[Mesa-dev] [PATCH v3] r600g: Fix special negative immediate constants when using ABS modifier.
ikalvachev at gmail.com
Wed Oct 28 17:52:34 PDT 2015
---------- Forwarded message ----------
From: Ivan Kalvachev <ikalvachev at gmail.com>
Date: Wed, 28 Oct 2015 23:46:44 +0200
Subject: [PATCH v3] r600g: Fix special negative immediate constants
when using ABS modifier.
To: Nicolai Hähnle <nhaehnle at gmail.com>
On 10/26/15, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
> Hi Ivan,
> On 25.10.2015 02:00, Ivan Kalvachev wrote:
>> Some constants (like 1.0 and 0.5) could be inlined as immediate inputs
>> without using their literal value. The r600_bytecode_special_constants()
>> function emulates the negative of these constants by using NEG modifier.
>> However some shaders define -1.0 constant and want to use it as 1.0.
>> They do so by using ABS modifier. But r600_bytecode_special_constants()
>> set NEG in addition to ABS. Since NEG modifier have priority over ABS
>> we get -|1.0| as result, instead of |1.0|.
>> The patch simply prevents the additional switching of NEG when ABS is
> Nice catch. Is there a simple test case (e.g. in piglit) that exposes
> the incorrect behavior?
Not that I know of.
I've located the bug investigating visual problem in Nine.
I also heard that it fixes artifacts in "Need for Speed: Undercover"
and "Skyrim", once again, when using Nine.
>> Signed-off-by: Ivan Kalvachev <ikalvachev at gmail.com>
>> src/gallium/drivers/r600/r600_asm.c | 9 +++++----
>> src/gallium/drivers/r600/r600_shader.c | 2 +-
>> 2 files changed, 6 insertions(+), 5 deletions(-)
>> diff --git a/src/gallium/drivers/r600/r600_asm.c
>> index bc69806..8fc622c 100644
>> --- a/src/gallium/drivers/r600/r600_asm.c
>> +++ b/src/gallium/drivers/r600/r600_asm.c
>> @@ -635,8 +635,9 @@ static int replace_gpr_with_pv_ps(struct r600_bytecode
>> return 0;
>> -void r600_bytecode_special_constants(uint32_t value, unsigned *sel,
>> unsigned *neg)
>> +void r600_bytecode_special_constants(uint32_t value, unsigned *sel,
>> unsigned *neg, unsigned abs)
> Please remove the extra whitespace line.
I'm attaching v3 of the patch. Same as v2, but without the extra empty line.
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