[Mesa-dev] [PATCH 1/2] nvc0/ir: detect AND/SHR pairs and convert into EXTBF

[Matt Turner]

On Tue, Aug 18, 2015 at 6:49 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> Some shaders appear to extract bits using shift/and combos. Detect
> (some) of those and convert to EXTBF instead.

What is EXTBF? Extract byte to float?

I ask because Unigine Heaven has shaders that pack 3x byte-integers
into one component of a vec4 and extracts them with shifts/ands and
converts them to floats, and i965 could do the extraction and
conversion in a single instruction. I'm curious if this is the same
thing you're optimizing.

I thought about adding an extract_byte(src, byte_num) operation, but
i965's copy propagation caused me some headache and I shelved it.