LLVM  8.0.0svn
Chrono.h
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1 //===- llvm/Support/Chrono.h - Utilities for Timing Manipulation-*- 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 #ifndef LLVM_SUPPORT_CHRONO_H
11 #define LLVM_SUPPORT_CHRONO_H
12 
13 #include "llvm/Support/Compiler.h"
15 
16 #include <chrono>
17 #include <ctime>
18 
19 namespace llvm {
20 
21 class raw_ostream;
22 
23 namespace sys {
24 
25 /// A time point on the system clock. This is provided for two reasons:
26 /// - to insulate us agains subtle differences in behavoir to differences in
27 /// system clock precision (which is implementation-defined and differs between
28 /// platforms).
29 /// - to shorten the type name
30 /// The default precision is nanoseconds. If need a specific precision specify
31 /// it explicitly. If unsure, use the default. If you need a time point on a
32 /// clock other than the system_clock, use std::chrono directly.
33 template <typename D = std::chrono::nanoseconds>
34 using TimePoint = std::chrono::time_point<std::chrono::system_clock, D>;
35 
36 /// Convert a TimePoint to std::time_t
38  using namespace std::chrono;
39  return system_clock::to_time_t(
40  time_point_cast<system_clock::time_point::duration>(TP));
41 }
42 
43 /// Convert a std::time_t to a TimePoint
45 toTimePoint(std::time_t T) {
46  using namespace std::chrono;
47  return time_point_cast<seconds>(system_clock::from_time_t(T));
48 }
49 
50 /// Convert a std::time_t + nanoseconds to a TimePoint
52 toTimePoint(std::time_t T, uint32_t nsec) {
53  using namespace std::chrono;
54  return time_point_cast<nanoseconds>(system_clock::from_time_t(T))
55  + nanoseconds(nsec);
56 }
57 
58 } // namespace sys
59 
60 raw_ostream &operator<<(raw_ostream &OS, sys::TimePoint<> TP);
61 
62 /// Format provider for TimePoint<>
63 ///
64 /// The options string is a strftime format string, with extensions:
65 /// - %L is millis: 000-999
66 /// - %f is micros: 000000-999999
67 /// - %N is nanos: 000000000 - 999999999
68 ///
69 /// If no options are given, the default format is "%Y-%m-%d %H:%M:%S.%N".
70 template <>
71 struct format_provider<sys::TimePoint<>> {
72  static void format(const sys::TimePoint<> &TP, llvm::raw_ostream &OS,
74 };
75 
76 /// Implementation of format_provider<T> for duration types.
77 ///
78 /// The options string of a duration type has the grammar:
79 ///
80 /// duration_options ::= [unit][show_unit [number_options]]
81 /// unit ::= `h`|`m`|`s`|`ms|`us`|`ns`
82 /// show_unit ::= `+` | `-`
83 /// number_options ::= options string for a integral or floating point type
84 ///
85 /// Examples
86 /// =================================
87 /// | options | Input | Output |
88 /// =================================
89 /// | "" | 1s | 1 s |
90 /// | "ms" | 1s | 1000 ms |
91 /// | "ms-" | 1s | 1000 |
92 /// | "ms-n" | 1s | 1,000 |
93 /// | "" | 1.0s | 1.00 s |
94 /// =================================
95 ///
96 /// If the unit of the duration type is not one of the units specified above,
97 /// it is still possible to format it, provided you explicitly request a
98 /// display unit or you request that the unit is not displayed.
99 
100 namespace detail {
101 template <typename Period> struct unit { static const char value[]; };
102 template <typename Period> const char unit<Period>::value[] = "";
103 
104 template <> struct unit<std::ratio<3600>> { static const char value[]; };
105 template <> struct unit<std::ratio<60>> { static const char value[]; };
106 template <> struct unit<std::ratio<1>> { static const char value[]; };
107 template <> struct unit<std::milli> { static const char value[]; };
108 template <> struct unit<std::micro> { static const char value[]; };
109 template <> struct unit<std::nano> { static const char value[]; };
110 } // namespace detail
111 
112 template <typename Rep, typename Period>
113 struct format_provider<std::chrono::duration<Rep, Period>> {
114 private:
115  typedef std::chrono::duration<Rep, Period> Dur;
116  typedef typename std::conditional<
117  std::chrono::treat_as_floating_point<Rep>::value, double, intmax_t>::type
118  InternalRep;
119 
120  template <typename AsPeriod> static InternalRep getAs(const Dur &D) {
121  using namespace std::chrono;
122  return duration_cast<duration<InternalRep, AsPeriod>>(D).count();
123  }
124 
125  static std::pair<InternalRep, StringRef> consumeUnit(StringRef &Style,
126  const Dur &D) {
127  using namespace std::chrono;
128  if (Style.consume_front("ns"))
129  return {getAs<std::nano>(D), "ns"};
130  if (Style.consume_front("us"))
131  return {getAs<std::micro>(D), "us"};
132  if (Style.consume_front("ms"))
133  return {getAs<std::milli>(D), "ms"};
134  if (Style.consume_front("s"))
135  return {getAs<std::ratio<1>>(D), "s"};
136  if (Style.consume_front("m"))
137  return {getAs<std::ratio<60>>(D), "m"};
138  if (Style.consume_front("h"))
139  return {getAs<std::ratio<3600>>(D), "h"};
140  return {D.count(), detail::unit<Period>::value};
141  }
142 
143  static bool consumeShowUnit(StringRef &Style) {
144  if (Style.empty())
145  return true;
146  if (Style.consume_front("-"))
147  return false;
148  if (Style.consume_front("+"))
149  return true;
150  assert(0 && "Unrecognised duration format");
151  return true;
152  }
153 
154 public:
155  static void format(const Dur &D, llvm::raw_ostream &Stream, StringRef Style) {
156  InternalRep count;
157  StringRef unit;
158  std::tie(count, unit) = consumeUnit(Style, D);
159  bool show_unit = consumeShowUnit(Style);
160 
161  format_provider<InternalRep>::format(count, Stream, Style);
162 
163  if (show_unit) {
164  assert(!unit.empty());
165  Stream << " " << unit;
166  }
167  }
168 };
169 
170 } // namespace llvm
171 
172 #endif // LLVM_SUPPORT_CHRONO_H
LLVM_ATTRIBUTE_ALWAYS_INLINE std::time_t toTimeT(TimePoint<> TP)
Convert a TimePoint to std::time_t.
Definition: Chrono.h:37
This class represents lattice values for constants.
Definition: AllocatorList.h:24
static void format(const Dur &D, llvm::raw_ostream &Stream, StringRef Style)
Definition: Chrono.h:155
format_object< Ts... > format(const char *Fmt, const Ts &... Vals)
These are helper functions used to produce formatted output.
Definition: Format.h:124
LLVM_ATTRIBUTE_ALWAYS_INLINE TimePoint< std::chrono::seconds > toTimePoint(std::time_t T)
Convert a std::time_t to a TimePoint.
Definition: Chrono.h:45
Definition: BitVector.h:938
LLVM_ATTRIBUTE_ALWAYS_INLINE bool consume_front(StringRef Prefix)
Returns true if this StringRef has the given prefix and removes that prefix.
Definition: StringRef.h:678
#define LLVM_ATTRIBUTE_ALWAYS_INLINE
LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do so, mark a method "always...
Definition: Compiler.h:214
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE bool empty() const
empty - Check if the string is empty.
Definition: StringRef.h:133
auto count(R &&Range, const E &Element) -> typename std::iterator_traits< decltype(adl_begin(Range))>::difference_type
Wrapper function around std::count to count the number of times an element Element occurs in the give...
Definition: STLExtras.h:1246
static GCRegistry::Add< StatepointGC > D("statepoint-example", "an example strategy for statepoint")
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:46
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
std::chrono::time_point< std::chrono::system_clock, D > TimePoint
A time point on the system clock.
Definition: Chrono.h:34