Re: Ping, Ping: [Patch, fortran] PR27411 - crashes in sra_walk_expr and emit_move_insn

[Paul Thomas <paulthomas2 at wanadoo dot fr>]

Roger,

> This is not an objection, I'm just curious.  Could you explain the
> sequence of events whereby adding parenthesis around an expression
> in the source code avoids an ICE in emit_move_insn?  I don't know
> enough fortran to understand "outputs%signal_number", or how this
> would cause the scalarizer to generate mismatched types that can
> survive thoughout tree-ssa, only to crash at RTL expansion time.
>  
I am surprised that it survives through tree_ssa. Take a look at 
Andrew's comment in the PR; it is spot on. gfortran is not following the 
references far enough in translating the index array. In consequence, a 
structure is taken as the index array - look at the code in the PR, or 
better still, dump it yourself. After this, put some brackets around the 
index array , which has the effect of creating an integer temporary and 
this is visible in the code. Presumably, emit_move_insn is the bad thing 
that happens when you try to use a structure as an index array?

> Not fully understanding the issues, I can't tell whether it would
> be helpful to add additional sanity checking to the gimplifier, or
> elsewhere in the middle-end, to help catch this earlier.
>  
As I remarked when I submitted, this patch might not be considered to be 
sufficient and that one should fix this in the middle-end. One the 
otherhand, I have been contemplating an internal_parentheses operator 
that makes temporaries for the scalarizer, in order to make gfortran a 
bit more maintainable. This fix would fall naturally into such a framework.

I hope that this helps

Paul