LowerIntrinsics.cc

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/*
    Copyright (c) 2002-2009 Tampere University.
 
    This file is part of TTA-Based Codesign Environment (TCE).
 
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/**
 * @file LowerIntrinsics.cc
 *
 * Converts llvm intrinsics to libcalls.
 *
 * @author Veli-Pekka Jaaskelainen 2008 (vjaaskel-no.spam-cs.tut.fi)
 * @author Mikael Lepistö 2009 (mikael.lepisto-no.spam-tut.fi)
 */
 
#define DEBUG_TYPE "lowerintrinsics"
 
#include "CompilerWarnings.hh"
IGNORE_COMPILER_WARNING("-Wunused-parameter")
 
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
#include "tce_config.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Pass.h"
#include "llvm/CodeGen/IntrinsicLowering.h"
#include "tce_config.h"
 
POP_COMPILER_DIAGS
 
#include "llvm/IR/DataLayout.h"
typedef llvm::DataLayout TargetData;
 
using namespace llvm;
 
#include <iostream>
#include <set>
 
namespace {
    class LowerIntrinsics : public FunctionPass {
    public:
        static char ID; // Pass ID, replacement for typeid       
        LowerIntrinsics();
        virtual ~LowerIntrinsics();
 
        // from llvm::Pass:
        bool doInitialization(Module &M);
        bool doFinalization (Module &M);
 
        // to suppress Clang warnings
        using llvm::FunctionPass::doInitialization;
        using llvm::FunctionPass::doFinalization;
 
        bool runOnBasicBlock(BasicBlock &BB);
        bool runOnFunction(Function &F) override;
       
     private:
        /// List of intrinsics to replace.
        std::set<unsigned> replace_;
        IntrinsicLowering* iLowering_;
        TargetData* td_;
    };
 
    char LowerIntrinsics::ID = 0;
    RegisterPass<LowerIntrinsics>
    X("lowerintrinsics", "Lower llvm intrinsics back to libcalls.");
}
 
 
/**
 * Constructor
 */
LowerIntrinsics::LowerIntrinsics() :
    FunctionPass(ID),
    iLowering_(NULL), td_(NULL) {
}
 
/**
 * Destructor
 */
LowerIntrinsics::~LowerIntrinsics() {
}
 
 
bool
LowerIntrinsics::doInitialization(Module &M) {
   
    // Initialize list of intrinsics to lower.
    replace_.insert(Intrinsic::flt_rounds);
    replace_.insert(Intrinsic::ceil);
    replace_.insert(Intrinsic::floor);
    replace_.insert(Intrinsic::round);
    replace_.insert(Intrinsic::exp2);
    replace_.insert(Intrinsic::memcpy);
    replace_.insert(Intrinsic::memset);
    replace_.insert(Intrinsic::memmove);
    
    assert(iLowering_ == NULL && td_ == NULL);
    td_ = new TargetData(&M);
    iLowering_ = new IntrinsicLowering(*td_);
    return true;
}
 
bool
LowerIntrinsics::doFinalization(Module& /*M*/) {
    if (iLowering_ != NULL) { 
        delete iLowering_;
        iLowering_ = NULL;
    }
    if (td_ != NULL) {
        delete td_;
        td_ = NULL;
    }    
    return true;
}
 
 
bool
LowerIntrinsics::runOnBasicBlock(BasicBlock &BB) {
    
   bool changed = true;
   while (changed)  {
       changed = false;
       for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) {
           CallInst* ci = dyn_cast<CallInst>(&(*I));
           if (ci != NULL && ci->arg_size() != 0) {
               Function* callee = ci->getCalledFunction();
               if (callee != NULL && callee->isIntrinsic() &&
                   replace_.find(callee->getIntrinsicID()) != replace_.end()) {
                   if (callee->getIntrinsicID() == Intrinsic::flt_rounds) {
                       // Replace FLT_ROUNDS intrinsic with the actual
                       // constant value to avoid stupid  "if (1 == 0)"
                       // code even with full optimizations.
                       I->replaceAllUsesWith(
                           ConstantInt::get(
                               Type::getInt32Ty(BB.getContext()), 0, true));
                       I->eraseFromParent();
                       changed = true;
                       break;
                   } else {
                       iLowering_->LowerIntrinsicCall(ci);
                       changed = true;
                       break;
                   }
               }
           }
       }
   }
   return true;
}
 
bool
LowerIntrinsics::runOnFunction(Function &F) {
 
    for (BasicBlock &BB : F) {
        runOnBasicBlock(BB);
    }
 
    return true;
}