double squared_distance_between_particles(double *P1, double *P2) {
  int component;
  double squared_distance;
  squared_distance = 0.0;
  for (component = 0; component < 3; component++) {
    squared_distance +=
        (P1[component] - P2[component]) * (P1[component] - P2[component]);
  }
  return (squared_distance);
}


x86 assembly (clang, -O0):
<squared_distance_between_particles>:
push   %rbp
mov    %rsp,%rbp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
xorps  %xmm0,%xmm0
movsd  %xmm0,-0x20(%rbp)
movl   $0x0,-0x14(%rbp)
cmpl   $0x3,-0x14(%rbp)
jge    1179 <squared_distance_between_particles+0x79>
mov    -0x8(%rbp),%rax
movslq -0x14(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm0
mov    -0x10(%rbp),%rax
movslq -0x14(%rbp),%rcx
subsd  (%rax,%rcx,8),%xmm0
mov    -0x8(%rbp),%rax
movslq -0x14(%rbp),%rcx
movsd  (%rax,%rcx,8),%xmm2
mov    -0x10(%rbp),%rax
movslq -0x14(%rbp),%rcx
subsd  (%rax,%rcx,8),%xmm2
movsd  -0x20(%rbp),%xmm1
mulsd  %xmm2,%xmm0
addsd  %xmm1,%xmm0
movsd  %xmm0,-0x20(%rbp)
mov    -0x14(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x14(%rbp)
jmp    111b <squared_distance_between_particles+0x1b>
movsd  -0x20(%rbp),%xmm0
pop    %rbp
ret

x86 assembly (clang, -O2):
<squared_distance_between_particles>:
movsd  (%rdi),%xmm0
movsd  0x8(%rdi),%xmm1
subsd  (%rsi),%xmm0
mulsd  %xmm0,%xmm0
xorpd  %xmm2,%xmm2
subsd  0x8(%rsi),%xmm1
addsd  %xmm0,%xmm2
mulsd  %xmm1,%xmm1
addsd  %xmm2,%xmm1
movsd  0x10(%rdi),%xmm0
subsd  0x10(%rsi),%xmm0
mulsd  %xmm0,%xmm0
addsd  %xmm1,%xmm0
ret

LLVM IR (-O0):
define double @squared_distance_between_particles(double* %0, double* %1) {
%3 = alloca double*
%4 = alloca double*
%5 = alloca i32
%6 = alloca double
store double* %0, double** %3
store double* %1, double** %4
store double 0.000000e+00, double* %6
store i32 0, i32* %5
br label %7
7: ; preds = %35, %2
%8 = load i32, i32* %5
%9 = icmp slt i32 %8, 3
br i1 %9, label %10, label %38
10: ; preds = %7
%11 = load double*, double** %3
%12 = load i32, i32* %5
%13 = sext i32 %12 to i64
%14 = getelementptr inbounds double, double* %11, i64 %13
%15 = load double, double* %14
%16 = load double*, double** %4
%17 = load i32, i32* %5
%18 = sext i32 %17 to i64
%19 = getelementptr inbounds double, double* %16, i64 %18
%20 = load double, double* %19
%21 = fsub double %15, %20
%22 = load double*, double** %3
%23 = load i32, i32* %5
%24 = sext i32 %23 to i64
%25 = getelementptr inbounds double, double* %22, i64 %24
%26 = load double, double* %25
%27 = load double*, double** %4
%28 = load i32, i32* %5
%29 = sext i32 %28 to i64
%30 = getelementptr inbounds double, double* %27, i64 %29
%31 = load double, double* %30
%32 = fsub double %26, %31
%33 = load double, double* %6
%34 = call double @llvm.fmuladd.f64(double %21, double %32, double %33)
store double %34, double* %6
br label %35
35: ; preds = %10
%36 = load i32, i32* %5
%37 = add nsw i32 %36, 1
store i32 %37, i32* %5
br label %7
38: ; preds = %7
%39 = load double, double* %6
ret double %39
}

LLVM IR (-O2):
define double @squared_distance_between_particles(double* nocapture %0, double* nocapture %1) {
%3 = load double, double* %0
%4 = load double, double* %1
%5 = fsub double %3, %4
%6 = tail call double @llvm.fmuladd.f64(double %5, double %5, double 0.000000e+00)
%7 = getelementptr inbounds double, double* %0, i64 1
%8 = load double, double* %7
%9 = getelementptr inbounds double, double* %1, i64 1
%10 = load double, double* %9
%11 = fsub double %8, %10
%12 = tail call double @llvm.fmuladd.f64(double %11, double %11, double %6)
%13 = getelementptr inbounds double, double* %0, i64 2
%14 = load double, double* %13
%15 = getelementptr inbounds double, double* %1, i64 2
%16 = load double, double* %15
%17 = fsub double %14, %16
%18 = tail call double @llvm.fmuladd.f64(double %17, double %17, double %12)
ret double %18
}