Re: [PATCH, testsuite] Add effective target stack_size

[Christophe Lyon <christophe.lyon@linaro.org>]

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On 12 June 2017 at 16:28, Tom de Vries <Tom_deVries@mentor.com> wrote:
> On 06/12/2017 02:28 PM, Christophe Lyon wrote:
>>
>> Hi Tom,
>>
>> On 9 June 2017 at 17:25, Mike Stump <mikestump@comcast.net> wrote:
>>>
>>> On Jun 9, 2017, at 7:24 AM, Tom de Vries <Tom_deVries@mentor.com> wrote:
>>>>
>>>> this patch adds effective target stack_size.
>>>
>>>
>>>> OK for trunk if x86_64 and nvptx testing succeeds?
>>>
>>>
>>> Ok.
>>>
>>> The only last issue in this area that I know about is that there are a
>>> few more test cases that need up to 48 MB to run, the problem is that
>>> targets might have substantially less memory.  Stack size is one of the ways
>>> this problem can be exposed.  The failure to load case is or can be handled
>>> in other ways, but the dynamic allocation case I think is relatively poorly
>>> handled.  On my machine, I just punted by running on a virtual simulator
>>> that I pushed memory up to 48 MB and ignored the issue.  If anyone wants to
>>> try their hand at it, I'd be happy to review some patches.  For those on
>>> demand virtual memory systems, of course, the problem is invisible.  I
>>> didn't have any good ideas in this area.  Marking large memory test cases
>>> with size information, and then just trimming based upon size was my only
>>> thought.  Not exactly portable, as the exact size of any test case is of
>>> course target dependent; but, if we get close enough, it can provide enough
>>> of a solution I think.
>>>
>>> If people have better ideas in this area, even if you don't want to
>>> implement them, it'd be nice to hear about them.
>>
>>
>> After this commit (r249090), I've noticed that badalloc1.C fails at
>> execution on aarch64 and arm bare-metal targets.
>>
>> It is compiled with -DSTACK_SIZE=16384, maybe that's too small?
>
>
> I think that what's going on is the following:
> - your board description file for aarch64 and arm bare-metal sets
>   gcc,stack_size
> - before I committed the patch, STACK_SIZE was not defined when
>   compiling this testcase, because the activated .exp files do not
>   define it
> - after I committed the patch, STACK_SIZE started to be defined, and
>   the test started to fail
>

I think you are right.

> I'm not sure if this test was ever compiled with STACK_SIZE defined.
>
> Either way, the test-case uses the presence of STACK_SIZE, not the actual
> value, so changing the value of gcc,stack_size won't make a difference.
>
> Ideally you'd find out what the exact reason for the failure is, and update
> the test-case accordingly.
>
> The easiest thing we can do is to remove the STACK_SIZE setting in the
> test-case (and to avoid confusion, remove all the dead STACK_SIZE-enabled
> code), which returns the status quo of before the patch.
>

I tried to compile with -DSTACK_SIZE & execute the test on x86, and
the first call to malloc() (as defined in the testcase) aborts. This call occurs
before entering main() and tries to allocate size=72704, which is
way larger than arena_size = 256 + 8 * 128 (=1280). This is with a
shared libstdc++.

Linking with -static also implies using
-Wl,--allow-multiple-definition, and leads
to a failure to allocate size=5280.

I too wonder whether the test ever worked with STACK_SIZE defined?
(Yet, arena_size was updated when PR64535 was fixed)

The attached patch removes the support for STACK_SIZE in the testcase
as you suggested, and it works fine (cross-tested on aarch64/arm targets)

OK for trunk?

Thanks,

Christophe


> Thanks,
> - Tom

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2017-06-19  Christophe Lyon  <christophe.lyon@linaro.org>

	gcc/testsuite/
	* g++.old-deja/g++.eh/badalloc1.C: Remove code path for
	-DSTACK_SIZE.

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diff --git a/gcc/testsuite/g++.old-deja/g++.eh/badalloc1.C b/gcc/testsuite/g++.old-deja/g++.eh/badalloc1.C
index f63d5c6..b660e84 100644
--- a/gcc/testsuite/g++.old-deja/g++.eh/badalloc1.C
+++ b/gcc/testsuite/g++.old-deja/g++.eh/badalloc1.C
@@ -3,7 +3,6 @@
 // itself call malloc(), and will fail if there is no more
 // memory available.
 // { dg-do run { xfail { { xstormy16-*-* *-*-darwin[3-7]* } || vxworks_rtp } } }
-// { dg-additional-options "-DSTACK_SIZE=[dg-effective-target-value stack_size]" { target { stack_size } } }
 // Copyright (C) 2000, 2002, 2003, 2010, 2012, 2014 Free Software Foundation, Inc.
 // Contributed by Nathan Sidwell 6 June 2000 <nathan@codesourcery.com>
 
@@ -16,12 +15,6 @@ extern "C" void *memcpy(void *, const void *, size_t);
 // libstdc++ requires a large initialization time allocation for the
 // emergency EH allocation pool.  Add that to the arena size.
 
-// Assume that STACK_SIZE defined implies a system that does not have a
-// large data space either, and additionally that we're not linking against
-// a shared libstdc++ (which requires quite a bit more initialization space).
-#ifdef STACK_SIZE
-const int arena_size = 256 + 8 * 128;
-#else
 #if defined(__FreeBSD__) || defined(__sun__) || defined(__hpux__)
 // FreeBSD, Solaris and HP-UX require even more space at initialization time.
 // FreeBSD 5 now requires over 131072 bytes.
@@ -32,7 +25,6 @@ const int arena_size = 262144 + 72 * 1024;
 // 32-bit-systems-based estimate.
 const int arena_size = 32768 * ((sizeof (void *) + 3)/4) + 72 * 1024;
 #endif
-#endif
 
 struct object
 {