1 //===- AnalysisWrappers.cpp - Wrappers around non-pass analyses -----------===//
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 file defines pass wrappers around LLVM analyses that don't make sense to
10 // be passes.  It provides a nice standard pass interface to these classes so
11 // that they can be printed out by analyze.
12 //
13 // These classes are separated out of analyze.cpp so that it is more clear which
14 // code is the integral part of the analyze tool, and which part of the code is
15 // just making it so more passes are available.
16 //
17 //===----------------------------------------------------------------------===//
18 
19 #include "llvm/Analysis/CallGraph.h"
20 #include "llvm/IR/CallSite.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/Pass.h"
23 #include "llvm/Support/raw_ostream.h"
24 using namespace llvm;
25 
26 namespace {
27   /// ExternalFunctionsPassedConstants - This pass prints out call sites to
28   /// external functions that are called with constant arguments.  This can be
29   /// useful when looking for standard library functions we should constant fold
30   /// or handle in alias analyses.
31   struct ExternalFunctionsPassedConstants : public ModulePass {
32     static char ID; // Pass ID, replacement for typeid
33     ExternalFunctionsPassedConstants() : ModulePass(ID) {}
34     bool runOnModule(Module &M) override {
35       for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
36         if (!I->isDeclaration()) continue;
37 
38         bool PrintedFn = false;
39         for (User *U : I->users()) {
40           Instruction *UI = dyn_cast<Instruction>(U);
41           if (!UI) continue;
42 
43           CallSite CS(cast<Value>(UI));
44           if (!CS) continue;
45 
46           for (CallSite::arg_iterator AI = CS.arg_begin(),
47                E = CS.arg_end(); AI != E; ++AI) {
48             if (!isa<Constant>(*AI)) continue;
49 
50             if (!PrintedFn) {
51               errs() << "Function '" << I->getName() << "':\n";
52               PrintedFn = true;
53             }
54             errs() << *UI;
55             break;
56           }
57         }
58       }
59 
60       return false;
61     }
62 
63     void getAnalysisUsage(AnalysisUsage &AU) const override {
64       AU.setPreservesAll();
65     }
66   };
67 }
68 
69 char ExternalFunctionsPassedConstants::ID = 0;
70 static RegisterPass<ExternalFunctionsPassedConstants>
71   P1("print-externalfnconstants",
72      "Print external fn callsites passed constants");
73