document cpuid command line behavior

document cpuid command line behavior

cpu_info_ is zero for uninitialized state and all bits are off, disabling all cpu optimizations.
the 1 bit indicates cpu_info_ is initialized avoiding calling the detection code again for performance.

MaskCpuFlags initializes the cpu ignoring existing flags, then masks with the supplied flags and stores to cpu_info_.  
As a mask, -1 has no effect, enabling all cpu features that were detected, but nothing that wasnt detected.
Setting to 0 will cause the next call to re-initialize the cpu, which is same as enabling all features.
Setting mask to 1 will turn off all cpu features but keep the initialized bit on, so the next detection call wont reinitialize and the cpu features are all disabled.

So normal behavior for command line and programatic masking is:
1 = C
-1 = SIMD

TBR=harryjin@google.com
BUG=libyuv:600
TESTED=out64/Release/bin/run_libyuv_unittest -s libyuv_unittest --verbose --release --gtest_filter=*ARGBExtractAlpha* -a "--libyuv_width=1280 --libyuv_height=720 --libyuv_repeat=9999 --libyuv_flags=1 --libyuv_cpu_info=1"

Committed: https://chromium.googlesource.com/libyuv/libyuv/+/e2611a734955782ac9be1a64d080a6e52a57be82

[fbarchard1, 2016-06-07 21:57:56]

Description was changed from

==========
document cpuid behavior

BUG=None
TESTED=untested
==========

to

==========
document cpuid command line behavior

cpu_info_ is zero for uninitialized state and all bits are off, disabling all
cpu optimizations.
the 1 bit indicates cpu_info_ is initialized avoiding calling the detection code
again for performance.

MaskCpuFlags initializes the cpu ignoring existing flags, then masks with the
supplied flags and stores to cpu_info_.  
As a mask, -1 has no effect, enabling all cpu features that were detected, but
nothing that wasnt detected.
Setting to 0 will cause the next call to re-initialize the cpu, which is same as
enabling all features.
Setting mask to 1 will turn off all cpu features but keep the initialized bit
on, so the next detection call wont reinitialize and the cpu features are all
disabled.

So normal behavior for command line and programatic masking is:
1 = C
-1 = SIMD

BUG=None
TESTED=untested
==========

[fbarchard1, 2016-06-07 22:00:59]

Description was changed from

==========
document cpuid command line behavior

cpu_info_ is zero for uninitialized state and all bits are off, disabling all
cpu optimizations.
the 1 bit indicates cpu_info_ is initialized avoiding calling the detection code
again for performance.

MaskCpuFlags initializes the cpu ignoring existing flags, then masks with the
supplied flags and stores to cpu_info_.  
As a mask, -1 has no effect, enabling all cpu features that were detected, but
nothing that wasnt detected.
Setting to 0 will cause the next call to re-initialize the cpu, which is same as
enabling all features.
Setting mask to 1 will turn off all cpu features but keep the initialized bit
on, so the next detection call wont reinitialize and the cpu features are all
disabled.

So normal behavior for command line and programatic masking is:
1 = C
-1 = SIMD

BUG=None
TESTED=untested
==========

to

==========
document cpuid command line behavior

cpu_info_ is zero for uninitialized state and all bits are off, disabling all
cpu optimizations.
the 1 bit indicates cpu_info_ is initialized avoiding calling the detection code
again for performance.

MaskCpuFlags initializes the cpu ignoring existing flags, then masks with the
supplied flags and stores to cpu_info_.  
As a mask, -1 has no effect, enabling all cpu features that were detected, but
nothing that wasnt detected.
Setting to 0 will cause the next call to re-initialize the cpu, which is same as
enabling all features.
Setting mask to 1 will turn off all cpu features but keep the initialized bit
on, so the next detection call wont reinitialize and the cpu features are all
disabled.

So normal behavior for command line and programatic masking is:
1 = C
-1 = SIMD

BUG=libyuv:600
TESTED=out64/Release/bin/run_libyuv_unittest -s libyuv_unittest --verbose
--release --gtest_filter=*ARGBExtractAlpha* -a "--libyuv_width=1280
--libyuv_heigh
t=720 --libyuv_repeat=9999 --libyuv_flags=1 --libyuv_cpu_info=1"
==========

[fbarchard1, 2016-06-07 22:00:59]

fbarchard@google.com changed reviewers:
+ kjellander@chromium.org

[fbarchard1, 2016-06-07 23:58:04]

Description was changed from

==========
document cpuid command line behavior

cpu_info_ is zero for uninitialized state and all bits are off, disabling all
cpu optimizations.
the 1 bit indicates cpu_info_ is initialized avoiding calling the detection code
again for performance.

MaskCpuFlags initializes the cpu ignoring existing flags, then masks with the
supplied flags and stores to cpu_info_.  
As a mask, -1 has no effect, enabling all cpu features that were detected, but
nothing that wasnt detected.
Setting to 0 will cause the next call to re-initialize the cpu, which is same as
enabling all features.
Setting mask to 1 will turn off all cpu features but keep the initialized bit
on, so the next detection call wont reinitialize and the cpu features are all
disabled.

So normal behavior for command line and programatic masking is:
1 = C
-1 = SIMD

BUG=libyuv:600
TESTED=out64/Release/bin/run_libyuv_unittest -s libyuv_unittest --verbose
--release --gtest_filter=*ARGBExtractAlpha* -a "--libyuv_width=1280
--libyuv_heigh
t=720 --libyuv_repeat=9999 --libyuv_flags=1 --libyuv_cpu_info=1"
==========

to

==========
document cpuid command line behavior

cpu_info_ is zero for uninitialized state and all bits are off, disabling all
cpu optimizations.
the 1 bit indicates cpu_info_ is initialized avoiding calling the detection code
again for performance.

MaskCpuFlags initializes the cpu ignoring existing flags, then masks with the
supplied flags and stores to cpu_info_.  
As a mask, -1 has no effect, enabling all cpu features that were detected, but
nothing that wasnt detected.
Setting to 0 will cause the next call to re-initialize the cpu, which is same as
enabling all features.
Setting mask to 1 will turn off all cpu features but keep the initialized bit
on, so the next detection call wont reinitialize and the cpu features are all
disabled.

So normal behavior for command line and programatic masking is:
1 = C
-1 = SIMD

BUG=libyuv:600
TESTED=out64/Release/bin/run_libyuv_unittest -s libyuv_unittest --verbose
--release --gtest_filter=*ARGBExtractAlpha* -a "--libyuv_width=1280
--libyuv_height=720 --libyuv_repeat=9999 --libyuv_flags=1 --libyuv_cpu_info=1"
==========

[fbarchard1, 2016-06-07 23:58:28]

fbarchard@google.com changed reviewers:
+ harryjin@google.com

[fbarchard1, 2016-06-07 23:58:50]

Description was changed from

==========
document cpuid command line behavior

cpu_info_ is zero for uninitialized state and all bits are off, disabling all
cpu optimizations.
the 1 bit indicates cpu_info_ is initialized avoiding calling the detection code
again for performance.

MaskCpuFlags initializes the cpu ignoring existing flags, then masks with the
supplied flags and stores to cpu_info_.  
As a mask, -1 has no effect, enabling all cpu features that were detected, but
nothing that wasnt detected.
Setting to 0 will cause the next call to re-initialize the cpu, which is same as
enabling all features.
Setting mask to 1 will turn off all cpu features but keep the initialized bit
on, so the next detection call wont reinitialize and the cpu features are all
disabled.

So normal behavior for command line and programatic masking is:
1 = C
-1 = SIMD

BUG=libyuv:600
TESTED=out64/Release/bin/run_libyuv_unittest -s libyuv_unittest --verbose
--release --gtest_filter=*ARGBExtractAlpha* -a "--libyuv_width=1280
--libyuv_height=720 --libyuv_repeat=9999 --libyuv_flags=1 --libyuv_cpu_info=1"
==========

to

==========
document cpuid command line behavior

cpu_info_ is zero for uninitialized state and all bits are off, disabling all
cpu optimizations.
the 1 bit indicates cpu_info_ is initialized avoiding calling the detection code
again for performance.

MaskCpuFlags initializes the cpu ignoring existing flags, then masks with the
supplied flags and stores to cpu_info_.  
As a mask, -1 has no effect, enabling all cpu features that were detected, but
nothing that wasnt detected.
Setting to 0 will cause the next call to re-initialize the cpu, which is same as
enabling all features.
Setting mask to 1 will turn off all cpu features but keep the initialized bit
on, so the next detection call wont reinitialize and the cpu features are all
disabled.

So normal behavior for command line and programatic masking is:
1 = C
-1 = SIMD

TBR=harryjin@google.com
BUG=libyuv:600
TESTED=out64/Release/bin/run_libyuv_unittest -s libyuv_unittest --verbose
--release --gtest_filter=*ARGBExtractAlpha* -a "--libyuv_width=1280
--libyuv_height=720 --libyuv_repeat=9999 --libyuv_flags=1 --libyuv_cpu_info=1"
==========

[fbarchard1, 2016-06-08 17:37:26]

lint passed.  local build passes.  try bots pass.

[fbarchard1, 2016-06-08 17:38:13]

Description was changed from

==========
document cpuid command line behavior

cpu_info_ is zero for uninitialized state and all bits are off, disabling all
cpu optimizations.
the 1 bit indicates cpu_info_ is initialized avoiding calling the detection code
again for performance.

MaskCpuFlags initializes the cpu ignoring existing flags, then masks with the
supplied flags and stores to cpu_info_.  
As a mask, -1 has no effect, enabling all cpu features that were detected, but
nothing that wasnt detected.
Setting to 0 will cause the next call to re-initialize the cpu, which is same as
enabling all features.
Setting mask to 1 will turn off all cpu features but keep the initialized bit
on, so the next detection call wont reinitialize and the cpu features are all
disabled.

So normal behavior for command line and programatic masking is:
1 = C
-1 = SIMD

TBR=harryjin@google.com
BUG=libyuv:600
TESTED=out64/Release/bin/run_libyuv_unittest -s libyuv_unittest --verbose
--release --gtest_filter=*ARGBExtractAlpha* -a "--libyuv_width=1280
--libyuv_height=720 --libyuv_repeat=9999 --libyuv_flags=1 --libyuv_cpu_info=1"
==========

to

==========
document cpuid command line behavior

cpu_info_ is zero for uninitialized state and all bits are off, disabling all
cpu optimizations.
the 1 bit indicates cpu_info_ is initialized avoiding calling the detection code
again for performance.

MaskCpuFlags initializes the cpu ignoring existing flags, then masks with the
supplied flags and stores to cpu_info_.  
As a mask, -1 has no effect, enabling all cpu features that were detected, but
nothing that wasnt detected.
Setting to 0 will cause the next call to re-initialize the cpu, which is same as
enabling all features.
Setting mask to 1 will turn off all cpu features but keep the initialized bit
on, so the next detection call wont reinitialize and the cpu features are all
disabled.

So normal behavior for command line and programatic masking is:
1 = C
-1 = SIMD

TBR=harryjin@google.com
BUG=libyuv:600
TESTED=out64/Release/bin/run_libyuv_unittest -s libyuv_unittest --verbose
--release --gtest_filter=*ARGBExtractAlpha* -a "--libyuv_width=1280
--libyuv_height=720 --libyuv_repeat=9999 --libyuv_flags=1 --libyuv_cpu_info=1"

Committed:
https://chromium.googlesource.com/libyuv/libyuv/+/e2611a734955782ac9be1a64d08...
==========

[fbarchard1, 2016-06-08 17:38:15]

Committed patchset #7 (id:120001) manually as
e2611a734955782ac9be1a64d080a6e52a57be82 (presubmit successful).