void AddBorder(double *xmin, double *xmax, double *ymin, double *ymax) {
  double dz;
  dz = (*xmax - *xmin) / 50;
  if (dz == 0)
    dz = 1;
  *xmax += dz;
  *xmin -= dz;
  dz = (*ymax - *ymin) / 50;
  if (dz == 0)
    dz = 1;
  *ymax += dz;
  *ymin -= dz;
}


x86 assembly (clang, -O0):
<AddBorder>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    %rdx,-0x18(%rbp)
mov    %rcx,-0x20(%rbp)
mov    -0x10(%rbp),%rax
movsd  (%rax),%xmm0
mov    -0x8(%rbp),%rax
subsd  (%rax),%xmm0
movsd  0xed4(%rip),%xmm1
divsd  %xmm1,%xmm0
movsd  %xmm0,-0x28(%rbp)
movsd  -0x28(%rbp),%xmm0
xorps  %xmm1,%xmm1
ucomisd %xmm1,%xmm0
jne    115a <AddBorder+0x5a>
jp     115a <AddBorder+0x5a>
movsd  0xeb3(%rip),%xmm0
movsd  %xmm0,-0x28(%rbp)
movsd  -0x28(%rbp),%xmm0
mov    -0x10(%rbp),%rax
addsd  (%rax),%xmm0
movsd  %xmm0,(%rax)
movsd  -0x28(%rbp),%xmm1
mov    -0x8(%rbp),%rax
movsd  (%rax),%xmm0
subsd  %xmm1,%xmm0
movsd  %xmm0,(%rax)
mov    -0x20(%rbp),%rax
movsd  (%rax),%xmm0
mov    -0x18(%rbp),%rax
subsd  (%rax),%xmm0
movsd  0xe68(%rip),%xmm1
divsd  %xmm1,%xmm0
movsd  %xmm0,-0x28(%rbp)
movsd  -0x28(%rbp),%xmm0
xorps  %xmm1,%xmm1
ucomisd %xmm1,%xmm0
jne    11c6 <AddBorder+0xc6>
jp     11c6 <AddBorder+0xc6>
movsd  0xe47(%rip),%xmm0
movsd  %xmm0,-0x28(%rbp)
movsd  -0x28(%rbp),%xmm0
mov    -0x20(%rbp),%rax
addsd  (%rax),%xmm0
movsd  %xmm0,(%rax)
movsd  -0x28(%rbp),%xmm1
mov    -0x18(%rbp),%rax
movsd  (%rax),%xmm0
subsd  %xmm1,%xmm0
movsd  %xmm0,(%rax)
pop    %rbp
ret

x86 assembly (clang, -O2):
<AddBorder>:
movsd  (%rsi),%xmm1
movapd %xmm1,%xmm2
subsd  (%rdi),%xmm2
movsd  0xeec(%rip),%xmm3
divsd  %xmm3,%xmm2
xorpd  %xmm0,%xmm0
movapd %xmm2,%xmm4
cmpeqsd %xmm0,%xmm4
movapd %xmm4,%xmm5
andnpd %xmm2,%xmm5
movsd  0xed3(%rip),%xmm2
andpd  %xmm2,%xmm4
orpd   %xmm5,%xmm4
addsd  %xmm4,%xmm1
movsd  %xmm1,(%rsi)
movsd  (%rdi),%xmm1
subsd  %xmm4,%xmm1
movsd  %xmm1,(%rdi)
movsd  (%rcx),%xmm1
movapd %xmm1,%xmm4
subsd  (%rdx),%xmm4
divsd  %xmm3,%xmm4
cmpeqsd %xmm4,%xmm0
movapd %xmm0,%xmm3
andnpd %xmm4,%xmm3
andpd  %xmm2,%xmm0
orpd   %xmm3,%xmm0
addsd  %xmm0,%xmm1
movsd  %xmm1,(%rcx)
movsd  (%rdx),%xmm1
subsd  %xmm0,%xmm1
movsd  %xmm1,(%rdx)
ret

LLVM IR (-O0):
define void @AddBorder(double* %0, double* %1, double* %2, double* %3) {
%5 = alloca double*
%6 = alloca double*
%7 = alloca double*
%8 = alloca double*
%9 = alloca double
store double* %0, double** %5
store double* %1, double** %6
store double* %2, double** %7
store double* %3, double** %8
%10 = load double*, double** %6
%11 = load double, double* %10
%12 = load double*, double** %5
%13 = load double, double* %12
%14 = fsub double %11, %13
%15 = fdiv double %14, 5.000000e+01
store double %15, double* %9
%16 = load double, double* %9
%17 = fcmp oeq double %16, 0.000000e+00
br i1 %17, label %18, label %19
18: ; preds = %4
store double 1.000000e+00, double* %9
br label %19
19: ; preds = %18, %4
%20 = load double, double* %9
%21 = load double*, double** %6
%22 = load double, double* %21
%23 = fadd double %22, %20
store double %23, double* %21
%24 = load double, double* %9
%25 = load double*, double** %5
%26 = load double, double* %25
%27 = fsub double %26, %24
store double %27, double* %25
%28 = load double*, double** %8
%29 = load double, double* %28
%30 = load double*, double** %7
%31 = load double, double* %30
%32 = fsub double %29, %31
%33 = fdiv double %32, 5.000000e+01
store double %33, double* %9
%34 = load double, double* %9
%35 = fcmp oeq double %34, 0.000000e+00
br i1 %35, label %36, label %37
36: ; preds = %19
store double 1.000000e+00, double* %9
br label %37
37: ; preds = %36, %19
%38 = load double, double* %9
%39 = load double*, double** %8
%40 = load double, double* %39
%41 = fadd double %40, %38
store double %41, double* %39
%42 = load double, double* %9
%43 = load double*, double** %7
%44 = load double, double* %43
%45 = fsub double %44, %42
store double %45, double* %43
ret void
}

LLVM IR (-O2):
define void @AddBorder(double* nocapture %0, double* nocapture %1, double* nocapture %2, double* nocapture %3) {
%5 = load double, double* %1
%6 = load double, double* %0
%7 = fsub double %5, %6
%8 = fdiv double %7, 5.000000e+01
%9 = fcmp oeq double %8, 0.000000e+00
%10 = select i1 %9, double 1.000000e+00, double %8
%11 = fadd double %5, %10
store double %11, double* %1
%12 = load double, double* %0
%13 = fsub double %12, %10
store double %13, double* %0
%14 = load double, double* %3
%15 = load double, double* %2
%16 = fsub double %14, %15
%17 = fdiv double %16, 5.000000e+01
%18 = fcmp oeq double %17, 0.000000e+00
%19 = select i1 %18, double 1.000000e+00, double %17
%20 = fadd double %14, %19
store double %20, double* %3
%21 = load double, double* %2
%22 = fsub double %21, %19
store double %22, double* %2
ret void
}