Re: fix libcc1 dependencies in toplevel Makefile

[Olivier Hainque <hainque@adacore.com>]

Hi Alex,

> On Jun 26, 2017, at 09:16 , Olivier Hainque <hainque@adacore.com> wrote:
> 
>> I'd like to understand better what the concurrency problem is with the
>> current build machinery, before we proceed with this change.  If you
>> manage to trigger the problem again, could you try to further analyze
>> build logs to check for e.g. concurrent activation of all-gcc in both
>> the top-level Makefile and the recursed-into-for-stage1 Makefile, or
>> somesuch?  Something else worth considering is what the make targets
>> specified in the command line were.
> 
> The problems were showing pretty rarely, only on certain hosts, in
> certain load conditions. We should still have the logs around and I'll
> look into this. They are regular logs, without -d. I can almost for sure
> fetch the exact "make" command line involved.

This was:

make -j 32 BOOT_LDFLAGS=-Wl,--stack=0x2000000 CC=gcc 'ADAFLAGS=-W -Wall -gnatpg -gnata -gnatws -gnatU -gnatyN' CXXFLAGS=-O2 BOOT_CFLAGS=-O2 CFLAGS=-O2 'LN_S=cp -p' 'BOOT_ADAFLAGS=-gnatpgn -gnatU' 'STAGE1_CFLAGS=-O2 -O0 -g' bootstrap

From the logs of discussions we tracked, the understanding
of the dependency issue was that we *had* (before the patch),
possibilities to have stage_current and maybe-all-gcc targets
built concurrently, via

> configure-target-libquadmath: stage_current
> all-target-libquadmath: configure-target-libquadmath
> maybe-all-target-libquadmath: all-target-libquadmath

> all-target: maybe-all-target-libquadmath

on the one hand,

> all-libcc1: maybe-all-gcc

> maybe-all-libcc1: all-libcc1

> all-host: maybe-all-libcc1

on the other hand.

Does that make sense ?

Thanks for your feedback!

(Note that I'll be away from tomorrow to Monday)

Olivier