[FFmpeg-cvslog] configure: aarch64: Support assembling the dotprod and i8mm arch extensions
Martin Storsjö
git at videolan.org
Tue Jun 6 13:25:38 EEST 2023
ffmpeg | branch: master | Martin Storsjö <martin at martin.st> | Thu May 25 14:57:37 2023 +0300| [fb1b88af77cd39034cef4b6d08af79496cd75ed8] | committer: Martin Storsjö
configure: aarch64: Support assembling the dotprod and i8mm arch extensions
These are available since ARMv8.4-a and ARMv8.6-a respectively,
but can also be available optionally since ARMv8.2-a.
Check if ".arch armv8.2-a" and ".arch_extension {dotprod,i8mm}" are
supported, and check if the instructions can be assembled.
Current clang versions fail to support the dotprod and i8mm
features in the .arch_extension directive, but do support them
if enabled with -march=armv8.4-a on the command line. (Curiously,
lowering the arch level with ".arch armv8.2-a" doesn't make the
extensions unavailable if they were enabled with -march; if that
changes, Clang should also learn to support these extensions via
.arch_extension for them to remain usable here.)
Signed-off-by: Martin Storsjö <martin at martin.st>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=fb1b88af77cd39034cef4b6d08af79496cd75ed8
---
configure | 81 ++++++++++++++++++++++++++++++++++++++++++++++++-
libavutil/aarch64/asm.S | 11 +++++++
2 files changed, 91 insertions(+), 1 deletion(-)
diff --git a/configure b/configure
index ae56540f4e..c791679794 100755
--- a/configure
+++ b/configure
@@ -454,6 +454,8 @@ Optimization options (experts only):
--disable-armv6t2 disable armv6t2 optimizations
--disable-vfp disable VFP optimizations
--disable-neon disable NEON optimizations
+ --disable-dotprod disable DOTPROD optimizations
+ --disable-i8mm disable I8MM optimizations
--disable-inline-asm disable use of inline assembly
--disable-x86asm disable use of standalone x86 assembly
--disable-mipsdsp disable MIPS DSP ASE R1 optimizations
@@ -1154,6 +1156,43 @@ check_insn(){
check_as ${1}_external "$2"
}
+check_arch_level(){
+ log check_arch_level "$@"
+ level="$1"
+ check_as tested_arch_level ".arch $level"
+ enabled tested_arch_level && as_arch_level="$level"
+}
+
+check_archext_insn(){
+ log check_archext_insn "$@"
+ feature="$1"
+ instr="$2"
+ # Check if the assembly is accepted in inline assembly.
+ check_inline_asm ${feature}_inline "\"$instr\""
+ # We don't check if the instruction is supported out of the box by the
+ # external assembler (we don't try to set ${feature}_external) as we don't
+ # need to use these instructions in non-runtime detected codepaths.
+
+ disable $feature
+
+ enabled as_arch_directive && arch_directive=".arch $as_arch_level" || arch_directive=""
+
+ # Test if the assembler supports the .arch_extension $feature directive.
+ arch_extension_directive=".arch_extension $feature"
+ test_as <<EOF && enable as_archext_${feature}_directive || arch_extension_directive=""
+$arch_directive
+$arch_extension_directive
+EOF
+
+ # Test if we can assemble the instruction after potential .arch and
+ # .arch_extension directives.
+ test_as <<EOF && enable ${feature}
+$arch_directive
+$arch_extension_directive
+$instr
+EOF
+}
+
check_x86asm(){
log check_x86asm "$@"
name=$1
@@ -2059,6 +2098,8 @@ ARCH_EXT_LIST_ARM="
armv6
armv6t2
armv8
+ dotprod
+ i8mm
neon
vfp
vfpv3
@@ -2322,6 +2363,8 @@ SYSTEM_LIBRARIES="
TOOLCHAIN_FEATURES="
as_arch_directive
+ as_archext_dotprod_directive
+ as_archext_i8mm_directive
as_dn_directive
as_fpu_directive
as_func
@@ -2622,6 +2665,8 @@ intrinsics_neon_deps="neon"
vfp_deps_any="aarch64 arm"
vfpv3_deps="vfp"
setend_deps="arm"
+dotprod_deps="aarch64 neon"
+i8mm_deps="aarch64 neon"
map 'eval ${v}_inline_deps=inline_asm' $ARCH_EXT_LIST_ARM
@@ -5988,12 +6033,27 @@ check_inline_asm inline_asm_labels '"1:\n"'
check_inline_asm inline_asm_nonlocal_labels '"Label:\n"'
if enabled aarch64; then
+ as_arch_level="armv8-a"
+ check_as as_arch_directive ".arch $as_arch_level"
+ enabled as_arch_directive && check_arch_level armv8.2-a
+
enabled armv8 && check_insn armv8 'prfm pldl1strm, [x0]'
# internal assembler in clang 3.3 does not support this instruction
enabled neon && check_insn neon 'ext v0.8B, v0.8B, v1.8B, #1'
enabled vfp && check_insn vfp 'fmadd d0, d0, d1, d2'
- map 'enabled_any ${v}_external ${v}_inline || disable $v' $ARCH_EXT_LIST_ARM
+ archext_list="dotprod i8mm"
+ enabled dotprod && check_archext_insn dotprod 'udot v0.4s, v0.16b, v0.16b'
+ enabled i8mm && check_archext_insn i8mm 'usdot v0.4s, v0.16b, v0.16b'
+
+ # Disable the main feature (e.g. HAVE_NEON) if neither inline nor external
+ # assembly support the feature out of the box. Skip this for the features
+ # checked with check_archext_insn above, as that function takes care of
+ # updating all the variables as necessary.
+ for v in $ARCH_EXT_LIST_ARM; do
+ is_in $v $archext_list && continue
+ enabled_any ${v}_external ${v}_inline || disable $v
+ done
elif enabled alpha; then
@@ -6022,6 +6082,12 @@ EOF
warn "Compiler does not indicate floating-point ABI, guessing $fpabi."
fi
+ # Test for various instruction sets, testing support both in inline and
+ # external assembly. This sets the ${v}_inline or ${v}_external flags
+ # if the instruction can be used unconditionally in either inline or
+ # external assembly. This means that if the ${v}_external feature is set,
+ # that feature can be used unconditionally in various support macros
+ # anywhere in external assembly, in any function.
enabled armv5te && check_insn armv5te 'qadd r0, r0, r0'
enabled armv6 && check_insn armv6 'sadd16 r0, r0, r0'
enabled armv6t2 && check_insn armv6t2 'movt r0, #0'
@@ -6030,6 +6096,14 @@ EOF
enabled vfpv3 && check_insn vfpv3 'vmov.f32 s0, #1.0'
enabled setend && check_insn setend 'setend be'
+ # If neither inline nor external assembly can use the feature by default,
+ # disable the main unsuffixed feature (e.g. HAVE_NEON).
+ #
+ # For targets that support runtime CPU feature detection, don't disable
+ # the main feature flag - there we assume that all supported toolchains
+ # can assemble code for all instruction set features (e.g. NEON) with
+ # suitable assembly flags (such as ".fpu neon"); we don't check
+ # specifically that they really do.
[ $target_os = linux ] || [ $target_os = android ] ||
map 'enabled_any ${v}_external ${v}_inline || disable $v' \
$ARCH_EXT_LIST_ARM
@@ -7610,6 +7684,8 @@ fi
if enabled aarch64; then
echo "NEON enabled ${neon-no}"
echo "VFP enabled ${vfp-no}"
+ echo "DOTPROD enabled ${dotprod-no}"
+ echo "I8MM enabled ${i8mm-no}"
fi
if enabled arm; then
echo "ARMv5TE enabled ${armv5te-no}"
@@ -7900,6 +7976,9 @@ test -n "$assert_level" &&
test -n "$malloc_prefix" &&
echo "#define MALLOC_PREFIX $malloc_prefix" >>$TMPH
+enabled aarch64 &&
+ echo "#define AS_ARCH_LEVEL $as_arch_level" >>$TMPH
+
if enabled x86asm; then
append config_files $TMPASM
cat > $TMPASM <<EOF
diff --git a/libavutil/aarch64/asm.S b/libavutil/aarch64/asm.S
index a7782415d7..8589cf74fc 100644
--- a/libavutil/aarch64/asm.S
+++ b/libavutil/aarch64/asm.S
@@ -36,6 +36,17 @@
# define __has_feature(x) 0
#endif
+#if HAVE_AS_ARCH_DIRECTIVE
+ .arch AS_ARCH_LEVEL
+#endif
+
+#if HAVE_AS_ARCHEXT_DOTPROD_DIRECTIVE
+ .arch_extension dotprod
+#endif
+#if HAVE_AS_ARCHEXT_I8MM_DIRECTIVE
+ .arch_extension i8mm
+#endif
+
/* Support macros for
* - Armv8.3-A Pointer Authentication and
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