Re: [RFC] Optimization Diary

[Paul Brook <paul at codesourcery dot com>]

> > I still don't see how gcc maintainers would know to make this
> > distinction.  Perhaps I'm misunderstanding the distinction between
> > command and display.
>
> for (i=0; i<4; i++)
> {
>   C[i] = A[i] + C[i+3];
> }
>
> Auto vectorizer emits three messages.
> 1) This loop is not vectorized because of data dependency.
> 2) Highlight C[i]
> 3) Highlight C[i+3]
>
> Here vectorizer knows that 2) and 3) are commands and 1) is display
> message.

I don't buy this. Whether things are highlighted or comments added seems like 
something that the consumer should decide. ie. the compiler generates:

1) {points at for loop} Loop not vectorized because of data dependency
1a) {points at C[i]} Conflicting data element
1b) {points at C[i+3]} Conflicting data element

Paul