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](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 StartAfter,
94                         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(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   if (EnableFastISelOption == cl::BOU_TRUE ||
129       (TM->getOptLevel() == CodeGenOpt::None &&
130        EnableFastISelOption != cl::BOU_FALSE))
131     TM->setFastISel(true);
132 
133   // Ask the target for an isel.
134   if (PassConfig->addInstSelector())
135     return nullptr;
136 
137   PassConfig->addMachinePasses();
138 
139   PassConfig->setInitialized();
140 
141   return &MMI->getContext();
142 }
143 
144 bool LLVMTargetMachine::addPassesToEmitFile(
145     PassManagerBase &PM, raw_pwrite_stream &Out, CodeGenFileType FileType,
146     bool DisableVerify, AnalysisID StartAfter, AnalysisID StopAfter,
147     MachineFunctionInitializer *MFInitializer) {
148   // Add common CodeGen passes.
149   MCContext *Context = addPassesToGenerateCode(
150       this, PM, DisableVerify, StartAfter, StopAfter, MFInitializer);
151   if (!Context)
152     return true;
153 
154   if (StopAfter) {
155     PM.add(createPrintMIRPass(outs()));
156     return false;
157   }
158 
159   if (Options.MCOptions.MCSaveTempLabels)
160     Context->setAllowTemporaryLabels(false);
161 
162   const MCSubtargetInfo &STI = *getMCSubtargetInfo();
163   const MCAsmInfo &MAI = *getMCAsmInfo();
164   const MCRegisterInfo &MRI = *getMCRegisterInfo();
165   const MCInstrInfo &MII = *getMCInstrInfo();
166 
167   std::unique_ptr<MCStreamer> AsmStreamer;
168 
169   switch (FileType) {
170   case CGFT_AssemblyFile: {
171     MCInstPrinter *InstPrinter = getTarget().createMCInstPrinter(
172         getTargetTriple(), MAI.getAssemblerDialect(), MAI, MII, MRI);
173 
174     // Create a code emitter if asked to show the encoding.
175     MCCodeEmitter *MCE = nullptr;
176     if (Options.MCOptions.ShowMCEncoding)
177       MCE = getTarget().createMCCodeEmitter(MII, MRI, *Context);
178 
179     MCAsmBackend *MAB =
180         getTarget().createMCAsmBackend(MRI, getTargetTriple().str(), TargetCPU);
181     auto FOut = llvm::make_unique<formatted_raw_ostream>(Out);
182     MCStreamer *S = getTarget().createAsmStreamer(
183         *Context, std::move(FOut), Options.MCOptions.AsmVerbose,
184         Options.MCOptions.MCUseDwarfDirectory, InstPrinter, MCE, MAB,
185         Options.MCOptions.ShowMCInst);
186     AsmStreamer.reset(S);
187     break;
188   }
189   case CGFT_ObjectFile: {
190     // Create the code emitter for the target if it exists.  If not, .o file
191     // emission fails.
192     MCCodeEmitter *MCE = getTarget().createMCCodeEmitter(MII, MRI, *Context);
193     MCAsmBackend *MAB =
194         getTarget().createMCAsmBackend(MRI, getTargetTriple().str(), TargetCPU);
195     if (!MCE || !MAB)
196       return true;
197 
198     // Don't waste memory on names of temp labels.
199     Context->setUseNamesOnTempLabels(false);
200 
201     Triple T(getTargetTriple().str());
202     AsmStreamer.reset(getTarget().createMCObjectStreamer(
203         T, *Context, *MAB, Out, MCE, STI, Options.MCOptions.MCRelaxAll,
204         /*DWARFMustBeAtTheEnd*/ true));
205     break;
206   }
207   case CGFT_Null:
208     // The Null output is intended for use for performance analysis and testing,
209     // not real users.
210     AsmStreamer.reset(getTarget().createNullStreamer(*Context));
211     break;
212   }
213 
214   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
215   FunctionPass *Printer =
216       getTarget().createAsmPrinter(*this, std::move(AsmStreamer));
217   if (!Printer)
218     return true;
219 
220   PM.add(Printer);
221 
222   return false;
223 }
224 
225 /// addPassesToEmitMC - Add passes to the specified pass manager to get
226 /// machine code emitted with the MCJIT. This method returns true if machine
227 /// code is not supported. It fills the MCContext Ctx pointer which can be
228 /// used to build custom MCStreamer.
229 ///
230 bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM, MCContext *&Ctx,
231                                           raw_pwrite_stream &Out,
232                                           bool DisableVerify) {
233   // Add common CodeGen passes.
234   Ctx = addPassesToGenerateCode(this, PM, DisableVerify, nullptr, nullptr);
235   if (!Ctx)
236     return true;
237 
238   if (Options.MCOptions.MCSaveTempLabels)
239     Ctx->setAllowTemporaryLabels(false);
240 
241   // Create the code emitter for the target if it exists.  If not, .o file
242   // emission fails.
243   const MCRegisterInfo &MRI = *getMCRegisterInfo();
244   MCCodeEmitter *MCE =
245       getTarget().createMCCodeEmitter(*getMCInstrInfo(), MRI, *Ctx);
246   MCAsmBackend *MAB =
247       getTarget().createMCAsmBackend(MRI, getTargetTriple().str(), TargetCPU);
248   if (!MCE || !MAB)
249     return true;
250 
251   const Triple &T = getTargetTriple();
252   const MCSubtargetInfo &STI = *getMCSubtargetInfo();
253   std::unique_ptr<MCStreamer> AsmStreamer(getTarget().createMCObjectStreamer(
254       T, *Ctx, *MAB, Out, MCE, STI, Options.MCOptions.MCRelaxAll,
255       /*DWARFMustBeAtTheEnd*/ true));
256 
257   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
258   FunctionPass *Printer =
259       getTarget().createAsmPrinter(*this, std::move(AsmStreamer));
260   if (!Printer)
261     return true;
262 
263   PM.add(Printer);
264 
265   return false; // success!
266 }
267