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 MCSubtargetInfo &STI = getSubtarget<MCSubtargetInfo>();
169   OwningPtr<MCStreamer> AsmStreamer;
170 
171   switch (FileType) {
172   case CGFT_AssemblyFile: {
173     MCInstPrinter *InstPrinter =
174       getTarget().createMCInstPrinter(MAI.getAssemblerDialect(), MAI,
175                                       Context->getRegisterInfo(), STI);
176 
177     // Create a code emitter if asked to show the encoding.
178     MCCodeEmitter *MCE = 0;
179     MCAsmBackend *MAB = 0;
180     if (ShowMCEncoding) {
181       const MCSubtargetInfo &STI = getSubtarget<MCSubtargetInfo>();
182       MCE = getTarget().createMCCodeEmitter(*getInstrInfo(), STI, *Context);
183       MAB = getTarget().createMCAsmBackend(getTargetTriple());
184     }
185 
186     MCStreamer *S = getTarget().createAsmStreamer(*Context, Out,
187                                                   getVerboseAsm(),
188                                                   hasMCUseLoc(),
189                                                   hasMCUseCFI(),
190                                                   hasMCUseDwarfDirectory(),
191                                                   InstPrinter,
192                                                   MCE, MAB,
193                                                   ShowMCInst);
194     AsmStreamer.reset(S);
195     break;
196   }
197   case CGFT_ObjectFile: {
198     // Create the code emitter for the target if it exists.  If not, .o file
199     // emission fails.
200     MCCodeEmitter *MCE = getTarget().createMCCodeEmitter(*getInstrInfo(), STI,
201                                                          *Context);
202     MCAsmBackend *MAB = getTarget().createMCAsmBackend(getTargetTriple());
203     if (MCE == 0 || MAB == 0)
204       return true;
205 
206     AsmStreamer.reset(getTarget().createMCObjectStreamer(getTargetTriple(),
207                                                          *Context, *MAB, Out,
208                                                          MCE, hasMCRelaxAll(),
209                                                          hasMCNoExecStack()));
210     AsmStreamer.get()->InitSections();
211     break;
212   }
213   case CGFT_Null:
214     // The Null output is intended for use for performance analysis and testing,
215     // not real users.
216     AsmStreamer.reset(createNullStreamer(*Context));
217     break;
218   }
219 
220   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
221   FunctionPass *Printer = getTarget().createAsmPrinter(*this, *AsmStreamer);
222   if (Printer == 0)
223     return true;
224 
225   // If successful, createAsmPrinter took ownership of AsmStreamer.
226   AsmStreamer.take();
227 
228   PM.add(Printer);
229 
230   PM.add(createGCInfoDeleter());
231   return false;
232 }
233 
234 /// addPassesToEmitMachineCode - Add passes to the specified pass manager to
235 /// get machine code emitted.  This uses a JITCodeEmitter object to handle
236 /// actually outputting the machine code and resolving things like the address
237 /// of functions.  This method should returns true if machine code emission is
238 /// not supported.
239 ///
240 bool LLVMTargetMachine::addPassesToEmitMachineCode(PassManagerBase &PM,
241                                                    JITCodeEmitter &JCE,
242                                                    bool DisableVerify) {
243   // Add common CodeGen passes.
244   MCContext *Context = addPassesToGenerateCode(this, PM, DisableVerify);
245   if (!Context)
246     return true;
247 
248   addCodeEmitter(PM, JCE);
249   PM.add(createGCInfoDeleter());
250 
251   return false; // success!
252 }
253 
254 /// addPassesToEmitMC - Add passes to the specified pass manager to get
255 /// machine code emitted with the MCJIT. This method returns true if machine
256 /// code is not supported. It fills the MCContext Ctx pointer which can be
257 /// used to build custom MCStreamer.
258 ///
259 bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM,
260                                           MCContext *&Ctx,
261                                           raw_ostream &Out,
262                                           bool DisableVerify) {
263   // Add common CodeGen passes.
264   Ctx = addPassesToGenerateCode(this, PM, DisableVerify);
265   if (!Ctx)
266     return true;
267 
268   if (hasMCSaveTempLabels())
269     Ctx->setAllowTemporaryLabels(false);
270 
271   // Create the code emitter for the target if it exists.  If not, .o file
272   // emission fails.
273   const MCSubtargetInfo &STI = getSubtarget<MCSubtargetInfo>();
274   MCCodeEmitter *MCE = getTarget().createMCCodeEmitter(*getInstrInfo(),STI,
275                                                        *Ctx);
276   MCAsmBackend *MAB = getTarget().createMCAsmBackend(getTargetTriple());
277   if (MCE == 0 || MAB == 0)
278     return true;
279 
280   OwningPtr<MCStreamer> AsmStreamer;
281   AsmStreamer.reset(getTarget().createMCObjectStreamer(getTargetTriple(), *Ctx,
282                                                        *MAB, Out, MCE,
283                                                        hasMCRelaxAll(),
284                                                        hasMCNoExecStack()));
285   AsmStreamer.get()->InitSections();
286 
287   // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
288   FunctionPass *Printer = getTarget().createAsmPrinter(*this, *AsmStreamer);
289   if (Printer == 0)
290     return true;
291 
292   // If successful, createAsmPrinter took ownership of AsmStreamer.
293   AsmStreamer.take();
294 
295   PM.add(Printer);
296 
297   return false; // success!
298 }
299