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/CodeGen/AsmPrinter.h"
16 #include "llvm/CodeGen/MachineFunctionAnalysis.h"
17 #include "llvm/CodeGen/MachineModuleInfo.h"
18 #include "llvm/CodeGen/Passes.h"
19 #include "llvm/IR/IRPrintingPasses.h"
20 #include "llvm/MC/MCAsmInfo.h"
21 #include "llvm/MC/MCContext.h"
22 #include "llvm/MC/MCInstrInfo.h"
23 #include "llvm/MC/MCStreamer.h"
24 #include "llvm/MC/MCSubtargetInfo.h"
25 #include "llvm/PassManager.h"
26 #include "llvm/Support/CommandLine.h"
27 #include "llvm/Support/ErrorHandling.h"
28 #include "llvm/Support/FormattedStream.h"
29 #include "llvm/Support/TargetRegistry.h"
30 #include "llvm/Target/TargetInstrInfo.h"
31 #include "llvm/Target/TargetLowering.h"
32 #include "llvm/Target/TargetLoweringObjectFile.h"
33 #include "llvm/Target/TargetOptions.h"
34 #include "llvm/Target/TargetRegisterInfo.h"
35 #include "llvm/Target/TargetSubtargetInfo.h"
36 #include "llvm/Transforms/Scalar.h"
37 using namespace llvm;
38 
39 // Enable or disable FastISel. Both options are needed, because
40 // FastISel is enabled by default with -fast, and we wish to be
41 // able to enable or disable fast-isel independently from -O0.
42 static cl::opt<cl::boolOrDefault>
43 EnableFastISelOption("fast-isel", cl::Hidden,
44   cl::desc("Enable the \"fast\" instruction selector"));
45 
46 void LLVMTargetMachine::initAsmInfo() {
47   MCAsmInfo *TmpAsmInfo = TheTarget.createMCAsmInfo(*getRegisterInfo(),
48                                                     TargetTriple);
49   // TargetSelect.h moved to a different directory between LLVM 2.9 and 3.0,
50   // and if the old one gets included then MCAsmInfo will be NULL and
51   // we'll crash later.
52   // Provide the user with a useful error message about what's wrong.
53   assert(TmpAsmInfo && "MCAsmInfo not initialized. "
54          "Make sure you include the correct TargetSelect.h"
55          "and that InitializeAllTargetMCs() is being invoked!");
56 
57   if (Options.DisableIntegratedAS)
58     TmpAsmInfo->setUseIntegratedAssembler(false);
59 
60   if (Options.CompressDebugSections)
61     TmpAsmInfo->setCompressDebugSections(true);
62 
63   AsmInfo = TmpAsmInfo;
64 }
65 
66 LLVMTargetMachine::LLVMTargetMachine(const Target &T, StringRef Triple,
67                                      StringRef CPU, StringRef FS,
68                                      TargetOptions Options,
69                                      Reloc::Model RM, CodeModel::Model CM,
70                                      CodeGenOpt::Level OL)
71   : TargetMachine(T, Triple, CPU, FS, Options) {
72   CodeGenInfo = T.createMCCodeGenInfo(Triple, RM, CM, OL);
73 }
74 
75 void LLVMTargetMachine::addAnalysisPasses(PassManagerBase &PM) {
76   PM.add(createBasicTargetTransformInfoPass(this));
77 }
78 
79 /// addPassesToX helper drives creation and initialization of TargetPassConfig.
80 static MCContext *addPassesToGenerateCode(LLVMTargetMachine *TM,
81                                           PassManagerBase &PM,
82                                           bool DisableVerify,
83                                           AnalysisID StartAfter,
84                                           AnalysisID StopAfter) {
85   // Add internal analysis passes from the target machine.
86   TM->addAnalysisPasses(PM);
87 
88   // Targets may override createPassConfig to provide a target-specific
89   // subclass.
90   TargetPassConfig *PassConfig = TM->createPassConfig(PM);
91   PassConfig->setStartStopPasses(StartAfter, StopAfter);
92 
93   // Set PassConfig options provided by TargetMachine.
94   PassConfig->setDisableVerify(DisableVerify);
95 
96   PM.add(PassConfig);
97 
98   PassConfig->addIRPasses();
99 
100   PassConfig->addCodeGenPrepare();
101 
102   PassConfig->addPassesToHandleExceptions();
103 
104   PassConfig->addISelPrepare();
105 
106   // Install a MachineModuleInfo class, which is an immutable pass that holds
107   // all the per-module stuff we're generating, including MCContext.
108   MachineModuleInfo *MMI =
109     new MachineModuleInfo(*TM->getMCAsmInfo(), *TM->getRegisterInfo(),
110                           &TM->getTargetLowering()->getObjFileLowering());
111   PM.add(MMI);
112 
113   // Set up a MachineFunction for the rest of CodeGen to work on.
114   PM.add(new MachineFunctionAnalysis(*TM));
115 
116   // Enable FastISel with -fast, but allow that to be overridden.
117   if (EnableFastISelOption == cl::BOU_TRUE ||
118       (TM->getOptLevel() == CodeGenOpt::None &&
119        EnableFastISelOption != cl::BOU_FALSE))
120     TM->setFastISel(true);
121 
122   // Ask the target for an isel.
123   if (PassConfig->addInstSelector())
124     return nullptr;
125 
126   PassConfig->addMachinePasses();
127 
128   PassConfig->setInitialized();
129 
130   return &MMI->getContext();
131 }
132 
133 bool LLVMTargetMachine::addPassesToEmitFile(PassManagerBase &PM,
134                                             formatted_raw_ostream &Out,
135                                             CodeGenFileType FileType,
136                                             bool DisableVerify,
137                                             AnalysisID StartAfter,
138                                             AnalysisID StopAfter) {
139   // Add common CodeGen passes.
140   MCContext *Context = addPassesToGenerateCode(this, PM, DisableVerify,
141                                                StartAfter, StopAfter);
142   if (!Context)
143     return true;
144 
145   if (StopAfter) {
146     // FIXME: The intent is that this should eventually write out a YAML file,
147     // containing the LLVM IR, the machine-level IR (when stopping after a
148     // machine-level pass), and whatever other information is needed to
149     // deserialize the code and resume compilation.  For now, just write the
150     // LLVM IR.
151     PM.add(createPrintModulePass(Out));
152     return false;
153   }
154 
155   if (Options.MCOptions.MCSaveTempLabels)
156     Context->setAllowTemporaryLabels(false);
157 
158   const MCAsmInfo &MAI = *getMCAsmInfo();
159   const MCRegisterInfo &MRI = *getRegisterInfo();
160   const MCInstrInfo &MII = *getInstrInfo();
161   const MCSubtargetInfo &STI = getSubtarget<MCSubtargetInfo>();
162   std::unique_ptr<MCStreamer> AsmStreamer;
163 
164   switch (FileType) {
165   case CGFT_AssemblyFile: {
166     MCInstPrinter *InstPrinter =
167       getTarget().createMCInstPrinter(MAI.getAssemblerDialect(), MAI,
168                                       MII, MRI, STI);
169 
170     // Create a code emitter if asked to show the encoding.
171     MCCodeEmitter *MCE = nullptr;
172     if (Options.MCOptions.ShowMCEncoding)
173       MCE = getTarget().createMCCodeEmitter(MII, MRI, STI, *Context);
174 
175     MCAsmBackend *MAB = getTarget().createMCAsmBackend(MRI, getTargetTriple(),
176                                                        TargetCPU);
177     MCStreamer *S = getTarget().createAsmStreamer(
178         *Context, Out, Options.MCOptions.AsmVerbose,
179         Options.MCOptions.MCUseDwarfDirectory, InstPrinter, MCE, MAB,
180         Options.MCOptions.ShowMCInst);
181     AsmStreamer.reset(S);
182     break;
183   }
184   case CGFT_ObjectFile: {
185     // Create the code emitter for the target if it exists.  If not, .o file
186     // emission fails.
187     MCCodeEmitter *MCE = getTarget().createMCCodeEmitter(MII, MRI, STI,
188                                                          *Context);
189     MCAsmBackend *MAB = getTarget().createMCAsmBackend(MRI, getTargetTriple(),
190                                                        TargetCPU);
191     if (!MCE || !MAB)
192       return true;
193 
194     AsmStreamer.reset(getTarget().createMCObjectStreamer(
195         getTargetTriple(), *Context, *MAB, Out, MCE, STI,
196         Options.MCOptions.MCRelaxAll, Options.MCOptions.MCNoExecStack));
197     break;
198   }
199   case CGFT_Null:
200     // The Null output is intended for use for performance analysis and testing,
201     // not real users.
202     AsmStreamer.reset(createNullStreamer(*Context));
203     break;
204   }
205 
206   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
207   FunctionPass *Printer = getTarget().createAsmPrinter(*this, *AsmStreamer);
208   if (!Printer)
209     return true;
210 
211   // If successful, createAsmPrinter took ownership of AsmStreamer.
212   AsmStreamer.release();
213 
214   PM.add(Printer);
215 
216   return false;
217 }
218 
219 /// addPassesToEmitMachineCode - Add passes to the specified pass manager to
220 /// get machine code emitted.  This uses a JITCodeEmitter object to handle
221 /// actually outputting the machine code and resolving things like the address
222 /// of functions.  This method should return true if machine code emission is
223 /// not supported.
224 ///
225 bool LLVMTargetMachine::addPassesToEmitMachineCode(PassManagerBase &PM,
226                                                    JITCodeEmitter &JCE,
227                                                    bool DisableVerify) {
228   // Add common CodeGen passes.
229   MCContext *Context = addPassesToGenerateCode(this, PM, DisableVerify, nullptr,
230                                                nullptr);
231   if (!Context)
232     return true;
233 
234   addCodeEmitter(PM, JCE);
235 
236   return false; // success!
237 }
238 
239 /// addPassesToEmitMC - Add passes to the specified pass manager to get
240 /// machine code emitted with the MCJIT. This method returns true if machine
241 /// code is not supported. It fills the MCContext Ctx pointer which can be
242 /// used to build custom MCStreamer.
243 ///
244 bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM,
245                                           MCContext *&Ctx,
246                                           raw_ostream &Out,
247                                           bool DisableVerify) {
248   // Add common CodeGen passes.
249   Ctx = addPassesToGenerateCode(this, PM, DisableVerify, nullptr, nullptr);
250   if (!Ctx)
251     return true;
252 
253   if (Options.MCOptions.MCSaveTempLabels)
254     Ctx->setAllowTemporaryLabels(false);
255 
256   // Create the code emitter for the target if it exists.  If not, .o file
257   // emission fails.
258   const MCRegisterInfo &MRI = *getRegisterInfo();
259   const MCSubtargetInfo &STI = getSubtarget<MCSubtargetInfo>();
260   MCCodeEmitter *MCE = getTarget().createMCCodeEmitter(*getInstrInfo(), MRI,
261                                                        STI, *Ctx);
262   MCAsmBackend *MAB = getTarget().createMCAsmBackend(MRI, getTargetTriple(),
263                                                      TargetCPU);
264   if (!MCE || !MAB)
265     return true;
266 
267   std::unique_ptr<MCStreamer> AsmStreamer;
268   AsmStreamer.reset(getTarget().createMCObjectStreamer(
269       getTargetTriple(), *Ctx, *MAB, Out, MCE, STI,
270       Options.MCOptions.MCRelaxAll, Options.MCOptions.MCNoExecStack));
271 
272   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
273   FunctionPass *Printer = getTarget().createAsmPrinter(*this, *AsmStreamer);
274   if (!Printer)
275     return true;
276 
277   // If successful, createAsmPrinter took ownership of AsmStreamer.
278   AsmStreamer.release();
279 
280   PM.add(Printer);
281 
282   return false; // success!
283 }
284