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1 //===-- LTOModule.cpp - LLVM Link Time Optimizer --------------------------===//
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 Link Time Optimization library. This library is
11 // intended to be used by linker to optimize code at link time.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "LTOModule.h"
16 #include "llvm/Constants.h"
17 #include "llvm/LLVMContext.h"
18 #include "llvm/Module.h"
19 #include "llvm/Bitcode/ReaderWriter.h"
20 #include "llvm/MC/MCExpr.h"
21 #include "llvm/MC/MCInst.h"
22 #include "llvm/MC/MCStreamer.h"
23 #include "llvm/MC/MCSubtargetInfo.h"
24 #include "llvm/MC/MCSymbol.h"
25 #include "llvm/MC/MCTargetAsmParser.h"
26 #include "llvm/MC/SubtargetFeature.h"
27 #include "llvm/MC/MCParser/MCAsmParser.h"
28 #include "llvm/Target/TargetRegisterInfo.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/Host.h"
31 #include "llvm/Support/MemoryBuffer.h"
32 #include "llvm/Support/Path.h"
33 #include "llvm/Support/SourceMgr.h"
34 #include "llvm/Support/TargetRegistry.h"
35 #include "llvm/Support/TargetSelect.h"
36 #include "llvm/Support/system_error.h"
37 #include "llvm/ADT/OwningPtr.h"
38 #include "llvm/ADT/Triple.h"
39 using namespace llvm;
40 
41 static cl::opt<bool>
42 EnableFPMAD("enable-fp-mad",
43   cl::desc("Enable less precise MAD instructions to be generated"),
44   cl::init(false));
45 
46 static cl::opt<bool>
47 DisableFPElim("disable-fp-elim",
48   cl::desc("Disable frame pointer elimination optimization"),
49   cl::init(false));
50 
51 static cl::opt<bool>
52 DisableFPElimNonLeaf("disable-non-leaf-fp-elim",
53   cl::desc("Disable frame pointer elimination optimization for non-leaf funcs"),
54   cl::init(false));
55 
56 static cl::opt<bool>
57 EnableUnsafeFPMath("enable-unsafe-fp-math",
58   cl::desc("Enable optimizations that may decrease FP precision"),
59   cl::init(false));
60 
61 static cl::opt<bool>
62 EnableNoInfsFPMath("enable-no-infs-fp-math",
63   cl::desc("Enable FP math optimizations that assume no +-Infs"),
64   cl::init(false));
65 
66 static cl::opt<bool>
67 EnableNoNaNsFPMath("enable-no-nans-fp-math",
68   cl::desc("Enable FP math optimizations that assume no NaNs"),
69   cl::init(false));
70 
71 static cl::opt<bool>
72 EnableHonorSignDependentRoundingFPMath("enable-sign-dependent-rounding-fp-math",
73   cl::Hidden,
74   cl::desc("Force codegen to assume rounding mode can change dynamically"),
75   cl::init(false));
76 
77 static cl::opt<bool>
78 GenerateSoftFloatCalls("soft-float",
79   cl::desc("Generate software floating point library calls"),
80   cl::init(false));
81 
82 static cl::opt<llvm::FloatABI::ABIType>
83 FloatABIForCalls("float-abi",
84   cl::desc("Choose float ABI type"),
85   cl::init(FloatABI::Default),
86   cl::values(
87     clEnumValN(FloatABI::Default, "default",
88                "Target default float ABI type"),
89     clEnumValN(FloatABI::Soft, "soft",
90                "Soft float ABI (implied by -soft-float)"),
91     clEnumValN(FloatABI::Hard, "hard",
92                "Hard float ABI (uses FP registers)"),
93     clEnumValEnd));
94 
95 static cl::opt<llvm::FPOpFusion::FPOpFusionMode>
96 FuseFPOps("fp-contract",
97   cl::desc("Enable aggresive formation of fused FP ops"),
98   cl::init(FPOpFusion::Standard),
99   cl::values(
100     clEnumValN(FPOpFusion::Fast, "fast",
101                "Fuse FP ops whenever profitable"),
102     clEnumValN(FPOpFusion::Standard, "on",
103                "Only fuse 'blessed' FP ops."),
104     clEnumValN(FPOpFusion::Strict, "off",
105                "Only fuse FP ops when the result won't be effected."),
106     clEnumValEnd));
107 
108 static cl::opt<bool>
109 DontPlaceZerosInBSS("nozero-initialized-in-bss",
110   cl::desc("Don't place zero-initialized symbols into bss section"),
111   cl::init(false));
112 
113 static cl::opt<bool>
114 EnableGuaranteedTailCallOpt("tailcallopt",
115   cl::desc("Turn fastcc calls into tail calls by (potentially) changing ABI."),
116   cl::init(false));
117 
118 static cl::opt<bool>
119 DisableTailCalls("disable-tail-calls",
120   cl::desc("Never emit tail calls"),
121   cl::init(false));
122 
123 static cl::opt<unsigned>
124 OverrideStackAlignment("stack-alignment",
125   cl::desc("Override default stack alignment"),
126   cl::init(0));
127 
128 static cl::opt<bool>
129 EnableRealignStack("realign-stack",
130   cl::desc("Realign stack if needed"),
131   cl::init(true));
132 
133 static cl::opt<std::string>
134 TrapFuncName("trap-func", cl::Hidden,
135   cl::desc("Emit a call to trap function rather than a trap instruction"),
136   cl::init(""));
137 
138 static cl::opt<bool>
139 EnablePIE("enable-pie",
140   cl::desc("Assume the creation of a position independent executable."),
141   cl::init(false));
142 
143 static cl::opt<bool>
144 SegmentedStacks("segmented-stacks",
145   cl::desc("Use segmented stacks if possible."),
146   cl::init(false));
147 
148 static cl::opt<bool>
149 UseInitArray("use-init-array",
150   cl::desc("Use .init_array instead of .ctors."),
151   cl::init(false));
152 
153 static cl::opt<unsigned>
154 SSPBufferSize("stack-protector-buffer-size", cl::init(8),
155               cl::desc("Lower bound for a buffer to be considered for "
156                        "stack protection"));
157 
LTOModule(llvm::Module * m,llvm::TargetMachine * t)158 LTOModule::LTOModule(llvm::Module *m, llvm::TargetMachine *t)
159   : _module(m), _target(t),
160     _context(*_target->getMCAsmInfo(), *_target->getRegisterInfo(), NULL),
161     _mangler(_context, *_target->getTargetData()) {}
162 
163 /// isBitcodeFile - Returns 'true' if the file (or memory contents) is LLVM
164 /// bitcode.
isBitcodeFile(const void * mem,size_t length)165 bool LTOModule::isBitcodeFile(const void *mem, size_t length) {
166   return llvm::sys::IdentifyFileType((const char*)mem, length)
167     == llvm::sys::Bitcode_FileType;
168 }
169 
isBitcodeFile(const char * path)170 bool LTOModule::isBitcodeFile(const char *path) {
171   return llvm::sys::Path(path).isBitcodeFile();
172 }
173 
174 /// isBitcodeFileForTarget - Returns 'true' if the file (or memory contents) is
175 /// LLVM bitcode for the specified triple.
isBitcodeFileForTarget(const void * mem,size_t length,const char * triplePrefix)176 bool LTOModule::isBitcodeFileForTarget(const void *mem, size_t length,
177                                        const char *triplePrefix) {
178   MemoryBuffer *buffer = makeBuffer(mem, length);
179   if (!buffer)
180     return false;
181   return isTargetMatch(buffer, triplePrefix);
182 }
183 
isBitcodeFileForTarget(const char * path,const char * triplePrefix)184 bool LTOModule::isBitcodeFileForTarget(const char *path,
185                                        const char *triplePrefix) {
186   OwningPtr<MemoryBuffer> buffer;
187   if (MemoryBuffer::getFile(path, buffer))
188     return false;
189   return isTargetMatch(buffer.take(), triplePrefix);
190 }
191 
192 /// isTargetMatch - Returns 'true' if the memory buffer is for the specified
193 /// target triple.
isTargetMatch(MemoryBuffer * buffer,const char * triplePrefix)194 bool LTOModule::isTargetMatch(MemoryBuffer *buffer, const char *triplePrefix) {
195   std::string Triple = getBitcodeTargetTriple(buffer, getGlobalContext());
196   delete buffer;
197   return strncmp(Triple.c_str(), triplePrefix, strlen(triplePrefix)) == 0;
198 }
199 
200 /// makeLTOModule - Create an LTOModule. N.B. These methods take ownership of
201 /// the buffer.
makeLTOModule(const char * path,std::string & errMsg)202 LTOModule *LTOModule::makeLTOModule(const char *path, std::string &errMsg) {
203   OwningPtr<MemoryBuffer> buffer;
204   if (error_code ec = MemoryBuffer::getFile(path, buffer)) {
205     errMsg = ec.message();
206     return NULL;
207   }
208   return makeLTOModule(buffer.take(), errMsg);
209 }
210 
makeLTOModule(int fd,const char * path,size_t size,std::string & errMsg)211 LTOModule *LTOModule::makeLTOModule(int fd, const char *path,
212                                     size_t size, std::string &errMsg) {
213   return makeLTOModule(fd, path, size, size, 0, errMsg);
214 }
215 
makeLTOModule(int fd,const char * path,size_t file_size,size_t map_size,off_t offset,std::string & errMsg)216 LTOModule *LTOModule::makeLTOModule(int fd, const char *path,
217                                     size_t file_size,
218                                     size_t map_size,
219                                     off_t offset,
220                                     std::string &errMsg) {
221   OwningPtr<MemoryBuffer> buffer;
222   if (error_code ec = MemoryBuffer::getOpenFile(fd, path, buffer, file_size,
223                                                 map_size, offset, false)) {
224     errMsg = ec.message();
225     return NULL;
226   }
227   return makeLTOModule(buffer.take(), errMsg);
228 }
229 
makeLTOModule(const void * mem,size_t length,std::string & errMsg)230 LTOModule *LTOModule::makeLTOModule(const void *mem, size_t length,
231                                     std::string &errMsg) {
232   OwningPtr<MemoryBuffer> buffer(makeBuffer(mem, length));
233   if (!buffer)
234     return NULL;
235   return makeLTOModule(buffer.take(), errMsg);
236 }
237 
getTargetOptions(TargetOptions & Options)238 void LTOModule::getTargetOptions(TargetOptions &Options) {
239   Options.LessPreciseFPMADOption = EnableFPMAD;
240   Options.NoFramePointerElim = DisableFPElim;
241   Options.NoFramePointerElimNonLeaf = DisableFPElimNonLeaf;
242   Options.AllowFPOpFusion = FuseFPOps;
243   Options.UnsafeFPMath = EnableUnsafeFPMath;
244   Options.NoInfsFPMath = EnableNoInfsFPMath;
245   Options.NoNaNsFPMath = EnableNoNaNsFPMath;
246   Options.HonorSignDependentRoundingFPMathOption =
247     EnableHonorSignDependentRoundingFPMath;
248   Options.UseSoftFloat = GenerateSoftFloatCalls;
249   if (FloatABIForCalls != FloatABI::Default)
250     Options.FloatABIType = FloatABIForCalls;
251   Options.NoZerosInBSS = DontPlaceZerosInBSS;
252   Options.GuaranteedTailCallOpt = EnableGuaranteedTailCallOpt;
253   Options.DisableTailCalls = DisableTailCalls;
254   Options.StackAlignmentOverride = OverrideStackAlignment;
255   Options.RealignStack = EnableRealignStack;
256   Options.TrapFuncName = TrapFuncName;
257   Options.PositionIndependentExecutable = EnablePIE;
258   Options.EnableSegmentedStacks = SegmentedStacks;
259   Options.UseInitArray = UseInitArray;
260   Options.SSPBufferSize = SSPBufferSize;
261 }
262 
makeLTOModule(MemoryBuffer * buffer,std::string & errMsg)263 LTOModule *LTOModule::makeLTOModule(MemoryBuffer *buffer,
264                                     std::string &errMsg) {
265   static bool Initialized = false;
266   if (!Initialized) {
267     InitializeAllTargets();
268     InitializeAllTargetMCs();
269     InitializeAllAsmParsers();
270     Initialized = true;
271   }
272 
273   // parse bitcode buffer
274   OwningPtr<Module> m(getLazyBitcodeModule(buffer, getGlobalContext(),
275                                            &errMsg));
276   if (!m) {
277     delete buffer;
278     return NULL;
279   }
280 
281   std::string Triple = m->getTargetTriple();
282   if (Triple.empty())
283     Triple = sys::getDefaultTargetTriple();
284 
285   // find machine architecture for this module
286   const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
287   if (!march)
288     return NULL;
289 
290   // construct LTOModule, hand over ownership of module and target
291   SubtargetFeatures Features;
292   Features.getDefaultSubtargetFeatures(llvm::Triple(Triple));
293   std::string FeatureStr = Features.getString();
294   std::string CPU;
295   TargetOptions Options;
296   getTargetOptions(Options);
297   TargetMachine *target = march->createTargetMachine(Triple, CPU, FeatureStr,
298                                                      Options);
299   LTOModule *Ret = new LTOModule(m.take(), target);
300   if (Ret->parseSymbols(errMsg)) {
301     delete Ret;
302     return NULL;
303   }
304 
305   return Ret;
306 }
307 
308 /// makeBuffer - Create a MemoryBuffer from a memory range.
makeBuffer(const void * mem,size_t length)309 MemoryBuffer *LTOModule::makeBuffer(const void *mem, size_t length) {
310   const char *startPtr = (const char*)mem;
311   return MemoryBuffer::getMemBuffer(StringRef(startPtr, length), "", false);
312 }
313 
314 /// objcClassNameFromExpression - Get string that the data pointer points to.
objcClassNameFromExpression(Constant * c,std::string & name)315 bool LTOModule::objcClassNameFromExpression(Constant *c, std::string &name) {
316   if (ConstantExpr *ce = dyn_cast<ConstantExpr>(c)) {
317     Constant *op = ce->getOperand(0);
318     if (GlobalVariable *gvn = dyn_cast<GlobalVariable>(op)) {
319       Constant *cn = gvn->getInitializer();
320       if (ConstantDataArray *ca = dyn_cast<ConstantDataArray>(cn)) {
321         if (ca->isCString()) {
322           name = ".objc_class_name_" + ca->getAsCString().str();
323           return true;
324         }
325       }
326     }
327   }
328   return false;
329 }
330 
331 /// addObjCClass - Parse i386/ppc ObjC class data structure.
addObjCClass(GlobalVariable * clgv)332 void LTOModule::addObjCClass(GlobalVariable *clgv) {
333   ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer());
334   if (!c) return;
335 
336   // second slot in __OBJC,__class is pointer to superclass name
337   std::string superclassName;
338   if (objcClassNameFromExpression(c->getOperand(1), superclassName)) {
339     NameAndAttributes info;
340     StringMap<NameAndAttributes>::value_type &entry =
341       _undefines.GetOrCreateValue(superclassName);
342     if (!entry.getValue().name) {
343       const char *symbolName = entry.getKey().data();
344       info.name = symbolName;
345       info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
346       info.isFunction = false;
347       info.symbol = clgv;
348       entry.setValue(info);
349     }
350   }
351 
352   // third slot in __OBJC,__class is pointer to class name
353   std::string className;
354   if (objcClassNameFromExpression(c->getOperand(2), className)) {
355     StringSet::value_type &entry = _defines.GetOrCreateValue(className);
356     entry.setValue(1);
357 
358     NameAndAttributes info;
359     info.name = entry.getKey().data();
360     info.attributes = LTO_SYMBOL_PERMISSIONS_DATA |
361       LTO_SYMBOL_DEFINITION_REGULAR | LTO_SYMBOL_SCOPE_DEFAULT;
362     info.isFunction = false;
363     info.symbol = clgv;
364     _symbols.push_back(info);
365   }
366 }
367 
368 /// addObjCCategory - Parse i386/ppc ObjC category data structure.
addObjCCategory(GlobalVariable * clgv)369 void LTOModule::addObjCCategory(GlobalVariable *clgv) {
370   ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer());
371   if (!c) return;
372 
373   // second slot in __OBJC,__category is pointer to target class name
374   std::string targetclassName;
375   if (!objcClassNameFromExpression(c->getOperand(1), targetclassName))
376     return;
377 
378   NameAndAttributes info;
379   StringMap<NameAndAttributes>::value_type &entry =
380     _undefines.GetOrCreateValue(targetclassName);
381 
382   if (entry.getValue().name)
383     return;
384 
385   const char *symbolName = entry.getKey().data();
386   info.name = symbolName;
387   info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
388   info.isFunction = false;
389   info.symbol = clgv;
390   entry.setValue(info);
391 }
392 
393 /// addObjCClassRef - Parse i386/ppc ObjC class list data structure.
addObjCClassRef(GlobalVariable * clgv)394 void LTOModule::addObjCClassRef(GlobalVariable *clgv) {
395   std::string targetclassName;
396   if (!objcClassNameFromExpression(clgv->getInitializer(), targetclassName))
397     return;
398 
399   NameAndAttributes info;
400   StringMap<NameAndAttributes>::value_type &entry =
401     _undefines.GetOrCreateValue(targetclassName);
402   if (entry.getValue().name)
403     return;
404 
405   const char *symbolName = entry.getKey().data();
406   info.name = symbolName;
407   info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
408   info.isFunction = false;
409   info.symbol = clgv;
410   entry.setValue(info);
411 }
412 
413 /// addDefinedDataSymbol - Add a data symbol as defined to the list.
addDefinedDataSymbol(GlobalValue * v)414 void LTOModule::addDefinedDataSymbol(GlobalValue *v) {
415   // Add to list of defined symbols.
416   addDefinedSymbol(v, false);
417 
418   if (!v->hasSection() /* || !isTargetDarwin */)
419     return;
420 
421   // Special case i386/ppc ObjC data structures in magic sections:
422   // The issue is that the old ObjC object format did some strange
423   // contortions to avoid real linker symbols.  For instance, the
424   // ObjC class data structure is allocated statically in the executable
425   // that defines that class.  That data structures contains a pointer to
426   // its superclass.  But instead of just initializing that part of the
427   // struct to the address of its superclass, and letting the static and
428   // dynamic linkers do the rest, the runtime works by having that field
429   // instead point to a C-string that is the name of the superclass.
430   // At runtime the objc initialization updates that pointer and sets
431   // it to point to the actual super class.  As far as the linker
432   // knows it is just a pointer to a string.  But then someone wanted the
433   // linker to issue errors at build time if the superclass was not found.
434   // So they figured out a way in mach-o object format to use an absolute
435   // symbols (.objc_class_name_Foo = 0) and a floating reference
436   // (.reference .objc_class_name_Bar) to cause the linker into erroring when
437   // a class was missing.
438   // The following synthesizes the implicit .objc_* symbols for the linker
439   // from the ObjC data structures generated by the front end.
440 
441   // special case if this data blob is an ObjC class definition
442   if (v->getSection().compare(0, 15, "__OBJC,__class,") == 0) {
443     if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
444       addObjCClass(gv);
445     }
446   }
447 
448   // special case if this data blob is an ObjC category definition
449   else if (v->getSection().compare(0, 18, "__OBJC,__category,") == 0) {
450     if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
451       addObjCCategory(gv);
452     }
453   }
454 
455   // special case if this data blob is the list of referenced classes
456   else if (v->getSection().compare(0, 18, "__OBJC,__cls_refs,") == 0) {
457     if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
458       addObjCClassRef(gv);
459     }
460   }
461 }
462 
463 /// addDefinedFunctionSymbol - Add a function symbol as defined to the list.
addDefinedFunctionSymbol(Function * f)464 void LTOModule::addDefinedFunctionSymbol(Function *f) {
465   // add to list of defined symbols
466   addDefinedSymbol(f, true);
467 }
468 
469 /// addDefinedSymbol - Add a defined symbol to the list.
addDefinedSymbol(GlobalValue * def,bool isFunction)470 void LTOModule::addDefinedSymbol(GlobalValue *def, bool isFunction) {
471   // ignore all llvm.* symbols
472   if (def->getName().startswith("llvm."))
473     return;
474 
475   // string is owned by _defines
476   SmallString<64> Buffer;
477   _mangler.getNameWithPrefix(Buffer, def, false);
478 
479   // set alignment part log2() can have rounding errors
480   uint32_t align = def->getAlignment();
481   uint32_t attr = align ? CountTrailingZeros_32(def->getAlignment()) : 0;
482 
483   // set permissions part
484   if (isFunction) {
485     attr |= LTO_SYMBOL_PERMISSIONS_CODE;
486   } else {
487     GlobalVariable *gv = dyn_cast<GlobalVariable>(def);
488     if (gv && gv->isConstant())
489       attr |= LTO_SYMBOL_PERMISSIONS_RODATA;
490     else
491       attr |= LTO_SYMBOL_PERMISSIONS_DATA;
492   }
493 
494   // set definition part
495   if (def->hasWeakLinkage() || def->hasLinkOnceLinkage() ||
496       def->hasLinkerPrivateWeakLinkage())
497     attr |= LTO_SYMBOL_DEFINITION_WEAK;
498   else if (def->hasCommonLinkage())
499     attr |= LTO_SYMBOL_DEFINITION_TENTATIVE;
500   else
501     attr |= LTO_SYMBOL_DEFINITION_REGULAR;
502 
503   // set scope part
504   if (def->hasHiddenVisibility())
505     attr |= LTO_SYMBOL_SCOPE_HIDDEN;
506   else if (def->hasProtectedVisibility())
507     attr |= LTO_SYMBOL_SCOPE_PROTECTED;
508   else if (def->hasExternalLinkage() || def->hasWeakLinkage() ||
509            def->hasLinkOnceLinkage() || def->hasCommonLinkage() ||
510            def->hasLinkerPrivateWeakLinkage())
511     attr |= LTO_SYMBOL_SCOPE_DEFAULT;
512   else if (def->hasLinkOnceODRAutoHideLinkage())
513     attr |= LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
514   else
515     attr |= LTO_SYMBOL_SCOPE_INTERNAL;
516 
517   StringSet::value_type &entry = _defines.GetOrCreateValue(Buffer);
518   entry.setValue(1);
519 
520   // fill information structure
521   NameAndAttributes info;
522   StringRef Name = entry.getKey();
523   info.name = Name.data();
524   assert(info.name[Name.size()] == '\0');
525   info.attributes = attr;
526   info.isFunction = isFunction;
527   info.symbol = def;
528 
529   // add to table of symbols
530   _symbols.push_back(info);
531 }
532 
533 /// addAsmGlobalSymbol - Add a global symbol from module-level ASM to the
534 /// defined list.
addAsmGlobalSymbol(const char * name,lto_symbol_attributes scope)535 void LTOModule::addAsmGlobalSymbol(const char *name,
536                                    lto_symbol_attributes scope) {
537   StringSet::value_type &entry = _defines.GetOrCreateValue(name);
538 
539   // only add new define if not already defined
540   if (entry.getValue())
541     return;
542 
543   entry.setValue(1);
544 
545   NameAndAttributes &info = _undefines[entry.getKey().data()];
546 
547   if (info.symbol == 0) {
548     // FIXME: This is trying to take care of module ASM like this:
549     //
550     //   module asm ".zerofill __FOO, __foo, _bar_baz_qux, 0"
551     //
552     // but is gross and its mother dresses it funny. Have the ASM parser give us
553     // more details for this type of situation so that we're not guessing so
554     // much.
555 
556     // fill information structure
557     info.name = entry.getKey().data();
558     info.attributes =
559       LTO_SYMBOL_PERMISSIONS_DATA | LTO_SYMBOL_DEFINITION_REGULAR | scope;
560     info.isFunction = false;
561     info.symbol = 0;
562 
563     // add to table of symbols
564     _symbols.push_back(info);
565     return;
566   }
567 
568   if (info.isFunction)
569     addDefinedFunctionSymbol(cast<Function>(info.symbol));
570   else
571     addDefinedDataSymbol(info.symbol);
572 
573   _symbols.back().attributes &= ~LTO_SYMBOL_SCOPE_MASK;
574   _symbols.back().attributes |= scope;
575 }
576 
577 /// addAsmGlobalSymbolUndef - Add a global symbol from module-level ASM to the
578 /// undefined list.
addAsmGlobalSymbolUndef(const char * name)579 void LTOModule::addAsmGlobalSymbolUndef(const char *name) {
580   StringMap<NameAndAttributes>::value_type &entry =
581     _undefines.GetOrCreateValue(name);
582 
583   _asm_undefines.push_back(entry.getKey().data());
584 
585   // we already have the symbol
586   if (entry.getValue().name)
587     return;
588 
589   uint32_t attr = LTO_SYMBOL_DEFINITION_UNDEFINED;;
590   attr |= LTO_SYMBOL_SCOPE_DEFAULT;
591   NameAndAttributes info;
592   info.name = entry.getKey().data();
593   info.attributes = attr;
594   info.isFunction = false;
595   info.symbol = 0;
596 
597   entry.setValue(info);
598 }
599 
600 /// addPotentialUndefinedSymbol - Add a symbol which isn't defined just yet to a
601 /// list to be resolved later.
addPotentialUndefinedSymbol(GlobalValue * decl,bool isFunc)602 void LTOModule::addPotentialUndefinedSymbol(GlobalValue *decl, bool isFunc) {
603   // ignore all llvm.* symbols
604   if (decl->getName().startswith("llvm."))
605     return;
606 
607   // ignore all aliases
608   if (isa<GlobalAlias>(decl))
609     return;
610 
611   SmallString<64> name;
612   _mangler.getNameWithPrefix(name, decl, false);
613 
614   StringMap<NameAndAttributes>::value_type &entry =
615     _undefines.GetOrCreateValue(name);
616 
617   // we already have the symbol
618   if (entry.getValue().name)
619     return;
620 
621   NameAndAttributes info;
622 
623   info.name = entry.getKey().data();
624 
625   if (decl->hasExternalWeakLinkage())
626     info.attributes = LTO_SYMBOL_DEFINITION_WEAKUNDEF;
627   else
628     info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
629 
630   info.isFunction = isFunc;
631   info.symbol = decl;
632 
633   entry.setValue(info);
634 }
635 
636 namespace {
637   class RecordStreamer : public MCStreamer {
638   public:
639     enum State { NeverSeen, Global, Defined, DefinedGlobal, Used };
640 
641   private:
642     StringMap<State> Symbols;
643 
markDefined(const MCSymbol & Symbol)644     void markDefined(const MCSymbol &Symbol) {
645       State &S = Symbols[Symbol.getName()];
646       switch (S) {
647       case DefinedGlobal:
648       case Global:
649         S = DefinedGlobal;
650         break;
651       case NeverSeen:
652       case Defined:
653       case Used:
654         S = Defined;
655         break;
656       }
657     }
markGlobal(const MCSymbol & Symbol)658     void markGlobal(const MCSymbol &Symbol) {
659       State &S = Symbols[Symbol.getName()];
660       switch (S) {
661       case DefinedGlobal:
662       case Defined:
663         S = DefinedGlobal;
664         break;
665 
666       case NeverSeen:
667       case Global:
668       case Used:
669         S = Global;
670         break;
671       }
672     }
markUsed(const MCSymbol & Symbol)673     void markUsed(const MCSymbol &Symbol) {
674       State &S = Symbols[Symbol.getName()];
675       switch (S) {
676       case DefinedGlobal:
677       case Defined:
678       case Global:
679         break;
680 
681       case NeverSeen:
682       case Used:
683         S = Used;
684         break;
685       }
686     }
687 
688     // FIXME: mostly copied for the obj streamer.
AddValueSymbols(const MCExpr * Value)689     void AddValueSymbols(const MCExpr *Value) {
690       switch (Value->getKind()) {
691       case MCExpr::Target:
692         // FIXME: What should we do in here?
693         break;
694 
695       case MCExpr::Constant:
696         break;
697 
698       case MCExpr::Binary: {
699         const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
700         AddValueSymbols(BE->getLHS());
701         AddValueSymbols(BE->getRHS());
702         break;
703       }
704 
705       case MCExpr::SymbolRef:
706         markUsed(cast<MCSymbolRefExpr>(Value)->getSymbol());
707         break;
708 
709       case MCExpr::Unary:
710         AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
711         break;
712       }
713     }
714 
715   public:
716     typedef StringMap<State>::const_iterator const_iterator;
717 
begin()718     const_iterator begin() {
719       return Symbols.begin();
720     }
721 
end()722     const_iterator end() {
723       return Symbols.end();
724     }
725 
RecordStreamer(MCContext & Context)726     RecordStreamer(MCContext &Context) : MCStreamer(Context) {}
727 
EmitInstruction(const MCInst & Inst)728     virtual void EmitInstruction(const MCInst &Inst) {
729       // Scan for values.
730       for (unsigned i = Inst.getNumOperands(); i--; )
731         if (Inst.getOperand(i).isExpr())
732           AddValueSymbols(Inst.getOperand(i).getExpr());
733     }
EmitLabel(MCSymbol * Symbol)734     virtual void EmitLabel(MCSymbol *Symbol) {
735       Symbol->setSection(*getCurrentSection());
736       markDefined(*Symbol);
737     }
EmitAssignment(MCSymbol * Symbol,const MCExpr * Value)738     virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
739       // FIXME: should we handle aliases?
740       markDefined(*Symbol);
741     }
EmitSymbolAttribute(MCSymbol * Symbol,MCSymbolAttr Attribute)742     virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) {
743       if (Attribute == MCSA_Global)
744         markGlobal(*Symbol);
745     }
EmitZerofill(const MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)746     virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
747                               uint64_t Size , unsigned ByteAlignment) {
748       markDefined(*Symbol);
749     }
EmitCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)750     virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
751                                   unsigned ByteAlignment) {
752       markDefined(*Symbol);
753     }
754 
755     // Noop calls.
ChangeSection(const MCSection * Section)756     virtual void ChangeSection(const MCSection *Section) {}
InitSections()757     virtual void InitSections() {}
EmitAssemblerFlag(MCAssemblerFlag Flag)758     virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) {}
EmitThumbFunc(MCSymbol * Func)759     virtual void EmitThumbFunc(MCSymbol *Func) {}
EmitSymbolDesc(MCSymbol * Symbol,unsigned DescValue)760     virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}
EmitWeakReference(MCSymbol * Alias,const MCSymbol * Symbol)761     virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {}
BeginCOFFSymbolDef(const MCSymbol * Symbol)762     virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {}
EmitCOFFSymbolStorageClass(int StorageClass)763     virtual void EmitCOFFSymbolStorageClass(int StorageClass) {}
EmitCOFFSymbolType(int Type)764     virtual void EmitCOFFSymbolType(int Type) {}
EndCOFFSymbolDef()765     virtual void EndCOFFSymbolDef() {}
EmitELFSize(MCSymbol * Symbol,const MCExpr * Value)766     virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
EmitLocalCommonSymbol(MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)767     virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
768                                        unsigned ByteAlignment) {}
EmitTBSSSymbol(const MCSection * Section,MCSymbol * Symbol,uint64_t Size,unsigned ByteAlignment)769     virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
770                                 uint64_t Size, unsigned ByteAlignment) {}
EmitBytes(StringRef Data,unsigned AddrSpace)771     virtual void EmitBytes(StringRef Data, unsigned AddrSpace) {}
EmitValueImpl(const MCExpr * Value,unsigned Size,unsigned AddrSpace)772     virtual void EmitValueImpl(const MCExpr *Value, unsigned Size,
773                                unsigned AddrSpace) {}
EmitULEB128Value(const MCExpr * Value)774     virtual void EmitULEB128Value(const MCExpr *Value) {}
EmitSLEB128Value(const MCExpr * Value)775     virtual void EmitSLEB128Value(const MCExpr *Value) {}
EmitValueToAlignment(unsigned ByteAlignment,int64_t Value,unsigned ValueSize,unsigned MaxBytesToEmit)776     virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
777                                       unsigned ValueSize,
778                                       unsigned MaxBytesToEmit) {}
EmitCodeAlignment(unsigned ByteAlignment,unsigned MaxBytesToEmit)779     virtual void EmitCodeAlignment(unsigned ByteAlignment,
780                                    unsigned MaxBytesToEmit) {}
EmitValueToOffset(const MCExpr * Offset,unsigned char Value)781     virtual bool EmitValueToOffset(const MCExpr *Offset,
782                                    unsigned char Value ) { return false; }
EmitFileDirective(StringRef Filename)783     virtual void EmitFileDirective(StringRef Filename) {}
EmitDwarfAdvanceLineAddr(int64_t LineDelta,const MCSymbol * LastLabel,const MCSymbol * Label,unsigned PointerSize)784     virtual void EmitDwarfAdvanceLineAddr(int64_t LineDelta,
785                                           const MCSymbol *LastLabel,
786                                           const MCSymbol *Label,
787                                           unsigned PointerSize) {}
FinishImpl()788     virtual void FinishImpl() {}
789   };
790 } // end anonymous namespace
791 
792 /// addAsmGlobalSymbols - Add global symbols from module-level ASM to the
793 /// defined or undefined lists.
addAsmGlobalSymbols(std::string & errMsg)794 bool LTOModule::addAsmGlobalSymbols(std::string &errMsg) {
795   const std::string &inlineAsm = _module->getModuleInlineAsm();
796   if (inlineAsm.empty())
797     return false;
798 
799   OwningPtr<RecordStreamer> Streamer(new RecordStreamer(_context));
800   MemoryBuffer *Buffer = MemoryBuffer::getMemBuffer(inlineAsm);
801   SourceMgr SrcMgr;
802   SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
803   OwningPtr<MCAsmParser> Parser(createMCAsmParser(SrcMgr,
804                                                   _context, *Streamer,
805                                                   *_target->getMCAsmInfo()));
806   const Target &T = _target->getTarget();
807   OwningPtr<MCSubtargetInfo>
808     STI(T.createMCSubtargetInfo(_target->getTargetTriple(),
809                                 _target->getTargetCPU(),
810                                 _target->getTargetFeatureString()));
811   OwningPtr<MCTargetAsmParser> TAP(T.createMCAsmParser(*STI, *Parser.get()));
812   if (!TAP) {
813     errMsg = "target " + std::string(T.getName()) +
814       " does not define AsmParser.";
815     return true;
816   }
817 
818   Parser->setTargetParser(*TAP);
819   if (Parser->Run(false))
820     return true;
821 
822   for (RecordStreamer::const_iterator i = Streamer->begin(),
823          e = Streamer->end(); i != e; ++i) {
824     StringRef Key = i->first();
825     RecordStreamer::State Value = i->second;
826     if (Value == RecordStreamer::DefinedGlobal)
827       addAsmGlobalSymbol(Key.data(), LTO_SYMBOL_SCOPE_DEFAULT);
828     else if (Value == RecordStreamer::Defined)
829       addAsmGlobalSymbol(Key.data(), LTO_SYMBOL_SCOPE_INTERNAL);
830     else if (Value == RecordStreamer::Global ||
831              Value == RecordStreamer::Used)
832       addAsmGlobalSymbolUndef(Key.data());
833   }
834 
835   return false;
836 }
837 
838 /// isDeclaration - Return 'true' if the global value is a declaration.
isDeclaration(const GlobalValue & V)839 static bool isDeclaration(const GlobalValue &V) {
840   if (V.hasAvailableExternallyLinkage())
841     return true;
842 
843   if (V.isMaterializable())
844     return false;
845 
846   return V.isDeclaration();
847 }
848 
849 /// parseSymbols - Parse the symbols from the module and model-level ASM and add
850 /// them to either the defined or undefined lists.
parseSymbols(std::string & errMsg)851 bool LTOModule::parseSymbols(std::string &errMsg) {
852   // add functions
853   for (Module::iterator f = _module->begin(), e = _module->end(); f != e; ++f) {
854     if (isDeclaration(*f))
855       addPotentialUndefinedSymbol(f, true);
856     else
857       addDefinedFunctionSymbol(f);
858   }
859 
860   // add data
861   for (Module::global_iterator v = _module->global_begin(),
862          e = _module->global_end(); v !=  e; ++v) {
863     if (isDeclaration(*v))
864       addPotentialUndefinedSymbol(v, false);
865     else
866       addDefinedDataSymbol(v);
867   }
868 
869   // add asm globals
870   if (addAsmGlobalSymbols(errMsg))
871     return true;
872 
873   // add aliases
874   for (Module::alias_iterator a = _module->alias_begin(),
875          e = _module->alias_end(); a != e; ++a) {
876     if (isDeclaration(*a->getAliasedGlobal()))
877       // Is an alias to a declaration.
878       addPotentialUndefinedSymbol(a, false);
879     else
880       addDefinedDataSymbol(a);
881   }
882 
883   // make symbols for all undefines
884   for (StringMap<NameAndAttributes>::iterator u =_undefines.begin(),
885          e = _undefines.end(); u != e; ++u) {
886     // If this symbol also has a definition, then don't make an undefine because
887     // it is a tentative definition.
888     if (_defines.count(u->getKey())) continue;
889     NameAndAttributes info = u->getValue();
890     _symbols.push_back(info);
891   }
892 
893   return false;
894 }
895