@@ -28,22 +28,28 @@
#define av_bswap16 av_bswap16
static av_always_inline av_const unsigned av_bswap16(unsigned x)
{
- __asm__("rev16 %w0, %w0" : "+r"(x));
- return 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)
{
- __asm__("rev %w0, %w0" : "+r"(x));
- return 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)
{
- __asm__("rev %0, %0" : "+r"(x));
- return x;
+ uint64_t y;
+
+ __asm__("rev %0, %1" : "=r"(y) : "r"(x));
+ return y;
}
#endif /* HAVE_INLINE_ASM */
From: Rémi Denis-Courmont <remi@remlab.net> There are no particular reasons to force the compiler to use the same register as output and input operand. This forces an extra MOV instruction if the input value needs to be reused after the swap. In most cases, this makes no differences, as the compiler will seleect the same register for both operands either way. --- libavutil/aarch64/bswap.h | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)