1 //===- NativeFormatting.cpp - Low level formatting helpers -------*- 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 #include "llvm/Support/NativeFormatting.h"
10 #include "llvm/ADT/ArrayRef.h"
11 #include "llvm/ADT/SmallString.h"
12 #include "llvm/ADT/StringExtras.h"
13 #include "llvm/Support/Format.h"
14 #include "llvm/Support/MathExtras.h"
15 #include "llvm/Support/raw_ostream.h"
16 
17 #if defined(_WIN32) && !defined(__MINGW32__)
18 #include <float.h> // For _fpclass in llvm::write_double.
19 #endif
20 
21 using namespace llvm;
22 
23 template<typename T, std::size_t N>
24 static int format_to_buffer(T Value, char (&Buffer)[N]) {
25   char *EndPtr = std::end(Buffer);
26   char *CurPtr = EndPtr;
27 
28   do {
29     *--CurPtr = '0' + char(Value % 10);
30     Value /= 10;
31   } while (Value);
32   return EndPtr - CurPtr;
33 }
34 
35 static void writeWithCommas(raw_ostream &S, ArrayRef<char> Buffer) {
36   assert(!Buffer.empty());
37 
38   ArrayRef<char> ThisGroup;
39   int InitialDigits = ((Buffer.size() - 1) % 3) + 1;
40   ThisGroup = Buffer.take_front(InitialDigits);
41   S.write(ThisGroup.data(), ThisGroup.size());
42 
43   Buffer = Buffer.drop_front(InitialDigits);
44   assert(Buffer.size() % 3 == 0);
45   while (!Buffer.empty()) {
46     S << ',';
47     ThisGroup = Buffer.take_front(3);
48     S.write(ThisGroup.data(), 3);
49     Buffer = Buffer.drop_front(3);
50   }
51 }
52 
53 template <typename T>
54 static void write_unsigned_impl(raw_ostream &S, T N, size_t MinDigits,
55                                 IntegerStyle Style, bool IsNegative) {
56   static_assert(std::is_unsigned<T>::value, "Value is not unsigned!");
57 
58   char NumberBuffer[128];
59   std::memset(NumberBuffer, '0', sizeof(NumberBuffer));
60 
61   size_t Len = 0;
62   Len = format_to_buffer(N, NumberBuffer);
63 
64   if (IsNegative)
65     S << '-';
66 
67   if (Len < MinDigits && Style != IntegerStyle::Number) {
68     for (size_t I = Len; I < MinDigits; ++I)
69       S << '0';
70   }
71 
72   if (Style == IntegerStyle::Number) {
73     writeWithCommas(S, ArrayRef<char>(std::end(NumberBuffer) - Len, Len));
74   } else {
75     S.write(std::end(NumberBuffer) - Len, Len);
76   }
77 }
78 
79 template <typename T>
80 static void write_unsigned(raw_ostream &S, T N, size_t MinDigits,
81                            IntegerStyle Style, bool IsNegative = false) {
82   // Output using 32-bit div/mod if possible.
83   if (N == static_cast<uint32_t>(N))
84     write_unsigned_impl(S, static_cast<uint32_t>(N), MinDigits, Style,
85                         IsNegative);
86   else
87     write_unsigned_impl(S, N, MinDigits, Style, IsNegative);
88 }
89 
90 template <typename T>
91 static void write_signed(raw_ostream &S, T N, size_t MinDigits,
92                          IntegerStyle Style) {
93   static_assert(std::is_signed<T>::value, "Value is not signed!");
94 
95   using UnsignedT = std::make_unsigned_t<T>;
96 
97   if (N >= 0) {
98     write_unsigned(S, static_cast<UnsignedT>(N), MinDigits, Style);
99     return;
100   }
101 
102   UnsignedT UN = -(UnsignedT)N;
103   write_unsigned(S, UN, MinDigits, Style, true);
104 }
105 
106 void llvm::write_integer(raw_ostream &S, unsigned int N, size_t MinDigits,
107                          IntegerStyle Style) {
108   write_unsigned(S, N, MinDigits, Style);
109 }
110 
111 void llvm::write_integer(raw_ostream &S, int N, size_t MinDigits,
112                          IntegerStyle Style) {
113   write_signed(S, N, MinDigits, Style);
114 }
115 
116 void llvm::write_integer(raw_ostream &S, unsigned long N, size_t MinDigits,
117                          IntegerStyle Style) {
118   write_unsigned(S, N, MinDigits, Style);
119 }
120 
121 void llvm::write_integer(raw_ostream &S, long N, size_t MinDigits,
122                          IntegerStyle Style) {
123   write_signed(S, N, MinDigits, Style);
124 }
125 
126 void llvm::write_integer(raw_ostream &S, unsigned long long N, size_t MinDigits,
127                          IntegerStyle Style) {
128   write_unsigned(S, N, MinDigits, Style);
129 }
130 
131 void llvm::write_integer(raw_ostream &S, long long N, size_t MinDigits,
132                          IntegerStyle Style) {
133   write_signed(S, N, MinDigits, Style);
134 }
135 
136 void llvm::write_hex(raw_ostream &S, uint64_t N, HexPrintStyle Style,
137                      Optional<size_t> Width) {
138   const size_t kMaxWidth = 128u;
139 
140   size_t W = std::min(kMaxWidth, Width.value_or(0u));
141 
142   unsigned Nibbles = (64 - countLeadingZeros(N) + 3) / 4;
143   bool Prefix = (Style == HexPrintStyle::PrefixLower ||
144                  Style == HexPrintStyle::PrefixUpper);
145   bool Upper =
146       (Style == HexPrintStyle::Upper || Style == HexPrintStyle::PrefixUpper);
147   unsigned PrefixChars = Prefix ? 2 : 0;
148   unsigned NumChars =
149       std::max(static_cast<unsigned>(W), std::max(1u, Nibbles) + PrefixChars);
150 
151   char NumberBuffer[kMaxWidth];
152   ::memset(NumberBuffer, '0', llvm::array_lengthof(NumberBuffer));
153   if (Prefix)
154     NumberBuffer[1] = 'x';
155   char *EndPtr = NumberBuffer + NumChars;
156   char *CurPtr = EndPtr;
157   while (N) {
158     unsigned char x = static_cast<unsigned char>(N) % 16;
159     *--CurPtr = hexdigit(x, !Upper);
160     N /= 16;
161   }
162 
163   S.write(NumberBuffer, NumChars);
164 }
165 
166 void llvm::write_double(raw_ostream &S, double N, FloatStyle Style,
167                         Optional<size_t> Precision) {
168   size_t Prec = Precision.value_or(getDefaultPrecision(Style));
169 
170   if (std::isnan(N)) {
171     S << "nan";
172     return;
173   } else if (std::isinf(N)) {
174     S << (std::signbit(N) ? "-INF" : "INF");
175     return;
176   }
177 
178   char Letter;
179   if (Style == FloatStyle::Exponent)
180     Letter = 'e';
181   else if (Style == FloatStyle::ExponentUpper)
182     Letter = 'E';
183   else
184     Letter = 'f';
185 
186   SmallString<8> Spec;
187   llvm::raw_svector_ostream Out(Spec);
188   Out << "%." << Prec << Letter;
189 
190   if (Style == FloatStyle::Exponent || Style == FloatStyle::ExponentUpper) {
191 #ifdef _WIN32
192 // On MSVCRT and compatible, output of %e is incompatible to Posix
193 // by default. Number of exponent digits should be at least 2. "%+03d"
194 // FIXME: Implement our formatter to here or Support/Format.h!
195 #if defined(__MINGW32__)
196     // FIXME: It should be generic to C++11.
197     if (N == 0.0 && std::signbit(N)) {
198       char NegativeZero[] = "-0.000000e+00";
199       if (Style == FloatStyle::ExponentUpper)
200         NegativeZero[strlen(NegativeZero) - 4] = 'E';
201       S << NegativeZero;
202       return;
203     }
204 #else
205     int fpcl = _fpclass(N);
206 
207     // negative zero
208     if (fpcl == _FPCLASS_NZ) {
209       char NegativeZero[] = "-0.000000e+00";
210       if (Style == FloatStyle::ExponentUpper)
211         NegativeZero[strlen(NegativeZero) - 4] = 'E';
212       S << NegativeZero;
213       return;
214     }
215 #endif
216 
217     char buf[32];
218     unsigned len;
219     len = format(Spec.c_str(), N).snprint(buf, sizeof(buf));
220     if (len <= sizeof(buf) - 2) {
221       if (len >= 5 && (buf[len - 5] == 'e' || buf[len - 5] == 'E') &&
222           buf[len - 3] == '0') {
223         int cs = buf[len - 4];
224         if (cs == '+' || cs == '-') {
225           int c1 = buf[len - 2];
226           int c0 = buf[len - 1];
227           if (isdigit(static_cast<unsigned char>(c1)) &&
228               isdigit(static_cast<unsigned char>(c0))) {
229             // Trim leading '0': "...e+012" -> "...e+12\0"
230             buf[len - 3] = c1;
231             buf[len - 2] = c0;
232             buf[--len] = 0;
233           }
234         }
235       }
236       S << buf;
237       return;
238     }
239 #endif
240   }
241 
242   if (Style == FloatStyle::Percent)
243     N *= 100.0;
244 
245   char Buf[32];
246   format(Spec.c_str(), N).snprint(Buf, sizeof(Buf));
247   S << Buf;
248   if (Style == FloatStyle::Percent)
249     S << '%';
250 }
251 
252 bool llvm::isPrefixedHexStyle(HexPrintStyle S) {
253   return (S == HexPrintStyle::PrefixLower || S == HexPrintStyle::PrefixUpper);
254 }
255 
256 size_t llvm::getDefaultPrecision(FloatStyle Style) {
257   switch (Style) {
258   case FloatStyle::Exponent:
259   case FloatStyle::ExponentUpper:
260     return 6; // Number of decimal places.
261   case FloatStyle::Fixed:
262   case FloatStyle::Percent:
263     return 2; // Number of decimal places.
264   }
265   llvm_unreachable("Unknown FloatStyle enum");
266 }
267