[FFmpeg-devel] [PATCH 1/2] avutil/intmath: use AV_HAS_BUILTIN to detect builtin availability

[FFmpeg-devel] [PATCH 1/2] avutil/intmath: use AV_HAS_BUILTIN to detect builtin availability

[Kacper Michajłow]

Fixes use of bultins on clang x86_64-pc-windows-msvc which does not
define any __GNUC__. Also on other targets __GNUC__ is defined to 4 by
default, so any feature testing based on version is not really valid.

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
---
 libavutil/intmath.h     | 12 +++++-------
 libavutil/x86/intmath.h |  4 ++--
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/libavutil/intmath.h b/libavutil/intmath.h
index 52e11a8d5f..b177a848c6 100644
--- a/libavutil/intmath.h
+++ b/libavutil/intmath.h
@@ -35,7 +35,7 @@
 #endif
 
 #if HAVE_FAST_CLZ
-#if AV_GCC_VERSION_AT_LEAST(3,4)
+#if AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_clz)
 #ifndef ff_log2
 #   define ff_log2(x) (31 - __builtin_clz((x)|1))
 #   ifndef ff_log2_16bit
@@ -90,18 +90,16 @@ static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
  */
 
 #if HAVE_FAST_CLZ
-#if AV_GCC_VERSION_AT_LEAST(3,4)
-#ifndef ff_ctz
+#if !defined(ff_ctz) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_ctz))
 #define ff_ctz(v) __builtin_ctz(v)
 #endif
-#ifndef ff_ctzll
+#if !defined(ff_ctzll) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_ctzll))
 #define ff_ctzll(v) __builtin_ctzll(v)
 #endif
-#ifndef ff_clz
+#if !defined(ff_clz) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_clz))
 #define ff_clz(v) __builtin_clz(v)
 #endif
 #endif
-#endif
 
 #ifndef ff_ctz
 #define ff_ctz ff_ctz_c
@@ -154,7 +152,7 @@ static av_always_inline av_const unsigned ff_clz_c(unsigned x)
 }
 #endif
 
-#if AV_GCC_VERSION_AT_LEAST(3,4)
+#if AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_parity)
 #ifndef av_parity
 #define av_parity __builtin_parity
 #endif
diff --git a/libavutil/x86/intmath.h b/libavutil/x86/intmath.h
index 4893a1f1b4..030ded6b6f 100644
--- a/libavutil/x86/intmath.h
+++ b/libavutil/x86/intmath.h
@@ -66,7 +66,7 @@ static av_always_inline av_const int ff_ctzll_x86(long long v)
 
 #endif /* HAVE_FAST_CLZ */
 
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 
 /* Our generic version of av_popcount is faster than GCC's built-in on
  * CPUs that don't support the popcnt instruction.
@@ -81,7 +81,7 @@ static av_always_inline av_const int ff_ctzll_x86(long long v)
 
 #if defined(__BMI2__)
 
-#if AV_GCC_VERSION_AT_LEAST(5,1)
+#if AV_GCC_VERSION_AT_LEAST(5,1) || AV_HAS_BUILTIN(__builtin_ia32_bzhi_si)
 #if defined(ASSERT_LEVEL) && ASSERT_LEVEL >= 2
 #define av_zero_extend av_zero_extend_bmi2
 static av_always_inline av_const unsigned av_zero_extend_bmi2(unsigned a, unsigned p)
-- 
2.45.1

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[FFmpeg-devel] [PATCH 2/2] avformat/internal: add missing __clang__ check

[Kacper Michajłow]

Clang x86_64-pc-windows-msvc doesn't define __GNUC__.

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
---
 libavformat/internal.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavformat/internal.h b/libavformat/internal.h
index fe428d85eb..bf83571430 100644
--- a/libavformat/internal.h
+++ b/libavformat/internal.h
@@ -354,7 +354,7 @@ static av_always_inline const FFStream *cffstream(const AVStream *st)
     return (const FFStream*)st;
 }
 
-#ifdef __GNUC__
+#if defined (__GNUC__) || defined (__clang__)
 #define dynarray_add(tab, nb_ptr, elem)\
 do {\
     __typeof__(tab) _tab = (tab);\
-- 
2.45.1

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Re: [FFmpeg-devel] [PATCH 2/2] avformat/internal: add missing __clang__ check

[Kacper Michajlow]

On Mon, 31 Mar 2025 at 14:03, Kacper Michajłow <kasper93@gmail.com> wrote:
>
> Clang x86_64-pc-windows-msvc doesn't define __GNUC__.
>
> Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
> ---
>  libavformat/internal.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavformat/internal.h b/libavformat/internal.h
> index fe428d85eb..bf83571430 100644
> --- a/libavformat/internal.h
> +++ b/libavformat/internal.h
> @@ -354,7 +354,7 @@ static av_always_inline const FFStream *cffstream(const AVStream *st)
>      return (const FFStream*)st;
>  }
>
> -#ifdef __GNUC__
> +#if defined (__GNUC__) || defined (__clang__)
>  #define dynarray_add(tab, nb_ptr, elem)\
>  do {\
>      __typeof__(tab) _tab = (tab);\
> --
> 2.45.1
>

bump
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Re: [FFmpeg-devel] [PATCH 2/2] avformat/internal: add missing __clang__ check

[Martin Storsjö]

On Mon, 31 Mar 2025, Kacper Michajłow wrote:

> Clang x86_64-pc-windows-msvc doesn't define __GNUC__.
>
> Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
> ---
> libavformat/internal.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavformat/internal.h b/libavformat/internal.h
> index fe428d85eb..bf83571430 100644
> --- a/libavformat/internal.h
> +++ b/libavformat/internal.h
> @@ -354,7 +354,7 @@ static av_always_inline const FFStream *cffstream(const AVStream *st)
>     return (const FFStream*)st;
> }
> 
> -#ifdef __GNUC__
> +#if defined (__GNUC__) || defined (__clang__)
> #define dynarray_add(tab, nb_ptr, elem)\
> do {\
>     __typeof__(tab) _tab = (tab);\
> -- 
> 2.45.1

This patch also looks good, so I'll push it.

But as with the other one as I asked yesterday, it would be good to 
describe the status quo and what the change gains. In this case I presume 
that it gains the type checking abilities of the GCC compatible version of 
dynarray_add?

Also, regarding these patchs for clang in msvc mode; when testing things I 
ran into another build failure, which is fixed by 
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20250612093933.395475-1-martin@martin.st/. 
I wonder if you haven't run into this as well, or why it isn't happening 
for you?

(With that fixed, I'll try to set up fate instances with this build mode; 
I already have such for Clang in MSVC mode targeting arm/aarch64, but no 
for x86/x86_64 yet.)

// Martin
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Re: [FFmpeg-devel] [PATCH 1/2] avutil/intmath: use AV_HAS_BUILTIN to detect builtin availability

[Kacper Michajlow]

On Mon, 31 Mar 2025 at 14:03, Kacper Michajłow <kasper93@gmail.com> wrote:
>
> Fixes use of bultins on clang x86_64-pc-windows-msvc which does not
> define any __GNUC__. Also on other targets __GNUC__ is defined to 4 by
> default, so any feature testing based on version is not really valid.
>
> Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
> ---
>  libavutil/intmath.h     | 12 +++++-------
>  libavutil/x86/intmath.h |  4 ++--
>  2 files changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/libavutil/intmath.h b/libavutil/intmath.h
> index 52e11a8d5f..b177a848c6 100644
> --- a/libavutil/intmath.h
> +++ b/libavutil/intmath.h
> @@ -35,7 +35,7 @@
>  #endif
>
>  #if HAVE_FAST_CLZ
> -#if AV_GCC_VERSION_AT_LEAST(3,4)
> +#if AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_clz)
>  #ifndef ff_log2
>  #   define ff_log2(x) (31 - __builtin_clz((x)|1))
>  #   ifndef ff_log2_16bit
> @@ -90,18 +90,16 @@ static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
>   */
>
>  #if HAVE_FAST_CLZ
> -#if AV_GCC_VERSION_AT_LEAST(3,4)
> -#ifndef ff_ctz
> +#if !defined(ff_ctz) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_ctz))
>  #define ff_ctz(v) __builtin_ctz(v)
>  #endif
> -#ifndef ff_ctzll
> +#if !defined(ff_ctzll) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_ctzll))
>  #define ff_ctzll(v) __builtin_ctzll(v)
>  #endif
> -#ifndef ff_clz
> +#if !defined(ff_clz) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_clz))
>  #define ff_clz(v) __builtin_clz(v)
>  #endif
>  #endif
> -#endif
>
>  #ifndef ff_ctz
>  #define ff_ctz ff_ctz_c
> @@ -154,7 +152,7 @@ static av_always_inline av_const unsigned ff_clz_c(unsigned x)
>  }
>  #endif
>
> -#if AV_GCC_VERSION_AT_LEAST(3,4)
> +#if AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_parity)
>  #ifndef av_parity
>  #define av_parity __builtin_parity
>  #endif
> diff --git a/libavutil/x86/intmath.h b/libavutil/x86/intmath.h
> index 4893a1f1b4..030ded6b6f 100644
> --- a/libavutil/x86/intmath.h
> +++ b/libavutil/x86/intmath.h
> @@ -66,7 +66,7 @@ static av_always_inline av_const int ff_ctzll_x86(long long v)
>
>  #endif /* HAVE_FAST_CLZ */
>
> -#if defined(__GNUC__)
> +#if defined(__GNUC__) || defined(__clang__)
>
>  /* Our generic version of av_popcount is faster than GCC's built-in on
>   * CPUs that don't support the popcnt instruction.
> @@ -81,7 +81,7 @@ static av_always_inline av_const int ff_ctzll_x86(long long v)
>
>  #if defined(__BMI2__)
>
> -#if AV_GCC_VERSION_AT_LEAST(5,1)
> +#if AV_GCC_VERSION_AT_LEAST(5,1) || AV_HAS_BUILTIN(__builtin_ia32_bzhi_si)
>  #if defined(ASSERT_LEVEL) && ASSERT_LEVEL >= 2
>  #define av_zero_extend av_zero_extend_bmi2
>  static av_always_inline av_const unsigned av_zero_extend_bmi2(unsigned a, unsigned p)
> --
> 2.45.1
>

bump
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Re: [FFmpeg-devel] [PATCH 1/2] avutil/intmath: use AV_HAS_BUILTIN to detect builtin availability

[Martin Storsjö]

On Wed, 11 Jun 2025, Kacper Michajlow wrote:

> On Mon, 31 Mar 2025 at 14:03, Kacper Michajłow <kasper93@gmail.com> wrote:
>>
>> Fixes use of bultins on clang x86_64-pc-windows-msvc which does not
>> define any __GNUC__. Also on other targets __GNUC__ is defined to 4 by
>> default, so any feature testing based on version is not really valid.
>>
>> Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
>> ---
>>  libavutil/intmath.h     | 12 +++++-------
>>  libavutil/x86/intmath.h |  4 ++--
>>  2 files changed, 7 insertions(+), 9 deletions(-)
>>
>> diff --git a/libavutil/intmath.h b/libavutil/intmath.h
>> index 52e11a8d5f..b177a848c6 100644
>> --- a/libavutil/intmath.h
>> +++ b/libavutil/intmath.h
>> @@ -35,7 +35,7 @@
>>  #endif
>>
>>  #if HAVE_FAST_CLZ
>> -#if AV_GCC_VERSION_AT_LEAST(3,4)
>> +#if AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_clz)
>>  #ifndef ff_log2
>>  #   define ff_log2(x) (31 - __builtin_clz((x)|1))
>>  #   ifndef ff_log2_16bit
>> @@ -90,18 +90,16 @@ static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
>>   */
>>
>>  #if HAVE_FAST_CLZ
>> -#if AV_GCC_VERSION_AT_LEAST(3,4)
>> -#ifndef ff_ctz
>> +#if !defined(ff_ctz) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_ctz))
>>  #define ff_ctz(v) __builtin_ctz(v)
>>  #endif
>> -#ifndef ff_ctzll
>> +#if !defined(ff_ctzll) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_ctzll))
>>  #define ff_ctzll(v) __builtin_ctzll(v)
>>  #endif
>> -#ifndef ff_clz
>> +#if !defined(ff_clz) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_clz))
>>  #define ff_clz(v) __builtin_clz(v)
>>  #endif
>>  #endif
>> -#endif
>>
>>  #ifndef ff_ctz
>>  #define ff_ctz ff_ctz_c
>> @@ -154,7 +152,7 @@ static av_always_inline av_const unsigned ff_clz_c(unsigned x)
>>  }
>>  #endif
>>
>> -#if AV_GCC_VERSION_AT_LEAST(3,4)
>> +#if AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_parity)
>>  #ifndef av_parity
>>  #define av_parity __builtin_parity
>>  #endif
>> diff --git a/libavutil/x86/intmath.h b/libavutil/x86/intmath.h
>> index 4893a1f1b4..030ded6b6f 100644
>> --- a/libavutil/x86/intmath.h
>> +++ b/libavutil/x86/intmath.h
>> @@ -66,7 +66,7 @@ static av_always_inline av_const int ff_ctzll_x86(long long v)
>>
>>  #endif /* HAVE_FAST_CLZ */
>>
>> -#if defined(__GNUC__)
>> +#if defined(__GNUC__) || defined(__clang__)
>>
>>  /* Our generic version of av_popcount is faster than GCC's built-in on
>>   * CPUs that don't support the popcnt instruction.
>> @@ -81,7 +81,7 @@ static av_always_inline av_const int ff_ctzll_x86(long long v)
>>
>>  #if defined(__BMI2__)
>>
>> -#if AV_GCC_VERSION_AT_LEAST(5,1)
>> +#if AV_GCC_VERSION_AT_LEAST(5,1) || AV_HAS_BUILTIN(__builtin_ia32_bzhi_si)
>>  #if defined(ASSERT_LEVEL) && ASSERT_LEVEL >= 2
>>  #define av_zero_extend av_zero_extend_bmi2
>>  static av_always_inline av_const unsigned av_zero_extend_bmi2(unsigned a, unsigned p)
>> --
>> 2.45.1
>>
>
> bump

Can you specify the symptoms that are fixed? Is there a specific build 
configuration that fails, or is it a case of using more optimal builtins 
where suitable? (Same goes for 2/2 probably.)

// Martin
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Re: [FFmpeg-devel] [PATCH 1/2] avutil/intmath: use AV_HAS_BUILTIN to detect builtin availability

[Kacper Michajlow]

On Wed, 11 Jun 2025 at 20:45, Martin Storsjö <martin@martin.st> wrote:
>
> On Wed, 11 Jun 2025, Kacper Michajlow wrote:
>
> > On Mon, 31 Mar 2025 at 14:03, Kacper Michajłow <kasper93@gmail.com> wrote:
> >>
> >> Fixes use of bultins on clang x86_64-pc-windows-msvc which does not
> >> define any __GNUC__. Also on other targets __GNUC__ is defined to 4 by
> >> default, so any feature testing based on version is not really valid.
> >>
> >> Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
> >> ---
> >>  libavutil/intmath.h     | 12 +++++-------
> >>  libavutil/x86/intmath.h |  4 ++--
> >>  2 files changed, 7 insertions(+), 9 deletions(-)
> >>
> >> diff --git a/libavutil/intmath.h b/libavutil/intmath.h
> >> index 52e11a8d5f..b177a848c6 100644
> >> --- a/libavutil/intmath.h
> >> +++ b/libavutil/intmath.h
> >> @@ -35,7 +35,7 @@
> >>  #endif
> >>
> >>  #if HAVE_FAST_CLZ
> >> -#if AV_GCC_VERSION_AT_LEAST(3,4)
> >> +#if AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_clz)
> >>  #ifndef ff_log2
> >>  #   define ff_log2(x) (31 - __builtin_clz((x)|1))
> >>  #   ifndef ff_log2_16bit
> >> @@ -90,18 +90,16 @@ static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
> >>   */
> >>
> >>  #if HAVE_FAST_CLZ
> >> -#if AV_GCC_VERSION_AT_LEAST(3,4)
> >> -#ifndef ff_ctz
> >> +#if !defined(ff_ctz) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_ctz))
> >>  #define ff_ctz(v) __builtin_ctz(v)
> >>  #endif
> >> -#ifndef ff_ctzll
> >> +#if !defined(ff_ctzll) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_ctzll))
> >>  #define ff_ctzll(v) __builtin_ctzll(v)
> >>  #endif
> >> -#ifndef ff_clz
> >> +#if !defined(ff_clz) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_clz))
> >>  #define ff_clz(v) __builtin_clz(v)
> >>  #endif
> >>  #endif
> >> -#endif
> >>
> >>  #ifndef ff_ctz
> >>  #define ff_ctz ff_ctz_c
> >> @@ -154,7 +152,7 @@ static av_always_inline av_const unsigned ff_clz_c(unsigned x)
> >>  }
> >>  #endif
> >>
> >> -#if AV_GCC_VERSION_AT_LEAST(3,4)
> >> +#if AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_parity)
> >>  #ifndef av_parity
> >>  #define av_parity __builtin_parity
> >>  #endif
> >> diff --git a/libavutil/x86/intmath.h b/libavutil/x86/intmath.h
> >> index 4893a1f1b4..030ded6b6f 100644
> >> --- a/libavutil/x86/intmath.h
> >> +++ b/libavutil/x86/intmath.h
> >> @@ -66,7 +66,7 @@ static av_always_inline av_const int ff_ctzll_x86(long long v)
> >>
> >>  #endif /* HAVE_FAST_CLZ */
> >>
> >> -#if defined(__GNUC__)
> >> +#if defined(__GNUC__) || defined(__clang__)
> >>
> >>  /* Our generic version of av_popcount is faster than GCC's built-in on
> >>   * CPUs that don't support the popcnt instruction.
> >> @@ -81,7 +81,7 @@ static av_always_inline av_const int ff_ctzll_x86(long long v)
> >>
> >>  #if defined(__BMI2__)
> >>
> >> -#if AV_GCC_VERSION_AT_LEAST(5,1)
> >> +#if AV_GCC_VERSION_AT_LEAST(5,1) || AV_HAS_BUILTIN(__builtin_ia32_bzhi_si)
> >>  #if defined(ASSERT_LEVEL) && ASSERT_LEVEL >= 2
> >>  #define av_zero_extend av_zero_extend_bmi2
> >>  static av_always_inline av_const unsigned av_zero_extend_bmi2(unsigned a, unsigned p)
> >> --
> >> 2.45.1
> >>
> >
> > bump
>
> Can you specify the symptoms that are fixed? Is there a specific build
> configuration that fails, or is it a case of using more optimal builtins
> where suitable? (Same goes for 2/2 probably.)

As the commit message says it "Fixes use of bultins on clang
x86_64-pc-windows-msvc". It now uses builtins where previously it
would fallback to C implementation.

- Kacper
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Re: [FFmpeg-devel] [PATCH 1/2] avutil/intmath: use AV_HAS_BUILTIN to detect builtin availability

[Kacper Michajlow]

On Wed, 11 Jun 2025 at 20:51, Kacper Michajlow <kasper93@gmail.com> wrote:
>
> On Wed, 11 Jun 2025 at 20:45, Martin Storsjö <martin@martin.st> wrote:
> >
> > On Wed, 11 Jun 2025, Kacper Michajlow wrote:
> >
> > > On Mon, 31 Mar 2025 at 14:03, Kacper Michajłow <kasper93@gmail.com> wrote:
> > >>
> > >> Fixes use of bultins on clang x86_64-pc-windows-msvc which does not
> > >> define any __GNUC__. Also on other targets __GNUC__ is defined to 4 by
> > >> default, so any feature testing based on version is not really valid.
> > >>
> > >> Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
> > >> ---
> > >>  libavutil/intmath.h     | 12 +++++-------
> > >>  libavutil/x86/intmath.h |  4 ++--
> > >>  2 files changed, 7 insertions(+), 9 deletions(-)
> > >>
> > >> diff --git a/libavutil/intmath.h b/libavutil/intmath.h
> > >> index 52e11a8d5f..b177a848c6 100644
> > >> --- a/libavutil/intmath.h
> > >> +++ b/libavutil/intmath.h
> > >> @@ -35,7 +35,7 @@
> > >>  #endif
> > >>
> > >>  #if HAVE_FAST_CLZ
> > >> -#if AV_GCC_VERSION_AT_LEAST(3,4)
> > >> +#if AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_clz)
> > >>  #ifndef ff_log2
> > >>  #   define ff_log2(x) (31 - __builtin_clz((x)|1))
> > >>  #   ifndef ff_log2_16bit
> > >> @@ -90,18 +90,16 @@ static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
> > >>   */
> > >>
> > >>  #if HAVE_FAST_CLZ
> > >> -#if AV_GCC_VERSION_AT_LEAST(3,4)
> > >> -#ifndef ff_ctz
> > >> +#if !defined(ff_ctz) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_ctz))
> > >>  #define ff_ctz(v) __builtin_ctz(v)
> > >>  #endif
> > >> -#ifndef ff_ctzll
> > >> +#if !defined(ff_ctzll) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_ctzll))
> > >>  #define ff_ctzll(v) __builtin_ctzll(v)
> > >>  #endif
> > >> -#ifndef ff_clz
> > >> +#if !defined(ff_clz) && (AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_clz))
> > >>  #define ff_clz(v) __builtin_clz(v)
> > >>  #endif
> > >>  #endif
> > >> -#endif
> > >>
> > >>  #ifndef ff_ctz
> > >>  #define ff_ctz ff_ctz_c
> > >> @@ -154,7 +152,7 @@ static av_always_inline av_const unsigned ff_clz_c(unsigned x)
> > >>  }
> > >>  #endif
> > >>
> > >> -#if AV_GCC_VERSION_AT_LEAST(3,4)
> > >> +#if AV_GCC_VERSION_AT_LEAST(3,4) || AV_HAS_BUILTIN(__builtin_parity)
> > >>  #ifndef av_parity
> > >>  #define av_parity __builtin_parity
> > >>  #endif
> > >> diff --git a/libavutil/x86/intmath.h b/libavutil/x86/intmath.h
> > >> index 4893a1f1b4..030ded6b6f 100644
> > >> --- a/libavutil/x86/intmath.h
> > >> +++ b/libavutil/x86/intmath.h
> > >> @@ -66,7 +66,7 @@ static av_always_inline av_const int ff_ctzll_x86(long long v)
> > >>
> > >>  #endif /* HAVE_FAST_CLZ */
> > >>
> > >> -#if defined(__GNUC__)
> > >> +#if defined(__GNUC__) || defined(__clang__)
> > >>
> > >>  /* Our generic version of av_popcount is faster than GCC's built-in on
> > >>   * CPUs that don't support the popcnt instruction.
> > >> @@ -81,7 +81,7 @@ static av_always_inline av_const int ff_ctzll_x86(long long v)
> > >>
> > >>  #if defined(__BMI2__)
> > >>
> > >> -#if AV_GCC_VERSION_AT_LEAST(5,1)
> > >> +#if AV_GCC_VERSION_AT_LEAST(5,1) || AV_HAS_BUILTIN(__builtin_ia32_bzhi_si)
> > >>  #if defined(ASSERT_LEVEL) && ASSERT_LEVEL >= 2
> > >>  #define av_zero_extend av_zero_extend_bmi2
> > >>  static av_always_inline av_const unsigned av_zero_extend_bmi2(unsigned a, unsigned p)
> > >> --
> > >> 2.45.1
> > >>
> > >
> > > bump
> >
> > Can you specify the symptoms that are fixed? Is there a specific build
> > configuration that fails, or is it a case of using more optimal builtins
> > where suitable? (Same goes for 2/2 probably.)
>
> As the commit message says it "Fixes use of bultins on clang
> x86_64-pc-windows-msvc". It now uses builtins where previously it
> would fallback to C implementation.
>
> - Kacper

Additionally for __builtin_ia32_bzhi_si check, currently it uses
AV_GCC_VERSION_AT_LEAST(5,1), which wouldn't work on any platform,
because clang always defines __GNUC__ to 4 for compatibility reasons
only.

- Kacper
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Re: [FFmpeg-devel] [PATCH 1/2] avutil/intmath: use AV_HAS_BUILTIN to detect builtin availability

[Martin Storsjö]

On Mon, 31 Mar 2025, Kacper Michajłow wrote:

> Fixes use of bultins on clang x86_64-pc-windows-msvc which does not
> define any __GNUC__. Also on other targets __GNUC__ is defined to 4 by
> default, so any feature testing based on version is not really valid.
>
> Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
> ---
> libavutil/intmath.h     | 12 +++++-------
> libavutil/x86/intmath.h |  4 ++--
> 2 files changed, 7 insertions(+), 9 deletions(-)

LGTM, will push.

// Martin
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