#define NULL ((void *)0)
typedef unsigned long size_t; // Customize by platform.
typedef long intptr_t;
typedef unsigned long uintptr_t;
typedef long scalar_t__; // Either arithmetic or pointer type.
/* By default, we understand bool (as a convenience). */
typedef int bool;
#define false 0
#define true 1

/* Forward declarations */

/* Type definitions */
struct timespec {
  scalar_t__ tv_nsec;
  scalar_t__ tv_sec;
};

/* Variables and functions */
int /*<<< orphan*/ CLOCK_MONOTONIC;
scalar_t__ clock_gettime(int /*<<< orphan*/, struct timespec *);
unsigned long long usec_monotonic(void) {
  struct timespec ts;
  if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
    return 0;
  return (unsigned long long)ts.tv_sec * 1000000ULL +
         (unsigned long long)ts.tv_nsec / 1000ULL;
}


x86 assembly (clang, -O0):
<usec_monotonic>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    0x2ec9(%rip),%rax
mov    (%rax),%edi
lea    -0x18(%rbp),%rsi
call   1030 <clock_gettime@plt>
cmp    $0x0,%rax
je     1141 <usec_monotonic+0x31>
movq   $0x0,-0x8(%rbp)
jmp    1169 <usec_monotonic+0x59>
imul   $0xf4240,-0x10(%rbp),%rax
mov    %rax,-0x20(%rbp)
mov    -0x18(%rbp),%rax
mov    $0x3e8,%ecx
xor    %edx,%edx
div    %rcx
mov    %rax,%rcx
mov    -0x20(%rbp),%rax
add    %rcx,%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<usec_monotonic>:
sub    $0x18,%rsp
mov    0x2ecd(%rip),%rax
mov    (%rax),%edi
lea    0x8(%rsp),%rsi
call   1030 <clock_gettime@plt>
test   %rax,%rax
je     1133 <usec_monotonic+0x23>
xor    %eax,%eax
add    $0x18,%rsp
ret
imul   $0xf4240,0x10(%rsp),%rcx
mov    0x8(%rsp),%rax
shr    $0x3,%rax
movabs $0x20c49ba5e353f7cf,%rdx
9b c4 20
mul    %rdx
mov    %rdx,%rax
shr    $0x4,%rax
add    %rcx,%rax
add    $0x18,%rsp
ret

LLVM IR (-O0):
%struct.timespec = type { i64, i64 }
@CLOCK_MONOTONIC = global i32 0
define i64 @usec_monotonic() {
%1 = alloca i64
%2 = alloca %struct.timespec
%3 = load i32, i32* @CLOCK_MONOTONIC
%4 = call i64 @clock_gettime(i32 %3, %struct.timespec* %2)
%5 = icmp ne i64 %4, 0
br i1 %5, label %6, label %7
6: ; preds = %0
store i64 0, i64* %1
br label %15
7: ; preds = %0
%8 = getelementptr inbounds %struct.timespec, %struct.timespec* %2, i32 0, i32 1
%9 = load i64, i64* %8
%10 = mul i64 %9, 1000000
%11 = getelementptr inbounds %struct.timespec, %struct.timespec* %2, i32 0, i32 0
%12 = load i64, i64* %11
%13 = udiv i64 %12, 1000
%14 = add i64 %10, %13
store i64 %14, i64* %1
br label %15
15: ; preds = %7, %6
%16 = load i64, i64* %1
ret i64 %16
}

LLVM IR (-O2):
%struct.timespec = type { i64, i64 }
@CLOCK_MONOTONIC = global i32 0
define i64 @usec_monotonic() {
%1 = alloca %struct.timespec
%2 = bitcast %struct.timespec* %1 to i8*
%3 = load i32, i32* @CLOCK_MONOTONIC
%4 = call i64 @clock_gettime(i32 %3, %struct.timespec* %1)
%5 = icmp eq i64 %4, 0
br i1 %5, label %6, label %14
6: ; preds = %0
%7 = getelementptr inbounds %struct.timespec, %struct.timespec* %1, i64 0, i32 1
%8 = load i64, i64* %7
%9 = mul i64 %8, 1000000
%10 = getelementptr inbounds %struct.timespec, %struct.timespec* %1, i64 0, i32 0
%11 = load i64, i64* %10
%12 = udiv i64 %11, 1000
%13 = add i64 %12, %9
br label %14
14: ; preds = %0, %6
%15 = phi i64 [ %13, %6 ], [ 0, %0 ]
ret i64 %15
}