path: root/lib/Module/OptimizeLegacy.cpp

// FIXME: This file is a bastard child of opt.cpp and llvm-ld's
// Optimize.cpp. This stuff should live in common code.

//===- Optimize.cpp - Optimize a complete program -------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements all optimization of the linked module for llvm-ld.
//
//===----------------------------------------------------------------------===//

#include "klee/Config/Version.h"
#include "klee/Support/OptionCategories.h"

#include "klee/Support/CompilerWarning.h"

#include "ModuleHelper.h"

DISABLE_WARNING_PUSH
DISABLE_WARNING_DEPRECATED_DECLARATIONS
#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/FunctionAttrs.h"
#include "llvm/Transforms/InstCombine/InstCombine.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Scalar/GVN.h"
#include "llvm/Transforms/Utils.h"
DISABLE_WARNING_POP

using namespace llvm;
using namespace klee;

namespace {
static cl::opt<bool>
    DisableInline("disable-inlining",
                  cl::desc("Do not run the inliner pass (default=false)"),
                  cl::init(false), cl::cat(klee::ModuleCat));

static cl::opt<bool> DisableInternalize(
    "disable-internalize",
    cl::desc("Do not mark all symbols as internal (default=false)"),
    cl::init(false), cl::cat(klee::ModuleCat));

static cl::opt<bool> VerifyEach("verify-each",
                                cl::desc("Verify intermediate results of all "
                                         "optimization passes (default=false)"),
                                cl::init(false), cl::cat(klee::ModuleCat));

static cl::opt<bool>
    Strip("strip-all", cl::desc("Strip all symbol information from executable (default=false)"),
          cl::init(false), cl::cat(klee::ModuleCat));

static cl::opt<bool>
    StripDebug("strip-debug",
               cl::desc("Strip debugger symbol info from executable (default=false)"),
               cl::init(false), cl::cat(klee::ModuleCat));

// A utility function that adds a pass to the pass manager but will also add
// a verifier pass after if we're supposed to verify.
static inline void addPass(legacy::PassManager &PM, Pass *P) {
  // Add the pass to the pass manager...
  PM.add(P);

  // If we are verifying all of the intermediate steps, add the verifier...
  if (VerifyEach)
    PM.add(createVerifierPass());
}
} // namespace

static void AddStandardCompilePasses(legacy::PassManager &PM) {
  PM.add(createVerifierPass()); // Verify that input is correct

  // If the -strip-debug command line option was specified, do it.
  if (StripDebug)
    addPass(PM, createStripSymbolsPass(true));

  addPass(PM, createCFGSimplificationPass());       // Clean up disgusting code
  addPass(PM, createPromoteMemoryToRegisterPass()); // Kill useless allocas
  addPass(PM, createGlobalOptimizerPass());         // Optimize out global vars
  addPass(PM, createGlobalDCEPass()); // Remove unused fns and globs
#if LLVM_VERSION_CODE >= LLVM_VERSION(11, 0)
  addPass(PM, createSCCPPass()); // Constant prop with SCCP
#else
  addPass(PM, createIPConstantPropagationPass()); // IP Constant Propagation
#endif
  addPass(PM, createDeadArgEliminationPass());   // Dead argument elimination
  addPass(PM, createInstructionCombiningPass()); // Clean up after IPCP & DAE
  addPass(PM, createCFGSimplificationPass());    // Clean up after IPCP & DAE

#if LLVM_VERSION_CODE <= LLVM_VERSION(15, 0)
  addPass(PM, createPruneEHPass()); // Remove dead EH info
#endif
  addPass(PM, createPostOrderFunctionAttrsLegacyPass());
  addPass(PM,
          createReversePostOrderFunctionAttrsPass()); // Deduce function attrs

  if (!DisableInline)
    addPass(PM, createFunctionInliningPass()); // Inline small functions
#if LLVM_VERSION_CODE <= LLVM_VERSION(14, 0)
  addPass(PM, createArgumentPromotionPass()); // Scalarize uninlined fn args
#endif

  addPass(PM, createInstructionCombiningPass()); // Cleanup for scalarrepl.
  addPass(PM, createJumpThreadingPass());        // Thread jumps.
  addPass(PM, createCFGSimplificationPass());    // Merge & remove BBs
  addPass(PM, createSROAPass());                 // Break up aggregate allocas
  addPass(PM, createInstructionCombiningPass()); // Combine silly seq's

  addPass(PM, createTailCallEliminationPass()); // Eliminate tail calls
  addPass(PM, createCFGSimplificationPass());   // Merge & remove BBs
  addPass(PM, createReassociatePass());         // Reassociate expressions
  addPass(PM, createLoopRotatePass());
  addPass(PM, createLICMPass());         // Hoist loop invariants
#if LLVM_VERSION_CODE <= LLVM_VERSION(14, 0)
  addPass(PM, createLoopUnswitchPass()); // Unswitch loops.
#endif
  // FIXME : Removing instcombine causes nestedloop regression.
  addPass(PM, createInstructionCombiningPass());
  addPass(PM, createIndVarSimplifyPass());       // Canonicalize indvars
  addPass(PM, createLoopDeletionPass());         // Delete dead loops
  addPass(PM, createLoopUnrollPass());           // Unroll small loops
  addPass(PM, createInstructionCombiningPass()); // Clean up after the unroller
  addPass(PM, createGVNPass());                  // Remove redundancies
  addPass(PM, createMemCpyOptPass());            // Remove memcpy / form memset
  addPass(PM, createSCCPPass());                 // Constant prop with SCCP

  // Run instcombine after redundancy elimination to exploit opportunities
  // opened up by them.
  addPass(PM, createInstructionCombiningPass());

  addPass(PM, createDeadStoreEliminationPass()); // Delete dead stores
  addPass(PM, createAggressiveDCEPass());        // Delete dead instructions
  addPass(PM, createCFGSimplificationPass());    // Merge & remove BBs
  addPass(PM, createStripDeadPrototypesPass());  // Get rid of dead prototypes
  addPass(PM, createConstantMergePass());        // Merge dup global constants
}

/// Optimize - Perform link time optimizations. This will run the scalar
/// optimizations, any loaded plugin-optimization modules, and then the
/// inter-procedural optimizations if applicable.
void klee::optimizeModule(llvm::Module *M,
                          llvm::ArrayRef<const char *> preservedFunctions) {

  // Instantiate the pass manager to organize the passes.
  legacy::PassManager Passes;

  // If we're verifying, start off with a verification pass.
  if (VerifyEach)
    Passes.add(createVerifierPass());

  // DWD - Run the opt standard pass list as well.
  AddStandardCompilePasses(Passes);

  // Now that composite has been compiled, scan through the module, looking
  // for a main function.  If main is defined, mark all other functions
  // internal.
  if (!DisableInternalize) {
    auto PreserveFunctions = [=](const llvm::GlobalValue &GV) {
      StringRef GVName = GV.getName();

      for (const char *fun : preservedFunctions)
        if (GVName.equals(fun))
          return true;

      return false;
    };
    ModulePass *pass = createInternalizePass(PreserveFunctions);
    addPass(Passes, pass);
  }

  // Propagate constants at call sites into the functions they call.  This
  // opens opportunities for globalopt (and inlining) by substituting function
  // pointers passed as arguments to direct uses of functions.
  addPass(Passes, createIPSCCPPass());

  // Now that we internalized some globals, see if we can hack on them!
  addPass(Passes, createGlobalOptimizerPass());

  // Linking modules together can lead to duplicated global constants, only
  // keep one copy of each constant...
  addPass(Passes, createConstantMergePass());

  // Remove unused arguments from functions...
  addPass(Passes, createDeadArgEliminationPass());

  // Reduce the code after globalopt and ipsccp.  Both can open up significant
  // simplification opportunities, and both can propagate functions through
  // function pointers.  When this happens, we often have to resolve varargs
  // calls, etc, so let instcombine do this.
  addPass(Passes, createInstructionCombiningPass());

  if (!DisableInline)
    addPass(Passes, createFunctionInliningPass()); // Inline small functions

#if LLVM_VERSION_CODE <= LLVM_VERSION(15, 0)
  addPass(Passes, createPruneEHPass()); // Remove dead EH info
#endif
  addPass(Passes, createGlobalOptimizerPass()); // Optimize globals again.
  addPass(Passes, createGlobalDCEPass());       // Remove dead functions

#if LLVM_VERSION_CODE <= LLVM_VERSION(14, 0)
  // If we didn't decide to inline a function, check to see if we can
  // transform it to pass arguments by value instead of by reference.
  addPass(Passes, createArgumentPromotionPass());
#endif

  // The IPO passes may leave cruft around.  Clean up after them.
  addPass(Passes, createInstructionCombiningPass());
  addPass(Passes, createJumpThreadingPass()); // Thread jumps.
  addPass(Passes, createSROAPass());          // Break up allocas

  // Run a few AA driven optimizations here and now, to cleanup the code.
  addPass(Passes, createPostOrderFunctionAttrsLegacyPass());
  addPass(Passes, createReversePostOrderFunctionAttrsPass()); // Add nocapture
  addPass(Passes, createGlobalsAAWrapperPass()); // IP alias analysis

  addPass(Passes, createLICMPass());                 // Hoist loop invariants
  addPass(Passes, createGVNPass());                  // Remove redundancies
  addPass(Passes, createMemCpyOptPass());            // Remove dead memcpy's
  addPass(Passes, createDeadStoreEliminationPass()); // Nuke dead stores

  // Cleanup and simplify the code after the scalar optimizations.
  addPass(Passes, createInstructionCombiningPass());

  addPass(Passes, createJumpThreadingPass());           // Thread jumps.
  addPass(Passes, createPromoteMemoryToRegisterPass()); // Cleanup jumpthread.

  // Delete basic blocks, which optimization passes may have killed...
  addPass(Passes, createCFGSimplificationPass());

  // Now that we have optimized the program, discard unreachable functions...
  addPass(Passes, createGlobalDCEPass());

  // If the -s or -S command line options were specified, strip the symbols out
  // of the resulting program to make it smaller.  -s and -S are GNU ld options
  // that we are supporting; they alias -strip-all and -strip-debug.
  if (Strip || StripDebug)
    addPass(Passes, createStripSymbolsPass(StripDebug && !Strip));

  // The user's passes may leave cruft around; clean up after them.
  addPass(Passes, createInstructionCombiningPass());
  addPass(Passes, createCFGSimplificationPass());
  addPass(Passes, createAggressiveDCEPass());
  addPass(Passes, createGlobalDCEPass());

  // Run our queue of passes all at once now, efficiently.
  Passes.run(*M);
}