#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 */

/* Variables and functions */
double acos(double);
int /*<<< orphan*/ printf(char *);
double rand_double();
double tic();
double benchmark() {
  double elapsed;
  double x;
  double y;
  double t;
  int i;
  t = tic();
  for (i = 0; i < 1000000; i++) {
    x = (2.0 * rand_double()) - 1.0;
    y = acos(x);
    if (y != y) {
      printf("should not return NaN\n");
      break;
    }
  }
  elapsed = tic() - t;
  if (y != y) {
    printf("should not return NaN\n");
  }
  return elapsed;
}


x86 assembly (clang, -O0):
<benchmark>:
push   %rbp
mov    %rsp,%rbp
sub    $0x30,%rsp
mov    $0x0,%al
call   1040 <tic@plt>
movsd  %xmm0,-0x20(%rbp)
movl   $0x0,-0x24(%rbp)
cmpl   $0xf4240,-0x24(%rbp)
jge    11d2 <benchmark+0x92>
mov    $0x0,%al
call   1060 <rand_double@plt>
addsd  %xmm0,%xmm0
movsd  0xe85(%rip),%xmm1
addsd  %xmm1,%xmm0
movsd  %xmm0,-0x10(%rbp)
movsd  -0x10(%rbp),%xmm0
call   1050 <acos@plt>
movsd  %xmm0,-0x18(%rbp)
movsd  -0x18(%rbp),%xmm0
ucomisd -0x18(%rbp),%xmm0
jne    11ae <benchmark+0x6e>
jp     11ae <benchmark+0x6e>
jmp    11bf <benchmark+0x7f>
lea    0xe53(%rip),%rdi
call   1030 <printf@plt>
jmp    11d2 <benchmark+0x92>
jmp    11c4 <benchmark+0x84>
mov    -0x24(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x24(%rbp)
jmp    115b <benchmark+0x1b>
mov    $0x0,%al
call   1040 <tic@plt>
subsd  -0x20(%rbp),%xmm0
movsd  %xmm0,-0x8(%rbp)
movsd  -0x18(%rbp),%xmm0
ucomisd -0x18(%rbp),%xmm0
jne    11fe <benchmark+0xbe>
jp     11fe <benchmark+0xbe>
jmp    120a <benchmark+0xca>
lea    0xe03(%rip),%rdi
call   1030 <printf@plt>
movsd  -0x8(%rbp),%xmm0
add    $0x30,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<benchmark>:
push   %rbx
sub    $0x10,%rsp
xor    %eax,%eax
call   1040 <tic@plt>
movsd  %xmm0,0x8(%rsp)
mov    $0xf4240,%ebx
nopw   0x0(%rax,%rax,1)
xor    %eax,%eax
call   1060 <rand_double@plt>
addsd  %xmm0,%xmm0
addsd  0xe8d(%rip),%xmm0
call   1050 <acos@plt>
ucomisd %xmm0,%xmm0
jp     118c <benchmark+0x4c>
add    $0xffffffff,%ebx
jne    1160 <benchmark+0x20>
xor    %eax,%eax
call   1040 <tic@plt>
jmp    11b4 <benchmark+0x74>
lea    0xe75(%rip),%rbx
mov    %rbx,%rdi
call   1030 <puts@plt>
xor    %eax,%eax
call   1040 <tic@plt>
movsd  %xmm0,(%rsp)
mov    %rbx,%rdi
call   1030 <puts@plt>
movsd  (%rsp),%xmm0
subsd  0x8(%rsp),%xmm0
add    $0x10,%rsp
pop    %rbx
ret

LLVM IR (-O0):
@.str = [23 x i8] c"should not return NaN\0A\00"
define double @benchmark() {
%1 = alloca double
%2 = alloca double
%3 = alloca double
%4 = alloca double
%5 = alloca i32
%6 = call double (...) @tic()
store double %6, double* %4
store i32 0, i32* %5
br label %7
7: ; preds = %21, %0
%8 = load i32, i32* %5
%9 = icmp slt i32 %8, 1000000
br i1 %9, label %10, label %24
10: ; preds = %7
%11 = call double (...) @rand_double()
%12 = call double @llvm.fmuladd.f64(double 2.000000e+00, double %11, double -1.000000e+00)
store double %12, double* %2
%13 = load double, double* %2
%14 = call double @acos(double %13)
store double %14, double* %3
%15 = load double, double* %3
%16 = load double, double* %3
%17 = fcmp une double %15, %16
br i1 %17, label %18, label %20
18: ; preds = %10
%19 = call i32 @printf(i8* getelementptr inbounds ([23 x i8], [23 x i8]* @.str, i64 0, i64 0))
br label %24
20: ; preds = %10
br label %21
21: ; preds = %20
%22 = load i32, i32* %5
%23 = add nsw i32 %22, 1
store i32 %23, i32* %5
br label %7
24: ; preds = %18, %7
%25 = call double (...) @tic()
%26 = load double, double* %4
%27 = fsub double %25, %26
store double %27, double* %1
%28 = load double, double* %3
%29 = load double, double* %3
%30 = fcmp une double %28, %29
br i1 %30, label %31, label %33
31: ; preds = %24
%32 = call i32 @printf(i8* getelementptr inbounds ([23 x i8], [23 x i8]* @.str, i64 0, i64 0))
br label %33
33: ; preds = %31, %24
%34 = load double, double* %1
ret double %34
}

LLVM IR (-O2):
@str.1 = [22 x i8] c"should not return NaN\00"
define double @benchmark() {
%1 = tail call double (...) @tic()
br label %5
2: ; preds = %5
%3 = add nuw nsw i32 %6, 1
%4 = icmp eq i32 %3, 1000000
br i1 %4, label %11, label %5
5: ; preds = %0, %2
%6 = phi i32 [ 0, %0 ], [ %3, %2 ]
%7 = tail call double (...) @rand_double()
%8 = tail call double @llvm.fmuladd.f64(double %7, double 2.000000e+00, double -1.000000e+00)
%9 = tail call double @acos(double %8)
%10 = fcmp uno double %9, 0.000000e+00
br i1 %10, label %13, label %2
11: ; preds = %2
%12 = tail call double (...) @tic()
br label %17
13: ; preds = %5
%14 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([22 x i8], [22 x i8]* @str.1, i64 0, i64 0))
%15 = tail call double (...) @tic()
%16 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([22 x i8], [22 x i8]* @str.1, i64 0, i64 0))
br label %17
17: ; preds = %11, %13
%18 = phi double [ %15, %13 ], [ %12, %11 ]
%19 = fsub double %18, %1
ret double %19
}