LowerIntrinsics.cc

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    Copyright (c) 2002-2023 Tampere University.
 
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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)
 * @author Joonas Multanen 2023 (joonas.multanen-no.spam-tuni.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/IR/Function.h>
#include <llvm/Pass.h>
#include <llvm/Passes/PassBuilder.h>
#include <llvm/Passes/PassPlugin.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>
 
 
class LowerIntrinsics : public PassInfoMixin<LowerIntrinsics> {
public:
    PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
 
    // to suppress Clang warnings
    //using llvm::FunctionPass::doInitialization;
    //using llvm::FunctionPass::doFinalization;
 
    bool runOnBasicBlock(BasicBlock &BB);
 
private:
    bool doInitialization(Module &M);
    bool doFinalization (Module &M);
    /// List of intrinsics to replace.
    std::set<unsigned> replace_;
    IntrinsicLowering* iLowering_;
    TargetData* td_;
};
 
PreservedAnalyses LowerIntrinsics::run(Function &F,
                                       FunctionAnalysisManager &AM) {
    //errs() << F.getName() << "\n";
  Module *parentModule = F.getParent();
  doInitialization(*parentModule);
  for (BasicBlock &BB : F) {
      runOnBasicBlock(BB);
  }
  doFinalization(*parentModule);
  return PreservedAnalyses::all();
}
 
 
bool
LowerIntrinsics::doInitialization(Module &M) {
 
    // Initialize list of intrinsics to lower.
    replace_.insert(Intrinsic::get_rounding);
    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::get_rounding) {
                        // Replace GET_ROUNDING 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;
}
 
 
/* New PM Registration */
llvm::PassPluginLibraryInfo getLowerIntrinsicsPluginInfo() {
  return {LLVM_PLUGIN_API_VERSION, "LowerIntrinsics", LLVM_VERSION_STRING,
          [](PassBuilder &PB) {
            PB.registerVectorizerStartEPCallback(
                [](llvm::FunctionPassManager &PM, OptimizationLevel Level) {
                  PM.addPass(LowerIntrinsics());
                });
            PB.registerPipelineParsingCallback(
                [](StringRef Name, llvm::FunctionPassManager &PM,
                   ArrayRef<llvm::PassBuilder::PipelineElement>) {
                  if (Name == "lowerintrinsic") {
                    PM.addPass(LowerIntrinsics());
                    return true;
                  }
                  return false;
                });
          }};
}
 
#ifndef LLVM_LOWERINTRINSICS_LINK_INTO_TOOLS
extern "C" LLVM_ATTRIBUTE_WEAK ::llvm::PassPluginLibraryInfo
llvmGetPassPluginInfo() {
  return getLowerIntrinsicsPluginInfo();
}
#endif