void mov_m8abs_reg8(unsigned char *m8, int reg8) {
  if ((long)m8 & 0xFFFFFFFF80000000LL) {
    printf("Error: destination %lx not in lower 2GB for mov_m8abs_reg8()\n",
           (long)m8);
    asm(" int $3; ");
  }
  put8(0x88);
  put8((reg8 << 3) | 4);
  put8(0x25);
  put32((int)(unsigned long)m8);
}


x86 assembly (clang, -O0):
<mov_m8abs_reg8>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
mov    %rdi,-0x8(%rbp)
mov    %esi,-0xc(%rbp)
mov    -0x8(%rbp),%rax
and    $0xffffffff80000000,%rax
cmp    $0x0,%rax
je     1166 <mov_m8abs_reg8+0x36>
mov    -0x8(%rbp),%rsi
lea    0xea2(%rip),%rdi
mov    $0x0,%al
call   1040 <printf@plt>
int3
mov    $0x88,%edi
mov    $0x0,%al
call   1030 <put8@plt>
mov    -0xc(%rbp),%edi
shl    $0x3,%edi
or     $0x4,%edi
mov    $0x0,%al
call   1030 <put8@plt>
mov    $0x25,%edi
mov    $0x0,%al
call   1030 <put8@plt>
mov    -0x8(%rbp),%rax
mov    %eax,%edi
mov    $0x0,%al
call   1050 <put32@plt>
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<mov_m8abs_reg8>:
push   %r14
push   %rbx
push   %rax
mov    %esi,%r14d
mov    %rdi,%rbx
test   $0xffffffff80000000,%rdi
je     1155 <mov_m8abs_reg8+0x25>
lea    0xeb6(%rip),%rdi
mov    %rbx,%rsi
xor    %eax,%eax
call   1040 <printf@plt>
int3
mov    $0x88,%edi
xor    %eax,%eax
call   1030 <put8@plt>
lea    0x4(,%r14,8),%edi
xor    %eax,%eax
call   1030 <put8@plt>
mov    $0x25,%edi
xor    %eax,%eax
call   1030 <put8@plt>
mov    %ebx,%edi
xor    %eax,%eax
add    $0x8,%rsp
pop    %rbx
pop    %r14
jmp    1050 <put32@plt>

LLVM IR (-O0):
@.str = [62 x i8] c"Error: destination %lx not in lower 2GB for mov_m8abs_reg8()\0A\00"
define void @mov_m8abs_reg8(i8* %0, i32 %1) {
%3 = alloca i8*
%4 = alloca i32
store i8* %0, i8** %3
store i32 %1, i32* %4
%5 = load i8*, i8** %3
%6 = ptrtoint i8* %5 to i64
%7 = and i64 %6, -2147483648
%8 = icmp ne i64 %7, 0
br i1 %8, label %9, label %13
9: ; preds = %2
%10 = load i8*, i8** %3
%11 = ptrtoint i8* %10 to i64
%12 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([62 x i8], [62 x i8]* @.str, i64 0, i64 0), i64 %11)
br label %13
13: ; preds = %9, %2
%14 = call i32 (i32, ...) bitcast (i32 (...)* @put8 to i32 (i32, ...)*)(i32 136)
%15 = load i32, i32* %4
%16 = shl i32 %15, 3
%17 = or i32 %16, 4
%18 = call i32 (i32, ...) bitcast (i32 (...)* @put8 to i32 (i32, ...)*)(i32 %17)
%19 = call i32 (i32, ...) bitcast (i32 (...)* @put8 to i32 (i32, ...)*)(i32 37)
%20 = load i8*, i8** %3
%21 = ptrtoint i8* %20 to i64
%22 = trunc i64 %21 to i32
%23 = call i32 (i32, ...) bitcast (i32 (...)* @put32 to i32 (i32, ...)*)(i32 %22)
ret void
}

LLVM IR (-O2):
@.str = [62 x i8] c"Error: destination %lx not in lower 2GB for mov_m8abs_reg8()\0A\00"
define void @mov_m8abs_reg8(i8* %0, i32 %1) {
%3 = ptrtoint i8* %0 to i64
%4 = icmp ult i8* %0, inttoptr (i64 2147483648 to i8*)
br i1 %4, label %7, label %5
5: ; preds = %2
%6 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([62 x i8], [62 x i8]* @.str, i64 0, i64 0), i64 %3)
tail call void asm sideeffect " int $$3; ", "~{dirflag},~{fpsr},~{flags}"()
br label %7
7: ; preds = %5, %2
%8 = tail call i32 (i32, ...) bitcast (i32 (...)* @put8 to i32 (i32, ...)*)(i32 136)
%9 = shl i32 %1, 3
%10 = or i32 %9, 4
%11 = tail call i32 (i32, ...) bitcast (i32 (...)* @put8 to i32 (i32, ...)*)(i32 %10)
%12 = tail call i32 (i32, ...) bitcast (i32 (...)* @put8 to i32 (i32, ...)*)(i32 37)
%13 = trunc i64 %3 to i32
%14 = tail call i32 (i32, ...) bitcast (i32 (...)* @put32 to i32 (i32, ...)*)(i32 %13)
ret void
}