Any decent C/C++ compiler will give the same code. For example, this: int f1(int n) { int sum = 0; for (int i = 0; i < n; i++) {

Any decent C/C++ compiler will give the same code. For example, this: int f1(int n) { int sum = 0; for (int i = 0; i < n; i++) { int x = i + i; sum = x - i; } return sum; } int f2(int n) { int sum = 0; int x; for (int i = 0; i < n; i++) { x = i + i; sum = x - i; } return sum; } when compiled with 'gcc -O -S' gives: .file "loop.c" .text .globl f1 .type f1, @function f1: .LFB0: .cfi_startproc testl %edi, %edi jle .L4 movl $0, %eax .L3: addl $1, %eax cmpl %eax, %edi jne .L3 subl $1, %eax ret .L4: movl $0, %eax ret .cfi_endproc .LFE0: .size f1, .-f1 .globl f2 .type f2, @function f2: .LFB1: .cfi_startproc testl %edi, %edi jle .L9 movl $0, %eax .L8: addl $1, %eax cmpl %eax, %edi jne .L8 subl $1, %eax ret .L9: movl $0, %eax ret .cfi_endproc .LFE1: .size f2, .-f2 .ident "GCC: (GNU) 7.2.0" .section .note.GNU-stack,"",@progbits Even when compiled without optimization, the generated assembly was the same, though it was messier so I don't show it.