1 //===--- CodeGenAction.cpp - LLVM Code Generation Frontend Action ---------===//
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 #include "clang/CodeGen/CodeGenAction.h"
11 #include "clang/Basic/FileManager.h"
12 #include "clang/Basic/SourceManager.h"
13 #include "clang/Basic/TargetInfo.h"
14 #include "clang/AST/ASTConsumer.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/DeclGroup.h"
17 #include "clang/CodeGen/BackendUtil.h"
18 #include "clang/CodeGen/ModuleBuilder.h"
19 #include "clang/Frontend/CompilerInstance.h"
20 #include "clang/Frontend/FrontendDiagnostic.h"
21 #include "llvm/LLVMContext.h"
22 #include "llvm/Linker.h"
23 #include "llvm/Module.h"
24 #include "llvm/Pass.h"
25 #include "llvm/ADT/OwningPtr.h"
26 #include "llvm/Bitcode/ReaderWriter.h"
27 #include "llvm/Support/IRReader.h"
28 #include "llvm/Support/MemoryBuffer.h"
29 #include "llvm/Support/SourceMgr.h"
30 #include "llvm/Support/Timer.h"
31 using namespace clang;
32 using namespace llvm;
33 
34 namespace clang {
35   class BackendConsumer : public ASTConsumer {
36     DiagnosticsEngine &Diags;
37     BackendAction Action;
38     const CodeGenOptions &CodeGenOpts;
39     const TargetOptions &TargetOpts;
40     const LangOptions &LangOpts;
41     raw_ostream *AsmOutStream;
42     ASTContext *Context;
43 
44     Timer LLVMIRGeneration;
45 
46     llvm::OwningPtr<CodeGenerator> Gen;
47 
48     llvm::OwningPtr<llvm::Module> TheModule, LinkModule;
49 
50   public:
51     BackendConsumer(BackendAction action, DiagnosticsEngine &_Diags,
52                     const CodeGenOptions &compopts,
53                     const TargetOptions &targetopts,
54                     const LangOptions &langopts,
55                     bool TimePasses,
56                     const std::string &infile,
57                     llvm::Module *LinkModule,
58                     raw_ostream *OS,
59                     LLVMContext &C) :
60       Diags(_Diags),
61       Action(action),
62       CodeGenOpts(compopts),
63       TargetOpts(targetopts),
64       LangOpts(langopts),
65       AsmOutStream(OS),
66       LLVMIRGeneration("LLVM IR Generation Time"),
67       Gen(CreateLLVMCodeGen(Diags, infile, compopts, C)),
68       LinkModule(LinkModule) {
69       llvm::TimePassesIsEnabled = TimePasses;
70     }
71 
72     llvm::Module *takeModule() { return TheModule.take(); }
73     llvm::Module *takeLinkModule() { return LinkModule.take(); }
74 
75     virtual void Initialize(ASTContext &Ctx) {
76       Context = &Ctx;
77 
78       if (llvm::TimePassesIsEnabled)
79         LLVMIRGeneration.startTimer();
80 
81       Gen->Initialize(Ctx);
82 
83       TheModule.reset(Gen->GetModule());
84 
85       if (llvm::TimePassesIsEnabled)
86         LLVMIRGeneration.stopTimer();
87     }
88 
89     virtual void HandleTopLevelDecl(DeclGroupRef D) {
90       PrettyStackTraceDecl CrashInfo(*D.begin(), SourceLocation(),
91                                      Context->getSourceManager(),
92                                      "LLVM IR generation of declaration");
93 
94       if (llvm::TimePassesIsEnabled)
95         LLVMIRGeneration.startTimer();
96 
97       Gen->HandleTopLevelDecl(D);
98 
99       if (llvm::TimePassesIsEnabled)
100         LLVMIRGeneration.stopTimer();
101     }
102 
103     virtual void HandleTranslationUnit(ASTContext &C) {
104       {
105         PrettyStackTraceString CrashInfo("Per-file LLVM IR generation");
106         if (llvm::TimePassesIsEnabled)
107           LLVMIRGeneration.startTimer();
108 
109         Gen->HandleTranslationUnit(C);
110 
111         if (llvm::TimePassesIsEnabled)
112           LLVMIRGeneration.stopTimer();
113       }
114 
115       // Silently ignore if we weren't initialized for some reason.
116       if (!TheModule)
117         return;
118 
119       // Make sure IR generation is happy with the module. This is released by
120       // the module provider.
121       Module *M = Gen->ReleaseModule();
122       if (!M) {
123         // The module has been released by IR gen on failures, do not double
124         // free.
125         TheModule.take();
126         return;
127       }
128 
129       assert(TheModule.get() == M &&
130              "Unexpected module change during IR generation");
131 
132       // Link LinkModule into this module if present, preserving its validity.
133       if (LinkModule) {
134         std::string ErrorMsg;
135         if (Linker::LinkModules(M, LinkModule.get(), Linker::PreserveSource,
136                                 &ErrorMsg)) {
137           Diags.Report(diag::err_fe_cannot_link_module)
138             << LinkModule->getModuleIdentifier() << ErrorMsg;
139           return;
140         }
141       }
142 
143       // Install an inline asm handler so that diagnostics get printed through
144       // our diagnostics hooks.
145       LLVMContext &Ctx = TheModule->getContext();
146       LLVMContext::InlineAsmDiagHandlerTy OldHandler =
147         Ctx.getInlineAsmDiagnosticHandler();
148       void *OldContext = Ctx.getInlineAsmDiagnosticContext();
149       Ctx.setInlineAsmDiagnosticHandler(InlineAsmDiagHandler, this);
150 
151       EmitBackendOutput(Diags, CodeGenOpts, TargetOpts, LangOpts,
152                         TheModule.get(), Action, AsmOutStream);
153 
154       Ctx.setInlineAsmDiagnosticHandler(OldHandler, OldContext);
155     }
156 
157     virtual void HandleTagDeclDefinition(TagDecl *D) {
158       PrettyStackTraceDecl CrashInfo(D, SourceLocation(),
159                                      Context->getSourceManager(),
160                                      "LLVM IR generation of declaration");
161       Gen->HandleTagDeclDefinition(D);
162     }
163 
164     virtual void CompleteTentativeDefinition(VarDecl *D) {
165       Gen->CompleteTentativeDefinition(D);
166     }
167 
168     virtual void HandleVTable(CXXRecordDecl *RD, bool DefinitionRequired) {
169       Gen->HandleVTable(RD, DefinitionRequired);
170     }
171 
172     static void InlineAsmDiagHandler(const llvm::SMDiagnostic &SM,void *Context,
173                                      unsigned LocCookie) {
174       SourceLocation Loc = SourceLocation::getFromRawEncoding(LocCookie);
175       ((BackendConsumer*)Context)->InlineAsmDiagHandler2(SM, Loc);
176     }
177 
178     void InlineAsmDiagHandler2(const llvm::SMDiagnostic &,
179                                SourceLocation LocCookie);
180   };
181 }
182 
183 /// ConvertBackendLocation - Convert a location in a temporary llvm::SourceMgr
184 /// buffer to be a valid FullSourceLoc.
185 static FullSourceLoc ConvertBackendLocation(const llvm::SMDiagnostic &D,
186                                             SourceManager &CSM) {
187   // Get both the clang and llvm source managers.  The location is relative to
188   // a memory buffer that the LLVM Source Manager is handling, we need to add
189   // a copy to the Clang source manager.
190   const llvm::SourceMgr &LSM = *D.getSourceMgr();
191 
192   // We need to copy the underlying LLVM memory buffer because llvm::SourceMgr
193   // already owns its one and clang::SourceManager wants to own its one.
194   const MemoryBuffer *LBuf =
195   LSM.getMemoryBuffer(LSM.FindBufferContainingLoc(D.getLoc()));
196 
197   // Create the copy and transfer ownership to clang::SourceManager.
198   llvm::MemoryBuffer *CBuf =
199   llvm::MemoryBuffer::getMemBufferCopy(LBuf->getBuffer(),
200                                        LBuf->getBufferIdentifier());
201   FileID FID = CSM.createFileIDForMemBuffer(CBuf);
202 
203   // Translate the offset into the file.
204   unsigned Offset = D.getLoc().getPointer()  - LBuf->getBufferStart();
205   SourceLocation NewLoc =
206   CSM.getLocForStartOfFile(FID).getLocWithOffset(Offset);
207   return FullSourceLoc(NewLoc, CSM);
208 }
209 
210 
211 /// InlineAsmDiagHandler2 - This function is invoked when the backend hits an
212 /// error parsing inline asm.  The SMDiagnostic indicates the error relative to
213 /// the temporary memory buffer that the inline asm parser has set up.
214 void BackendConsumer::InlineAsmDiagHandler2(const llvm::SMDiagnostic &D,
215                                             SourceLocation LocCookie) {
216   // There are a couple of different kinds of errors we could get here.  First,
217   // we re-format the SMDiagnostic in terms of a clang diagnostic.
218 
219   // Strip "error: " off the start of the message string.
220   StringRef Message = D.getMessage();
221   if (Message.startswith("error: "))
222     Message = Message.substr(7);
223 
224   // If the SMDiagnostic has an inline asm source location, translate it.
225   FullSourceLoc Loc;
226   if (D.getLoc() != SMLoc())
227     Loc = ConvertBackendLocation(D, Context->getSourceManager());
228 
229 
230   // If this problem has clang-level source location information, report the
231   // issue as being an error in the source with a note showing the instantiated
232   // code.
233   if (LocCookie.isValid()) {
234     Diags.Report(LocCookie, diag::err_fe_inline_asm).AddString(Message);
235 
236     if (D.getLoc().isValid()) {
237       DiagnosticBuilder B = Diags.Report(Loc, diag::note_fe_inline_asm_here);
238       // Convert the SMDiagnostic ranges into SourceRange and attach them
239       // to the diagnostic.
240       for (unsigned i = 0, e = D.getRanges().size(); i != e; ++i) {
241         std::pair<unsigned, unsigned> Range = D.getRanges()[i];
242         unsigned Column = D.getColumnNo();
243         B << SourceRange(Loc.getLocWithOffset(Range.first - Column),
244                          Loc.getLocWithOffset(Range.second - Column));
245       }
246     }
247     return;
248   }
249 
250   // Otherwise, report the backend error as occurring in the generated .s file.
251   // If Loc is invalid, we still need to report the error, it just gets no
252   // location info.
253   Diags.Report(Loc, diag::err_fe_inline_asm).AddString(Message);
254 }
255 
256 //
257 
258 CodeGenAction::CodeGenAction(unsigned _Act, LLVMContext *_VMContext)
259   : Act(_Act), LinkModule(0),
260     VMContext(_VMContext ? _VMContext : new LLVMContext),
261     OwnsVMContext(!_VMContext) {}
262 
263 CodeGenAction::~CodeGenAction() {
264   TheModule.reset();
265   if (OwnsVMContext)
266     delete VMContext;
267 }
268 
269 bool CodeGenAction::hasIRSupport() const { return true; }
270 
271 void CodeGenAction::EndSourceFileAction() {
272   // If the consumer creation failed, do nothing.
273   if (!getCompilerInstance().hasASTConsumer())
274     return;
275 
276   // If we were given a link module, release consumer's ownership of it.
277   if (LinkModule)
278     BEConsumer->takeLinkModule();
279 
280   // Steal the module from the consumer.
281   TheModule.reset(BEConsumer->takeModule());
282 }
283 
284 llvm::Module *CodeGenAction::takeModule() {
285   return TheModule.take();
286 }
287 
288 llvm::LLVMContext *CodeGenAction::takeLLVMContext() {
289   OwnsVMContext = false;
290   return VMContext;
291 }
292 
293 static raw_ostream *GetOutputStream(CompilerInstance &CI,
294                                     StringRef InFile,
295                                     BackendAction Action) {
296   switch (Action) {
297   case Backend_EmitAssembly:
298     return CI.createDefaultOutputFile(false, InFile, "s");
299   case Backend_EmitLL:
300     return CI.createDefaultOutputFile(false, InFile, "ll");
301   case Backend_EmitBC:
302     return CI.createDefaultOutputFile(true, InFile, "bc");
303   case Backend_EmitNothing:
304     return 0;
305   case Backend_EmitMCNull:
306   case Backend_EmitObj:
307     return CI.createDefaultOutputFile(true, InFile, "o");
308   }
309 
310   llvm_unreachable("Invalid action!");
311 }
312 
313 ASTConsumer *CodeGenAction::CreateASTConsumer(CompilerInstance &CI,
314                                               StringRef InFile) {
315   BackendAction BA = static_cast<BackendAction>(Act);
316   llvm::OwningPtr<raw_ostream> OS(GetOutputStream(CI, InFile, BA));
317   if (BA != Backend_EmitNothing && !OS)
318     return 0;
319 
320   llvm::Module *LinkModuleToUse = LinkModule;
321 
322   // If we were not given a link module, and the user requested that one be
323   // loaded from bitcode, do so now.
324   const std::string &LinkBCFile = CI.getCodeGenOpts().LinkBitcodeFile;
325   if (!LinkModuleToUse && !LinkBCFile.empty()) {
326     std::string ErrorStr;
327 
328     llvm::MemoryBuffer *BCBuf =
329       CI.getFileManager().getBufferForFile(LinkBCFile, &ErrorStr);
330     if (!BCBuf) {
331       CI.getDiagnostics().Report(diag::err_cannot_open_file)
332         << LinkBCFile << ErrorStr;
333       return 0;
334     }
335 
336     LinkModuleToUse = getLazyBitcodeModule(BCBuf, *VMContext, &ErrorStr);
337     if (!LinkModuleToUse) {
338       CI.getDiagnostics().Report(diag::err_cannot_open_file)
339         << LinkBCFile << ErrorStr;
340       return 0;
341     }
342   }
343 
344   BEConsumer =
345       new BackendConsumer(BA, CI.getDiagnostics(),
346                           CI.getCodeGenOpts(), CI.getTargetOpts(),
347                           CI.getLangOpts(),
348                           CI.getFrontendOpts().ShowTimers, InFile,
349                           LinkModuleToUse, OS.take(), *VMContext);
350   return BEConsumer;
351 }
352 
353 void CodeGenAction::ExecuteAction() {
354   // If this is an IR file, we have to treat it specially.
355   if (getCurrentFileKind() == IK_LLVM_IR) {
356     BackendAction BA = static_cast<BackendAction>(Act);
357     CompilerInstance &CI = getCompilerInstance();
358     raw_ostream *OS = GetOutputStream(CI, getCurrentFile(), BA);
359     if (BA != Backend_EmitNothing && !OS)
360       return;
361 
362     bool Invalid;
363     SourceManager &SM = CI.getSourceManager();
364     const llvm::MemoryBuffer *MainFile = SM.getBuffer(SM.getMainFileID(),
365                                                       &Invalid);
366     if (Invalid)
367       return;
368 
369     // FIXME: This is stupid, IRReader shouldn't take ownership.
370     llvm::MemoryBuffer *MainFileCopy =
371       llvm::MemoryBuffer::getMemBufferCopy(MainFile->getBuffer(),
372                                            getCurrentFile().c_str());
373 
374     llvm::SMDiagnostic Err;
375     TheModule.reset(ParseIR(MainFileCopy, Err, *VMContext));
376     if (!TheModule) {
377       // Translate from the diagnostic info to the SourceManager location.
378       SourceLocation Loc = SM.translateFileLineCol(
379         SM.getFileEntryForID(SM.getMainFileID()), Err.getLineNo(),
380         Err.getColumnNo() + 1);
381 
382       // Get a custom diagnostic for the error. We strip off a leading
383       // diagnostic code if there is one.
384       StringRef Msg = Err.getMessage();
385       if (Msg.startswith("error: "))
386         Msg = Msg.substr(7);
387       unsigned DiagID = CI.getDiagnostics().getCustomDiagID(
388           DiagnosticsEngine::Error, Msg);
389 
390       CI.getDiagnostics().Report(Loc, DiagID);
391       return;
392     }
393 
394     EmitBackendOutput(CI.getDiagnostics(), CI.getCodeGenOpts(),
395                       CI.getTargetOpts(), CI.getLangOpts(),
396                       TheModule.get(),
397                       BA, OS);
398     return;
399   }
400 
401   // Otherwise follow the normal AST path.
402   this->ASTFrontendAction::ExecuteAction();
403 }
404 
405 //
406 
407 EmitAssemblyAction::EmitAssemblyAction(llvm::LLVMContext *_VMContext)
408   : CodeGenAction(Backend_EmitAssembly, _VMContext) {}
409 
410 EmitBCAction::EmitBCAction(llvm::LLVMContext *_VMContext)
411   : CodeGenAction(Backend_EmitBC, _VMContext) {}
412 
413 EmitLLVMAction::EmitLLVMAction(llvm::LLVMContext *_VMContext)
414   : CodeGenAction(Backend_EmitLL, _VMContext) {}
415 
416 EmitLLVMOnlyAction::EmitLLVMOnlyAction(llvm::LLVMContext *_VMContext)
417   : CodeGenAction(Backend_EmitNothing, _VMContext) {}
418 
419 EmitCodeGenOnlyAction::EmitCodeGenOnlyAction(llvm::LLVMContext *_VMContext)
420   : CodeGenAction(Backend_EmitMCNull, _VMContext) {}
421 
422 EmitObjAction::EmitObjAction(llvm::LLVMContext *_VMContext)
423   : CodeGenAction(Backend_EmitObj, _VMContext) {}
424