effect of goto on C++ compiler optimization

Question

What are the performance benefits or penalties of using goto with a modern C++ compiler?

I am writing a C++ code generator and use of

Answer 1

How do you think that loops are represented, at the assembly level ?

Using jump instructions to labels...

Many compilers will actually use jumps even in their Intermediate Representation:

int loop(int* i) {
  int result = 0;
  while(*i) {
    result += *i;
  }
  return result;
}

int jump(int* i) {
  int result = 0;
  while (true) {
    if (not *i) { goto end; }
    result += *i;
  }

end:
  return result;
}

Yields in LLVM:

define i32 @_Z4loopPi(i32* nocapture %i) nounwind uwtable readonly {
  %1 = load i32* %i, align 4, !tbaa !0
  %2 = icmp eq i32 %1, 0
  br i1 %2, label %3, label %.lr.ph..lr.ph.split_crit_edge

.lr.ph..lr.ph.split_crit_edge:                    ; preds = %.lr.ph..lr.ph.split_crit_edge, %0
  br label %.lr.ph..lr.ph.split_crit_edge

; :3                                       ; preds = %0
  ret i32 0
}

define i32 @_Z4jumpPi(i32* nocapture %i) nounwind uwtable readonly {
  %1 = load i32* %i, align 4, !tbaa !0
  %2 = icmp eq i32 %1, 0
  br i1 %2, label %3, label %.lr.ph..lr.ph.split_crit_edge

.lr.ph..lr.ph.split_crit_edge:                    ; preds = %.lr.ph..lr.ph.split_crit_edge, %0
  br label %.lr.ph..lr.ph.split_crit_edge

; :3                                       ; preds = %0
  ret i32 0
}

Where br is the branch instruction (a conditional jump).

All optimizations are performed on this structure. So, goto is the bread and butter of optimizers.