Re: Buildbot failure in Wildebeest Builder on whole buildset

[Mark Wielaard <mark@klomp.org>]

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Hi,

On Tue, 2020-10-27 at 12:30 +0100, Mark Wielaard wrote:
> The Buildbot has detected a failed build on builder
> > whole buildset while building libabigail.
> > Full details are available at:
> >     https://builder.wildebeest.org/buildbot/#builders/9/builds/535
> > 
> > Buildbot URL: https://builder.wildebeest.org/buildbot/
> > 
> > Worker for this Build: fedora-s390x
> > 
> > Build Reason: <unknown>
> > Blamelist: Mark Wielaard <mark@klomp.org>
> > 
> > BUILD FAILED: failed test (failure)
> 
> This fails make distcheck with:
> 
> ERROR: files left in build directory after distclean:
> ./tests/core.2971518
> make[2]: *** [Makefile:859: distcleancheck] Error 1
> 
> Oddly no check fails. But there is another core file present in the
> make check directory.
> 
> Inspecting that core file provides the following backtrace:
> 
> #0  0x000003ff965c9026 in raise () from /lib64/libc.so.6
> #1  0x000003ff965ab162 in abort () from /lib64/libc.so.6
> #2  0x000003ff965c0af0 in __assert_fail_base () from /lib64/libc.so.6
> #3  0x000003ff965c0b6e in __assert_fail () from /lib64/libc.so.6
> #4  0x000003ff9706c3e6 in
> abigail::ir::array_type_def::subrange_type::get_length
> (this=0x125c220) at abg-ir.cc:14558
> #5  abigail::ir::array_type_def::subrange_type::get_length
> (this=0x125c220) at abg-ir.cc:14558
> [...]
> #36 main (argc=<optimized out>, argv=0x3ffecf7e948) at
> abidiff.cc:1241
> 
> So that is here:
> 
> 14557	uint64_t
> 14558	array_type_def::subrange_type::get_length() const
> 14559	{
> 14560	  if (is_infinite())
> 14561	    return 0;
> 14562	
> (gdb) 
> 14563	  ABG_ASSERT(get_upper_bound() >= get_lower_bound());
> 14564	  return get_upper_bound() - get_lower_bound() + 1;
> 14565	}
> 
> With
> 
> (gdb) print this
> $1 = (const abigail::ir::array_type_def::subrange_type * const) 0x125c220
> (gdb) print *this
> $2 = {<abigail::ir::type_base> = {<abigail::ir::type_or_decl_base> = {<abigail::ir::ir_traversable_base> = {<abigail::ir::traversable_base> = {_vptr.traversable_base = 0x3ff972f5f40 <vtable for abigail::ir::array_type_def::subrange_type+304>, 
>           priv_ = std::shared_ptr<abigail::ir::traversable_base::priv> (use count 1, weak count 0) = {get() = 0x125c290}}, <No data fields>}, priv_ = std::shared_ptr<abigail::ir::type_or_decl_base::priv> (use count 1, weak count 0) = {
>         get() = 0x125c160}}, _vptr.type_base = 0x3ff972f5ec8 <vtable for abigail::ir::array_type_def::subrange_type+184>, priv_ = 0x125c2f0}, <abigail::ir::decl_base> = {
>     _vptr.decl_base = 0x3ff972f5fd0 <vtable for abigail::ir::array_type_def::subrange_type+448>, priv_ = 0x125c330}, _vptr.subrange_type = 0x3ff972f5e38 <vtable for abigail::ir::array_type_def::subrange_type+40>, 
>   priv_ = std::shared_ptr<abigail::ir::array_type_def::subrange_type::priv> (use count 1, weak count 0) = {get() = 0x125c3c0}}
> (gdb) print *this.priv_ 
> $3 = {lower_bound_ = {s_ = abigail::ir::array_type_def::subrange_type::bound_value::UNSIGNED_SIGNEDNESS, v_ = {unsigned_ = 0, signed_ = 0}}, upper_bound_ = {s_ = abigail::ir::array_type_def::subrange_type::bound_value::SIGNED_SIGNEDNESS, v_ = {
>       unsigned_ = 18446744073709551559, signed_ = -57}}, underlying_type_ = std::weak_ptr<abigail::ir::type_base> (empty) = {get() = 0x0}, language_ = abigail::ir::translation_unit::LANG_C11, infinite_ = false}
> 
> Looking through the main argv this must be:
> abidiff --no-default-suppression --no-linkage-name --no-show-locs --no-redundant /home/mjw/bb/wildebeest/libabigail-fedora-s390x/build/libabigail-1.8/_build/sub/../../tests/data/test-diff-filter/test34-libjemalloc.so.2-gcc-6.1.0 /home/mjw/bb/wildebeest/libabigail-fedora-s390x/build/libabigail-1.8/_build/sub/../../tests/data/test-diff-filter/test34-libjemalloc.so.2-intel-16.0.3

I could replicate this locally with ulimit -c unlimited
Then make check or the above invocation of abidiff caused a crash that
produced a core file. The testcase doesn't FAIL however! I don't yet
know why a crash still makes the test PASS.

The reason is because test34-libjemalloc.so.2-intel-16.0.3 contains
subranges without a type that use data1 or data2 forms for the
upper_bound. If no underlying type is given for the subrange then we
default to assuming the value is signed. Flipping that assumption to
unsigned, as done in the attached patch, makes everything work again,
no more crashes/core dumps.

Cheers,

Mark

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From d7253e475b6d04445d62ae5b55c03facbd6ab87d Mon Sep 17 00:00:00 2001
From: Mark Wielaard <mark@klomp.org>
Date: Tue, 27 Oct 2020 14:06:03 +0100
Subject: [PATCH] Assume subrange bounds types are unsigned if no underlying
 type is given.

When running abidiff on test34-libjemalloc.so.2-intel-16.0.3 it would
crash in array_type_def::subrange_type::get_length on the ABG_ASSERT
get_upper_bound() >= get_lower_bound(). This was because that file
contained a subrange upper_bound value encoded with data1 or data2
without an underlying type. In that case we assumed the value was
encoded as a signed value which caused some of the upper bounds to
be negative (while the lower bound, which wasn't given, was assumed
to be zero).

	* src/abg-dwarf-reader.cc (build_subrange_type): Default
	is_signed to false.

Signed-off-by: Mark Wielaard <mark@klomp.org>
---
 src/abg-dwarf-reader.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/abg-dwarf-reader.cc b/src/abg-dwarf-reader.cc
index aa1bb2b5..7a2b7ae0 100644
--- a/src/abg-dwarf-reader.cc
+++ b/src/abg-dwarf-reader.cc
@@ -14666,7 +14666,7 @@ build_subrange_type(read_context&	ctxt,
   Dwarf_Die underlying_type_die;
   type_base_sptr underlying_type;
   /* Unless there is an underlying type which says differently.  */
-  bool is_signed = true;
+  bool is_signed = false;
   if (die_die_attribute(die, DW_AT_type, underlying_type_die))
     underlying_type =
       is_type(build_ir_node_from_die(ctxt,
-- 
2.18.4