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