#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()) - 0.0;
    y = acos(1.0 - 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    11ce <benchmark+0x8e>
mov    $0x0,%al
call   1060 <rand_double@plt>
addsd  %xmm0,%xmm0
movsd  %xmm0,-0x10(%rbp)
movsd  0xe80(%rip),%xmm0
subsd  -0x10(%rbp),%xmm0
call   1050 <acos@plt>
movsd  %xmm0,-0x18(%rbp)
movsd  -0x18(%rbp),%xmm0
ucomisd -0x18(%rbp),%xmm0
jne    11aa <benchmark+0x6a>
jp     11aa <benchmark+0x6a>
jmp    11bb <benchmark+0x7b>
lea    0xe57(%rip),%rdi
call   1030 <printf@plt>
jmp    11ce <benchmark+0x8e>
jmp    11c0 <benchmark+0x80>
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    11fa <benchmark+0xba>
jp     11fa <benchmark+0xba>
jmp    1206 <benchmark+0xc6>
lea    0xe07(%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
movsd  0xe8d(%rip),%xmm1
subsd  %xmm0,%xmm1
movapd %xmm1,%xmm0
call   1050 <acos@plt>
ucomisd %xmm0,%xmm0
jp     1194 <benchmark+0x54>
add    $0xffffffff,%ebx
jne    1160 <benchmark+0x20>
xor    %eax,%eax
call   1040 <tic@plt>
jmp    11bc <benchmark+0x7c>
lea    0xe6d(%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 = %22, %0
%8 = load i32, i32* %5
%9 = icmp slt i32 %8, 1000000
br i1 %9, label %10, label %25
10: ; preds = %7
%11 = call double (...) @rand_double()
%12 = call double @llvm.fmuladd.f64(double 2.000000e+00, double %11, double -0.000000e+00)
store double %12, double* %2
%13 = load double, double* %2
%14 = fsub double 1.000000e+00, %13
%15 = call double @acos(double %14)
store double %15, double* %3
%16 = load double, double* %3
%17 = load double, double* %3
%18 = fcmp une double %16, %17
br i1 %18, label %19, label %21
19: ; preds = %10
%20 = call i32 @printf(i8* getelementptr inbounds ([23 x i8], [23 x i8]* @.str, i64 0, i64 0))
br label %25
21: ; preds = %10
br label %22
22: ; preds = %21
%23 = load i32, i32* %5
%24 = add nsw i32 %23, 1
store i32 %24, i32* %5
br label %7
25: ; preds = %19, %7
%26 = call double (...) @tic()
%27 = load double, double* %4
%28 = fsub double %26, %27
store double %28, double* %1
%29 = load double, double* %3
%30 = load double, double* %3
%31 = fcmp une double %29, %30
br i1 %31, label %32, label %34
32: ; preds = %25
%33 = call i32 @printf(i8* getelementptr inbounds ([23 x i8], [23 x i8]* @.str, i64 0, i64 0))
br label %34
34: ; preds = %32, %25
%35 = load double, double* %1
ret double %35
}

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 %12, label %5
5: ; preds = %0, %2
%6 = phi i32 [ 0, %0 ], [ %3, %2 ]
%7 = tail call double (...) @rand_double()
%8 = fmul double %7, 2.000000e+00
%9 = fsub double 1.000000e+00, %8
%10 = tail call double @acos(double %9)
%11 = fcmp uno double %10, 0.000000e+00
br i1 %11, label %14, label %2
12: ; preds = %2
%13 = tail call double (...) @tic()
br label %18
14: ; preds = %5
%15 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([22 x i8], [22 x i8]* @str.1, i64 0, i64 0))
%16 = tail call double (...) @tic()
%17 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([22 x i8], [22 x i8]* @str.1, i64 0, i64 0))
br label %18
18: ; preds = %12, %14
%19 = phi double [ %16, %14 ], [ %13, %12 ]
%20 = fsub double %19, %1
ret double %20
}