void transfer_YUVA8888_to_UYVA8888(unsigned char *(*output),
                                   unsigned char *input) {
  *(*output)++ = input[1];
  *(*output)++ = input[0];
  *(*output)++ = input[2];
  *(*output)++ = input[3];
}


x86 assembly (clang, -O0):
<transfer_YUVA8888_to_UYVA8888>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    -0x10(%rbp),%rax
mov    0x1(%rax),%cl
mov    -0x8(%rbp),%rdx
mov    (%rdx),%rax
mov    %rax,%rsi
add    $0x1,%rsi
mov    %rsi,(%rdx)
mov    %cl,(%rax)
mov    -0x10(%rbp),%rax
mov    (%rax),%cl
mov    -0x8(%rbp),%rdx
mov    (%rdx),%rax
mov    %rax,%rsi
add    $0x1,%rsi
mov    %rsi,(%rdx)
mov    %cl,(%rax)
mov    -0x10(%rbp),%rax
mov    0x2(%rax),%cl
mov    -0x8(%rbp),%rdx
mov    (%rdx),%rax
mov    %rax,%rsi
add    $0x1,%rsi
mov    %rsi,(%rdx)
mov    %cl,(%rax)
mov    -0x10(%rbp),%rax
mov    0x3(%rax),%cl
mov    -0x8(%rbp),%rdx
mov    (%rdx),%rax
mov    %rax,%rsi
add    $0x1,%rsi
mov    %rsi,(%rdx)
mov    %cl,(%rax)
pop    %rbp
ret

x86 assembly (clang, -O2):
<transfer_YUVA8888_to_UYVA8888>:
mov    0x1(%rsi),%al
mov    (%rdi),%rcx
lea    0x1(%rcx),%rdx
mov    %rdx,(%rdi)
mov    %al,(%rcx)
mov    (%rsi),%al
mov    (%rdi),%rcx
lea    0x1(%rcx),%rdx
mov    %rdx,(%rdi)
mov    %al,(%rcx)
mov    0x2(%rsi),%al
mov    (%rdi),%rcx
lea    0x1(%rcx),%rdx
mov    %rdx,(%rdi)
mov    %al,(%rcx)
mov    0x3(%rsi),%al
mov    (%rdi),%rcx
lea    0x1(%rcx),%rdx
mov    %rdx,(%rdi)
mov    %al,(%rcx)
ret

LLVM IR (-O0):
define void @transfer_YUVA8888_to_UYVA8888(i8** %0, i8* %1) {
%3 = alloca i8**
%4 = alloca i8*
store i8** %0, i8*** %3
store i8* %1, i8** %4
%5 = load i8*, i8** %4
%6 = getelementptr inbounds i8, i8* %5, i64 1
%7 = load i8, i8* %6
%8 = load i8**, i8*** %3
%9 = load i8*, i8** %8
%10 = getelementptr inbounds i8, i8* %9, i32 1
store i8* %10, i8** %8
store i8 %7, i8* %9
%11 = load i8*, i8** %4
%12 = getelementptr inbounds i8, i8* %11, i64 0
%13 = load i8, i8* %12
%14 = load i8**, i8*** %3
%15 = load i8*, i8** %14
%16 = getelementptr inbounds i8, i8* %15, i32 1
store i8* %16, i8** %14
store i8 %13, i8* %15
%17 = load i8*, i8** %4
%18 = getelementptr inbounds i8, i8* %17, i64 2
%19 = load i8, i8* %18
%20 = load i8**, i8*** %3
%21 = load i8*, i8** %20
%22 = getelementptr inbounds i8, i8* %21, i32 1
store i8* %22, i8** %20
store i8 %19, i8* %21
%23 = load i8*, i8** %4
%24 = getelementptr inbounds i8, i8* %23, i64 3
%25 = load i8, i8* %24
%26 = load i8**, i8*** %3
%27 = load i8*, i8** %26
%28 = getelementptr inbounds i8, i8* %27, i32 1
store i8* %28, i8** %26
store i8 %25, i8* %27
ret void
}

LLVM IR (-O2):
define void @transfer_YUVA8888_to_UYVA8888(i8** nocapture %0, i8* nocapture %1) {
%3 = getelementptr inbounds i8, i8* %1, i64 1
%4 = load i8, i8* %3
%5 = load i8*, i8** %0
%6 = getelementptr inbounds i8, i8* %5, i64 1
store i8* %6, i8** %0
store i8 %4, i8* %5
%7 = load i8, i8* %1
%8 = load i8*, i8** %0
%9 = getelementptr inbounds i8, i8* %8, i64 1
store i8* %9, i8** %0
store i8 %7, i8* %8
%10 = getelementptr inbounds i8, i8* %1, i64 2
%11 = load i8, i8* %10
%12 = load i8*, i8** %0
%13 = getelementptr inbounds i8, i8* %12, i64 1
store i8* %13, i8** %0
store i8 %11, i8* %12
%14 = getelementptr inbounds i8, i8* %1, i64 3
%15 = load i8, i8* %14
%16 = load i8*, i8** %0
%17 = getelementptr inbounds i8, i8* %16, i64 1
store i8* %17, i8** %0
store i8 %15, i8* %16
ret void
}