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1 /* Copyright 2017 The TensorFlow Authors. All Rights Reserved.
2 
3 Licensed under the Apache License, Version 2.0 (the "License");
4 you may not use this file except in compliance with the License.
5 You may obtain a copy of the License at
6 
7     http://www.apache.org/licenses/LICENSE-2.0
8 
9 Unless required by applicable law or agreed to in writing, software
10 distributed under the License is distributed on an "AS IS" BASIS,
11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 See the License for the specific language governing permissions and
13 limitations under the License.
14 ==============================================================================*/
15 
16 // Generally useful utility functions that are common to (not specific to any
17 // given part of) the XLA code base.
18 
19 #ifndef TENSORFLOW_COMPILER_XLA_UTIL_H_
20 #define TENSORFLOW_COMPILER_XLA_UTIL_H_
21 
22 #include <algorithm>
23 #include <string>
24 #include <type_traits>
25 #include <vector>
26 
27 #include "absl/algorithm/container.h"
28 #include "absl/base/thread_annotations.h"
29 #include "absl/container/inlined_vector.h"
30 #include "absl/strings/str_cat.h"
31 #include "absl/strings/str_format.h"
32 #include "absl/strings/str_join.h"
33 #include "absl/strings/string_view.h"
34 #include "absl/types/span.h"
35 #include "tensorflow/compiler/xla/status.h"
36 #include "tensorflow/compiler/xla/status_macros.h"
37 #include "tensorflow/compiler/xla/types.h"
38 #include "tensorflow/compiler/xla/xla_data.pb.h"
39 #include "tensorflow/core/lib/core/errors.h"
40 #include "tensorflow/core/lib/core/status.h"
41 #include "tensorflow/core/lib/math/math_util.h"
42 #include "tensorflow/core/lib/strings/numbers.h"
43 #include "tensorflow/core/platform/logging.h"
44 #include "tensorflow/core/platform/macros.h"
45 #include "tensorflow/core/platform/mutex.h"
46 #include "tensorflow/core/platform/protobuf.h"
47 #include "tensorflow/core/platform/types.h"
48 
49 namespace xla {
50 
51 // Logs the provided status message with a backtrace.
52 //
53 // For use by Status-factories, logs a backtrace at the point where the status
54 // is created, such that we can use --vmodule=util=1 to see all status
55 // creation backtraces.
56 Status WithLogBacktrace(const Status& status);
57 
58 // Ranks greater than 8 are very rare, so use InlinedVector<int64, 8> to store
59 // the bounds and indices. And for the rare cases of ranks greater than 8,
60 // the InlinedVector will just behave like an std::vector<> and allocate the
61 // memory to store its values.
62 static constexpr int kInlineRank = 8;
63 using DimensionVector = absl::InlinedVector<int64, kInlineRank>;
64 
65 // RAII timer that logs with a given label the wall clock time duration in human
66 // readable form. This differs from base's ElapsedTimer primarily in that it
67 // spits out the human-readable duration form.
68 //
69 // Keeps track of global maximum and cumulative times across all invocations.
70 //
71 // By default, the timing traces are only printed at VLOG(1) and above:
72 //
73 //   XLA_SCOPED_LOGGING_TIMER("fooing bar");  // nop if !VLOG_IS_ON(1).
74 //
75 // but you can control this via:
76 //
77 //   XLA_SCOPED_LOGGING_TIMER_LEVEL("fooing bar", 2);  // nop if !VLOG_IS_ON(2)
78 //
79 #define XLA_SCOPED_LOGGING_TIMER(label) \
80   XLA_SCOPED_LOGGING_TIMER_HELPER(label, 1, __COUNTER__)
81 #define XLA_SCOPED_LOGGING_TIMER_LEVEL(label, level) \
82   XLA_SCOPED_LOGGING_TIMER_HELPER(label, level, __COUNTER__)
83 
84 // Helper for implementing macros above.  Do not use directly.
85 //
86 // Forces the evaluation of "counter", which we expect is equal to __COUNTER__.
87 #define XLA_SCOPED_LOGGING_TIMER_HELPER(label, level, counter) \
88   XLA_SCOPED_LOGGING_TIMER_HELPER2(label, level, counter)
89 
90 // Helper for macros above.  Don't use directly.
91 #define XLA_SCOPED_LOGGING_TIMER_HELPER2(label, level, counter)      \
92   static ::xla::TimerStats XLA_TimerStats##counter;                  \
93   ::xla::ScopedLoggingTimer XLA_ScopedLoggingTimerInstance##counter( \
94       label, /*enabled=*/VLOG_IS_ON(level), __FILE__, __LINE__,      \
95       &XLA_TimerStats##counter);
96 
97 struct TimerStats {
98   tensorflow::mutex stats_mutex;
99   double cumulative_secs ABSL_GUARDED_BY(stats_mutex) = 0;
100   double max_secs ABSL_GUARDED_BY(stats_mutex) = 0;
101   uint64 times_called ABSL_GUARDED_BY(stats_mutex) = 0;
102 };
103 
104 // RAII timer for XLA_SCOPED_LOGGING_TIMER and XLA_SCOPED_LOGGING_TIMER_LEVEL
105 // macros above.  Recommended usage is via the macros so you don't have to give
106 // the timer a name or worry about calling VLOG_IS_ON yourself.
107 class ScopedLoggingTimer {
108  public:
109   // label: Label to display for logging.
110   // enabled: Whether this timer should do anything at all.
111   // file: Filename to display in logging.
112   // line: Line number to display in logging.
113   // `timer_stats`: unowned non-null pointer which is used to populate the
114   // global timer statistics.
115   ScopedLoggingTimer(const std::string& label, bool enabled, const char* file,
116                      int line, TimerStats* timer_stats);
117 
118   // Stop the timer and log the tracked time. Timer is disabled after this
119   // function is called.
120   void StopAndLog();
121 
122   ~ScopedLoggingTimer();
123 
124  private:
125   bool enabled_;
126   const char* file_;
127   int line_;
128   string label_;
129   uint64 start_micros_;
130   TimerStats* timer_stats_;
131 };
132 
133 // Given a vector<T>, returns a Span<char> that points at its
134 // internals.
135 //
136 // Warning: if the vector is updated its storage pointer may change, so use this
137 // with caution (ideally in limited scopes with temporary lifetimes).
138 template <typename T>
MutableByteSlice(std::vector<T> * v)139 absl::Span<uint8> MutableByteSlice(std::vector<T>* v) {
140   return absl::Span<uint8>(reinterpret_cast<uint8*>(v->data()),
141                            v->size() * sizeof(T));
142 }
143 
144 // Turns an immutable slice of type T into an immutable slice of bytes with the
145 // same byte size.
146 template <typename T>
CastToByteSlice(absl::Span<const T> slice)147 absl::Span<const uint8> CastToByteSlice(absl::Span<const T> slice) {
148   return absl::Span<const uint8>(reinterpret_cast<const uint8*>(slice.data()),
149                                  slice.size() * sizeof(T));
150 }
151 
152 // Casts a byte slice to a non-byte type T, checking that the original slice
153 // length is a multiple of sizeof(T).
154 template <typename T>
CastByteSlice(absl::Span<const uint8> slice)155 absl::Span<const T> CastByteSlice(absl::Span<const uint8> slice) {
156   CHECK_EQ(0, slice.size() % sizeof(T));
157   return absl::Span<const T>(reinterpret_cast<const T*>(slice.data()),
158                              slice.size() / sizeof(T));
159 }
160 
161 // Convenience function to force a vector to convert to an immutable slice.
162 template <typename T>
AsSlice(const std::vector<T> & v)163 absl::Span<const T> AsSlice(const std::vector<T>& v) {
164   return absl::Span<const T>(v);
165 }
166 
167 // Converts a mutable vector pointer into a Span of the same
168 // type.
169 template <typename T>
AsMutableSlice(std::vector<T> * v)170 absl::Span<T> AsMutableSlice(std::vector<T>* v) {
171   return absl::Span<T>(v->data(), v->size());
172 }
173 
174 // xla::int64 is not the same type as tensorflow::protobuf_int64 in open-source.
175 // Wrapper function that gives an int64 array slice view of a repeated int64
176 // protobuf field.
AsInt64Slice(const tensorflow::protobuf::RepeatedField<tensorflow::protobuf_int64> & v)177 static inline absl::Span<const int64> AsInt64Slice(
178     const tensorflow::protobuf::RepeatedField<tensorflow::protobuf_int64>& v) {
179   absl::Span<const tensorflow::protobuf_int64> slice(v);
180   return absl::Span<const int64>(reinterpret_cast<const int64*>(slice.data()),
181                                  slice.size());
182 }
183 
184 // TODO(b/29771030): This nop overload was added to simplify the migration of
185 // Shape from a proto to a C++ class. Remove after class has been migrated.
AsInt64Slice(absl::Span<const int64> slice)186 static inline absl::Span<const int64> AsInt64Slice(
187     absl::Span<const int64> slice) {
188   return slice;
189 }
190 
191 // As above, but for uint64 types.
AsUInt64Slice(const tensorflow::protobuf::RepeatedField<tensorflow::protobuf_uint64> & v)192 static inline absl::Span<const uint64> AsUInt64Slice(
193     const tensorflow::protobuf::RepeatedField<tensorflow::protobuf_uint64>& v) {
194   absl::Span<const tensorflow::protobuf_uint64> slice(v);
195   return absl::Span<const uint64>(reinterpret_cast<const uint64*>(slice.data()),
196                                   slice.size());
197 }
198 
199 // Compares two containers for equality. Returns true iff the two containers
200 // have the same size and all their elements compare equal using their
201 // operator==. Like std::equal, but forces size equality.
202 template <typename Container1T, typename Container2T>
ContainersEqual(const Container1T & c1,const Container2T & c2)203 bool ContainersEqual(const Container1T& c1, const Container2T& c2) {
204   return ((c1.size() == c2.size()) &&
205           std::equal(std::begin(c1), std::end(c1), std::begin(c2)));
206 }
207 
208 template <typename Container1T,
209           typename ElementType = typename Container1T::value_type>
ContainersEqual(const Container1T & c1,std::initializer_list<ElementType> il)210 bool ContainersEqual(const Container1T& c1,
211                      std::initializer_list<ElementType> il) {
212   absl::Span<const ElementType> c2{il};
213   return ContainersEqual(c1, c2);
214 }
215 
216 // Compares two containers for equality. Returns true iff the two containers
217 // have the same size and all their elements compare equal using the predicate
218 // p. Like std::equal, but forces size equality.
219 template <typename Container1T, typename Container2T, class PredicateT>
ContainersEqual(const Container1T & c1,const Container2T & c2,PredicateT p)220 bool ContainersEqual(const Container1T& c1, const Container2T& c2,
221                      PredicateT p) {
222   return ((c1.size() == c2.size()) &&
223           std::equal(std::begin(c1), std::end(c1), std::begin(c2), p));
224 }
225 
226 // Performs a copy of count values from src to dest, using different strides for
227 // source and destination. The source starting index is src_base, while the
228 // destination one is dest_base.
229 template <typename D, typename S>
StridedCopy(absl::Span<D> dest,int64 dest_base,int64 dest_stride,absl::Span<const S> src,int64 src_base,int64 src_stride,int64 count)230 void StridedCopy(absl::Span<D> dest, int64 dest_base, int64 dest_stride,
231                  absl::Span<const S> src, int64 src_base, int64 src_stride,
232                  int64 count) {
233   for (; count > 0; --count, dest_base += dest_stride, src_base += src_stride) {
234     dest[dest_base] = static_cast<D>(src[src_base]);
235   }
236 }
237 
238 // Adds some context information to the error message in a
239 // Status.  This is useful as Statuses are
240 // propagated upwards.
241 Status AddStatus(Status prior, absl::string_view context);
242 Status AppendStatus(Status prior, absl::string_view context);
243 
244 // Status error shorthands -- StrFormat's the arguments to be used as an error
245 // message and returns a status in the canonical error space.
246 template <typename... Args>
InvalidArgument(const absl::FormatSpec<Args...> & format,const Args &...args)247 Status InvalidArgument(const absl::FormatSpec<Args...>& format,
248                        const Args&... args) {
249   return WithLogBacktrace(
250       tensorflow::errors::InvalidArgument(absl::StrFormat(format, args...)));
251 }
252 template <typename... Args>
Unimplemented(const absl::FormatSpec<Args...> & format,const Args &...args)253 Status Unimplemented(const absl::FormatSpec<Args...>& format,
254                      const Args&... args) {
255   return WithLogBacktrace(
256       tensorflow::errors::Unimplemented(absl::StrFormat(format, args...)));
257 }
258 template <typename... Args>
InternalError(const absl::FormatSpec<Args...> & format,const Args &...args)259 Status InternalError(const absl::FormatSpec<Args...>& format,
260                      const Args&... args) {
261   return WithLogBacktrace(
262       tensorflow::errors::Internal(absl::StrFormat(format, args...)));
263 }
264 template <typename... Args>
FailedPrecondition(const absl::FormatSpec<Args...> & format,const Args &...args)265 Status FailedPrecondition(const absl::FormatSpec<Args...>& format,
266                           const Args&... args) {
267   return WithLogBacktrace(
268       tensorflow::errors::FailedPrecondition(absl::StrFormat(format, args...)));
269 }
270 template <typename... Args>
Cancelled(const absl::FormatSpec<Args...> & format,const Args &...args)271 Status Cancelled(const absl::FormatSpec<Args...>& format, const Args&... args) {
272   return WithLogBacktrace(
273       tensorflow::errors::Cancelled(absl::StrFormat(format, args...)));
274 }
275 template <typename... Args>
ResourceExhausted(const absl::FormatSpec<Args...> & format,const Args &...args)276 Status ResourceExhausted(const absl::FormatSpec<Args...>& format,
277                          const Args&... args) {
278   return WithLogBacktrace(
279       tensorflow::errors::ResourceExhausted(absl::StrFormat(format, args...)));
280 }
281 template <typename... Args>
NotFound(const absl::FormatSpec<Args...> & format,const Args &...args)282 Status NotFound(const absl::FormatSpec<Args...>& format, const Args&... args) {
283   return WithLogBacktrace(
284       tensorflow::errors::NotFound(absl::StrFormat(format, args...)));
285 }
286 template <typename... Args>
Unavailable(const absl::FormatSpec<Args...> & format,const Args &...args)287 Status Unavailable(const absl::FormatSpec<Args...>& format,
288                    const Args&... args) {
289   return WithLogBacktrace(
290       tensorflow::errors::Unavailable(absl::StrFormat(format, args...)));
291 }
292 template <typename... Args>
Unknown(const absl::FormatSpec<Args...> & format,const Args &...args)293 Status Unknown(const absl::FormatSpec<Args...>& format, const Args&... args) {
294   return WithLogBacktrace(
295       tensorflow::errors::Unknown(absl::StrFormat(format, args...)));
296 }
297 template <typename... Args>
Internal(const absl::FormatSpec<Args...> & format,const Args &...args)298 Status Internal(const absl::FormatSpec<Args...>& format, const Args&... args) {
299   return WithLogBacktrace(
300       tensorflow::errors::Internal(absl::StrFormat(format, args...)));
301 }
302 
303 template <typename... Args>
InvalidArgumentStrCat(Args &&...concat)304 Status InvalidArgumentStrCat(Args&&... concat) {
305   return InvalidArgument("%s", absl::StrCat(std::forward<Args>(concat)...));
306 }
307 
308 template <typename... Args>
UnimplementedStrCat(Args &&...concat)309 Status UnimplementedStrCat(Args&&... concat) {
310   return Unimplemented("%s", absl::StrCat(std::forward<Args>(concat)...));
311 }
312 
313 template <typename... Args>
InternalErrorStrCat(Args &&...concat)314 Status InternalErrorStrCat(Args&&... concat) {
315   return InternalError("%s", absl::StrCat(std::forward<Args>(concat)...));
316 }
317 
318 template <typename... Args>
ResourceExhaustedStrCat(Args &&...concat)319 Status ResourceExhaustedStrCat(Args&&... concat) {
320   return ResourceExhausted("%s", absl::StrCat(std::forward<Args>(concat)...));
321 }
322 
323 // Splits the lines of the original, replaces leading whitespace with the prefix
324 // given by "indentation", and returns the string joined by newlines again. As a
325 // side effect, any additional trailing whitespace is removed.
326 //
327 // Note: even different amounts of leading whitespace on different lines will be
328 // uniformly replaced with "indentation".
329 string Reindent(absl::string_view original, absl::string_view indentation);
330 
331 template <typename Container>
PositionInContainer(const Container & container,int64 value)332 int64 PositionInContainer(const Container& container, int64 value) {
333   return std::distance(container.begin(), absl::c_find(container, value));
334 }
335 
336 // Formats the container as a comma-separated string. StrAppend must support
337 // appending the elements of the container. Prefix is prepended and suffix is
338 // appended to the returned string.
339 template <typename Container>
340 string CommaSeparatedString(const Container& c, const char* prefix = "",
341                             const char* suffix = "") {
342   // Not using Join() since the implementation here is simple anyway and this
343   // avoids copying the string to append prefix.
344   string comma_separated = prefix;
345   const char* separator = "";
346   for (const auto& entry : c) {
347     absl::StrAppend(&comma_separated, separator, entry);
348     separator = ", ";
349   }
350   comma_separated += suffix;
351   return comma_separated;
352 }
353 
354 // Overload needed to allow the container to be an initializer list. The default
355 // type for T makes an empty initializer list work as well.
356 template <typename T = int>
357 string CommaSeparatedString(const std::initializer_list<T>& c,
358                             const char* prefix = "", const char* suffix = "") {
359   return CommaSeparatedString<std::initializer_list<T>>(c, prefix, suffix);
360 }
361 
362 // Formats the container in the mathematical notation for a vector, e.g. (1, 3,
363 // 7). StrAppend must support appending the elements of c.
364 template <typename Container>
VectorString(const Container & c)365 string VectorString(const Container& c) {
366   return CommaSeparatedString(c, "(", ")");
367 }
368 
369 // Overload needed to allow the container to be an initializer list. The default
370 // type for T makes an empty initializer list work as well.
371 template <typename T = int>
VectorString(const std::initializer_list<T> & c)372 string VectorString(const std::initializer_list<T>& c) {
373   return VectorString<std::initializer_list<T>>(c);
374 }
375 
376 // Returns a string which can losslessly round trip to a bfloat.
377 string RoundTripFpToString(tensorflow::bfloat16 value);
378 
379 // Returns a string which can losslessly round trip to a fp16.
380 string RoundTripFpToString(Eigen::half value);
381 
382 // Returns a string which can losslessly round trip to a float.
383 string RoundTripFpToString(float value);
384 
385 // Returns a string which can losslessly round trip to a double.
386 string RoundTripFpToString(double value);
387 
388 // Returns a PaddingConfig object that represents no padding for the given rank.
389 PaddingConfig MakeNoPaddingConfig(int64 rank);
390 
391 // Returns a PaddingConfig object where 'padding' contains
392 // (low edge padding, high edge padding) pairs for each dimension.
393 PaddingConfig MakeEdgePaddingConfig(
394     absl::Span<const std::pair<int64, int64>> padding);
395 
396 // Returns true if the padding configuration has at least one dimension with
397 // non-zero interior padding.
398 bool HasInteriorPadding(const PaddingConfig& config);
399 
400 // Imports the templated FloorOfRatio math function from the TensorFlow
401 // namespace, as it is very commonly used.
402 template <typename T>
FloorOfRatio(T dividend,T divisor)403 T FloorOfRatio(T dividend, T divisor) {
404   return tensorflow::MathUtil::FloorOfRatio<T>(dividend, divisor);
405 }
406 
407 // Imports the templated CeilOfRatio math function from the TensorFlow
408 // namespace, as it is very commonly used.
409 template <typename T>
CeilOfRatio(T dividend,T divisor)410 T CeilOfRatio(T dividend, T divisor) {
411   return tensorflow::MathUtil::CeilOfRatio<T>(dividend, divisor);
412 }
413 
414 // Rounds the value up to a multiple of the divisor by first calling CeilOfRatio
415 // then multiplying by the divisor. For example: RoundUpToNearest(13, 8) => 16
416 template <typename T>
RoundUpToNearest(T value,T divisor)417 T RoundUpToNearest(T value, T divisor) {
418   return CeilOfRatio(value, divisor) * divisor;
419 }
420 
421 // Rounds the value down to a multiple of the divisor by first calling
422 // FloorOfRatio then multiplying by the divisor. For example:
423 // RoundDownToNearest(13, 8) => 8
424 template <typename T>
RoundDownToNearest(T value,T divisor)425 T RoundDownToNearest(T value, T divisor) {
426   return FloorOfRatio(value, divisor) * divisor;
427 }
428 
429 // Given a number of flops executed in an amount of time, produces a string that
430 // represents the throughput;
431 // e.g. HumanReadableNumFlops(1e9, 1e9) => 1.00GFLOP/s.
432 string HumanReadableNumFlops(double flops, double nanoseconds);
433 
434 // Given a number of transcendental ops executed in an amount of time, produces
435 // a string that represents the throughput;
436 // e.g. HumanReadableNumTranscendentalOps(1e9, 1e9) => 1.00GTROP/s.
437 string HumanReadableNumTranscendentalOps(double trops, double nanoseconds);
438 
439 // Split the text into multiple lines and log each line with the given
440 // severity, filename, and line number.
441 void LogLines(int sev, absl::string_view text, const char* fname, int lineno);
442 
443 template <typename T>
IsPowerOfTwo(T x)444 inline bool IsPowerOfTwo(T x) {
445   static_assert(!std::numeric_limits<T>::is_signed, "unsigned types only");
446   return x != 0 && (x & (x - 1)) == 0;
447 }
448 
449 // Returns a mask with "bits" number of least significant bits set.
LsbMaskU32(int bits)450 inline uint32 LsbMaskU32(int bits) {
451   CHECK_GE(bits, 0);
452   return (1U << bits) - 1;
453 }
454 
455 // Utility for performing a static_cast<> on a std::unique_ptr<>.
456 template <typename Derived, typename Base>
unique_ptr_static_cast(std::unique_ptr<Base> ptr)457 std::unique_ptr<Derived> unique_ptr_static_cast(std::unique_ptr<Base> ptr) {
458   return std::unique_ptr<Derived>(static_cast<Derived*>(ptr.release()));
459 }
460 
461 int64 Product(absl::Span<const int64> xs);
462 
463 // Returns the start indices of consecutive non-overlapping subsequences of `a`
464 // and `b` with the same product, i.e. `(i, j)` so
465 // • a = {a[0 = i_0], ..., a[i_1 - 1], a[i_1], ... , a[i_2 - 1], ...}
466 // • b = {b[0 = j_0], ..., b[j_1 - 1], b[j_1], ... , b[j_2 - 1], ...}
467 // • ∀ k . 0 <= k < CommonFactors(a, b).size - 1 =>
468 //         a[i_k] × a[i_k + 1] × ... × a[i_(k+1) - 1] =
469 //         b[j_k] × b[j_k + 1] × ... × b[j_(k+1) - 1]
470 // where `CommonFactors(a, b)[CommonFactors(a, b).size - 1] = (a.size, b.size)`
471 //
472 // If input and output are the same, return {(0, 0), {1, 1}, ... {a.size,
473 // b.size}}, otherwise if the given shapes have non-zero size, returns the
474 // bounds of the shortest possible such subsequences; else, returns `{(0, 0),
475 // (a.size, b.size)}`.
476 absl::InlinedVector<std::pair<int64, int64>, 8> CommonFactors(
477     absl::Span<const int64> a, absl::Span<const int64> b);
478 
479 struct ConvertedDimensionNumbers {
480   DimensionVector transformed_from_dimensions;
481   DimensionVector untransformed_from_dimensions;
482   DimensionVector to_dimensions;
483 };
484 
485 // Convert and unsorted list of dimensions from one shapes dimension sizes to
486 // another shapes dimensions sizes.
487 ConvertedDimensionNumbers ConvertDimensionNumbers(
488     absl::Span<const int64> from_dimensions, absl::Span<const int64> from_sizes,
489     absl::Span<const int64> to_sizes);
490 
491 // Removes illegal characters from filenames.
492 string SanitizeFileName(string file_name);
493 
494 template <typename C, typename Value>
FindIndex(const C & c,Value && value)495 int64 FindIndex(const C& c, Value&& value) {
496   auto it = absl::c_find(c, std::forward<Value>(value));
497   return std::distance(c.begin(), it);
498 }
499 
500 template <typename C, typename Value>
InsertAt(C * c,int64 index,Value && value)501 void InsertAt(C* c, int64 index, Value&& value) {
502   c->insert(c->begin() + index, std::forward<Value>(value));
503 }
504 
505 template <typename C>
EraseAt(C * c,int64 index)506 void EraseAt(C* c, int64 index) {
507   c->erase(c->begin() + index);
508 }
509 
510 template <typename T>
SpanToVector(absl::Span<const T> slice)511 std::vector<T> SpanToVector(absl::Span<const T> slice) {
512   return std::vector<T>(slice.begin(), slice.end());
513 }
514 
515 template <typename T, size_t N>
InlinedVectorToVector(const absl::InlinedVector<T,N> & inlined_vector)516 std::vector<T> InlinedVectorToVector(
517     const absl::InlinedVector<T, N>& inlined_vector) {
518   return std::vector<T>(inlined_vector.begin(), inlined_vector.end());
519 }
520 
521 // Returns true if `x` fits in 32-bits.
522 template <typename T>
IsInt32(T x)523 bool IsInt32(T x) {
524   // Following conversion rules: "the value is unchanged if it can be
525   // represented in the destination type (and bit-field width); otherwise, the
526   // value is implementation-defined."
527   return static_cast<int32>(x) == x;
528 }
529 
530 template <typename T>
EraseElementFromVector(std::vector<T> * container,const T & value)531 Status EraseElementFromVector(std::vector<T>* container, const T& value) {
532   // absl::c_find returns a const_iterator which does not seem to work on
533   // gcc 4.8.4, and this breaks the ubuntu/xla_gpu build bot.
534   auto it = std::find(container->begin(), container->end(), value);
535   TF_RET_CHECK(it != container->end());
536   container->erase(it);
537   return Status::OK();
538 }
539 
540 // Utility function which splits a double-precision float (F64) into a pair of
541 // single-precision floating point numbers. The most significant 49 bits (out of
542 // the total 53 available) in the mantissa of the F64 is represented as the
543 // unevaluated sum of two non-overlapping single-precision F32s; the 'high' part
544 // contains 24 bits in its mantissa, and the 'low' part contains 25 bits in its
545 // sign bit and its mantissa.
546 // Note: The resulting representation can still only represent 8-bit exponent
547 // range that is available in F32s (out of a total of 11 exponent bits in F64s).
548 std::pair<float, float> SplitF64ToF32(double x);
549 
550 // MakeCleanup(f) returns an RAII cleanup object that calls 'f' in its
551 // destructor. The easiest way to use MakeCleanup is with a lambda argument,
552 // capturing the return value in an 'auto' local variable. Most users will not
553 // need more sophisticated syntax than that.
554 //
555 // Example:
556 //   void func() {
557 //     auto resource = acquire_resource();
558 //     auto cleanup = MakeCleanup([&] { release_resource(resource); });
559 //     TF_RETURN_IF_ERROR(...);  // phew, calls release_resource!
560 //   }
561 //
562 // You can use Cleanup<F> directly, instead of using MakeCleanup and auto,
563 // but there's rarely a reason to do that.
564 //
565 // You can call 'release()' on a Cleanup object to cancel the cleanup
566 //
567 // You probably do not want to capture by reference in the cleanup lambda a
568 // variable that is returned by the function.  This can lead to disabling of RVO
569 // at best, and undefined behavior at worst.
570 template <typename F>
571 class Cleanup {
572  public:
Cleanup()573   Cleanup() : released_(true), f_() {}
574 
575   template <typename G>
Cleanup(G && f)576   explicit Cleanup(G&& f) : f_(std::forward<G>(f)) {}
577 
Cleanup(Cleanup && src)578   Cleanup(Cleanup&& src) : released_(src.is_released()), f_(src.release()) {}
579 
580   // Implicitly move-constructible from any compatible Cleanup<G>. The source
581   // will be released as if src.release() were called. A moved-from Cleanup can
582   // be safely destroyed or reassigned.
583   template <typename G>
Cleanup(Cleanup<G> && src)584   Cleanup(Cleanup<G>&& src) : released_(src.is_released()), f_(src.release()) {}
585 
586   // Assignment to a Cleanup object behaves like destroying it and making a new
587   // one in its place, analogous to unique_ptr semantics.
588   Cleanup& operator=(Cleanup&& src) {
589     if (!released_) std::move(f_)();
590     released_ = src.released_;
591     f_ = src.release();
592     return *this;
593   }
594 
~Cleanup()595   ~Cleanup() {
596     if (!released_) std::move(f_)();
597   }
598 
599   // Releases the cleanup function instead of running it. Hint: use
600   // c.release()() to run early.
release()601   F release() {
602     released_ = true;
603     return std::move(f_);
604   }
605 
is_released()606   bool is_released() const { return released_; }
607 
608  private:
609   static_assert(!std::is_reference<F>::value, "F must not be a reference");
610 
611   bool released_ = false;
612   F f_;
613 };
614 
615 template <int&... ExplicitParameterBarrier, typename F,
616           typename DecayF = typename std::decay<F>::type>
MakeCleanup(F && f)617 ABSL_MUST_USE_RESULT Cleanup<DecayF> MakeCleanup(F&& f) {
618   return Cleanup<DecayF>(std::forward<F>(f));
619 }
620 
621 }  // namespace xla
622 
623 #define XLA_LOG_LINES(SEV, STRING) \
624   ::xla::LogLines(SEV, STRING, __FILE__, __LINE__)
625 
626 #define XLA_VLOG_LINES(LEVEL, STRING)                                 \
627   do {                                                                \
628     if (VLOG_IS_ON(LEVEL)) XLA_LOG_LINES(::tensorflow::INFO, STRING); \
629   } while (false);
630 
631 // Utility macro that performs the equivalent of what one would expect
632 // LOG_LINES(FATAL, X) to do but can be used at the end of a function that
633 // returns a value without getting a compiler warning that no value is returned.
634 #define XLA_FATAL_LOG(X)                 \
635   XLA_LOG_LINES(::tensorflow::ERROR, X); \
636   LOG(FATAL) << "Aborting in " << __FUNCTION__ << " due to previous errors.";
637 
638 #endif  // TENSORFLOW_COMPILER_XLA_UTIL_H_
639