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 static cl::opt<cl::boolOrDefault>
47 AsmVerbose("asm-verbose", cl::desc("Add comments to directives."),
48            cl::init(cl::BOU_UNSET));
49 
50 static bool getVerboseAsm() {
51   switch (AsmVerbose) {
52   case cl::BOU_UNSET: return TargetMachine::getAsmVerbosityDefault();
53   case cl::BOU_TRUE:  return true;
54   case cl::BOU_FALSE: return false;
55   }
56   llvm_unreachable("Invalid verbose asm state");
57 }
58 
59 void LLVMTargetMachine::initAsmInfo() {
60   MCAsmInfo *TmpAsmInfo = TheTarget.createMCAsmInfo(*getRegisterInfo(),
61                                                     TargetTriple);
62   // TargetSelect.h moved to a different directory between LLVM 2.9 and 3.0,
63   // and if the old one gets included then MCAsmInfo will be NULL and
64   // we'll crash later.
65   // Provide the user with a useful error message about what's wrong.
66   assert(TmpAsmInfo && "MCAsmInfo not initialized. "
67          "Make sure you include the correct TargetSelect.h"
68          "and that InitializeAllTargetMCs() is being invoked!");
69 
70   if (Options.DisableIntegratedAS)
71     TmpAsmInfo->setUseIntegratedAssembler(false);
72 
73   if (Options.CompressDebugSections)
74     TmpAsmInfo->setCompressDebugSections(true);
75 
76   AsmInfo = TmpAsmInfo;
77 }
78 
79 LLVMTargetMachine::LLVMTargetMachine(const Target &T, StringRef Triple,
80                                      StringRef CPU, StringRef FS,
81                                      TargetOptions Options,
82                                      Reloc::Model RM, CodeModel::Model CM,
83                                      CodeGenOpt::Level OL)
84   : TargetMachine(T, Triple, CPU, FS, Options) {
85   CodeGenInfo = T.createMCCodeGenInfo(Triple, RM, CM, OL);
86 }
87 
88 void LLVMTargetMachine::addAnalysisPasses(PassManagerBase &PM) {
89   PM.add(createBasicTargetTransformInfoPass(this));
90 }
91 
92 /// addPassesToX helper drives creation and initialization of TargetPassConfig.
93 static MCContext *addPassesToGenerateCode(LLVMTargetMachine *TM,
94                                           PassManagerBase &PM,
95                                           bool DisableVerify,
96                                           AnalysisID StartAfter,
97                                           AnalysisID StopAfter) {
98   // Add internal analysis passes from the target machine.
99   TM->addAnalysisPasses(PM);
100 
101   // Targets may override createPassConfig to provide a target-specific sublass.
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 =
121     new MachineModuleInfo(*TM->getMCAsmInfo(), *TM->getRegisterInfo(),
122                           &TM->getTargetLowering()->getObjFileLowering());
123   PM.add(MMI);
124 
125   // Set up a MachineFunction for the rest of CodeGen to work on.
126   PM.add(new MachineFunctionAnalysis(*TM));
127 
128   // Enable FastISel with -fast, but allow that to be overridden.
129   if (EnableFastISelOption == cl::BOU_TRUE ||
130       (TM->getOptLevel() == CodeGenOpt::None &&
131        EnableFastISelOption != cl::BOU_FALSE))
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(PassManagerBase &PM,
146                                             formatted_raw_ostream &Out,
147                                             CodeGenFileType FileType,
148                                             bool DisableVerify,
149                                             AnalysisID StartAfter,
150                                             AnalysisID StopAfter) {
151   // Add common CodeGen passes.
152   MCContext *Context = addPassesToGenerateCode(this, PM, DisableVerify,
153                                                StartAfter, StopAfter);
154   if (!Context)
155     return true;
156 
157   if (StopAfter) {
158     // FIXME: The intent is that this should eventually write out a YAML file,
159     // containing the LLVM IR, the machine-level IR (when stopping after a
160     // machine-level pass), and whatever other information is needed to
161     // deserialize the code and resume compilation.  For now, just write the
162     // LLVM IR.
163     PM.add(createPrintModulePass(Out));
164     return false;
165   }
166 
167   if (Options.MCOptions.MCSaveTempLabels)
168     Context->setAllowTemporaryLabels(false);
169 
170   const MCAsmInfo &MAI = *getMCAsmInfo();
171   const MCRegisterInfo &MRI = *getRegisterInfo();
172   const MCInstrInfo &MII = *getInstrInfo();
173   const MCSubtargetInfo &STI = getSubtarget<MCSubtargetInfo>();
174   std::unique_ptr<MCStreamer> AsmStreamer;
175 
176   switch (FileType) {
177   case CGFT_AssemblyFile: {
178     MCInstPrinter *InstPrinter =
179       getTarget().createMCInstPrinter(MAI.getAssemblerDialect(), MAI,
180                                       MII, MRI, STI);
181 
182     // Create a code emitter if asked to show the encoding.
183     MCCodeEmitter *MCE = nullptr;
184     if (Options.MCOptions.ShowMCEncoding)
185       MCE = getTarget().createMCCodeEmitter(MII, MRI, STI, *Context);
186 
187     MCAsmBackend *MAB = getTarget().createMCAsmBackend(MRI, getTargetTriple(),
188                                                        TargetCPU);
189     MCStreamer *S = getTarget().createAsmStreamer(
190         *Context, Out, getVerboseAsm(), Options.MCOptions.MCUseDwarfDirectory,
191         InstPrinter, MCE, MAB, Options.MCOptions.ShowMCInst);
192     AsmStreamer.reset(S);
193     break;
194   }
195   case CGFT_ObjectFile: {
196     // Create the code emitter for the target if it exists.  If not, .o file
197     // emission fails.
198     MCCodeEmitter *MCE = getTarget().createMCCodeEmitter(MII, MRI, STI,
199                                                          *Context);
200     MCAsmBackend *MAB = getTarget().createMCAsmBackend(MRI, getTargetTriple(),
201                                                        TargetCPU);
202     if (!MCE || !MAB)
203       return true;
204 
205     AsmStreamer.reset(getTarget().createMCObjectStreamer(
206         getTargetTriple(), *Context, *MAB, Out, MCE, STI,
207         Options.MCOptions.MCRelaxAll, Options.MCOptions.MCNoExecStack));
208     break;
209   }
210   case CGFT_Null:
211     // The Null output is intended for use for performance analysis and testing,
212     // not real users.
213     AsmStreamer.reset(createNullStreamer(*Context));
214     break;
215   }
216 
217   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
218   FunctionPass *Printer = getTarget().createAsmPrinter(*this, *AsmStreamer);
219   if (!Printer)
220     return true;
221 
222   // If successful, createAsmPrinter took ownership of AsmStreamer.
223   AsmStreamer.release();
224 
225   PM.add(Printer);
226 
227   return false;
228 }
229 
230 /// addPassesToEmitMachineCode - Add passes to the specified pass manager to
231 /// get machine code emitted.  This uses a JITCodeEmitter object to handle
232 /// actually outputting the machine code and resolving things like the address
233 /// of functions.  This method should return true if machine code emission is
234 /// not supported.
235 ///
236 bool LLVMTargetMachine::addPassesToEmitMachineCode(PassManagerBase &PM,
237                                                    JITCodeEmitter &JCE,
238                                                    bool DisableVerify) {
239   // Add common CodeGen passes.
240   MCContext *Context = addPassesToGenerateCode(this, PM, DisableVerify, nullptr,
241                                                nullptr);
242   if (!Context)
243     return true;
244 
245   addCodeEmitter(PM, JCE);
246 
247   return false; // success!
248 }
249 
250 /// addPassesToEmitMC - Add passes to the specified pass manager to get
251 /// machine code emitted with the MCJIT. This method returns true if machine
252 /// code is not supported. It fills the MCContext Ctx pointer which can be
253 /// used to build custom MCStreamer.
254 ///
255 bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM,
256                                           MCContext *&Ctx,
257                                           raw_ostream &Out,
258                                           bool DisableVerify) {
259   // Add common CodeGen passes.
260   Ctx = addPassesToGenerateCode(this, PM, DisableVerify, nullptr, nullptr);
261   if (!Ctx)
262     return true;
263 
264   if (Options.MCOptions.MCSaveTempLabels)
265     Ctx->setAllowTemporaryLabels(false);
266 
267   // Create the code emitter for the target if it exists.  If not, .o file
268   // emission fails.
269   const MCRegisterInfo &MRI = *getRegisterInfo();
270   const MCSubtargetInfo &STI = getSubtarget<MCSubtargetInfo>();
271   MCCodeEmitter *MCE = getTarget().createMCCodeEmitter(*getInstrInfo(), MRI,
272                                                        STI, *Ctx);
273   MCAsmBackend *MAB = getTarget().createMCAsmBackend(MRI, getTargetTriple(),
274                                                      TargetCPU);
275   if (!MCE || !MAB)
276     return true;
277 
278   std::unique_ptr<MCStreamer> AsmStreamer;
279   AsmStreamer.reset(getTarget().createMCObjectStreamer(
280       getTargetTriple(), *Ctx, *MAB, Out, MCE, STI,
281       Options.MCOptions.MCRelaxAll, Options.MCOptions.MCNoExecStack));
282 
283   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
284   FunctionPass *Printer = getTarget().createAsmPrinter(*this, *AsmStreamer);
285   if (!Printer)
286     return true;
287 
288   // If successful, createAsmPrinter took ownership of AsmStreamer.
289   AsmStreamer.release();
290 
291   PM.add(Printer);
292 
293   return false; // success!
294 }
295