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 static cl::opt<bool>
46     EnableGlobalISel("global-isel", cl::Hidden, cl::init(false),
47                      cl::desc("Enable the \"global\" instruction selector"));
48 
49 void LLVMTargetMachine::initAsmInfo() {
50   MRI = TheTarget.createMCRegInfo(getTargetTriple().str());
51   MII = TheTarget.createMCInstrInfo();
52   // FIXME: Having an MCSubtargetInfo on the target machine is a hack due
53   // to some backends having subtarget feature dependent module level
54   // code generation. This is similar to the hack in the AsmPrinter for
55   // module level assembly etc.
56   STI = TheTarget.createMCSubtargetInfo(getTargetTriple().str(), getTargetCPU(),
57                                         getTargetFeatureString());
58 
59   MCAsmInfo *TmpAsmInfo =
60       TheTarget.createMCAsmInfo(*MRI, getTargetTriple().str());
61   // TargetSelect.h moved to a different directory between LLVM 2.9 and 3.0,
62   // and if the old one gets included then MCAsmInfo will be NULL and
63   // we'll crash later.
64   // Provide the user with a useful error message about what's wrong.
65   assert(TmpAsmInfo && "MCAsmInfo not initialized. "
66          "Make sure you include the correct TargetSelect.h"
67          "and that InitializeAllTargetMCs() is being invoked!");
68 
69   if (Options.DisableIntegratedAS)
70     TmpAsmInfo->setUseIntegratedAssembler(false);
71 
72   if (Options.CompressDebugSections)
73     TmpAsmInfo->setCompressDebugSections(true);
74 
75   AsmInfo = TmpAsmInfo;
76 }
77 
78 LLVMTargetMachine::LLVMTargetMachine(const Target &T,
79                                      StringRef DataLayoutString,
80                                      const Triple &TT, StringRef CPU,
81                                      StringRef FS, TargetOptions Options,
82                                      Reloc::Model RM, CodeModel::Model CM,
83                                      CodeGenOpt::Level OL)
84     : TargetMachine(T, DataLayoutString, TT, CPU, FS, Options) {
85   CodeGenInfo = T.createMCCodeGenInfo(TT.str(), RM, CM, OL);
86 }
87 
88 TargetIRAnalysis LLVMTargetMachine::getTargetIRAnalysis() {
89   return TargetIRAnalysis([this](const Function &F) {
90     return TargetTransformInfo(BasicTTIImpl(this, F));
91   });
92 }
93 
94 /// addPassesToX helper drives creation and initialization of TargetPassConfig.
95 static MCContext *
96 addPassesToGenerateCode(LLVMTargetMachine *TM, PassManagerBase &PM,
97                         bool DisableVerify, AnalysisID StartBefore,
98                         AnalysisID StartAfter, AnalysisID StopAfter,
99                         MachineFunctionInitializer *MFInitializer = nullptr) {
100 
101   // When in emulated TLS mode, add the LowerEmuTLS pass.
102   if (TM->Options.EmulatedTLS)
103     PM.add(createLowerEmuTLSPass(TM));
104 
105   // Add internal analysis passes from the target machine.
106   PM.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
107 
108   // Targets may override createPassConfig to provide a target-specific
109   // subclass.
110   TargetPassConfig *PassConfig = TM->createPassConfig(PM);
111   PassConfig->setStartStopPasses(StartBefore, StartAfter, StopAfter);
112 
113   // Set PassConfig options provided by TargetMachine.
114   PassConfig->setDisableVerify(DisableVerify);
115 
116   PM.add(PassConfig);
117 
118   PassConfig->addIRPasses();
119 
120   PassConfig->addCodeGenPrepare();
121 
122   PassConfig->addPassesToHandleExceptions();
123 
124   PassConfig->addISelPrepare();
125 
126   // Install a MachineModuleInfo class, which is an immutable pass that holds
127   // all the per-module stuff we're generating, including MCContext.
128   MachineModuleInfo *MMI = new MachineModuleInfo(
129       *TM->getMCAsmInfo(), *TM->getMCRegisterInfo(), TM->getObjFileLowering());
130   PM.add(MMI);
131 
132   // Set up a MachineFunction for the rest of CodeGen to work on.
133   PM.add(new MachineFunctionAnalysis(*TM, MFInitializer));
134 
135   // Enable FastISel with -fast, but allow that to be overridden.
136   TM->setO0WantsFastISel(EnableFastISelOption != cl::BOU_FALSE);
137   if (EnableFastISelOption == cl::BOU_TRUE ||
138       (TM->getOptLevel() == CodeGenOpt::None &&
139        TM->getO0WantsFastISel()))
140     TM->setFastISel(true);
141 
142   // Ask the target for an isel.
143   if (LLVM_UNLIKELY(EnableGlobalISel)) {
144     if (PassConfig->addIRTranslator())
145       return nullptr;
146 
147     // Before running the register bank selector, ask the target if it
148     // wants to run some passes.
149     PassConfig->addPreRegBankSelect();
150 
151     if (PassConfig->addRegBankSelect())
152       return nullptr;
153 
154   } else if (PassConfig->addInstSelector())
155     return nullptr;
156 
157   PassConfig->addMachinePasses();
158 
159   PassConfig->setInitialized();
160 
161   return &MMI->getContext();
162 }
163 
164 bool LLVMTargetMachine::addPassesToEmitFile(
165     PassManagerBase &PM, raw_pwrite_stream &Out, CodeGenFileType FileType,
166     bool DisableVerify, AnalysisID StartBefore, AnalysisID StartAfter,
167     AnalysisID StopAfter, MachineFunctionInitializer *MFInitializer) {
168   // Add common CodeGen passes.
169   MCContext *Context =
170       addPassesToGenerateCode(this, PM, DisableVerify, StartBefore, StartAfter,
171                               StopAfter, MFInitializer);
172   if (!Context)
173     return true;
174 
175   if (StopAfter) {
176     PM.add(createPrintMIRPass(errs()));
177     return false;
178   }
179 
180   if (Options.MCOptions.MCSaveTempLabels)
181     Context->setAllowTemporaryLabels(false);
182 
183   const MCSubtargetInfo &STI = *getMCSubtargetInfo();
184   const MCAsmInfo &MAI = *getMCAsmInfo();
185   const MCRegisterInfo &MRI = *getMCRegisterInfo();
186   const MCInstrInfo &MII = *getMCInstrInfo();
187 
188   std::unique_ptr<MCStreamer> AsmStreamer;
189 
190   switch (FileType) {
191   case CGFT_AssemblyFile: {
192     MCInstPrinter *InstPrinter = getTarget().createMCInstPrinter(
193         getTargetTriple(), MAI.getAssemblerDialect(), MAI, MII, MRI);
194 
195     // Create a code emitter if asked to show the encoding.
196     MCCodeEmitter *MCE = nullptr;
197     if (Options.MCOptions.ShowMCEncoding)
198       MCE = getTarget().createMCCodeEmitter(MII, MRI, *Context);
199 
200     MCAsmBackend *MAB =
201         getTarget().createMCAsmBackend(MRI, getTargetTriple().str(), TargetCPU);
202     auto FOut = llvm::make_unique<formatted_raw_ostream>(Out);
203     MCStreamer *S = getTarget().createAsmStreamer(
204         *Context, std::move(FOut), Options.MCOptions.AsmVerbose,
205         Options.MCOptions.MCUseDwarfDirectory, InstPrinter, MCE, MAB,
206         Options.MCOptions.ShowMCInst);
207     AsmStreamer.reset(S);
208     break;
209   }
210   case CGFT_ObjectFile: {
211     // Create the code emitter for the target if it exists.  If not, .o file
212     // emission fails.
213     MCCodeEmitter *MCE = getTarget().createMCCodeEmitter(MII, MRI, *Context);
214     MCAsmBackend *MAB =
215         getTarget().createMCAsmBackend(MRI, getTargetTriple().str(), TargetCPU);
216     if (!MCE || !MAB)
217       return true;
218 
219     // Don't waste memory on names of temp labels.
220     Context->setUseNamesOnTempLabels(false);
221 
222     Triple T(getTargetTriple().str());
223     AsmStreamer.reset(getTarget().createMCObjectStreamer(
224         T, *Context, *MAB, Out, MCE, STI, Options.MCOptions.MCRelaxAll,
225         Options.MCOptions.MCIncrementalLinkerCompatible,
226         /*DWARFMustBeAtTheEnd*/ true));
227     break;
228   }
229   case CGFT_Null:
230     // The Null output is intended for use for performance analysis and testing,
231     // not real users.
232     AsmStreamer.reset(getTarget().createNullStreamer(*Context));
233     break;
234   }
235 
236   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
237   FunctionPass *Printer =
238       getTarget().createAsmPrinter(*this, std::move(AsmStreamer));
239   if (!Printer)
240     return true;
241 
242   PM.add(Printer);
243 
244   return false;
245 }
246 
247 /// addPassesToEmitMC - Add passes to the specified pass manager to get
248 /// machine code emitted with the MCJIT. This method returns true if machine
249 /// code is not supported. It fills the MCContext Ctx pointer which can be
250 /// used to build custom MCStreamer.
251 ///
252 bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM, MCContext *&Ctx,
253                                           raw_pwrite_stream &Out,
254                                           bool DisableVerify) {
255   // Add common CodeGen passes.
256   Ctx = addPassesToGenerateCode(this, PM, DisableVerify, nullptr, nullptr,
257                                 nullptr);
258   if (!Ctx)
259     return true;
260 
261   if (Options.MCOptions.MCSaveTempLabels)
262     Ctx->setAllowTemporaryLabels(false);
263 
264   // Create the code emitter for the target if it exists.  If not, .o file
265   // emission fails.
266   const MCRegisterInfo &MRI = *getMCRegisterInfo();
267   MCCodeEmitter *MCE =
268       getTarget().createMCCodeEmitter(*getMCInstrInfo(), MRI, *Ctx);
269   MCAsmBackend *MAB =
270       getTarget().createMCAsmBackend(MRI, getTargetTriple().str(), TargetCPU);
271   if (!MCE || !MAB)
272     return true;
273 
274   const Triple &T = getTargetTriple();
275   const MCSubtargetInfo &STI = *getMCSubtargetInfo();
276   std::unique_ptr<MCStreamer> AsmStreamer(getTarget().createMCObjectStreamer(
277       T, *Ctx, *MAB, Out, MCE, STI, Options.MCOptions.MCRelaxAll,
278       Options.MCOptions.MCIncrementalLinkerCompatible,
279       /*DWARFMustBeAtTheEnd*/ true));
280 
281   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
282   FunctionPass *Printer =
283       getTarget().createAsmPrinter(*this, std::move(AsmStreamer));
284   if (!Printer)
285     return true;
286 
287   PM.add(Printer);
288 
289   return false; // success!
290 }
291