LLVM  6.0.0svn
APSInt.cpp
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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 #include "llvm/ADT/StringRef.h"
18 
19 using namespace llvm;
20 
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.getMinSignedBits();
29  if (MinBits > 0 && MinBits < NumBits)
30  Tmp = Tmp.trunc(MinBits);
31  *this = APSInt(Tmp, /*IsUnsigned=*/false);
32  return;
33  }
34  unsigned ActiveBits = Tmp.getActiveBits();
35  if (ActiveBits > 0 && ActiveBits < NumBits)
36  Tmp = Tmp.trunc(ActiveBits);
37  *this = APSInt(Tmp, /*IsUnsigned=*/true);
38 }
39 
41  ID.AddInteger((unsigned) (IsUnsigned ? 1 : 0));
42  APInt::Profile(ID);
43 }
void Profile(FoldingSetNodeID &id) const
Used to insert APInt objects, or objects that contain APInt objects, into FoldingSets.
Definition: APInt.cpp:160
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE size_t size() const
size - Get the string size.
Definition: StringRef.h:138
APSInt()
Default constructor that creates an uninitialized APInt.
Definition: APSInt.h:27
APInt trunc(unsigned width) const
Truncate to new width.
Definition: APInt.cpp:818
void AddInteger(signed I)
Definition: FoldingSet.cpp:61
unsigned getActiveBits() const
Compute the number of active bits in the value.
Definition: APInt.h:1512
void Profile(FoldingSetNodeID &ID) const
Profile - Used to insert APSInt objects, or objects that contain APSInt objects, into FoldingSets...
Definition: APSInt.cpp:40
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE bool empty() const
empty - Check if the string is empty.
Definition: StringRef.h:133
FoldingSetNodeID - This class is used to gather all the unique data bits of a node.
Definition: FoldingSet.h:306
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:1531
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49