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 
APSInt(StringRef Str)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 
Profile(FoldingSetNodeID & ID) const39 void APSInt::Profile(FoldingSetNodeID& ID) const {
40   ID.AddInteger((unsigned) (IsUnsigned ? 1 : 0));
41   APInt::Profile(ID);
42 }
43