This does this following things:
- Default to the runtime automatic number of threads for pre-compiling shaders
- Adds a distinct automatic thread count computation for pre-compilation (which has less other things going on
and should scale better beyond 4 cores)
- Removes the unused logical_core_count field from the CPU detection
- Changes the semantics of num_cores from maximaum addressable number of cores to actually available CPU cores
(which is also how it was actually used)
- Updates the computation of the HTT flag now that AMD no longer lies about it for its Zen processors
- Background shader compilation is *not* enabled by default
SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
If the inputs are both float singles, and the top half is known to be identical
to the bottom half, we can use packed arithmetic instead of scalar to skip
the movddup.
This is slower on a few rather old CPUs, plus the Atom+Silvermont, so detect
Atom and disable it in that case.
Also avoid PPC_FP on stores if we know that the output came from a float op.
Before this commit, the two were reversed ("cpu_string" had the brand, e.g. "AuthenticAMD"; and "brand_string" had the CPU type, e.g. "AMD Phenom II X4 925").
