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Faith Ekstrand authored
The lowering we do for 64-bit instructions can cause a single NIR ALU instruction to blow up into hundreds or thousands of instructions potentially with control flow. If loop unrolling isn't aware of this, it can unroll a loop 20 times which contains a nir_op_fsqrt which we then lower to a full software implementation based on integer math. Those 20 invocations suddenly get a lot more expensive than NIR loop unrolling currently expects. By giving it an approximate estimate function, we can prevent loop unrolling from going to town when it shouldn't. Reviewed-by: Matt Turner <mattst88@gmail.com> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com> Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
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