   if (Options.CompressDebugSections)
69     TmpAsmInfo->setCompressDebugSections(true);
70 
71   AsmInfo = TmpAsmInfo;
72 }
73 
74 LLVMTargetMachine::LLVMTargetMachine(const Target &T,
75                                      StringRef DataLayoutString,
76                                      const Triple &TT, StringRef CPU,
77                                      StringRef FS, TargetOptions Options,
78                                      Reloc::Model RM, CodeModel::Model CM,
79                                      CodeGenOpt::Level OL)
80     : TargetMachine(T, DataLayoutString, TT, CPU, FS, Options) {
81   CodeGenInfo = T.createMCCodeGenInfo(TT.str(), RM, CM, OL);
82 }
83 
84 TargetIRAnalysis LLVMTargetMachine::getTargetIRAnalysis() {
85   return TargetIRAnalysis([this](const Function &F) {
86     return TargetTransformInfo(BasicTTIImpl(this, F));
87   });
88 }
89 
90 /// addPassesToX helper drives creation and initialization of TargetPassConfig.
91 static MCContext *
92 addPassesToGenerateCode(LLVMTargetMachine *TM, PassManagerBase &PM,
93                         bool DisableVerify, AnalysisID StartBefore,
94                         AnalysisID StartAfter, AnalysisID StopAfter,
95                         MachineFunctionInitializer *MFInitializer = nullptr) {
96 
97   // Add internal analysis passes from the target machine.
98   PM.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
99 
100   // Targets may override createPassConfig to provide a target-specific
101   // subclass.
102   TargetPassConfig *PassConfig = TM->createPassConfig(PM);
103   PassConfig->setStartStopPasses(StartBefore, StartAfter, StopAfter);
104 
105   // Set PassConfig options provided by TargetMachine.
106   PassConfig->setDisableVerify(DisableVerify);
107 
108   PM.add(PassConfig);
109 
110   PassConfig->addIRPasses();
111 
112   PassConfig->addCodeGenPrepare();
113 
114   PassConfig->addPassesToHandleExceptions();
115 
116   PassConfig->addISelPrepare();
117 
118   // Install a MachineModuleInfo class, which is an immutable pass that holds
119   // all the per-module stuff we're generating, including MCContext.
120   MachineModuleInfo *MMI = new MachineModuleInfo(
121       *TM->getMCAsmInfo(), *TM->getMCRegisterInfo(), TM->getObjFileLowering());
122   PM.add(MMI);
123 
124   // Set up a MachineFunction for the rest of CodeGen to work on.
125   PM.add(new MachineFunctionAnalysis(*TM, MFInitializer));
126 
127   // Enable FastISel with -fast, but allow that to be overridden.
128   TM->setO0WantsFastISel(EnableFastISelOption != cl::BOU_FALSE);
129   if (EnableFastISelOption == cl::BOU_TRUE ||
130       (TM->getOptLevel() == CodeGenOpt::None &&
131        TM->getO0WantsFastISel()))
132     TM->setFastISel(true);
133 
134   // Ask the target for an isel.
135   if (PassConfig->addInstSelector())
136     return nullptr;
137 
138   PassConfig->addMachinePasses();
139 
140   PassConfig->setInitialized();
141 
142   return &MMI->getContext();
143 }
144 
145 bool LLVMTargetMachine::addPassesToEmitFile(
146     PassManagerBase &PM, raw_pwrite_stream &Out, CodeGenFileType FileType,
147     bool DisableVerify, AnalysisID StartBefore, AnalysisID StartAfter,
148     AnalysisID StopAfter, MachineFunctionInitializer *MFInitializer) {
149   // Add common CodeGen passes.
150   MCContext *Context =
151       addPassesToGenerateCode(this, PM, DisableVerify, StartBefore, StartAfter,
152                               StopAfter, MFInitializer);
153   if (!Context)
154     return true;
155 
156   if (StopAfter) {
157     PM.add(createPrintMIRPass(outs()));
158     return false;
159   }
160 
161   if (Options.MCOptions.MCSaveTempLabels)
162     Context->setAllowTemporaryLabels(false);
163 
164   const MCSubtargetInfo &STI = *getMCSubtargetInfo();
165   const MCAsmInfo &MAI = *getMCAsmInfo();
166   const MCRegisterInfo &MRI = *getMCRegisterInfo();
167   const MCInstrInfo &MII = *getMCInstrInfo();
168 
169   std::unique_ptr<MCStreamer> AsmStreamer;
170 
171   switch (FileType) {
172   case CGFT_AssemblyFile: {
173     MCInstPrinter *InstPrinter = getTarget().createMCInstPrinter(
174         getTargetTriple(), MAI.getAssemblerDialect(), MAI, MII, MRI);
175 
176     // Create a code emitter if asked to show the encoding.
177     MCCodeEmitter *MCE = nullptr;
178     if (Options.MCOptions.ShowMCEncoding)
179       MCE = getTarget().createMCCodeEmitter(MII, MRI, *Context);
180 
181     MCAsmBackend *MAB =
182         getTarget().createMCAsmBackend(MRI, getTargetTriple().str(), TargetCPU);
183     auto FOut = llvm::make_unique<formatted_raw_ostream>(Out);
184     MCStreamer *S = getTarget().createAsmStreamer(
185         *Context, std::move(FOut), Options.MCOptions.AsmVerbose,
186         Options.MCOptions.MCUseDwarfDirectory, InstPrinter, MCE, MAB,
187         Options.MCOptions.ShowMCInst);
188     AsmStreamer.reset(S);
189     break;
190   }
191   case CGFT_ObjectFile: {
192     // Create the code emitter for the target if it exists.  If not, .o file
193     // emission fails.
194     MCCodeEmitter *MCE = getTarget().createMCCodeEmitter(MII, MRI, *Context);
195     MCAsmBackend *MAB =
196         getTarget().createMCAsmBackend(MRI, getTargetTriple().str(), TargetCPU);
197     if (!MCE || !MAB)
198       return true;
199 
200     // Don't waste memory on names of temp labels.
201     Context->setUseNamesOnTempLabels(false);
202 
203     Triple T(getTargetTriple().str());
204     AsmStreamer.reset(getTarget().createMCObjectStreamer(
205         T, *Context, *MAB, Out, MCE, STI, Options.MCOptions.MCRelaxAll,
206         /*DWARFMustBeAtTheEnd*/ true));
207     break;
208   }
209   case CGFT_Null:
210     // The Null output is intended for use for performance analysis and testing,
211     // not real users.
212     AsmStreamer.reset(getTarget().createNullStreamer(*Context));
213     break;
214   }
215 
216   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
217   FunctionPass *Printer =
218       getTarget().createAsmPrinter(*this, std::move(AsmStreamer));
219   if (!Printer)
220     return true;
221 
222   PM.add(Printer);
223 
224   return false;
225 }
226 
227 /// addPassesToEmitMC - Add passes to the specified pass manager to get
228 /// machine code emitted with the MCJIT. This method returns true if machine
229 /// code is not supported. It fills the MCContext Ctx pointer which can be
230 /// used to build custom MCStreamer.
231 ///
232 bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM, MCContext *&Ctx,
233                                           raw_pwrite_stream &Out,
234                                           bool DisableVerify) {
235   // Add common CodeGen passes.
236   Ctx = addPassesToGenerateCode(this, PM, DisableVerify, nullptr, nullptr,
237                                 nullptr);
238   if (!Ctx)
239     return true;
240 
241   if (Options.MCOptions.MCSaveTempLabels)
242     Ctx->setAllowTemporaryLabels(false);
243 
244   // Create the code emitter for the target if it exists.  If not, .o file
245   // emission fails.
246   const MCRegisterInfo &MRI = *getMCRegisterInfo();
247   MCCodeEmitter *MCE =
248       getTarget().createMCCodeEmitter(*getMCInstrInfo(), MRI, *Ctx);
249   MCAsmBackend *MAB =
250       getTarget().createMCAsmBackend(MRI, getTargetTriple().str(), TargetCPU);
251   if (!MCE || !MAB)
252     return true;
253 
254   const Triple &T = getTargetTriple();
255   const MCSubtargetInfo &STI = *getMCSubtargetInfo();
256   std::unique_ptr<MCStreamer> AsmStreamer(getTarget().createMCObjectStreamer(
257       T, *Ctx, *MAB, Out, MCE, STI, Options.MCOptions.MCRelaxAll,
258       /*DWARFMustBeAtTheEnd*/ true));
259 
260   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
261   FunctionPass *Printer =
262       getTarget().createAsmPrinter(*this, std::move(AsmStreamer));
263   if (!Printer)
264     return true;
265 
266   PM.add(Printer);
267 
268   return false; // success!
269 }
270