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 #include <cassert>
18 
19 using namespace llvm;
20 
21 APSInt::APSInt(StringRef Str) {
22   assert(!Str.empty() && "Invalid string length");
23 
24   // (Over-)estimate the required number of bits.
25   unsigned NumBits = ((Str.size() * 64) / 19) + 2;
26   APInt Tmp(NumBits, Str, /*radix=*/10);
27   if (Str[0] == '-') {
28     unsigned MinBits = Tmp.getSignificantBits();
29     if (MinBits < NumBits)
30       Tmp = Tmp.trunc(std::max<unsigned>(1, MinBits));
31     *this = APSInt(Tmp, /*isUnsigned=*/false);
32     return;
33   }
34   unsigned ActiveBits = Tmp.getActiveBits();
35   if (ActiveBits < NumBits)
36     Tmp = Tmp.trunc(std::max<unsigned>(1, ActiveBits));
37   *this = APSInt(Tmp, /*isUnsigned=*/true);
38 }
39 
40 void APSInt::Profile(FoldingSetNodeID& ID) const {
41   ID.AddInteger((unsigned) (IsUnsigned ? 1 : 0));
42   APInt::Profile(ID);
43 }
44