tools/opt/AnalysisWrappers.cpp

   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");