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LLVM alu32 was introduced in LLVM7: https://reviews.llvm.org/rL325987 https://reviews.llvm.org/rL325989 Experiments showed that in general performance is better with alu32 enabled: https://lwn.net/Articles/775316/ This patch turns on alu32 with no-flavor test_progs which is tested most often. The flavor test at no_alu32/test_progs can be used to test without alu32 enabled. The Makefile check for whether LLVM supports '-mattr=+alu32 -mcpu=v3' is removed as LLVM7 should be available for recent distributions and also latest LLVM is preferred to run BPF selftests. Note that jmp32 is checked by -mcpu=probe and will be enabled if the host kernel supports it. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20191022043119.2625263-1-yhs@fb.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.