radv/llvm: do not lower nir_op_fsat

To match ACO.

fossilds-db (Navi10):
Totals from 20869 (15.30% of 136420) affected shaders:
SGPRs: 1851128 -> 1851920 (+0.04%); split: -0.41%, +0.46%
VGPRs: 1607360 -> 1608212 (+0.05%); split: -0.20%, +0.25%
SpillSGPRs: 267331 -> 261350 (-2.24%); split: -3.67%, +1.43%
CodeSize: 155460104 -> 155303508 (-0.10%); split: -0.21%, +0.11%
MaxWaves: 179156 -> 178928 (-0.13%); split: +0.48%, -0.60%

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6932>
1 file changed