[dpdk-dev] [PATCH] build: check functionality rather than binutils version

[Bruce Richardson <bruce.richardson@intel.com>]

Rather than checking the binutils version number, which can lead to
unnecessary disabling of AVX512 if fixes have been backported to distro
versions, we can instead check the output of "as" from binutils to see if
it is correct.

These checks use the minimal assembly reproduction code posted to the
public bug tracker for gcc/binutils for those issues [1][2]. If the
binutils bug is present, the instruction parameters - specifically the
displacement parameter - will be different in the disassembled output
compared to the input. Therefore each check involves assembling a single
instruction and disassembling it again, checking that the two match.

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90028
[2] https://sourceware.org/bugzilla/show_bug.cgi?id=23465

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 buildtools/binutils-avx512-check.sh | 26 ++++++++++++++++++++++++++
 buildtools/meson.build              |  3 +--
 config/x86/meson.build              | 10 +++-------
 meson.build                         |  5 ++++-
 4 files changed, 34 insertions(+), 10 deletions(-)
 create mode 100755 buildtools/binutils-avx512-check.sh

diff --git a/buildtools/binutils-avx512-check.sh b/buildtools/binutils-avx512-check.sh
new file mode 100755
index 000000000..1e894d84d
--- /dev/null
+++ b/buildtools/binutils-avx512-check.sh
@@ -0,0 +1,26 @@
+#! /bin/sh
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2020 Intel Corporation
+
+AS=${AS:-as}
+MESON_BUILD_ROOT=${MESON_BUILD_ROOT:-/tmp}
+OBJFILE=$MESON_BUILD_ROOT/binutils-avx512-check.o
+# from https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90028
+GATHER_PARAMS='0x8(,%ymm1,1),%ymm0{%k2}'
+# from https://sourceware.org/bugzilla/show_bug.cgi?id=23465
+MOVAPS_PARAMS='0x40(,%rax,1),%zmm0'
+
+# assemble vmovaps statement to file
+echo "vmovaps $MOVAPS_PARAMS" | $AS --64 -o $OBJFILE -
+# check the parameters are correct in the output, using objdump
+objdump -d  --no-show-raw-insn $OBJFILE | grep -q $MOVAPS_PARAMS || {
+	echo "vmovaps displacement error with as"
+	exit 1
+}
+
+# assemble vpgather to file and similarly check
+echo "vpgatherqq $GATHER_PARAMS" | $AS --64 -o $OBJFILE -
+objdump -d  --no-show-raw-insn $OBJFILE | grep -q $GATHER_PARAMS || {
+	echo "vpgatherqq displacement error with as"
+	exit 1
+}
diff --git a/buildtools/meson.build b/buildtools/meson.build
index d5f8291be..73a847c52 100644
--- a/buildtools/meson.build
+++ b/buildtools/meson.build
@@ -1,13 +1,12 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # Copyright(c) 2017-2019 Intel Corporation
 
-subdir('pmdinfogen')
-
 pkgconf = find_program('pkg-config', 'pkgconf', required: false)
 pmdinfo = find_program('gen-pmdinfo-cfile.sh')
 list_dir_globs = find_program('list-dir-globs.py')
 check_symbols = find_program('check-symbols.sh')
 ldflags_ibverbs_static = find_program('options-ibverbs-static.sh')
+binutils_avx512_check = find_program('binutils-avx512-check.sh')
 
 # set up map-to-def script using python, either built-in or external
 python3 = import('python').find_installation(required: false)
diff --git a/config/x86/meson.build b/config/x86/meson.build
index adc857ba2..fbcd8e455 100644
--- a/config/x86/meson.build
+++ b/config/x86/meson.build
@@ -3,14 +3,10 @@
 
 # get binutils version for the workaround of Bug 97
 if not is_windows
-	ldver = run_command('ld', '-v').stdout().strip()
-	if ldver.contains('2.30') and cc.has_argument('-mno-avx512f')
+	as_ok = run_command(binutils_avx512_check)
+	if as_ok.returncode() != 0 and cc.has_argument('-mno-avx512f')
 		machine_args += '-mno-avx512f'
-		message('Binutils 2.30 detected, disabling AVX512 support as workaround for bug #97')
-	endif
-	if ldver.contains('2.31') and cc.has_argument('-mno-avx512f')
-		machine_args += '-mno-avx512f'
-		message('Binutils 2.31 detected, disabling AVX512 support as workaround for bug #249')
+		message('Binutils error with AVX512 assembly, disabling AVX512 support')
 	endif
 endif
 
diff --git a/meson.build b/meson.build
index 750fdeab1..ab4d60cfa 100644
--- a/meson.build
+++ b/meson.build
@@ -41,10 +41,13 @@ global_inc = include_directories('.', 'config',
 	'lib/librte_eal/@0@/include'.format(host_machine.system()),
 	'lib/librte_eal/@0@/include'.format(arch_subdir),
 )
+
+# do configuration and get tool paths
+subdir('buildtools')
 subdir('config')
 
 # build libs and drivers
-subdir('buildtools')
+subdir('buildtools/pmdinfogen')
 subdir('lib')
 subdir('drivers')
 
-- 
2.25.1