Re: Flags and pph...

[Gabriel Charette <gchare at google dot com>]

To demonstrate my point:
add /* { dg-options "-ffinite-math-only -fno-math-errno" } */
to c1builin-integral.cc

and watch the test pass (since now we are using the flags across all
compilations).

Or similarly, remove the same dg-options entry from
c0builtin-integral.h and watch the test pass (since now we are using
no additional flags across all compilations)

Gab

On Mon, Jul 18, 2011 at 5:29 PM, Gabriel Charette <gchare@google.com> wrote:
> Hey guys,
>
> so the asm diff we are seeing in c1builtin-integral is not something
> we are not streaming out, or any other logic being wrong in the pph.
>
> The problem is: we define a dg-options entry in the header file which
> tells deja-gnu to add flags to the compilation (so far so good...)
>
> The problem is: deja-gnu only sees those options when doing the pph
> compile (as deja-gnu takes its options by reading the file compiled it
> seems, not the full translation unit).
>
> In our case compiling the pph with -ffinite-math-only -fno-math-errno.
>
> When compiling the C file, those flags are no longer there (deja-gnu
> doesn't pass them in as they are not present in the C file)
>
> Furthermore, when doing the non-pph compile, those flags aren't passed either.
>
> It turns out, if we either:
> 1) Do the pph compile without the flags, and then the pph and non-pph
> compile: there is no asm diff
> 2) Do the pph compile with the flags, but also pass the flags when
> doing the C file compile (with and without pph): there is also no asm
> diff!
>
> So the question is: how do we want to treat flags passed to the pph
> compile? I don't think it makes sense to use these flags in the rest
> of the compilation, but not doing so also results in the flag only
> being use for half of the compilation...
> Maybe we should save the flags used as part of the pph compile and
> invalidate the pph file if we don't get the same set of flags when
> doing the real compilation (as we do, i think, with the
> identifier(macro) context present when compiling a given pph file)??
>
> Gab
>