tgsi/lowering: improved lowering for LRP
tgsi/lowering: improved lowering for LRP

Provide an improved lowering for LRP, which can be implemented in two
MAD instructions with a bit of rearranging of the equation, rather
than the literal implementation of two multiplies, an add and a
subtract.

Signed-off-by: Russell King <c2093e01fa868776d7876ac617ce6d2ac30cb904@arm.linux.org.uk>
Reviewed-by: Rob Clark <915c10c999604870200b6defbe633d857c856ca0@gmail.com>
Signed-off-by: Rob Clark <6f78cdb10adbe0a7fbbf4098125a51f401c77a5f@freedesktop.org>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler