On Wed, Jul 31, 2019 at 09:20:40AM +0200, Martin Liška wrote:
> One possible solution will be to adjust lto.exp:
>
> set LTO_OPTIONS [list \
> {-O0 -flto -flto-partition=none -fuse-linker-plugin} \
> {-O2 -flto -flto-partition=none -fuse-linker-plugin
> -fno-fat-lto-objects } \
> {-O0 -flto -flto-partition=1to1 -fno-use-linker-plugin } \
> {-O2 -flto -flto-partition=1to1 -fno-use-linker-plugin } \
>
> and replace all -flto with -flto=1. But still, many individual tests set
> -flto by themselves.
> Another solution would be to disable the auto-detection with an environment
> variable:
>
> diff --git a/gcc/lto-wrapper.c b/gcc/lto-wrapper.c
> index 353187c6043..bb6fb2b53ff 100644
> --- a/gcc/lto-wrapper.c
> +++ b/gcc/lto-wrapper.c
> @@ -1423,7 +1423,7 @@ run_gcc (unsigned argc, char *argv[])
> auto_parallel = 0;
> parallel = 0;
> }
> - else if (!jobserver && parallel)
> + else if (!jobserver && parallel && !getenv ("LTO_NO_AUTO_PARALLEL"))
> {
> /* If there's no explicit usage of jobserver and
> parallel is enabled, then automatically detect
> diff --git a/gcc/testsuite/lib/lto.exp b/gcc/testsuite/lib/lto.exp
> index 25c934731df..e303894e0b0 100644
> --- a/gcc/testsuite/lib/lto.exp
> +++ b/gcc/testsuite/lib/lto.exp
> @@ -209,6 +209,8 @@ proc lto_init { args } {
> ]
> }
> }
> +
> + setenv LTO_NO_AUTO_PARALLEL 1
> }
>
> #
>
> Can you Jakub test the patch or the s/-flto/-flto=1 solutions please?
Neither will work very well, we have thousands of -flto tests outside of
lto.exp, e.g. dg-torture.exp (or libgomp and others) cycle through various
options including -flto etc.
Some env var would be useful I guess, though shouldn't it have GCC in the
name? I mean, if we run into these fork-bomb problems in gcc, won't other
projects run into those as well?
Why doesn't the jobserver work in the tests? Is that because of missing +
somewhere in the Makefiles or is something unsetting MFLAGS or MAKEFLAGS
env vars?
Though, as I said on IRC, I think we might run out of filedescriptors when
using jobserver too, say if on 64 thread machine one does make -j64 -k check
and each test simultaneously tries to create 64 partitions, that would be
4096 connections to the jobserver, right?
Jakub
