This patch allows to form clauses even if the register pressure
is at the limit with the effect that VMEM instructions are less
scattered after the first clause in a Block.
It respects the previous clause size to avoid excessive moving
of VMEM instructions.
VMEM_CLAUSE_MAX_GRAB_DIST is further reduced to compensate
some of the effects.
Totals from 28922 (19.26% of 150170) affected shaders: (GFX10.3)
VGPRs: 1546568 -> 1523072 (-1.52%); split: -1.52%, +0.00%
CodeSize: 117524892 -> 117510288 (-0.01%); split: -0.08%, +0.07%
MaxWaves: 605554 -> 611120 (+0.92%)
Instrs: 22292568 -> 22291927 (-0.00%); split: -0.10%, +0.09%
Latency: 488975399 -> 490230904 (+0.26%); split: -0.06%, +0.32%
InvThroughput: 117842300 -> 116521653 (-1.12%); split: -1.15%, +0.03%
VClause: 541550 -> 522464 (-3.52%); split: -9.73%, +6.20%
SClause: 718185 -> 718298 (+0.02%); split: -0.00%, +0.02%
Copies: 1420603 -> 1386949 (-2.37%); split: -2.64%, +0.27%
Branches: 559559 -> 559278 (-0.05%); split: -0.06%, +0.01%
Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10896>
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