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/Transforms/Scalar.h"
15 #include "llvm/PassManager.h"
16 #include "llvm/CodeGen/AsmPrinter.h"
17 #include "llvm/CodeGen/Passes.h"
18 #include "llvm/CodeGen/MachineFunctionAnalysis.h"
19 #include "llvm/CodeGen/MachineModuleInfo.h"
20 #include "llvm/Target/TargetInstrInfo.h"
21 #include "llvm/Target/TargetLowering.h"
22 #include "llvm/Target/TargetLoweringObjectFile.h"
23 #include "llvm/Target/TargetMachine.h"
24 #include "llvm/Target/TargetOptions.h"
25 #include "llvm/Target/TargetSubtargetInfo.h"
26 #include "llvm/Target/TargetRegisterInfo.h"
27 #include "llvm/MC/MCAsmInfo.h"
28 #include "llvm/MC/MCContext.h"
29 #include "llvm/MC/MCInstrInfo.h"
30 #include "llvm/MC/MCStreamer.h"
31 #include "llvm/MC/MCSubtargetInfo.h"
32 #include "llvm/ADT/OwningPtr.h"
33 #include "llvm/Support/CommandLine.h"
34 #include "llvm/Support/FormattedStream.h"
35 #include "llvm/Support/ErrorHandling.h"
36 #include "llvm/Support/TargetRegistry.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<bool> ShowMCEncoding("show-mc-encoding", cl::Hidden,
47     cl::desc("Show encoding in .s output"));
48 static cl::opt<bool> ShowMCInst("show-mc-inst", cl::Hidden,
49     cl::desc("Show instruction structure in .s output"));
50 
51 static cl::opt<cl::boolOrDefault>
52 AsmVerbose("asm-verbose", cl::desc("Add comments to directives."),
53            cl::init(cl::BOU_UNSET));
54 
55 static bool getVerboseAsm() {
56   switch (AsmVerbose) {
57   case cl::BOU_UNSET: return TargetMachine::getAsmVerbosityDefault();
58   case cl::BOU_TRUE:  return true;
59   case cl::BOU_FALSE: return false;
60   }
61   llvm_unreachable("Invalid verbose asm state");
62 }
63 
64 LLVMTargetMachine::LLVMTargetMachine(const Target &T, StringRef Triple,
65                                      StringRef CPU, StringRef FS,
66                                      TargetOptions Options,
67                                      Reloc::Model RM, CodeModel::Model CM,
68                                      CodeGenOpt::Level OL)
69   : TargetMachine(T, Triple, CPU, FS, Options) {
70   CodeGenInfo = T.createMCCodeGenInfo(Triple, RM, CM, OL);
71   AsmInfo = T.createMCAsmInfo(Triple);
72   // TargetSelect.h moved to a different directory between LLVM 2.9 and 3.0,
73   // and if the old one gets included then MCAsmInfo will be NULL and
74   // we'll crash later.
75   // Provide the user with a useful error message about what's wrong.
76   assert(AsmInfo && "MCAsmInfo not initialized."
77          "Make sure you include the correct TargetSelect.h"
78          "and that InitializeAllTargetMCs() is being invoked!");
79 }
80 
81 /// Turn exception handling constructs into something the code generators can
82 /// handle.
83 static void addPassesToHandleExceptions(TargetMachine *TM,
84                                         PassManagerBase &PM) {
85   switch (TM->getMCAsmInfo()->getExceptionHandlingType()) {
86   case ExceptionHandling::SjLj:
87     // SjLj piggy-backs on dwarf for this bit. The cleanups done apply to both
88     // Dwarf EH prepare needs to be run after SjLj prepare. Otherwise,
89     // catch info can get misplaced when a selector ends up more than one block
90     // removed from the parent invoke(s). This could happen when a landing
91     // pad is shared by multiple invokes and is also a target of a normal
92     // edge from elsewhere.
93     PM.add(createSjLjEHPreparePass(TM->getTargetLowering()));
94     // FALLTHROUGH
95   case ExceptionHandling::DwarfCFI:
96   case ExceptionHandling::ARM:
97   case ExceptionHandling::Win64:
98     PM.add(createDwarfEHPass(TM));
99     break;
100   case ExceptionHandling::None:
101     PM.add(createLowerInvokePass(TM->getTargetLowering()));
102 
103     // The lower invoke pass may create unreachable code. Remove it.
104     PM.add(createUnreachableBlockEliminationPass());
105     break;
106   }
107 }
108 
109 /// addPassesToX helper drives creation and initialization of TargetPassConfig.
110 static MCContext *addPassesToGenerateCode(LLVMTargetMachine *TM,
111                                           PassManagerBase &PM,
112                                           bool DisableVerify) {
113   // Targets may override createPassConfig to provide a target-specific sublass.
114   TargetPassConfig *PassConfig = TM->createPassConfig(PM);
115 
116   // Set PassConfig options provided by TargetMachine.
117   PassConfig->setDisableVerify(DisableVerify);
118 
119   PM.add(PassConfig);
120 
121   PassConfig->addIRPasses();
122 
123   addPassesToHandleExceptions(TM, PM);
124 
125   PassConfig->addISelPrepare();
126 
127   // Install a MachineModuleInfo class, which is an immutable pass that holds
128   // all the per-module stuff we're generating, including MCContext.
129   MachineModuleInfo *MMI =
130     new MachineModuleInfo(*TM->getMCAsmInfo(), *TM->getRegisterInfo(),
131                           &TM->getTargetLowering()->getObjFileLowering());
132   PM.add(MMI);
133   MCContext *Context = &MMI->getContext(); // Return the MCContext by-ref.
134 
135   // Set up a MachineFunction for the rest of CodeGen to work on.
136   PM.add(new MachineFunctionAnalysis(*TM));
137 
138   // Enable FastISel with -fast, but allow that to be overridden.
139   if (EnableFastISelOption == cl::BOU_TRUE ||
140       (TM->getOptLevel() == CodeGenOpt::None &&
141        EnableFastISelOption != cl::BOU_FALSE))
142     TM->setFastISel(true);
143 
144   // Ask the target for an isel.
145   if (PassConfig->addInstSelector())
146     return NULL;
147 
148   PassConfig->addMachinePasses();
149 
150   PassConfig->setInitialized();
151 
152   return Context;
153 }
154 
155 bool LLVMTargetMachine::addPassesToEmitFile(PassManagerBase &PM,
156                                             formatted_raw_ostream &Out,
157                                             CodeGenFileType FileType,
158                                             bool DisableVerify) {
159   // Add common CodeGen passes.
160   MCContext *Context = addPassesToGenerateCode(this, PM, DisableVerify);
161   if (!Context)
162     return true;
163 
164   if (hasMCSaveTempLabels())
165     Context->setAllowTemporaryLabels(false);
166 
167   const MCAsmInfo &MAI = *getMCAsmInfo();
168   const MCRegisterInfo &MRI = *getRegisterInfo();
169   const MCSubtargetInfo &STI = getSubtarget<MCSubtargetInfo>();
170   OwningPtr<MCStreamer> AsmStreamer;
171 
172   switch (FileType) {
173   case CGFT_AssemblyFile: {
174     MCInstPrinter *InstPrinter =
175       getTarget().createMCInstPrinter(MAI.getAssemblerDialect(), MAI,
176                                       *getInstrInfo(),
177                                       Context->getRegisterInfo(), STI);
178 
179     // Create a code emitter if asked to show the encoding.
180     MCCodeEmitter *MCE = 0;
181     MCAsmBackend *MAB = 0;
182     if (ShowMCEncoding) {
183       const MCSubtargetInfo &STI = getSubtarget<MCSubtargetInfo>();
184       MCE = getTarget().createMCCodeEmitter(*getInstrInfo(), MRI, STI,
185                                             *Context);
186       MAB = getTarget().createMCAsmBackend(getTargetTriple());
187     }
188 
189     MCStreamer *S = getTarget().createAsmStreamer(*Context, Out,
190                                                   getVerboseAsm(),
191                                                   hasMCUseLoc(),
192                                                   hasMCUseCFI(),
193                                                   hasMCUseDwarfDirectory(),
194                                                   InstPrinter,
195                                                   MCE, MAB,
196                                                   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(*getInstrInfo(), MRI,
204                                                          STI, *Context);
205     MCAsmBackend *MAB = getTarget().createMCAsmBackend(getTargetTriple());
206     if (MCE == 0 || MAB == 0)
207       return true;
208 
209     AsmStreamer.reset(getTarget().createMCObjectStreamer(getTargetTriple(),
210                                                          *Context, *MAB, Out,
211                                                          MCE, hasMCRelaxAll(),
212                                                          hasMCNoExecStack()));
213     AsmStreamer.get()->InitSections();
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(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 == 0)
226     return true;
227 
228   // If successful, createAsmPrinter took ownership of AsmStreamer.
229   AsmStreamer.take();
230 
231   PM.add(Printer);
232 
233   PM.add(createGCInfoDeleter());
234   return false;
235 }
236 
237 /// addPassesToEmitMachineCode - Add passes to the specified pass manager to
238 /// get machine code emitted.  This uses a JITCodeEmitter object to handle
239 /// actually outputting the machine code and resolving things like the address
240 /// of functions.  This method should returns true if machine code emission is
241 /// not supported.
242 ///
243 bool LLVMTargetMachine::addPassesToEmitMachineCode(PassManagerBase &PM,
244                                                    JITCodeEmitter &JCE,
245                                                    bool DisableVerify) {
246   // Add common CodeGen passes.
247   MCContext *Context = addPassesToGenerateCode(this, PM, DisableVerify);
248   if (!Context)
249     return true;
250 
251   addCodeEmitter(PM, JCE);
252   PM.add(createGCInfoDeleter());
253 
254   return false; // success!
255 }
256 
257 /// addPassesToEmitMC - Add passes to the specified pass manager to get
258 /// machine code emitted with the MCJIT. This method returns true if machine
259 /// code is not supported. It fills the MCContext Ctx pointer which can be
260 /// used to build custom MCStreamer.
261 ///
262 bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM,
263                                           MCContext *&Ctx,
264                                           raw_ostream &Out,
265                                           bool DisableVerify) {
266   // Add common CodeGen passes.
267   Ctx = addPassesToGenerateCode(this, PM, DisableVerify);
268   if (!Ctx)
269     return true;
270 
271   if (hasMCSaveTempLabels())
272     Ctx->setAllowTemporaryLabels(false);
273 
274   // Create the code emitter for the target if it exists.  If not, .o file
275   // emission fails.
276   const MCRegisterInfo &MRI = *getRegisterInfo();
277   const MCSubtargetInfo &STI = getSubtarget<MCSubtargetInfo>();
278   MCCodeEmitter *MCE = getTarget().createMCCodeEmitter(*getInstrInfo(), MRI,
279                                                        STI, *Ctx);
280   MCAsmBackend *MAB = getTarget().createMCAsmBackend(getTargetTriple());
281   if (MCE == 0 || MAB == 0)
282     return true;
283 
284   OwningPtr<MCStreamer> AsmStreamer;
285   AsmStreamer.reset(getTarget().createMCObjectStreamer(getTargetTriple(), *Ctx,
286                                                        *MAB, Out, MCE,
287                                                        hasMCRelaxAll(),
288                                                        hasMCNoExecStack()));
289   AsmStreamer.get()->InitSections();
290 
291   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
292   FunctionPass *Printer = getTarget().createAsmPrinter(*this, *AsmStreamer);
293   if (Printer == 0)
294     return true;
295 
296   // If successful, createAsmPrinter took ownership of AsmStreamer.
297   AsmStreamer.take();
298 
299   PM.add(Printer);
300 
301   return false; // success!
302 }
303