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      1 //===-- llvm/ADT/APSInt.cpp - Arbitrary Precision Signed Int ---*- C++ -*--===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file implements the APSInt class, which is a simple class that
     11 // represents an arbitrary sized integer that knows its signedness.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "llvm/ADT/APSInt.h"
     16 #include "llvm/ADT/FoldingSet.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 }
     43