1 //===- llvm-extract.cpp - LLVM function extraction utility ----------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This utility changes the input module to only contain a single function,
10 // which is primarily used for debugging transformations.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/ADT/SetVector.h"
15 #include "llvm/ADT/SmallPtrSet.h"
16 #include "llvm/Bitcode/BitcodeWriterPass.h"
17 #include "llvm/IR/DataLayout.h"
18 #include "llvm/IR/IRPrintingPasses.h"
19 #include "llvm/IR/Instructions.h"
20 #include "llvm/IR/LLVMContext.h"
21 #include "llvm/IR/LegacyPassManager.h"
22 #include "llvm/IR/Module.h"
23 #include "llvm/IRReader/IRReader.h"
24 #include "llvm/Support/CommandLine.h"
25 #include "llvm/Support/Error.h"
26 #include "llvm/Support/FileSystem.h"
27 #include "llvm/Support/InitLLVM.h"
28 #include "llvm/Support/Regex.h"
29 #include "llvm/Support/SourceMgr.h"
30 #include "llvm/Support/SystemUtils.h"
31 #include "llvm/Support/ToolOutputFile.h"
32 #include "llvm/Transforms/IPO.h"
33 #include <memory>
34 #include <utility>
35 using namespace llvm;
36 
37 cl::OptionCategory ExtractCat("llvm-extract Options");
38 
39 // InputFilename - The filename to read from.
40 static cl::opt<std::string> InputFilename(cl::Positional,
41                                           cl::desc("<input bitcode file>"),
42                                           cl::init("-"),
43                                           cl::value_desc("filename"));
44 
45 static cl::opt<std::string> OutputFilename("o",
46                                            cl::desc("Specify output filename"),
47                                            cl::value_desc("filename"),
48                                            cl::init("-"), cl::cat(ExtractCat));
49 
50 static cl::opt<bool> Force("f", cl::desc("Enable binary output on terminals"),
51                            cl::cat(ExtractCat));
52 
53 static cl::opt<bool> DeleteFn("delete",
54                               cl::desc("Delete specified Globals from Module"),
55                               cl::cat(ExtractCat));
56 
57 static cl::opt<bool> KeepConstInit("keep-const-init",
58                               cl::desc("Keep initializers of constants"),
59                               cl::cat(ExtractCat));
60 
61 static cl::opt<bool>
62     Recursive("recursive", cl::desc("Recursively extract all called functions"),
63               cl::cat(ExtractCat));
64 
65 // ExtractFuncs - The functions to extract from the module.
66 static cl::list<std::string>
67     ExtractFuncs("func", cl::desc("Specify function to extract"),
68                  cl::ZeroOrMore, cl::value_desc("function"),
69                  cl::cat(ExtractCat));
70 
71 // ExtractRegExpFuncs - The functions, matched via regular expression, to
72 // extract from the module.
73 static cl::list<std::string>
74     ExtractRegExpFuncs("rfunc",
75                        cl::desc("Specify function(s) to extract using a "
76                                 "regular expression"),
77                        cl::ZeroOrMore, cl::value_desc("rfunction"),
78                        cl::cat(ExtractCat));
79 
80 // ExtractBlocks - The blocks to extract from the module.
81 static cl::list<std::string> ExtractBlocks(
82     "bb",
83     cl::desc(
84         "Specify <function, basic block1[;basic block2...]> pairs to extract.\n"
85         "Each pair will create a function.\n"
86         "If multiple basic blocks are specified in one pair,\n"
87         "the first block in the sequence should dominate the rest.\n"
88         "eg:\n"
89         "  --bb=f:bb1;bb2 will extract one function with both bb1 and bb2;\n"
90         "  --bb=f:bb1 --bb=f:bb2 will extract two functions, one with bb1, one "
91         "with bb2."),
92     cl::ZeroOrMore, cl::value_desc("function:bb1[;bb2...]"),
93     cl::cat(ExtractCat));
94 
95 // ExtractAlias - The alias to extract from the module.
96 static cl::list<std::string>
97     ExtractAliases("alias", cl::desc("Specify alias to extract"),
98                    cl::ZeroOrMore, cl::value_desc("alias"),
99                    cl::cat(ExtractCat));
100 
101 // ExtractRegExpAliases - The aliases, matched via regular expression, to
102 // extract from the module.
103 static cl::list<std::string>
104     ExtractRegExpAliases("ralias",
105                          cl::desc("Specify alias(es) to extract using a "
106                                   "regular expression"),
107                          cl::ZeroOrMore, cl::value_desc("ralias"),
108                          cl::cat(ExtractCat));
109 
110 // ExtractGlobals - The globals to extract from the module.
111 static cl::list<std::string>
112     ExtractGlobals("glob", cl::desc("Specify global to extract"),
113                    cl::ZeroOrMore, cl::value_desc("global"),
114                    cl::cat(ExtractCat));
115 
116 // ExtractRegExpGlobals - The globals, matched via regular expression, to
117 // extract from the module...
118 static cl::list<std::string>
119     ExtractRegExpGlobals("rglob",
120                          cl::desc("Specify global(s) to extract using a "
121                                   "regular expression"),
122                          cl::ZeroOrMore, cl::value_desc("rglobal"),
123                          cl::cat(ExtractCat));
124 
125 static cl::opt<bool> OutputAssembly("S",
126                                     cl::desc("Write output as LLVM assembly"),
127                                     cl::Hidden, cl::cat(ExtractCat));
128 
129 static cl::opt<bool> PreserveBitcodeUseListOrder(
130     "preserve-bc-uselistorder",
131     cl::desc("Preserve use-list order when writing LLVM bitcode."),
132     cl::init(true), cl::Hidden, cl::cat(ExtractCat));
133 
134 static cl::opt<bool> PreserveAssemblyUseListOrder(
135     "preserve-ll-uselistorder",
136     cl::desc("Preserve use-list order when writing LLVM assembly."),
137     cl::init(false), cl::Hidden, cl::cat(ExtractCat));
138 
main(int argc,char ** argv)139 int main(int argc, char **argv) {
140   InitLLVM X(argc, argv);
141 
142   LLVMContext Context;
143   cl::HideUnrelatedOptions(ExtractCat);
144   cl::ParseCommandLineOptions(argc, argv, "llvm extractor\n");
145 
146   // Use lazy loading, since we only care about selected global values.
147   SMDiagnostic Err;
148   std::unique_ptr<Module> M = getLazyIRFileModule(InputFilename, Err, Context);
149 
150   if (!M.get()) {
151     Err.print(argv[0], errs());
152     return 1;
153   }
154 
155   // Use SetVector to avoid duplicates.
156   SetVector<GlobalValue *> GVs;
157 
158   // Figure out which aliases we should extract.
159   for (size_t i = 0, e = ExtractAliases.size(); i != e; ++i) {
160     GlobalAlias *GA = M->getNamedAlias(ExtractAliases[i]);
161     if (!GA) {
162       errs() << argv[0] << ": program doesn't contain alias named '"
163              << ExtractAliases[i] << "'!\n";
164       return 1;
165     }
166     GVs.insert(GA);
167   }
168 
169   // Extract aliases via regular expression matching.
170   for (size_t i = 0, e = ExtractRegExpAliases.size(); i != e; ++i) {
171     std::string Error;
172     Regex RegEx(ExtractRegExpAliases[i]);
173     if (!RegEx.isValid(Error)) {
174       errs() << argv[0] << ": '" << ExtractRegExpAliases[i] << "' "
175         "invalid regex: " << Error;
176     }
177     bool match = false;
178     for (Module::alias_iterator GA = M->alias_begin(), E = M->alias_end();
179          GA != E; GA++) {
180       if (RegEx.match(GA->getName())) {
181         GVs.insert(&*GA);
182         match = true;
183       }
184     }
185     if (!match) {
186       errs() << argv[0] << ": program doesn't contain global named '"
187              << ExtractRegExpAliases[i] << "'!\n";
188       return 1;
189     }
190   }
191 
192   // Figure out which globals we should extract.
193   for (size_t i = 0, e = ExtractGlobals.size(); i != e; ++i) {
194     GlobalValue *GV = M->getNamedGlobal(ExtractGlobals[i]);
195     if (!GV) {
196       errs() << argv[0] << ": program doesn't contain global named '"
197              << ExtractGlobals[i] << "'!\n";
198       return 1;
199     }
200     GVs.insert(GV);
201   }
202 
203   // Extract globals via regular expression matching.
204   for (size_t i = 0, e = ExtractRegExpGlobals.size(); i != e; ++i) {
205     std::string Error;
206     Regex RegEx(ExtractRegExpGlobals[i]);
207     if (!RegEx.isValid(Error)) {
208       errs() << argv[0] << ": '" << ExtractRegExpGlobals[i] << "' "
209         "invalid regex: " << Error;
210     }
211     bool match = false;
212     for (auto &GV : M->globals()) {
213       if (RegEx.match(GV.getName())) {
214         GVs.insert(&GV);
215         match = true;
216       }
217     }
218     if (!match) {
219       errs() << argv[0] << ": program doesn't contain global named '"
220              << ExtractRegExpGlobals[i] << "'!\n";
221       return 1;
222     }
223   }
224 
225   // Figure out which functions we should extract.
226   for (size_t i = 0, e = ExtractFuncs.size(); i != e; ++i) {
227     GlobalValue *GV = M->getFunction(ExtractFuncs[i]);
228     if (!GV) {
229       errs() << argv[0] << ": program doesn't contain function named '"
230              << ExtractFuncs[i] << "'!\n";
231       return 1;
232     }
233     GVs.insert(GV);
234   }
235   // Extract functions via regular expression matching.
236   for (size_t i = 0, e = ExtractRegExpFuncs.size(); i != e; ++i) {
237     std::string Error;
238     StringRef RegExStr = ExtractRegExpFuncs[i];
239     Regex RegEx(RegExStr);
240     if (!RegEx.isValid(Error)) {
241       errs() << argv[0] << ": '" << ExtractRegExpFuncs[i] << "' "
242         "invalid regex: " << Error;
243     }
244     bool match = false;
245     for (Module::iterator F = M->begin(), E = M->end(); F != E;
246          F++) {
247       if (RegEx.match(F->getName())) {
248         GVs.insert(&*F);
249         match = true;
250       }
251     }
252     if (!match) {
253       errs() << argv[0] << ": program doesn't contain global named '"
254              << ExtractRegExpFuncs[i] << "'!\n";
255       return 1;
256     }
257   }
258 
259   // Figure out which BasicBlocks we should extract.
260   SmallVector<std::pair<Function *, SmallVector<StringRef, 16>>, 2> BBMap;
261   for (StringRef StrPair : ExtractBlocks) {
262     SmallVector<StringRef, 16> BBNames;
263     auto BBInfo = StrPair.split(':');
264     // Get the function.
265     Function *F = M->getFunction(BBInfo.first);
266     if (!F) {
267       errs() << argv[0] << ": program doesn't contain a function named '"
268              << BBInfo.first << "'!\n";
269       return 1;
270     }
271     // Add the function to the materialize list, and store the basic block names
272     // to check after materialization.
273     GVs.insert(F);
274     BBInfo.second.split(BBNames, ';', /*MaxSplit=*/-1, /*KeepEmpty=*/false);
275     BBMap.push_back({F, std::move(BBNames)});
276   }
277 
278   // Use *argv instead of argv[0] to work around a wrong GCC warning.
279   ExitOnError ExitOnErr(std::string(*argv) + ": error reading input: ");
280 
281   if (Recursive) {
282     std::vector<llvm::Function *> Workqueue;
283     for (GlobalValue *GV : GVs) {
284       if (auto *F = dyn_cast<Function>(GV)) {
285         Workqueue.push_back(F);
286       }
287     }
288     while (!Workqueue.empty()) {
289       Function *F = &*Workqueue.back();
290       Workqueue.pop_back();
291       ExitOnErr(F->materialize());
292       for (auto &BB : *F) {
293         for (auto &I : BB) {
294           CallBase *CB = dyn_cast<CallBase>(&I);
295           if (!CB)
296             continue;
297           Function *CF = CB->getCalledFunction();
298           if (!CF)
299             continue;
300           if (CF->isDeclaration() || GVs.count(CF))
301             continue;
302           GVs.insert(CF);
303           Workqueue.push_back(CF);
304         }
305       }
306     }
307   }
308 
309   auto Materialize = [&](GlobalValue &GV) { ExitOnErr(GV.materialize()); };
310 
311   // Materialize requisite global values.
312   if (!DeleteFn) {
313     for (size_t i = 0, e = GVs.size(); i != e; ++i)
314       Materialize(*GVs[i]);
315   } else {
316     // Deleting. Materialize every GV that's *not* in GVs.
317     SmallPtrSet<GlobalValue *, 8> GVSet(GVs.begin(), GVs.end());
318     for (auto &F : *M) {
319       if (!GVSet.count(&F))
320         Materialize(F);
321     }
322   }
323 
324   {
325     std::vector<GlobalValue *> Gvs(GVs.begin(), GVs.end());
326     legacy::PassManager Extract;
327     Extract.add(createGVExtractionPass(Gvs, DeleteFn, KeepConstInit));
328     Extract.run(*M);
329 
330     // Now that we have all the GVs we want, mark the module as fully
331     // materialized.
332     // FIXME: should the GVExtractionPass handle this?
333     ExitOnErr(M->materializeAll());
334   }
335 
336   // Extract the specified basic blocks from the module and erase the existing
337   // functions.
338   if (!ExtractBlocks.empty()) {
339     // Figure out which BasicBlocks we should extract.
340     SmallVector<SmallVector<BasicBlock *, 16>, 4> GroupOfBBs;
341     for (auto &P : BBMap) {
342       SmallVector<BasicBlock *, 16> BBs;
343       for (StringRef BBName : P.second) {
344         // The function has been materialized, so add its matching basic blocks
345         // to the block extractor list, or fail if a name is not found.
346         auto Res = llvm::find_if(*P.first, [&](const BasicBlock &BB) {
347           return BB.getName().equals(BBName);
348         });
349         if (Res == P.first->end()) {
350           errs() << argv[0] << ": function " << P.first->getName()
351                  << " doesn't contain a basic block named '" << BBName
352                  << "'!\n";
353           return 1;
354         }
355         BBs.push_back(&*Res);
356       }
357       GroupOfBBs.push_back(BBs);
358     }
359 
360     legacy::PassManager PM;
361     PM.add(createBlockExtractorPass(GroupOfBBs, true));
362     PM.run(*M);
363   }
364 
365   // In addition to deleting all other functions, we also want to spiff it
366   // up a little bit.  Do this now.
367   legacy::PassManager Passes;
368 
369   if (!DeleteFn)
370     Passes.add(createGlobalDCEPass());           // Delete unreachable globals
371   Passes.add(createStripDeadDebugInfoPass());    // Remove dead debug info
372   Passes.add(createStripDeadPrototypesPass());   // Remove dead func decls
373 
374   std::error_code EC;
375   ToolOutputFile Out(OutputFilename, EC, sys::fs::OF_None);
376   if (EC) {
377     errs() << EC.message() << '\n';
378     return 1;
379   }
380 
381   if (OutputAssembly)
382     Passes.add(
383         createPrintModulePass(Out.os(), "", PreserveAssemblyUseListOrder));
384   else if (Force || !CheckBitcodeOutputToConsole(Out.os()))
385     Passes.add(createBitcodeWriterPass(Out.os(), PreserveBitcodeUseListOrder));
386 
387   Passes.run(*M.get());
388 
389   // Declare success.
390   Out.keep();
391 
392   return 0;
393 }
394