Re: [Mesa-dev] [PATCH 2/6] nir: Turn bcsel of +/- 1.0 and 0.0 into b2f sequences.

[Ian Romanick]

On 08/10/2016 12:50 PM, Eric Anholt wrote:
> Connor Abbott  writes:
> 
>> On Wed, Aug 10, 2016 at 1:53 PM, Eric Anholt  wrote:
>>> Kenneth Graunke  writes:
>>>
 On Haswell (GL 3.3):

 total instructions in shared programs: 6208759 -> 6203860 (-0.08%)
 instructions in affected programs: 856541 -> 851642 (-0.57%)
 helped: 3157
 HURT: 113
 LOST:   7
 GAINED: 15

 On Broadwell (GL 4.4):

 total instructions in shared programs: 11637854 -> 11632016 (-0.05%)
 instructions in affected programs: 1055693 -> 1049855 (-0.55%)
 helped: 3900
 HURT: 176
 LOST:   1
 GAINED: 18

 Signed-off-by: Kenneth Graunke 
 ---
  src/compiler/nir/nir_opt_algebraic.py | 4 
  1 file changed, 4 insertions(+)

 diff --git a/src/compiler/nir/nir_opt_algebraic.py 
 b/src/compiler/nir/nir_opt_algebraic.py
 index 1cf614c..4e9896f 100644
 --- a/src/compiler/nir/nir_opt_algebraic.py
 +++ b/src/compiler/nir/nir_opt_algebraic.py
 @@ -251,6 +251,10 @@ optimizations = [
 (('ieq', 'a@bool', False), ('inot', 'a')),
 (('bcsel', a, True, False), ('ine', a, 0)),
 (('bcsel', a, False, True), ('ieq', a, 0)),
 +   (('bcsel@32', a, 1.0, 0.0), ('b2f', ('ine', a, 0))),
 +   (('bcsel@32', a, 0.0, 1.0), ('b2f', ('ieq', a, 0))),
 +   (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', ('ine', a, 0,
 +   (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('ieq', a, 0,
>>>
>>> Isn't bcsel's first arg guaranteed to be 0 or ~0?  I thought that was
>>> how nir's bcsel (and b2f) worked.  If not, it would be good to see this
>>> documented.
>>
>> Yes, any ALU operation that takes a boolean input can expect it to be
>> 0 or ~0. If that isn't true, then something else in the compiler has
>> messed up. So I think we can replace 'a != 0' with 'a' and 'a == 0'
>> with '!a'.
> 
> Yeah.  So, I like the contents of this series a lot, but it would be
> nice to see some of the @bool annotations dropped.

Right... because ('b2f', 'a@bool') is redundant.  I agree.

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Re: [Mesa-dev] [PATCH 2/6] nir: Turn bcsel of +/- 1.0 and 0.0 into b2f sequences.

[Connor Abbott]

On Wed, Aug 10, 2016 at 2:24 PM, Kenneth Graunke  wrote:
> On Wednesday, August 10, 2016 10:02:12 AM PDT Erik Faye-Lund wrote:
>> On Wed, Aug 10, 2016 at 4:30 AM, Kenneth Graunke  
>> wrote:
>> > On Haswell (GL 3.3):
>> >
>> > total instructions in shared programs: 6208759 -> 6203860 (-0.08%)
>> > instructions in affected programs: 856541 -> 851642 (-0.57%)
>> > helped: 3157
>> > HURT: 113
>> > LOST:   7
>> > GAINED: 15
>> >
>> > On Broadwell (GL 4.4):
>> >
>> > total instructions in shared programs: 11637854 -> 11632016 (-0.05%)
>> > instructions in affected programs: 1055693 -> 1049855 (-0.55%)
>> > helped: 3900
>> > HURT: 176
>> > LOST:   1
>> > GAINED: 18
>> >
>> > Signed-off-by: Kenneth Graunke 
>> > ---
>> >  src/compiler/nir/nir_opt_algebraic.py | 4 
>> >  1 file changed, 4 insertions(+)
>> >
>> > diff --git a/src/compiler/nir/nir_opt_algebraic.py 
>> > b/src/compiler/nir/nir_opt_algebraic.py
>> > index 1cf614c..4e9896f 100644
>> > --- a/src/compiler/nir/nir_opt_algebraic.py
>> > +++ b/src/compiler/nir/nir_opt_algebraic.py
>> > @@ -251,6 +251,10 @@ optimizations = [
>> > (('ieq', 'a@bool', False), ('inot', 'a')),
>> > (('bcsel', a, True, False), ('ine', a, 0)),
>> > (('bcsel', a, False, True), ('ieq', a, 0)),
>> > +   (('bcsel@32', a, 1.0, 0.0), ('b2f', ('ine', a, 0))),
>> > +   (('bcsel@32', a, 0.0, 1.0), ('b2f', ('ieq', a, 0))),
>> > +   (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', ('ine', a, 0,
>> > +   (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('ieq', a, 0,
>> > (('bcsel', True, b, c), b),
>> > (('bcsel', False, b, c), c),
>> > # The result of this should be hit by constant propagation and, in the
>>
>> Same as the previous patch, this smells like intel-isms. Hardware that
>> has native bcsel with support for two inline immediates will do better
>> without.
>
> It definitely feels a little strange replacing a single bcsel with
> a fneg/b2f/ine, as that's three operations instead of one.
>
> I expect the ine to go away - assuming 'a' is a properly formatted
> boolean (0 or 0x), "ine a 0" will just become 'a'.  ieq would
> turn into inot.

I made the point in another place in this thread, but you don't have
to assume -- things that take booleans as input should only ever get 0
or ~0. Anything else would be a bug in the compiler. Now that I have a
little more free time before school starts, I've been thinking about
making booleans have a bit-width of 1 (i.e. making them logical) and
then only lowering to their concrete representation very late, if at
all. That would keep this confusion from happening, in addition to
bringing a lot of other benefits, and it should be a lot easier now
that we have bit widths in NIR.

> If the boolean was a comparison, the inot could be
> folded in - i.e. inot(flt(a,b)) -> fge(a,b).  Or, some GPUs can handle
> boolean negation as a source modifier, so it might be free there too.
>
> Floating point negation can usually be done as a source modifier.
>
> For reference, here's a shader snippet from Goat Simulator which
> prompted me to write this optimization:
>
> const vec4 LocalConst1 = vec4(0.25, -0.25, 0.00, 1.00);
>
> void main()
> {
> ...
> InstrHelpTemp.r = ( ( Temporary1.r >= 0.0 ) ? LocalConst1.b : LocalConst1.a );
> ...
> }
>
> which could be turned into
>
> InstrHelpTemp.r = float(Temporary1.r < 0.0);
>
> which seems arguably better, regardless of hardware.
>
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Re: [Mesa-dev] [PATCH 2/6] nir: Turn bcsel of +/- 1.0 and 0.0 into b2f sequences.

[Eric Anholt]

Connor Abbott  writes:

> On Wed, Aug 10, 2016 at 1:53 PM, Eric Anholt  wrote:
>> Kenneth Graunke  writes:
>>
>>> On Haswell (GL 3.3):
>>>
>>> total instructions in shared programs: 6208759 -> 6203860 (-0.08%)
>>> instructions in affected programs: 856541 -> 851642 (-0.57%)
>>> helped: 3157
>>> HURT: 113
>>> LOST:   7
>>> GAINED: 15
>>>
>>> On Broadwell (GL 4.4):
>>>
>>> total instructions in shared programs: 11637854 -> 11632016 (-0.05%)
>>> instructions in affected programs: 1055693 -> 1049855 (-0.55%)
>>> helped: 3900
>>> HURT: 176
>>> LOST:   1
>>> GAINED: 18
>>>
>>> Signed-off-by: Kenneth Graunke 
>>> ---
>>>  src/compiler/nir/nir_opt_algebraic.py | 4 
>>>  1 file changed, 4 insertions(+)
>>>
>>> diff --git a/src/compiler/nir/nir_opt_algebraic.py 
>>> b/src/compiler/nir/nir_opt_algebraic.py
>>> index 1cf614c..4e9896f 100644
>>> --- a/src/compiler/nir/nir_opt_algebraic.py
>>> +++ b/src/compiler/nir/nir_opt_algebraic.py
>>> @@ -251,6 +251,10 @@ optimizations = [
>>> (('ieq', 'a@bool', False), ('inot', 'a')),
>>> (('bcsel', a, True, False), ('ine', a, 0)),
>>> (('bcsel', a, False, True), ('ieq', a, 0)),
>>> +   (('bcsel@32', a, 1.0, 0.0), ('b2f', ('ine', a, 0))),
>>> +   (('bcsel@32', a, 0.0, 1.0), ('b2f', ('ieq', a, 0))),
>>> +   (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', ('ine', a, 0,
>>> +   (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('ieq', a, 0,
>>
>> Isn't bcsel's first arg guaranteed to be 0 or ~0?  I thought that was
>> how nir's bcsel (and b2f) worked.  If not, it would be good to see this
>> documented.
>
> Yes, any ALU operation that takes a boolean input can expect it to be
> 0 or ~0. If that isn't true, then something else in the compiler has
> messed up. So I think we can replace 'a != 0' with 'a' and 'a == 0'
> with '!a'.

Yeah.  So, I like the contents of this series a lot, but it would be
nice to see some of the @bool annotations dropped.


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Re: [Mesa-dev] [PATCH 2/6] nir: Turn bcsel of +/- 1.0 and 0.0 into b2f sequences.

[Ian Romanick]

On 08/10/2016 11:24 AM, Kenneth Graunke wrote:
> On Wednesday, August 10, 2016 10:02:12 AM PDT Erik Faye-Lund wrote:
>> On Wed, Aug 10, 2016 at 4:30 AM, Kenneth Graunke  
>> wrote:
>>> On Haswell (GL 3.3):
>>>
>>> total instructions in shared programs: 6208759 -> 6203860 (-0.08%)
>>> instructions in affected programs: 856541 -> 851642 (-0.57%)
>>> helped: 3157
>>> HURT: 113
>>> LOST:   7
>>> GAINED: 15
>>>
>>> On Broadwell (GL 4.4):
>>>
>>> total instructions in shared programs: 11637854 -> 11632016 (-0.05%)
>>> instructions in affected programs: 1055693 -> 1049855 (-0.55%)
>>> helped: 3900
>>> HURT: 176
>>> LOST:   1
>>> GAINED: 18
>>>
>>> Signed-off-by: Kenneth Graunke 
>>> ---
>>>  src/compiler/nir/nir_opt_algebraic.py | 4 
>>>  1 file changed, 4 insertions(+)
>>>
>>> diff --git a/src/compiler/nir/nir_opt_algebraic.py 
>>> b/src/compiler/nir/nir_opt_algebraic.py
>>> index 1cf614c..4e9896f 100644
>>> --- a/src/compiler/nir/nir_opt_algebraic.py
>>> +++ b/src/compiler/nir/nir_opt_algebraic.py
>>> @@ -251,6 +251,10 @@ optimizations = [
>>> (('ieq', 'a@bool', False), ('inot', 'a')),
>>> (('bcsel', a, True, False), ('ine', a, 0)),
>>> (('bcsel', a, False, True), ('ieq', a, 0)),
>>> +   (('bcsel@32', a, 1.0, 0.0), ('b2f', ('ine', a, 0))),
>>> +   (('bcsel@32', a, 0.0, 1.0), ('b2f', ('ieq', a, 0))),
>>> +   (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', ('ine', a, 0,
>>> +   (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('ieq', a, 0,
>>> (('bcsel', True, b, c), b),
>>> (('bcsel', False, b, c), c),
>>> # The result of this should be hit by constant propagation and, in the
>>
>> Same as the previous patch, this smells like intel-isms. Hardware that
>> has native bcsel with support for two inline immediates will do better
>> without.
> 
> It definitely feels a little strange replacing a single bcsel with
> a fneg/b2f/ine, as that's three operations instead of one.
> 
> I expect the ine to go away - assuming 'a' is a properly formatted
> boolean (0 or 0x), "ine a 0" will just become 'a'.  ieq would
> turn into inot.  If the boolean was a comparison, the inot could be
> folded in - i.e. inot(flt(a,b)) -> fge(a,b).  Or, some GPUs can handle
> boolean negation as a source modifier, so it might be free there too.
> 
> Floating point negation can usually be done as a source modifier.
> 
> For reference, here's a shader snippet from Goat Simulator which
> prompted me to write this optimization:
> 
> const vec4 LocalConst1 = vec4(0.25, -0.25, 0.00, 1.00);
> 
> void main()
> {
> ...
> InstrHelpTemp.r = ( ( Temporary1.r >= 0.0 ) ? LocalConst1.b : LocalConst1.a );
> ...
> }
> 
> which could be turned into
> 
> InstrHelpTemp.r = float(Temporary1.r < 0.0);
> 
> which seems arguably better, regardless of hardware.

Yeah... I remember looking at that very shader.  I seem to recall that
InstrHelpTemp.r is then compared with 0.0 a little later to generate
another Boolean value. :)

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Re: [Mesa-dev] [PATCH 2/6] nir: Turn bcsel of +/- 1.0 and 0.0 into b2f sequences.

[Kenneth Graunke]

On Wednesday, August 10, 2016 10:02:12 AM PDT Erik Faye-Lund wrote:
> On Wed, Aug 10, 2016 at 4:30 AM, Kenneth Graunke  
> wrote:
> > On Haswell (GL 3.3):
> >
> > total instructions in shared programs: 6208759 -> 6203860 (-0.08%)
> > instructions in affected programs: 856541 -> 851642 (-0.57%)
> > helped: 3157
> > HURT: 113
> > LOST:   7
> > GAINED: 15
> >
> > On Broadwell (GL 4.4):
> >
> > total instructions in shared programs: 11637854 -> 11632016 (-0.05%)
> > instructions in affected programs: 1055693 -> 1049855 (-0.55%)
> > helped: 3900
> > HURT: 176
> > LOST:   1
> > GAINED: 18
> >
> > Signed-off-by: Kenneth Graunke 
> > ---
> >  src/compiler/nir/nir_opt_algebraic.py | 4 
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/src/compiler/nir/nir_opt_algebraic.py 
> > b/src/compiler/nir/nir_opt_algebraic.py
> > index 1cf614c..4e9896f 100644
> > --- a/src/compiler/nir/nir_opt_algebraic.py
> > +++ b/src/compiler/nir/nir_opt_algebraic.py
> > @@ -251,6 +251,10 @@ optimizations = [
> > (('ieq', 'a@bool', False), ('inot', 'a')),
> > (('bcsel', a, True, False), ('ine', a, 0)),
> > (('bcsel', a, False, True), ('ieq', a, 0)),
> > +   (('bcsel@32', a, 1.0, 0.0), ('b2f', ('ine', a, 0))),
> > +   (('bcsel@32', a, 0.0, 1.0), ('b2f', ('ieq', a, 0))),
> > +   (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', ('ine', a, 0,
> > +   (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('ieq', a, 0,
> > (('bcsel', True, b, c), b),
> > (('bcsel', False, b, c), c),
> > # The result of this should be hit by constant propagation and, in the
> 
> Same as the previous patch, this smells like intel-isms. Hardware that
> has native bcsel with support for two inline immediates will do better
> without.

It definitely feels a little strange replacing a single bcsel with
a fneg/b2f/ine, as that's three operations instead of one.

I expect the ine to go away - assuming 'a' is a properly formatted
boolean (0 or 0x), "ine a 0" will just become 'a'.  ieq would
turn into inot.  If the boolean was a comparison, the inot could be
folded in - i.e. inot(flt(a,b)) -> fge(a,b).  Or, some GPUs can handle
boolean negation as a source modifier, so it might be free there too.

Floating point negation can usually be done as a source modifier.

For reference, here's a shader snippet from Goat Simulator which
prompted me to write this optimization:

const vec4 LocalConst1 = vec4(0.25, -0.25, 0.00, 1.00);

void main()
{
...
InstrHelpTemp.r = ( ( Temporary1.r >= 0.0 ) ? LocalConst1.b : LocalConst1.a );
...
}

which could be turned into

InstrHelpTemp.r = float(Temporary1.r < 0.0);

which seems arguably better, regardless of hardware.


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Re: [Mesa-dev] [PATCH 2/6] nir: Turn bcsel of +/- 1.0 and 0.0 into b2f sequences.

[Connor Abbott]

On Wed, Aug 10, 2016 at 1:53 PM, Eric Anholt  wrote:
> Kenneth Graunke  writes:
>
>> On Haswell (GL 3.3):
>>
>> total instructions in shared programs: 6208759 -> 6203860 (-0.08%)
>> instructions in affected programs: 856541 -> 851642 (-0.57%)
>> helped: 3157
>> HURT: 113
>> LOST:   7
>> GAINED: 15
>>
>> On Broadwell (GL 4.4):
>>
>> total instructions in shared programs: 11637854 -> 11632016 (-0.05%)
>> instructions in affected programs: 1055693 -> 1049855 (-0.55%)
>> helped: 3900
>> HURT: 176
>> LOST:   1
>> GAINED: 18
>>
>> Signed-off-by: Kenneth Graunke 
>> ---
>>  src/compiler/nir/nir_opt_algebraic.py | 4 
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/src/compiler/nir/nir_opt_algebraic.py 
>> b/src/compiler/nir/nir_opt_algebraic.py
>> index 1cf614c..4e9896f 100644
>> --- a/src/compiler/nir/nir_opt_algebraic.py
>> +++ b/src/compiler/nir/nir_opt_algebraic.py
>> @@ -251,6 +251,10 @@ optimizations = [
>> (('ieq', 'a@bool', False), ('inot', 'a')),
>> (('bcsel', a, True, False), ('ine', a, 0)),
>> (('bcsel', a, False, True), ('ieq', a, 0)),
>> +   (('bcsel@32', a, 1.0, 0.0), ('b2f', ('ine', a, 0))),
>> +   (('bcsel@32', a, 0.0, 1.0), ('b2f', ('ieq', a, 0))),
>> +   (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', ('ine', a, 0,
>> +   (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('ieq', a, 0,
>
> Isn't bcsel's first arg guaranteed to be 0 or ~0?  I thought that was
> how nir's bcsel (and b2f) worked.  If not, it would be good to see this
> documented.

Yes, any ALU operation that takes a boolean input can expect it to be
0 or ~0. If that isn't true, then something else in the compiler has
messed up. So I think we can replace 'a != 0' with 'a' and 'a == 0'
with '!a'.

>
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Re: [Mesa-dev] [PATCH 2/6] nir: Turn bcsel of +/- 1.0 and 0.0 into b2f sequences.

[Ian Romanick]

On 08/09/2016 07:30 PM, Kenneth Graunke wrote:
> On Haswell (GL 3.3):
> 
> total instructions in shared programs: 6208759 -> 6203860 (-0.08%)
> instructions in affected programs: 856541 -> 851642 (-0.57%)
> helped: 3157
> HURT: 113
> LOST:   7
> GAINED: 15
> 
> On Broadwell (GL 4.4):
> 
> total instructions in shared programs: 11637854 -> 11632016 (-0.05%)
> instructions in affected programs: 1055693 -> 1049855 (-0.55%)
> helped: 3900
> HURT: 176
> LOST:   1
> GAINED: 18
> 
> Signed-off-by: Kenneth Graunke 
> ---
>  src/compiler/nir/nir_opt_algebraic.py | 4 
>  1 file changed, 4 insertions(+)
> 
> diff --git a/src/compiler/nir/nir_opt_algebraic.py 
> b/src/compiler/nir/nir_opt_algebraic.py
> index 1cf614c..4e9896f 100644
> --- a/src/compiler/nir/nir_opt_algebraic.py
> +++ b/src/compiler/nir/nir_opt_algebraic.py
> @@ -251,6 +251,10 @@ optimizations = [
> (('ieq', 'a@bool', False), ('inot', 'a')),
> (('bcsel', a, True, False), ('ine', a, 0)),
> (('bcsel', a, False, True), ('ieq', a, 0)),
> +   (('bcsel@32', a, 1.0, 0.0), ('b2f', ('ine', a, 0))),
> +   (('bcsel@32', a, 0.0, 1.0), ('b2f', ('ieq', a, 0))),
> +   (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', ('ine', a, 0,
> +   (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('ieq', a, 0,

One of the other things I was experimenting with, that had mixed
results, was rearranging larger sequences like  x * bcsel(b, 1.0, 0.0).
There were a few different ways to handle it, and the optimal way was
dependent on the way the Boolean value was generated and on the way the
result was used.  This dovetailed into my work in removing spurious b2f
(and f2i) expressions.

> (('bcsel', True, b, c), b),
> (('bcsel', False, b, c), c),
> # The result of this should be hit by constant propagation and, in the
> 

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Re: [Mesa-dev] [PATCH 2/6] nir: Turn bcsel of +/- 1.0 and 0.0 into b2f sequences.

[Eric Anholt]

Kenneth Graunke  writes:

> On Haswell (GL 3.3):
>
> total instructions in shared programs: 6208759 -> 6203860 (-0.08%)
> instructions in affected programs: 856541 -> 851642 (-0.57%)
> helped: 3157
> HURT: 113
> LOST:   7
> GAINED: 15
>
> On Broadwell (GL 4.4):
>
> total instructions in shared programs: 11637854 -> 11632016 (-0.05%)
> instructions in affected programs: 1055693 -> 1049855 (-0.55%)
> helped: 3900
> HURT: 176
> LOST:   1
> GAINED: 18
>
> Signed-off-by: Kenneth Graunke 
> ---
>  src/compiler/nir/nir_opt_algebraic.py | 4 
>  1 file changed, 4 insertions(+)
>
> diff --git a/src/compiler/nir/nir_opt_algebraic.py 
> b/src/compiler/nir/nir_opt_algebraic.py
> index 1cf614c..4e9896f 100644
> --- a/src/compiler/nir/nir_opt_algebraic.py
> +++ b/src/compiler/nir/nir_opt_algebraic.py
> @@ -251,6 +251,10 @@ optimizations = [
> (('ieq', 'a@bool', False), ('inot', 'a')),
> (('bcsel', a, True, False), ('ine', a, 0)),
> (('bcsel', a, False, True), ('ieq', a, 0)),
> +   (('bcsel@32', a, 1.0, 0.0), ('b2f', ('ine', a, 0))),
> +   (('bcsel@32', a, 0.0, 1.0), ('b2f', ('ieq', a, 0))),
> +   (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', ('ine', a, 0,
> +   (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('ieq', a, 0,

Isn't bcsel's first arg guaranteed to be 0 or ~0?  I thought that was
how nir's bcsel (and b2f) worked.  If not, it would be good to see this
documented.


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Re: [Mesa-dev] [PATCH 2/6] nir: Turn bcsel of +/- 1.0 and 0.0 into b2f sequences.

[Erik Faye-Lund]

On Wed, Aug 10, 2016 at 5:48 PM, Jason Ekstrand  wrote:
> On Aug 10, 2016 1:02 AM, "Erik Faye-Lund"  wrote:
>>
>> On Wed, Aug 10, 2016 at 4:30 AM, Kenneth Graunke 
>> wrote:
>> > On Haswell (GL 3.3):
>> >
>> > total instructions in shared programs: 6208759 -> 6203860 (-0.08%)
>> > instructions in affected programs: 856541 -> 851642 (-0.57%)
>> > helped: 3157
>> > HURT: 113
>> > LOST:   7
>> > GAINED: 15
>> >
>> > On Broadwell (GL 4.4):
>> >
>> > total instructions in shared programs: 11637854 -> 11632016 (-0.05%)
>> > instructions in affected programs: 1055693 -> 1049855 (-0.55%)
>> > helped: 3900
>> > HURT: 176
>> > LOST:   1
>> > GAINED: 18
>> >
>> > Signed-off-by: Kenneth Graunke 
>> > ---
>> >  src/compiler/nir/nir_opt_algebraic.py | 4 
>> >  1 file changed, 4 insertions(+)
>> >
>> > diff --git a/src/compiler/nir/nir_opt_algebraic.py
>> > b/src/compiler/nir/nir_opt_algebraic.py
>> > index 1cf614c..4e9896f 100644
>> > --- a/src/compiler/nir/nir_opt_algebraic.py
>> > +++ b/src/compiler/nir/nir_opt_algebraic.py
>> > @@ -251,6 +251,10 @@ optimizations = [
>> > (('ieq', 'a@bool', False), ('inot', 'a')),
>> > (('bcsel', a, True, False), ('ine', a, 0)),
>> > (('bcsel', a, False, True), ('ieq', a, 0)),
>> > +   (('bcsel@32', a, 1.0, 0.0), ('b2f', ('ine', a, 0))),
>> > +   (('bcsel@32', a, 0.0, 1.0), ('b2f', ('ieq', a, 0))),
>> > +   (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', ('ine', a, 0,
>> > +   (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('ieq', a, 0,
>> > (('bcsel', True, b, c), b),
>> > (('bcsel', False, b, c), c),
>> > # The result of this should be hit by constant propagation and, in
>> > the
>>
>> Same as the previous patch, this smells like intel-isms. Hardware that
>> has native bcsel with support for two inline immediates will do better
>> without.
>
> Why? If you're back-end handles b2f *worse* then bcsel of two components,
> then it's broken.   Also, we have a lot of optimization in NIR to help cut
> through "fake booleans" where shaders use 0.0 and 1.0 and math operations
> instead of actual booleans.  Recognising hand-coded b2f suddenly enables
> more of these optimization paths to run on the shader.  That 0.57% isn't all
> just immediates being removed.

You're right. I don't know what I was thinking.
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Re: [Mesa-dev] [PATCH 2/6] nir: Turn bcsel of +/- 1.0 and 0.0 into b2f sequences.

[Jason Ekstrand]

On Aug 10, 2016 1:02 AM, "Erik Faye-Lund"  wrote:
>
> On Wed, Aug 10, 2016 at 4:30 AM, Kenneth Graunke 
wrote:
> > On Haswell (GL 3.3):
> >
> > total instructions in shared programs: 6208759 -> 6203860 (-0.08%)
> > instructions in affected programs: 856541 -> 851642 (-0.57%)
> > helped: 3157
> > HURT: 113
> > LOST:   7
> > GAINED: 15
> >
> > On Broadwell (GL 4.4):
> >
> > total instructions in shared programs: 11637854 -> 11632016 (-0.05%)
> > instructions in affected programs: 1055693 -> 1049855 (-0.55%)
> > helped: 3900
> > HURT: 176
> > LOST:   1
> > GAINED: 18
> >
> > Signed-off-by: Kenneth Graunke 
> > ---
> >  src/compiler/nir/nir_opt_algebraic.py | 4 
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/src/compiler/nir/nir_opt_algebraic.py
b/src/compiler/nir/nir_opt_algebraic.py
> > index 1cf614c..4e9896f 100644
> > --- a/src/compiler/nir/nir_opt_algebraic.py
> > +++ b/src/compiler/nir/nir_opt_algebraic.py
> > @@ -251,6 +251,10 @@ optimizations = [
> > (('ieq', 'a@bool', False), ('inot', 'a')),
> > (('bcsel', a, True, False), ('ine', a, 0)),
> > (('bcsel', a, False, True), ('ieq', a, 0)),
> > +   (('bcsel@32', a, 1.0, 0.0), ('b2f', ('ine', a, 0))),
> > +   (('bcsel@32', a, 0.0, 1.0), ('b2f', ('ieq', a, 0))),
> > +   (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', ('ine', a, 0,
> > +   (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('ieq', a, 0,
> > (('bcsel', True, b, c), b),
> > (('bcsel', False, b, c), c),
> > # The result of this should be hit by constant propagation and, in
the
>
> Same as the previous patch, this smells like intel-isms. Hardware that
> has native bcsel with support for two inline immediates will do better
> without.

Why? If you're back-end handles b2f *worse* then bcsel of two components,
then it's broken.   Also, we have a lot of optimization in NIR to help cut
through "fake booleans" where shaders use 0.0 and 1.0 and math operations
instead of actual booleans.  Recognising hand-coded b2f suddenly enables
more of these optimization paths to run on the shader.  That 0.57% isn't
all just immediates being removed.
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Re: [Mesa-dev] [PATCH 2/6] nir: Turn bcsel of +/- 1.0 and 0.0 into b2f sequences.

[Erik Faye-Lund]

On Wed, Aug 10, 2016 at 4:30 AM, Kenneth Graunke  wrote:
> On Haswell (GL 3.3):
>
> total instructions in shared programs: 6208759 -> 6203860 (-0.08%)
> instructions in affected programs: 856541 -> 851642 (-0.57%)
> helped: 3157
> HURT: 113
> LOST:   7
> GAINED: 15
>
> On Broadwell (GL 4.4):
>
> total instructions in shared programs: 11637854 -> 11632016 (-0.05%)
> instructions in affected programs: 1055693 -> 1049855 (-0.55%)
> helped: 3900
> HURT: 176
> LOST:   1
> GAINED: 18
>
> Signed-off-by: Kenneth Graunke 
> ---
>  src/compiler/nir/nir_opt_algebraic.py | 4 
>  1 file changed, 4 insertions(+)
>
> diff --git a/src/compiler/nir/nir_opt_algebraic.py 
> b/src/compiler/nir/nir_opt_algebraic.py
> index 1cf614c..4e9896f 100644
> --- a/src/compiler/nir/nir_opt_algebraic.py
> +++ b/src/compiler/nir/nir_opt_algebraic.py
> @@ -251,6 +251,10 @@ optimizations = [
> (('ieq', 'a@bool', False), ('inot', 'a')),
> (('bcsel', a, True, False), ('ine', a, 0)),
> (('bcsel', a, False, True), ('ieq', a, 0)),
> +   (('bcsel@32', a, 1.0, 0.0), ('b2f', ('ine', a, 0))),
> +   (('bcsel@32', a, 0.0, 1.0), ('b2f', ('ieq', a, 0))),
> +   (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', ('ine', a, 0,
> +   (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('ieq', a, 0,
> (('bcsel', True, b, c), b),
> (('bcsel', False, b, c), c),
> # The result of this should be hit by constant propagation and, in the

Same as the previous patch, this smells like intel-isms. Hardware that
has native bcsel with support for two inline immediates will do better
without.
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