Dear FX, I am puzzled by this business of the SAVE_EXPR:
First, I agree entirely that it is a mystery as to why the SAVE_EXPR appears. It does not do so for array elements nor for arrays. Secondly, as far as I can tell, SAVE_EXPR_RESOLVED_P(…) merely implies that a pointer to a tree is returned. In fact, it does not seem to signify a usless expression since, in one case in trans-decl.c, it is actually used. Third, I do not see where the side effects will appear. Although this is a co-array element, assignment to it is a purely local affair. It has to be explicitly referenced from another process before communication occurs, does it not? This is where my ignorance surfaces in full force, however :-( I don't know what to do with this, other than to dereference a tree pointer if that appears. Ideally, the SAVE_EXPR should be suppressed at source, although I do not know how to accomplish that. I would bemore than happy to act on advice from other maintainers.... Cheers Paul On 8 September 2015 at 23:02, FX <fxcoud...@gmail.com> wrote: >> This is something of a corner case, where gfc_conv_expr comes back >> with a SAVE_EXPR, in the case of complex, scalar, coarray lvalues. The >> first field of the SAVE_EXPR is a perfectly viable expression to >> assign to, so I have taken that. If anybody out there has a better >> solution, please speak up! > > If the SAVE_EXPR is a useless one, it should have SAVE_EXPR_RESOLVED_P(…) be > true. Then you can simply discard it as you’re doing. > If not, we need to created a temp variable, as simply removing the SAVE_EXPR > will lead to multiple side-effects evalution in some cases otherwise. > > But I’m curious as to where the SAVE_EXPR is created. As far as I can tell, > all SAVE_EXPR in our front-end are created by explicit calls to save_expr(), > of which there are very few. I don’t see which one is the culprit here :( > But creating a SAVE_EXPR for a LHS is definitely not a good idea in the first > place. > > FX > > -- Outside of a dog, a book is a man's best friend. Inside of a dog it's too dark to read. Groucho Marx
