On 10/10/24 02:24, Daniel P. Berrangé wrote:
On Thu, Oct 10, 2024 at 11:13:22AM +0200, Paolo Bonzini wrote:
Just detect compiler support and always enable the optimizations if
it is avilable; warn if the user did request AVX2/AVX512 use via
-Dx86_version= but the intrinsics are not available.
Suggested-by: Richard Henderson <richard.hender...@linaro.org>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
meson.build | 30 +++++++++++++++++++-----------
meson_options.txt | 4 ----
scripts/meson-buildoptions.sh | 6 ------
3 files changed, 19 insertions(+), 21 deletions(-)
diff --git a/meson.build b/meson.build
index e4b2af138da..b4418d54e0a 100644
--- a/meson.build
+++ b/meson.build
@@ -2955,22 +2955,16 @@ config_host_data.set('CONFIG_ASM_HWPROBE_H',
cc.has_header_symbol('asm/hwprobe.h',
'RISCV_HWPROBE_EXT_ZBA'))
-config_host_data.set('CONFIG_AVX2_OPT', get_option('avx2') \
- .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot enable
AVX2') \
- .require(cc.links('''
- #include <cpuid.h>
+if have_cpuid_h
+ have_avx2 = cc.links('''
#include <immintrin.h>
static int __attribute__((target("avx2"))) bar(void *a) {
__m256i x = *(__m256i *)a;
return _mm256_testz_si256(x, x);
}
int main(int argc, char *argv[]) { return bar(argv[argc - 1]); }
- '''), error_message: 'AVX2 not available').allowed())
-
-config_host_data.set('CONFIG_AVX512BW_OPT', get_option('avx512bw') \
- .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot enable
AVX512BW') \
- .require(cc.links('''
- #include <cpuid.h>
+ ''')
+ have_avx512bw = cc.links('''
#include <immintrin.h>
static int __attribute__((target("avx512bw"))) bar(void *a) {
__m512i *x = a;
@@ -2978,7 +2972,21 @@ config_host_data.set('CONFIG_AVX512BW_OPT',
get_option('avx512bw') \
return res[1];
}
int main(int argc, char *argv[]) { return bar(argv[0]); }
- '''), error_message: 'AVX512BW not available').allowed())
+ ''')
+ if get_option('x86_version') >= '3' and not have_avx2
+ warning('Cannot enable AVX optimizations due to missing intrinsics')
+ elif get_option('x86_version') >= '4' and not have_avx512bw
+ warning('Cannot enable AVX512 optimizations due to missing intrinsics')
+ endif
Should these perhaps be error() rather than warning() ?
We only support GCC & CLang. If both GCC 7.4.0 and CLang 10.0 (our
min versions) have the intrinsics, then I'd say this is an impossible
scenario if x86_version is large, and thus would deserve error()
Agreed. Otherwise,
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
r~
