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