LLVM  9.0.0svn
APSInt.cpp
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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 
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 
40  ID.AddInteger((unsigned) (IsUnsigned ? 1 : 0));
41  APInt::Profile(ID);
42 }
void Profile(FoldingSetNodeID &id) const
Used to insert APInt objects, or objects that contain APInt objects, into FoldingSets.
Definition: APInt.cpp:159
This class represents lattice values for constants.
Definition: AllocatorList.h:23
APSInt()
Default constructor that creates an uninitialized APInt.
Definition: APSInt.h:26
APInt trunc(unsigned width) const
Truncate to new width.
Definition: APInt.cpp:810
void AddInteger(signed I)
Definition: FoldingSet.cpp:60
LLVM_NODISCARD bool empty() const
empty - Check if the string is empty.
Definition: StringRef.h:126
unsigned getActiveBits() const
Compute the number of active bits in the value.
Definition: APInt.h:1532
void Profile(FoldingSetNodeID &ID) const
Profile - Used to insert APSInt objects, or objects that contain APSInt objects, into FoldingSets...
Definition: APSInt.cpp:39
LLVM_NODISCARD size_t size() const
size - Get the string size.
Definition: StringRef.h:130
FoldingSetNodeID - This class is used to gather all the unique data bits of a node.
Definition: FoldingSet.h:305
Class for arbitrary precision integers.
Definition: APInt.h:69
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
unsigned getMinSignedBits() const
Get the minimum bit size for this signed APInt.
Definition: APInt.h:1551
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48