Regalloc conflict produces internal error when function is inlined

[sarranz]

The following gives internal compilation error in function main: Variable allocation: i (defined at "ble.jazz", line 16 (12-13)) and i (defined at "ble.jazz", line 16 (12-13)) : variable already set

fn f(reg ptr u8[1] p, reg u64 i) -> reg ptr u8[1] {
    while (i < 1) {
        p[(int) i] = 0;
        i += 1;
    }
    return p;
}

export
fn main () -> reg u8 {
    stack u8[1] c;
    reg ptr u8[1] p;
    p = c;

    reg u64 i;
    i = 0;

    while (i < 1) {
        #inline
        p = f(p, i);
        i += 1;
    }

    reg u8 tmp;
    tmp = p[0];
    return tmp;
}

I believe it's because f increases i but main does not see this. If I remove the #inline, then I get a register allocation error saying that these two is conflict, this is what I'd expect. Naturally, it works if I introduce i = i at the beginning of f, or return i in f. Is this really an internal error, then?

[vbgl]

Well spotted. Here is a smaller example:

inline fn f(reg u64 j) {
    while (j < 1) {
        j += 1;
    }
}

export
fn main (reg u64 i) {
    while (i < 1) {
        f(i);
        i += 1;
    }
}

I think the issue is in the “renaming” step that blindly trusts the “rename” tag attached to assignments that are introduced by the “inlining” phase.

A simple workaround is to add an explicit assignment “i = i;” at the beginning of the inlined function.