llvm-project/llvm/lib/VMCore/LLVMContextImpl.cpp

//===--------------- LLVMContextImpl.cpp - Implementation ------*- C++ -*--===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file implements LLVMContextImpl, the opaque implementation 
//  of LLVMContext.
//
//===----------------------------------------------------------------------===//

#include "LLVMContextImpl.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/LLVMContext.h"
using namespace llvm;

// Get a ConstantInt from an APInt. Note that the value stored in the DenseMap 
// as the key, is a DenseMapAPIntKeyInfo::KeyTy which has provided the
// operator== and operator!= to ensure that the DenseMap doesn't attempt to
// compare APInt's of different widths, which would violate an APInt class
// invariant which generates an assertion.
ConstantInt *LLVMContextImpl::getConstantInt(const APInt& V) {
  // Get the corresponding integer type for the bit width of the value.
  const IntegerType *ITy = Context.getIntegerType(V.getBitWidth());
  // get an existing value or the insertion position
  DenseMapAPIntKeyInfo::KeyTy Key(V, ITy);
  
  ConstantsLock.reader_acquire();
  ConstantInt *&Slot = IntConstants[Key]; 
  ConstantsLock.reader_release();
    
  if (!Slot) {
    sys::SmartScopedWriter<true> Writer(ConstantsLock);
    ConstantInt *&NewSlot = IntConstants[Key]; 
    if (!Slot) {
      NewSlot = new ConstantInt(ITy, V);
    }
    
    return NewSlot;
  } else {
    return Slot;
  }
}