int main() {
  float fahr, celcius;
  int lower, upper, step;
  lower = 0;
  upper = 300;
  step = 20;
  fahr = lower;
  printf("%s%s%s\n", "fahrenheit", "  ", "celcius");
  while (fahr <= upper) {
    celcius = (5.0 / 9.0) * (fahr - 32);
    printf("%10.0f%s%7.1f\n", fahr, "  ", celcius);
    fahr = fahr + step;
  }
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
movl   $0x0,-0x4(%rbp)
movl   $0x0,-0x10(%rbp)
movl   $0x12c,-0x14(%rbp)
movl   $0x14,-0x18(%rbp)
cvtsi2ssl -0x10(%rbp),%xmm0
movss  %xmm0,-0x8(%rbp)
lea    0xec7(%rip),%rdi
lea    0xec8(%rip),%rsi
lea    0xecc(%rip),%rdx
lea    0xec8(%rip),%rcx
mov    $0x0,%al
call   1030 <printf@plt>
movss  -0x8(%rbp),%xmm1
cvtsi2ssl -0x14(%rbp),%xmm0
ucomiss %xmm1,%xmm0
jb     11dd <main+0xcd>
movss  -0x8(%rbp),%xmm0
movss  0xe87(%rip),%xmm1
subss  %xmm1,%xmm0
cvtss2sd %xmm0,%xmm1
movsd  0xe6f(%rip),%xmm0
mulsd  %xmm1,%xmm0
cvtsd2ss %xmm0,%xmm0
movss  %xmm0,-0xc(%rbp)
movss  -0x8(%rbp),%xmm0
cvtss2sd %xmm0,%xmm0
movss  -0xc(%rbp),%xmm1
cvtss2sd %xmm1,%xmm1
lea    0xe73(%rip),%rdi
lea    0xe61(%rip),%rsi
mov    $0x2,%al
call   1030 <printf@plt>
movss  -0x8(%rbp),%xmm0
cvtsi2ssl -0x18(%rbp),%xmm1
addss  %xmm1,%xmm0
movss  %xmm0,-0x8(%rbp)
jmp    1161 <main+0x51>
mov    -0x4(%rbp),%eax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %rbp
push   %r14
push   %rbx
lea    0xef5(%rip),%rdi
lea    0xef6(%rip),%rsi
lea    0xefa(%rip),%r14
lea    0xef6(%rip),%rcx
mov    %r14,%rdx
xor    %eax,%eax
call   1030 <printf@plt>
mov    $0xffffffec,%ebp
lea    0xee8(%rip),%rbx
cs nopw 0x0(%rax,%rax,1)
add    $0x14,%ebp
xorps  %xmm1,%xmm1
cvtsi2ss %ebp,%xmm1
xorps  %xmm0,%xmm0
cvtss2sd %xmm1,%xmm0
addss  0xe97(%rip),%xmm1
cvtss2sd %xmm1,%xmm1
mulsd  0xe93(%rip),%xmm1
cvtsd2ss %xmm1,%xmm1
cvtss2sd %xmm1,%xmm1
mov    %rbx,%rdi
mov    %r14,%rsi
mov    $0x2,%al
call   1030 <printf@plt>
cmp    $0x119,%ebp
jb     1150 <main+0x40>
xor    %eax,%eax
pop    %rbx
pop    %r14
pop    %rbp
ret

LLVM IR (-O0):
@.str = [8 x i8] c"%s%s%s\0A\00"
@.str.1 = [11 x i8] c"fahrenheit\00"
@.str.2 = [3 x i8] c" \00"
@.str.3 = [8 x i8] c"celcius\00"
@.str.4 = [15 x i8] c"%10.0f%s%7.1f\0A\00"
define i32 @main() {
%1 = alloca i32
%2 = alloca float
%3 = alloca float
%4 = alloca i32
%5 = alloca i32
%6 = alloca i32
store i32 0, i32* %1
store i32 0, i32* %4
store i32 300, i32* %5
store i32 20, i32* %6
%7 = load i32, i32* %4
%8 = sitofp i32 %7 to float
store float %8, float* %2
%9 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str, i64 0, i64 0), i8* getelementptr inbounds ([11 x i8], [11 x i8]* @.str.1, i64 0, i64 0), i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.2, i64 0, i64 0), i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str.3, i64 0, i64 0))
br label %10
10: ; preds = %15, %0
%11 = load float, float* %2
%12 = load i32, i32* %5
%13 = sitofp i32 %12 to float
%14 = fcmp ole float %11, %13
br i1 %14, label %15, label %30
15: ; preds = %10
%16 = load float, float* %2
%17 = fsub float %16, 3.200000e+01
%18 = fpext float %17 to double
%19 = fmul double 0x3FE1C71C71C71C72, %18
%20 = fptrunc double %19 to float
store float %20, float* %3
%21 = load float, float* %2
%22 = fpext float %21 to double
%23 = load float, float* %3
%24 = fpext float %23 to double
%25 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.4, i64 0, i64 0), double %22, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.2, i64 0, i64 0), double %24)
%26 = load float, float* %2
%27 = load i32, i32* %6
%28 = sitofp i32 %27 to float
%29 = fadd float %26, %28
store float %29, float* %2
br label %10
30: ; preds = %10
%31 = load i32, i32* %1
ret i32 %31
}

LLVM IR (-O2):
@.str = [8 x i8] c"%s%s%s\0A\00"
@.str.1 = [11 x i8] c"fahrenheit\00"
@.str.2 = [3 x i8] c" \00"
@.str.3 = [8 x i8] c"celcius\00"
@.str.4 = [15 x i8] c"%10.0f%s%7.1f\0A\00"
define i32 @main() {
%1 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([8 x i8], [8 x i8]* @.str, i64 0, i64 0), i8* getelementptr inbounds ([11 x i8], [11 x i8]* @.str.1, i64 0, i64 0), i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.2, i64 0, i64 0), i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str.3, i64 0, i64 0))
br label %2
2: ; preds = %0, %2
%3 = phi i32 [ 0, %0 ], [ %12, %2 ]
%4 = sitofp i32 %3 to float
%5 = fadd float %4, -3.200000e+01
%6 = fpext float %5 to double
%7 = fmul double %6, 0x3FE1C71C71C71C72
%8 = fptrunc double %7 to float
%9 = fpext float %4 to double
%10 = fpext float %8 to double
%11 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([15 x i8], [15 x i8]* @.str.4, i64 0, i64 0), double %9, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.2, i64 0, i64 0), double %10)
%12 = add nuw nsw i32 %3, 20
%13 = icmp ugt i32 %3, 280
br i1 %13, label %14, label %2
14: ; preds = %2
ret i32 0
}