[FFmpeg-devel] [PATCH 1/2] lavu/bswap: remove some inline assembler

["Rémi Denis-Courmont" <remi@remlab.net>]

C code or compiler built-ins are preferable over inline assembler for
byte-swaps as it allows for better optimisations (e.g. instruction
scheduling) which would otherwise be impossible.

As with f64c2e710fa1a7b59753224e717f57c48462076f for x86 and Arm,
this removes the inline assembler on GCC (and Clang) since we now
require recent enough compiler versions (this indeed seems to work on
AArch64).
---
 libavutil/aarch64/bswap.h | 56 ---------------------------------------
 libavutil/avr32/bswap.h   | 44 ------------------------------
 libavutil/bswap.h         |  8 +-----
 libavutil/sh4/bswap.h     | 48 ---------------------------------
 4 files changed, 1 insertion(+), 155 deletions(-)
 delete mode 100644 libavutil/aarch64/bswap.h
 delete mode 100644 libavutil/avr32/bswap.h
 delete mode 100644 libavutil/sh4/bswap.h

diff --git a/libavutil/aarch64/bswap.h b/libavutil/aarch64/bswap.h
deleted file mode 100644
index 7abca657ba..0000000000
--- a/libavutil/aarch64/bswap.h
+++ /dev/null
@@ -1,56 +0,0 @@
-/*
- * This file is part of FFmpeg.
- *
- * FFmpeg is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * FFmpeg is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#ifndef AVUTIL_AARCH64_BSWAP_H
-#define AVUTIL_AARCH64_BSWAP_H
-
-#include <stdint.h>
-#include "config.h"
-#include "libavutil/attributes.h"
-
-#if HAVE_INLINE_ASM
-
-#define av_bswap16 av_bswap16
-static av_always_inline av_const unsigned av_bswap16(unsigned x)
-{
-    unsigned y;
-
-    __asm__("rev16 %w0, %w1" : "=r"(y) : "r"(x));
-    return y;
-}
-
-#define av_bswap32 av_bswap32
-static av_always_inline av_const uint32_t av_bswap32(uint32_t x)
-{
-    uint32_t y;
-
-    __asm__("rev %w0, %w1" : "=r"(y) : "r"(x));
-    return y;
-}
-
-#define av_bswap64 av_bswap64
-static av_always_inline av_const uint64_t av_bswap64(uint64_t x)
-{
-    uint64_t y;
-
-    __asm__("rev %0, %1" : "=r"(y) : "r"(x));
-    return y;
-}
-
-#endif /* HAVE_INLINE_ASM */
-#endif /* AVUTIL_AARCH64_BSWAP_H */
diff --git a/libavutil/avr32/bswap.h b/libavutil/avr32/bswap.h
deleted file mode 100644
index e79d53f369..0000000000
--- a/libavutil/avr32/bswap.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * This file is part of FFmpeg.
- *
- * FFmpeg is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * FFmpeg is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#ifndef AVUTIL_AVR32_BSWAP_H
-#define AVUTIL_AVR32_BSWAP_H
-
-#include <stdint.h>
-#include "config.h"
-#include "libavutil/attributes.h"
-
-#if HAVE_INLINE_ASM
-
-#define av_bswap16 av_bswap16
-static av_always_inline av_const uint16_t av_bswap16(uint16_t x)
-{
-    __asm__ ("swap.bh %0" : "+r"(x));
-    return x;
-}
-
-#define av_bswap32 av_bswap32
-static av_always_inline av_const uint32_t av_bswap32(uint32_t x)
-{
-    __asm__ ("swap.b  %0" : "+r"(x));
-    return x;
-}
-
-#endif /* HAVE_INLINE_ASM */
-
-#endif /* AVUTIL_AVR32_BSWAP_H */
diff --git a/libavutil/bswap.h b/libavutil/bswap.h
index 1528906f93..b339c90b9b 100644
--- a/libavutil/bswap.h
+++ b/libavutil/bswap.h
@@ -34,16 +34,10 @@
 
 #include "config.h"
 
-#if   ARCH_AARCH64
-#   include "aarch64/bswap.h"
-#elif ARCH_ARM
+#if ARCH_ARM
 #   include "arm/bswap.h"
-#elif ARCH_AVR32
-#   include "avr32/bswap.h"
 #elif ARCH_RISCV
 #   include "riscv/bswap.h"
-#elif ARCH_SH4
-#   include "sh4/bswap.h"
 #elif ARCH_X86
 #   include "x86/bswap.h"
 #endif
diff --git a/libavutil/sh4/bswap.h b/libavutil/sh4/bswap.h
deleted file mode 100644
index 48dd27f806..0000000000
--- a/libavutil/sh4/bswap.h
+++ /dev/null
@@ -1,48 +0,0 @@
-/*
- * This file is part of FFmpeg.
- *
- * FFmpeg is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * FFmpeg is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-/**
- * @file
- * byte swapping routines
- */
-
-#ifndef AVUTIL_SH4_BSWAP_H
-#define AVUTIL_SH4_BSWAP_H
-
-#include <stdint.h>
-#include "config.h"
-#include "libavutil/attributes.h"
-
-#define av_bswap16 av_bswap16
-static av_always_inline av_const uint16_t av_bswap16(uint16_t x)
-{
-    __asm__("swap.b %0,%0" : "+r"(x));
-    return x;
-}
-
-#define av_bswap32 av_bswap32
-static av_always_inline av_const uint32_t av_bswap32(uint32_t x)
-{
-    __asm__("swap.b %0,%0\n"
-            "swap.w %0,%0\n"
-            "swap.b %0,%0\n"
-            : "+r"(x));
-    return x;
-}
-
-#endif /* AVUTIL_SH4_BSWAP_H */
-- 
2.45.1

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