build: Prefer NASM assembler over YASM

NASM is more actively maintained and permits generating dependency information
as a sideeffect of assembling, thus cutting build times in half.
This commit is contained in:
Diego Biurrun 2016-10-13 20:33:15 +02:00
parent f54037da8a
commit 57b753b445
5 changed files with 17 additions and 15 deletions

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@ -6,7 +6,7 @@ os:
addons:
apt:
packages:
- yasm
- nasm
- diffutils
compiler:
- clang
@ -17,7 +17,7 @@ cache:
before_install:
- if [ "$TRAVIS_OS_NAME" == "osx" ]; then brew update --all; fi
install:
- if [ "$TRAVIS_OS_NAME" == "osx" ]; then brew install yasm; fi
- if [ "$TRAVIS_OS_NAME" == "osx" ]; then brew install nasm; fi
script:
- mkdir -p libav-samples
- ./configure --samples=libav-samples --cc=$CC

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@ -9,6 +9,8 @@ version <next>:
- config.log and other configuration files moved into avbuild/ directory
- VAAPI-accelerated MPEG-2 and VP8 encoding
- Apple Pixlet decoder
- The x86 assembler default switched from yasm to nasm, pass
--x86asmexe=yasm to configure to restore the old behavior.
version 12:

6
configure vendored
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@ -2563,7 +2563,7 @@ shlibdir_default="$libdir_default"
ar_default="ar"
cc_default="gcc"
host_cc_default="gcc"
x86asmexe_default="yasm"
x86asmexe_default="nasm"
ln_s="ln -s -f"
nm_default="nm -g"
pkg_config_default=pkg-config
@ -4493,7 +4493,7 @@ EOF
}
if ! disabled_any asm mmx x86asm; then
for program in $x86asmexe yasm nasm; do
for program in $x86asmexe nasm yasm; do
probe_x86asm $program
test -n "$x86asm_type" && break
done
@ -4505,7 +4505,7 @@ EOF
esac
check_x86asm "movbe ecx, [5]" && enable x86asm ||
die "yasm/nasm not found or too old. Use --disable-x86asm for a crippled build."
die "nasm/yasm not found or too old. Use --disable-x86asm for a crippled build."
check_x86asm "vextracti128 xmm0, ymm0, 0" || disable avx2_external
check_x86asm "vpmacsdd xmm0, xmm1, xmm2, xmm3" || disable xop_external
check_x86asm "vfmadd132ps ymm0, ymm1, ymm2" || disable fma3_external

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@ -161,8 +161,8 @@ do{
For x86, mark registers that are clobbered in your asm. This means both
general x86 registers (e.g. eax) as well as XMM registers. This last one is
particularly important on Win64, where xmm6-15 are callee-save, and not
restoring their contents leads to undefined results. In external asm (e.g.
yasm), you do this by using:
restoring their contents leads to undefined results. In external asm,
you do this by using:
cglobal function_name, num_args, num_regs, num_xmm_regs
In inline asm, you specify clobbered registers at the end of your asm:
__asm__(".." ::: "%eax").
@ -194,12 +194,12 @@ The latter requires a good optimizing compiler which gcc is not.
Inline asm vs. external asm
---------------------------
Both inline asm (__asm__("..") in a .c file, handled by a compiler such as gcc)
and external asm (.s or .asm files, handled by an assembler such as yasm/nasm)
and external asm (.s or .asm files, handled by an assembler such as nasm/yasm)
are accepted in Libav. Which one to use differs per specific case.
- if your code is intended to be inlined in a C function, inline asm is always
better, because external asm cannot be inlined
- if your code calls external functions, yasm is always better
- if your code calls external functions, external asm is always better
- if your code takes huge and complex structs as function arguments (e.g.
MpegEncContext; note that this is not ideal and is discouraged if there
are alternatives), then inline asm is always better, because predicting

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@ -69,9 +69,9 @@ OS X on PowerPC or ARM (iPhone) requires a preprocessor from
assembly functions. Put the Perl script somewhere
in your PATH, Libav's configure will pick it up automatically.
OS X on AMD64 and x86 requires @command{yasm} to build most of the
OS X on AMD64 and x86 requires @command{nasm} to build most of the
optimized assembly functions @url{http://mxcl.github.com/homebrew/, Homebrew},
@url{http://www.gentoo.org/proj/en/gentoo-alt/prefix/bootstrap-macos.xml, Gentoo Prefix}
@url{https://wiki.gentoo.org/wiki/Project:Prefix, Gentoo Prefix}
or @url{http://www.macports.org, MacPorts} can easily provide it.
@ -134,7 +134,7 @@ them under @command{MinGW-w64 Win64 Shell} and @command{MinGW-w64 Win32 Shell}.
pacman -S make pkgconf diffutils
# mingw-w64 packages and toolchains
pacman -S mingw-w64-x86_64-yasm mingw-w64-x86_64-gcc mingw-w64-x86_64-SDL
pacman -S mingw-w64-x86_64-nasm mingw-w64-x86_64-gcc mingw-w64-x86_64-SDL
@end example
To target 32 bits replace @code{x86_64} with @code{i686} in the command above.
@ -152,14 +152,14 @@ You will need the following prerequisites:
@item @uref{http://code.google.com/p/msinttypes/, msinttypes}
(if using MSVC 2012 or earlier)
@item @uref{http://msys2.github.io/, MSYS2}
@item @uref{http://yasm.tortall.net/, YASM}
@item @uref{http://www.nasm.us/, NASM}
(Also available via MSYS2's package manager.)
@end itemize
To set up a proper environment in MSYS2, you need to run @code{msys_shell.bat} from
the Visual Studio or Intel Compiler command prompt.
Place @code{yasm.exe} somewhere in your @code{PATH}. If using MSVC 2012 or
Place @code{nasm.exe} somewhere in your @code{PATH}. If using MSVC 2012 or
earlier, place @code{c99wrap.exe} and @code{c99conv.exe} somewhere in your
@code{PATH} as well.
@ -307,7 +307,7 @@ These library packages are only available from
@uref{http://sourceware.org/cygwinports/, Cygwin Ports}:
@example
yasm, libSDL-devel, libfaac-devel, libgsm-devel, libmp3lame-devel,
nasm, libSDL-devel, libfaac-devel, libgsm-devel, libmp3lame-devel,
libschroedinger1.0-devel, speex-devel, libtheora-devel, libxvidcore-devel
@end example