This is a shameless rip-off of https://github.com/google/benchmark/pull/646
I did promise to look into why that proposed PR was producing
so much worse assembly, and so i finally did.
The reason is - that diff changes `size_t` (unsigned) to `int64_t` (signed).
There is this nice little `assert`:
7a1c370283/include/benchmark/benchmark.h (L744)
It ensures that we didn't magically decide to advance our iterator
when we should have finished benchmarking.
When `cached_` was unsigned, the `assert` was `cached_ UGT 0`.
But we only ever get to that `assert` if `cached_ NE 0`,
and naturally if `cached_` is not `0`, then it is bigger than `0`,
so the `assert` is tautological, and gets folded away.
But now that `cached_` became signed, the assert became `cached_ SGT 0`.
And we still only know that `cached_ NE 0`, so the assert can't be
optimized out, or at least it doesn't currently.
Regardless of whether or not that is a bug in itself,
that particular diff would have regressed the normal 64-bit systems,
by halving the maximal iteration space (since we go from unsigned counter
to signed one, of the same bit-width), which seems like a bug.
And just so it happens, fixing *this* bug, fixes the other bug.
This produces fully (bit-by-bit) identical state_assembly_test.s
The filecheck change is actually needed regardless of this patch,
else this test does not pass for me even without this diff.
* Fix#444 - Use BENCHMARK_HAS_CXX11 over __cplusplus.
MSVC incorrectly defines __cplusplus to report C++03, despite the compiler
actually providing C++11 or greater. Therefore we have to detect C++11 differently
for MSVC. This patch uses `_MSVC_LANG` which has been defined since
Visual Studio 2015 Update 3; which should be sufficient for detecting C++11.
Secondly this patch changes over most usages of __cplusplus >= 201103L to
check BENCHMARK_HAS_CXX11 instead.
* remove redunant comment
* Added user counters, and move use of bytes_processed and items_processed to user counter logic.
Each counter is a string-value pair. The counters were
made available through the State class. Two helper virtual
methods were added to the Fixture class to allow convenient
initialization and termination of the counters: InitState()
and TerminateState(). The reporting of the counters is buggy
and is still a work in progress, to be completed in the next commits.
* fix bad removal of BenchmarkCounters code during the merge
* add myself to AUTHORS/CONTRIBUTORS
* fix printing to std::cout in csv_reporter
* bytes_per_second and items_per_second are now in the UserCounters class
* add user counters to json reporter
* moving bytes_per_second and items_per_second to their old state
* console reporter dealing ok with user counters.
* update unit tests for user counters
* CSVReporter now prints user counters too.
* cleanup user counters
* reverted changes to cmake files which should have gone into later commits
* fixture_test: fix gcc 4.6 compilation
* remove ctor with default argument
see https://github.com/google/benchmark/pull/262#discussion_r72298055
* use (auto-defined) BENCHMARK_HAS_CXX11 instead of BENCHMARK_INITLIST.
https://github.com/google/benchmark/pull/262#discussion_r72298310
* leanify counters API
Discussions:
API complexity: https://github.com/google/benchmark/pull/262#discussion_r72298731
remove std::string dependency (WIP): https://github.com/google/benchmark/pull/262#discussion_r72298142
spacing & alignment: https://github.com/google/benchmark/pull/262#discussion_r72298422
* remove std::string dependency on public API - changed counter name storage to char*
* Counter ctor: use overloads instead of default arguments
discussion:
https://github.com/google/benchmark/pull/262#discussion_r72298055
* Use raw pointers to remove dependency on std::vector from public API .
For more info, see discussion at https://github.com/google/benchmark/pull/262#discussion_r72319678 .
* Move counter implementation from benchmark.cc to counter.cc.
See discussion: https://github.com/google/benchmark/pull/262#discussion_r72298980 .
* Remove unused (commented-out) code.
* Moved thread counters to ThreadStats.
* Counters: fixed copy and move constructors.
* Counter: use an inplace buffer for small names.
* benchmark_test: move counters test out of CXX11 preprocessor conditional.
* Counter: fix VS2013 compilation error in char[] initialization.
* Fix typo.
* Expose counters from State.
See discussion: https://github.com/google/benchmark/pull/262#issuecomment-237156951
* Changed counters interface to map-like.
* Fix printing of user counters in ConsoleReporter.
* Applied clang-format to counter.cc and console_reporter.cc.
Command was `clang-format -style=Google -i counter.cc console_reporter.cc`
I also applied to all other files, but the changes were very
far-reaching so I rolled those back.
* Rename Counter::Flags_e to Counter::Flags
* Fix use of reserved names in Counter and BenchmarkCounters.
* Counter: Fix move ctor bug + change order of members.
* Fixture: remove tentative methods InitState() and TerminateState().
* Update fixture_test to the new Fixture interface.
* BenchmarkCounters: fixed a bug in the move ctor. Remove call to CHECK_LT().
CHECK_LT() was making the size_t lookup take ~double the time of a string lookup!
* BenchmarkCounters: add option to not print zero counters (defaults to false).
* Add test to compare counter storage and access with std::map.
* README: clarify cost of counter access modes.
* move counter access test to an own test.
* BenchmarkCounters: add move Insert()
* Counters access test: add accelerated lookup by name.
* Fix old range syntax.
* Fix missing include of cstdio
* Fix Visual Studio warning
* VS2013 and lower: fix use of snprintf()
* VS2013: fix use of char[] as a member of std::pair<>.
* change counter storage to std::map
* Remove skipZeroCounters logic
* Fix VS compilation error.
* Implemented request changes to PR #262.
* PR #262: More requested changes.
* README: cleanup counter text.
* PR #262: remove clang-format changes for preexisting code
* Complexity+Counters: fix counter flags which were being ignored.
* Document all Counter::Flag members
* fixed loss of counter values
* ConsoleReporter: remove tabular printing of user counters.
* ConsoleReporter: header printing should not be contingent on user counter names.
* Minor white space and alignment fixes.
* cxx03_test + counters: reuse the BM_empty() function.
* user counters: add note to README on how counters are gathered across threads
Dominic Hamon