lib/Support/APSInt.cpp

   1 //===-- llvm/ADT/APSInt.cpp - Arbitrary Precision Signed Int ---*- C++ -*--===//
   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 implements the APSInt class, which is a simple class that
  10 // represents an arbitrary sized integer that knows its signedness.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/ADT/APSInt.h"
  15 #include "llvm/ADT/FoldingSet.h"
  16 #include "llvm/ADT/StringRef.h"
  17
  18 using namespace llvm;
  19
  20 APSInt::APSInt(StringRef Str) {
  21   assert(!Str.empty() && "Invalid string length");
  22
  23   // (Over-)estimate the required number of bits.
  24   unsigned NumBits = ((Str.size() * 64) / 19) + 2;
  25   APInt Tmp(NumBits, Str, /*Radix=*/10);
  26   if (Str[0] == '-') {
  27     unsigned MinBits = Tmp.getMinSignedBits();
  28     if (MinBits > 0 && MinBits < NumBits)
  29       Tmp = Tmp.trunc(MinBits);
  30     *this = APSInt(Tmp, /*IsUnsigned=*/false);
  31     return;
  32   }
  33   unsigned ActiveBits = Tmp.getActiveBits();
  34   if (ActiveBits > 0 && ActiveBits < NumBits)
  35     Tmp = Tmp.trunc(ActiveBits);
  36   *this = APSInt(Tmp, /*IsUnsigned=*/true);
  37 }
  38
  39 void APSInt::Profile(FoldingSetNodeID& ID) const {
  40   ID.AddInteger((unsigned) (IsUnsigned ? 1 : 0));
  41   APInt::Profile(ID);
  42 }