[Mesa-dev] NIR linking optimisations for Gallium drivers

[Timothy Arceri]

This series depends on:
https://patchwork.freedesktop.org/series/34131/

Tested without regression on radeonsi. 

Shader-db results (still limited to GLSL 1.40 so not to interesting):

Totals from affected shaders:
SGPRS: 29440 -> 30464 (3.48 %)
VGPRS: 19620 -> 19584 (-0.18 %)
Spilled SGPRs: 131 -> 129 (-1.53 %)
Spilled VGPRs: 0 -> 0 (0.00 %)
Private memory VGPRs: 0 -> 0 (0.00 %)
Scratch size: 0 -> 0 (0.00 %) dwords per thread
Code Size: 749312 -> 749548 (0.03 %) bytes
LDS: 0 -> 0 (0.00 %) blocks
Max Waves: 4751 -> 4767 (0.34 %)
Wait states: 0 -> 0 (0.00 %)

The middle patches just move things around so that we can make use
of the linking opts, hopefully having them split up this much should
make regression testing easy for the existing gallium nir drivers.