llvm-extract.cpp revision 360784 
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>
34using namespace llvm;
35
36cl::OptionCategory ExtractCat("llvm-extract Options");
37
38// InputFilename - The filename to read from.
39static cl::opt<std::string> InputFilename(cl::Positional,
40                                          cl::desc("<input bitcode file>"),
41                                          cl::init("-"),
42                                          cl::value_desc("filename"));
43
44static cl::opt<std::string> OutputFilename("o",
45                                           cl::desc("Specify output filename"),
46                                           cl::value_desc("filename"),
47                                           cl::init("-"), cl::cat(ExtractCat));
48
49static cl::opt<bool> Force("f", cl::desc("Enable binary output on terminals"),
50                           cl::cat(ExtractCat));
51
52static cl::opt<bool> DeleteFn("delete",
53                              cl::desc("Delete specified Globals from Module"),
54                              cl::cat(ExtractCat));
55
56static cl::opt<bool>
57    Recursive("recursive", cl::desc("Recursively extract all called functions"),
58              cl::cat(ExtractCat));
59
60// ExtractFuncs - The functions to extract from the module.
61static cl::list<std::string>
62    ExtractFuncs("func", cl::desc("Specify function to extract"),
63                 cl::ZeroOrMore, cl::value_desc("function"),
64                 cl::cat(ExtractCat));
65
66// ExtractRegExpFuncs - The functions, matched via regular expression, to
67// extract from the module.
68static cl::list<std::string>
69    ExtractRegExpFuncs("rfunc",
70                       cl::desc("Specify function(s) to extract using a "
71                                "regular expression"),
72                       cl::ZeroOrMore, cl::value_desc("rfunction"),
73                       cl::cat(ExtractCat));
74
75// ExtractBlocks - The blocks to extract from the module.
76static cl::list<std::string> ExtractBlocks(
77    "bb",
78    cl::desc(
79        "Specify <function, basic block1[;basic block2...]> pairs to extract.\n"
80        "Each pair will create a function.\n"
81        "If multiple basic blocks are specified in one pair,\n"
82        "the first block in the sequence should dominate the rest.\n"
83        "eg:\n"
84        "  --bb=f:bb1;bb2 will extract one function with both bb1 and bb2;\n"
85        "  --bb=f:bb1 --bb=f:bb2 will extract two functions, one with bb1, one "
86        "with bb2."),
87    cl::ZeroOrMore, cl::value_desc("function:bb1[;bb2...]"),
88    cl::cat(ExtractCat));
89
90// ExtractAlias - The alias to extract from the module.
91static cl::list<std::string>
92    ExtractAliases("alias", cl::desc("Specify alias to extract"),
93                   cl::ZeroOrMore, cl::value_desc("alias"),
94                   cl::cat(ExtractCat));
95
96// ExtractRegExpAliases - The aliases, matched via regular expression, to
97// extract from the module.
98static cl::list<std::string>
99    ExtractRegExpAliases("ralias",
100                         cl::desc("Specify alias(es) to extract using a "
101                                  "regular expression"),
102                         cl::ZeroOrMore, cl::value_desc("ralias"),
103                         cl::cat(ExtractCat));
104
105// ExtractGlobals - The globals to extract from the module.
106static cl::list<std::string>
107    ExtractGlobals("glob", cl::desc("Specify global to extract"),
108                   cl::ZeroOrMore, cl::value_desc("global"),
109                   cl::cat(ExtractCat));
110
111// ExtractRegExpGlobals - The globals, matched via regular expression, to
112// extract from the module...
113static cl::list<std::string>
114    ExtractRegExpGlobals("rglob",
115                         cl::desc("Specify global(s) to extract using a "
116                                  "regular expression"),
117                         cl::ZeroOrMore, cl::value_desc("rglobal"),
118                         cl::cat(ExtractCat));
119
120static cl::opt<bool> OutputAssembly("S",
121                                    cl::desc("Write output as LLVM assembly"),
122                                    cl::Hidden, cl::cat(ExtractCat));
123
124static cl::opt<bool> PreserveBitcodeUseListOrder(
125    "preserve-bc-uselistorder",
126    cl::desc("Preserve use-list order when writing LLVM bitcode."),
127    cl::init(true), cl::Hidden, cl::cat(ExtractCat));
128
129static cl::opt<bool> PreserveAssemblyUseListOrder(
130    "preserve-ll-uselistorder",
131    cl::desc("Preserve use-list order when writing LLVM assembly."),
132    cl::init(false), cl::Hidden, cl::cat(ExtractCat));
133
134int main(int argc, char **argv) {
135  InitLLVM X(argc, argv);
136
137  LLVMContext Context;
138  cl::HideUnrelatedOptions(ExtractCat);
139  cl::ParseCommandLineOptions(argc, argv, "llvm extractor\n");
140
141  // Use lazy loading, since we only care about selected global values.
142  SMDiagnostic Err;
143  std::unique_ptr<Module> M = getLazyIRFileModule(InputFilename, Err, Context);
144
145  if (!M.get()) {
146    Err.print(argv[0], errs());
147    return 1;
148  }
149
150  // Use SetVector to avoid duplicates.
151  SetVector<GlobalValue *> GVs;
152
153  // Figure out which aliases we should extract.
154  for (size_t i = 0, e = ExtractAliases.size(); i != e; ++i) {
155    GlobalAlias *GA = M->getNamedAlias(ExtractAliases[i]);
156    if (!GA) {
157      errs() << argv[0] << ": program doesn't contain alias named '"
158             << ExtractAliases[i] << "'!\n";
159      return 1;
160    }
161    GVs.insert(GA);
162  }
163
164  // Extract aliases via regular expression matching.
165  for (size_t i = 0, e = ExtractRegExpAliases.size(); i != e; ++i) {
166    std::string Error;
167    Regex RegEx(ExtractRegExpAliases[i]);
168    if (!RegEx.isValid(Error)) {
169      errs() << argv[0] << ": '" << ExtractRegExpAliases[i] << "' "
170        "invalid regex: " << Error;
171    }
172    bool match = false;
173    for (Module::alias_iterator GA = M->alias_begin(), E = M->alias_end();
174         GA != E; GA++) {
175      if (RegEx.match(GA->getName())) {
176        GVs.insert(&*GA);
177        match = true;
178      }
179    }
180    if (!match) {
181      errs() << argv[0] << ": program doesn't contain global named '"
182             << ExtractRegExpAliases[i] << "'!\n";
183      return 1;
184    }
185  }
186
187  // Figure out which globals we should extract.
188  for (size_t i = 0, e = ExtractGlobals.size(); i != e; ++i) {
189    GlobalValue *GV = M->getNamedGlobal(ExtractGlobals[i]);
190    if (!GV) {
191      errs() << argv[0] << ": program doesn't contain global named '"
192             << ExtractGlobals[i] << "'!\n";
193      return 1;
194    }
195    GVs.insert(GV);
196  }
197
198  // Extract globals via regular expression matching.
199  for (size_t i = 0, e = ExtractRegExpGlobals.size(); i != e; ++i) {
200    std::string Error;
201    Regex RegEx(ExtractRegExpGlobals[i]);
202    if (!RegEx.isValid(Error)) {
203      errs() << argv[0] << ": '" << ExtractRegExpGlobals[i] << "' "
204        "invalid regex: " << Error;
205    }
206    bool match = false;
207    for (auto &GV : M->globals()) {
208      if (RegEx.match(GV.getName())) {
209        GVs.insert(&GV);
210        match = true;
211      }
212    }
213    if (!match) {
214      errs() << argv[0] << ": program doesn't contain global named '"
215             << ExtractRegExpGlobals[i] << "'!\n";
216      return 1;
217    }
218  }
219
220  // Figure out which functions we should extract.
221  for (size_t i = 0, e = ExtractFuncs.size(); i != e; ++i) {
222    GlobalValue *GV = M->getFunction(ExtractFuncs[i]);
223    if (!GV) {
224      errs() << argv[0] << ": program doesn't contain function named '"
225             << ExtractFuncs[i] << "'!\n";
226      return 1;
227    }
228    GVs.insert(GV);
229  }
230  // Extract functions via regular expression matching.
231  for (size_t i = 0, e = ExtractRegExpFuncs.size(); i != e; ++i) {
232    std::string Error;
233    StringRef RegExStr = ExtractRegExpFuncs[i];
234    Regex RegEx(RegExStr);
235    if (!RegEx.isValid(Error)) {
236      errs() << argv[0] << ": '" << ExtractRegExpFuncs[i] << "' "
237        "invalid regex: " << Error;
238    }
239    bool match = false;
240    for (Module::iterator F = M->begin(), E = M->end(); F != E;
241         F++) {
242      if (RegEx.match(F->getName())) {
243        GVs.insert(&*F);
244        match = true;
245      }
246    }
247    if (!match) {
248      errs() << argv[0] << ": program doesn't contain global named '"
249             << ExtractRegExpFuncs[i] << "'!\n";
250      return 1;
251    }
252  }
253
254  // Figure out which BasicBlocks we should extract.
255  SmallVector<SmallVector<BasicBlock *, 16>, 4> GroupOfBBs;
256  for (StringRef StrPair : ExtractBlocks) {
257    auto BBInfo = StrPair.split(':');
258    // Get the function.
259    Function *F = M->getFunction(BBInfo.first);
260    if (!F) {
261      errs() << argv[0] << ": program doesn't contain a function named '"
262             << BBInfo.first << "'!\n";
263      return 1;
264    }
265    // Do not materialize this function.
266    GVs.insert(F);
267    // Get the basic blocks.
268    SmallVector<BasicBlock *, 16> BBs;
269    SmallVector<StringRef, 16> BBNames;
270    BBInfo.second.split(BBNames, ';', /*MaxSplit=*/-1,
271                        /*KeepEmpty=*/false);
272    for (StringRef BBName : BBNames) {
273      auto Res = llvm::find_if(*F, [&](const BasicBlock &BB) {
274        return BB.getName().equals(BBName);
275      });
276      if (Res == F->end()) {
277        errs() << argv[0] << ": function " << F->getName()
278               << " doesn't contain a basic block named '" << BBInfo.second
279               << "'!\n";
280        return 1;
281      }
282      BBs.push_back(&*Res);
283    }
284    GroupOfBBs.push_back(BBs);
285  }
286
287  // Use *argv instead of argv[0] to work around a wrong GCC warning.
288  ExitOnError ExitOnErr(std::string(*argv) + ": error reading input: ");
289
290  if (Recursive) {
291    std::vector<llvm::Function *> Workqueue;
292    for (GlobalValue *GV : GVs) {
293      if (auto *F = dyn_cast<Function>(GV)) {
294        Workqueue.push_back(F);
295      }
296    }
297    while (!Workqueue.empty()) {
298      Function *F = &*Workqueue.back();
299      Workqueue.pop_back();
300      ExitOnErr(F->materialize());
301      for (auto &BB : *F) {
302        for (auto &I : BB) {
303          CallBase *CB = dyn_cast<CallBase>(&I);
304          if (!CB)
305            continue;
306          Function *CF = CB->getCalledFunction();
307          if (!CF)
308            continue;
309          if (CF->isDeclaration() || GVs.count(CF))
310            continue;
311          GVs.insert(CF);
312          Workqueue.push_back(CF);
313        }
314      }
315    }
316  }
317
318  auto Materialize = [&](GlobalValue &GV) { ExitOnErr(GV.materialize()); };
319
320  // Materialize requisite global values.
321  if (!DeleteFn) {
322    for (size_t i = 0, e = GVs.size(); i != e; ++i)
323      Materialize(*GVs[i]);
324  } else {
325    // Deleting. Materialize every GV that's *not* in GVs.
326    SmallPtrSet<GlobalValue *, 8> GVSet(GVs.begin(), GVs.end());
327    for (auto &F : *M) {
328      if (!GVSet.count(&F))
329        Materialize(F);
330    }
331  }
332
333  {
334    std::vector<GlobalValue *> Gvs(GVs.begin(), GVs.end());
335    legacy::PassManager Extract;
336    Extract.add(createGVExtractionPass(Gvs, DeleteFn));
337    Extract.run(*M);
338
339    // Now that we have all the GVs we want, mark the module as fully
340    // materialized.
341    // FIXME: should the GVExtractionPass handle this?
342    ExitOnErr(M->materializeAll());
343  }
344
345  // Extract the specified basic blocks from the module and erase the existing
346  // functions.
347  if (!ExtractBlocks.empty()) {
348    legacy::PassManager PM;
349    PM.add(createBlockExtractorPass(GroupOfBBs, true));
350    PM.run(*M);
351  }
352
353  // In addition to deleting all other functions, we also want to spiff it
354  // up a little bit.  Do this now.
355  legacy::PassManager Passes;
356
357  if (!DeleteFn)
358    Passes.add(createGlobalDCEPass());           // Delete unreachable globals
359  Passes.add(createStripDeadDebugInfoPass());    // Remove dead debug info
360  Passes.add(createStripDeadPrototypesPass());   // Remove dead func decls
361
362  std::error_code EC;
363  ToolOutputFile Out(OutputFilename, EC, sys::fs::OF_None);
364  if (EC) {
365    errs() << EC.message() << '\n';
366    return 1;
367  }
368
369  if (OutputAssembly)
370    Passes.add(
371        createPrintModulePass(Out.os(), "", PreserveAssemblyUseListOrder));
372  else if (Force || !CheckBitcodeOutputToConsole(Out.os(), true))
373    Passes.add(createBitcodeWriterPass(Out.os(), PreserveBitcodeUseListOrder));
374
375  Passes.run(*M.get());
376
377  // Declare success.
378  Out.keep();
379
380  return 0;
381}
382