On Thu, Jun 9, 2011 at 11:49, Diego Novillo <dnovillo@google.com> wrote:
>
> We were trying to generate PCH and PPH information at the same time.
> We never noticed because PPH is generated after PCH, so we were just
> clobbering over the previous dump.
>
> Found it by accident while debugging a GC ICE.  This should make
> testing slightly faster.
>
> Committed to the branch.

This version had problems and it was still abusing the PCH options
from specs.  The problem is that when compiling header files
separately, the compiler assumes that we want to generate PCH files.

In the long term, I think we will want to replace PCH with PPH, but
until then I'm adding a new flag -fpph-gen to distinguish the PCH from
the PPH generation.  So, when compiling a header file, if you want a
PPH image, you need to:

$ gcc -fpph-gen foo.h

This generate foo.pph instead of foo.gch.

The new patch also adds documentation on the three user-facing flags
used for pph.

Tested on x86_64.


Diego.