diff options
| author |  Abseil Team <absl-team@google.com> | 2022-03-14 08:43:59 -0700 |
|---|---|---|
| committer |  Andy Getz <durandal@google.com> | 2022-03-14 12:14:03 -0400 |
| commit | 5ed77665c4d697f657fa1362b5a482450f858cdc (patch) | |
| tree | 85ce8fd99e4e0418b1d48c14611dc4b0a1e7ec73 /absl/base/internal/unscaledcycleclock.h | |
| parent | c5a424a2a21005660b182516eb7a079cd8021699 (diff) | |
Export of internal Abseil changes
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d3b99682554d339c42556680f4d65f83226005e2 by Martijn Vels <mvels@google.com>:
Inline CycleClock code and remove branch for x86 CycleClockSource function
This CL removes the relaxed load for x86 as there is no acquire price to pay on x86. It inlines the UnscaledCycleClock::Now() which is a single RTDSC op for x86, and likewise inlines CycleClock::Now() for x86. The inlining should mostly have secondary benefits such as reducing spills on outlined calls.
LTO may eventually hoist these functions inline for the hotspots, but it doesn't hurt to default inline this for all builds and let the compiler decide on the first pass.
The perlab benchmark is noisy for the plain BM_Now, but the other benchmarks and the run on my local machine are clear.
------------- Local Benchy Benchmark
name old cpu/op new cpu/op delta
BM_Now 3.41ns ± 1% 2.30ns ± 2% -32.52% (p=0.000 n=50+50)
BM_NowWithRegisterPresure 4.96ns ± 2% 4.19ns ± 2% -15.57% (p=0.000 n=56+55)
BM_NowWithCallback 3.30ns ± 2% 1.91ns ± 2% -42.00% (p=0.000 n=47+60)
------------- Perflab Benchy Benchmark
name old cpu/op new cpu/op delta
BM_Now 8.20ns ±13% 4.32ns ±83% ~ (p=0.413 n=4+5)
BM_NowWithRegisterPresure 7.91ns ± 1% 3.68ns ± 2% -53.45% (p=0.029 n=4+4)
BM_NowWithCallback 2.66ns ±13% 1.58ns ± 0% -40.51% (p=0.008 n=5+5)
PiperOrigin-RevId: 434474766
Change-Id: I991d987ae9233e50f09606c874055cf4c5a56300
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b38330686a0af176a2679163e4d2fa1b90e2f667 by Laramie Leavitt <lar@google.com>:
Style, comment, and test updates
* Remove a redundant assert in uniform_real_distribution.
* Update comment in internal/generate_real.h
* Style updates to uniform_real_distribution_test
mainly replacing TypeParam with real_type, using aliases for some limits, etc.
* Add a few more minor tests.
PiperOrigin-RevId: 433902174
Change-Id: Id75be8e24be2fb8f6aea05feec13e3ef320a7254
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ab2da6047ff7f5dae3add3779fcddf73b03feabf by Abseil Team <absl-team@google.com>:
Remove declaration of method whose definition was previously removed.
PiperOrigin-RevId: 433507828
Change-Id: I0130b689813125250f7de2664e767e181f676c89
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df0c87f4ec2c010691931c1bef9d26470a6e63a2 by Derek Mauro <dmauro@google.com>:
Internal change
PiperOrigin-RevId: 433289136
Change-Id: Iba157dc83ed99dafd17a2223d2504e49f8afbb9e
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7445fa312f2995772900eda82467325b3401a17d by Martijn Vels <mvels@google.com>:
Optimize CordReader logic now that CONCAT is removed
This CL cleans up various helper functions and logic remaining from previous complex CONCAT logic that is no longer needed, simplifying the CordReader logic.
PiperOrigin-RevId: 433208748
Change-Id: I5f7b1883573c44e7c6f8af12c3cddbd197cb134d
GitOrigin-RevId: d3b99682554d339c42556680f4d65f83226005e2
Diffstat (limited to 'absl/base/internal/unscaledcycleclock.h')
| -rw-r--r-- | absl/base/internal/unscaledcycleclock.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/absl/base/internal/unscaledcycleclock.h b/absl/base/internal/unscaledcycleclock.h index 681ff8f9..07f867a6 100644 --- a/absl/base/internal/unscaledcycleclock.h +++ b/absl/base/internal/unscaledcycleclock.h @@ -115,6 +115,16 @@ class UnscaledCycleClock { friend class base_internal::UnscaledCycleClockWrapperForInitializeFrequency; }; +#if defined(__x86_64__) + +inline int64_t UnscaledCycleClock::Now() { + uint64_t low, high; + __asm__ volatile("rdtsc" : "=a"(low), "=d"(high)); + return (high << 32) | low; +} + +#endif + } // namespace base_internal ABSL_NAMESPACE_END } // namespace absl |