LLVM  6.0.0svn
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 } // namespace sys
51 
52 raw_ostream &operator<<(raw_ostream &OS, sys::TimePoint<> TP);
53 
54 /// Format provider for TimePoint<>
55 ///
56 /// The options string is a strftime format string, with extensions:
57 /// - %L is millis: 000-999
58 /// - %f is micros: 000000-999999
59 /// - %N is nanos: 000000000 - 999999999
60 ///
61 /// If no options are given, the default format is "%Y-%m-%d %H:%M:%S.%N".
62 template <>
63 struct format_provider<sys::TimePoint<>> {
64  static void format(const sys::TimePoint<> &TP, llvm::raw_ostream &OS,
66 };
67 
68 /// Implementation of format_provider<T> for duration types.
69 ///
70 /// The options string of a duration type has the grammar:
71 ///
72 /// duration_options ::= [unit][show_unit [number_options]]
73 /// unit ::= `h`|`m`|`s`|`ms|`us`|`ns`
74 /// show_unit ::= `+` | `-`
75 /// number_options ::= options string for a integral or floating point type
76 ///
77 /// Examples
78 /// =================================
79 /// | options | Input | Output |
80 /// =================================
81 /// | "" | 1s | 1 s |
82 /// | "ms" | 1s | 1000 ms |
83 /// | "ms-" | 1s | 1000 |
84 /// | "ms-n" | 1s | 1,000 |
85 /// | "" | 1.0s | 1.00 s |
86 /// =================================
87 ///
88 /// If the unit of the duration type is not one of the units specified above,
89 /// it is still possible to format it, provided you explicitly request a
90 /// display unit or you request that the unit is not displayed.
91 
92 namespace detail {
93 template <typename Period> struct unit { static const char value[]; };
94 template <typename Period> const char unit<Period>::value[] = "";
95 
96 template <> struct unit<std::ratio<3600>> { static const char value[]; };
97 template <> struct unit<std::ratio<60>> { static const char value[]; };
98 template <> struct unit<std::ratio<1>> { static const char value[]; };
99 template <> struct unit<std::milli> { static const char value[]; };
100 template <> struct unit<std::micro> { static const char value[]; };
101 template <> struct unit<std::nano> { static const char value[]; };
102 } // namespace detail
103 
104 template <typename Rep, typename Period>
105 struct format_provider<std::chrono::duration<Rep, Period>> {
106 private:
107  typedef std::chrono::duration<Rep, Period> Dur;
108  typedef typename std::conditional<
109  std::chrono::treat_as_floating_point<Rep>::value, double, intmax_t>::type
110  InternalRep;
111 
112  template <typename AsPeriod> static InternalRep getAs(const Dur &D) {
113  using namespace std::chrono;
114  return duration_cast<duration<InternalRep, AsPeriod>>(D).count();
115  }
116 
117  static std::pair<InternalRep, StringRef> consumeUnit(StringRef &Style,
118  const Dur &D) {
119  using namespace std::chrono;
120  if (Style.consume_front("ns"))
121  return {getAs<std::nano>(D), "ns"};
122  if (Style.consume_front("us"))
123  return {getAs<std::micro>(D), "us"};
124  if (Style.consume_front("ms"))
125  return {getAs<std::milli>(D), "ms"};
126  if (Style.consume_front("s"))
127  return {getAs<std::ratio<1>>(D), "s"};
128  if (Style.consume_front("m"))
129  return {getAs<std::ratio<60>>(D), "m"};
130  if (Style.consume_front("h"))
131  return {getAs<std::ratio<3600>>(D), "h"};
132  return {D.count(), detail::unit<Period>::value};
133  }
134 
135  static bool consumeShowUnit(StringRef &Style) {
136  if (Style.empty())
137  return true;
138  if (Style.consume_front("-"))
139  return false;
140  if (Style.consume_front("+"))
141  return true;
142  assert(0 && "Unrecognised duration format");
143  return true;
144  }
145 
146 public:
147  static void format(const Dur &D, llvm::raw_ostream &Stream, StringRef Style) {
148  InternalRep count;
149  StringRef unit;
150  std::tie(count, unit) = consumeUnit(Style, D);
151  bool show_unit = consumeShowUnit(Style);
152 
153  format_provider<InternalRep>::format(count, Stream, Style);
154 
155  if (show_unit) {
156  assert(!unit.empty());
157  Stream << " " << unit;
158  }
159  }
160 };
161 
162 } // namespace llvm
163 
164 #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
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
static void format(const Dur &D, llvm::raw_ostream &Stream, StringRef Style)
Definition: Chrono.h:147
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:920
#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:198
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
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:874
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:44
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