sleftv conversion: protect some more julia variables from intermediate garbage collections

[benlorenz]

This should fix one of the crashes observed in oscar-system/Oscar.jl#3184. I did some rr tracing and got a run where garbage collection was triggered by the jl_box_voidpointer call which then killed the array where the pointer was supposed to be stored.
The crash then happens when julia tries to compile a method instance for a type signature containing an invalid datatype pointer.

For testing it crashes pretty reliably with an explicit garbage collection in the middle:

jl_value_t * get_julia_type_from_sleftv(leftv ret)
{
  jl_array_t * result = jl_alloc_array_1d(jl_array_any_type, 3); 
  jl_array_ptr_set(result, 0, jl_false);
  jl_array_ptr_set(result, 1, jl_box_voidpointer(ret->data));
  jl_gc_collect(JL_GC_FULL);
  ret->data = 0;
  jl_array_ptr_set(result, 2, jl_box_int64(ret->Typ()));
  ret->rtyp = 0;
  return reinterpret_cast<jl_value_t *>(result);
}

Once the push is added this crash disappears.

I want to let it run for a bit longer without the explicit collect to make sure the original crash doesn't reappear.

The second JL_GC_PUSH2 change in lookup_singular_library_symbol_wo_rng is unrelated to the crashes but I think this is necessary as well.

Example backtrace with the explicit collect call:

[9856] signal (11.1): Segmentation fault
in expression starting at /home/datastore/lorenz/software/julia/Oscar.jl/test/AlgebraicGeometry/ToricVarieties/toric_schemes.jl:1
jl_object_id__cold at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/builtins.c:455
type_hash at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/jltypes.c:1575
typekey_hash at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/jltypes.c:1605
jl_precompute_memoized_dt at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/jltypes.c:1685
inst_datatype_inner at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/jltypes.c:2081
jl_inst_arg_tuple_type at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/jltypes.c:2176
arg_type_tuple at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:2232 [inlined]
jl_lookup_generic_ at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:3020 [inlined]
ijl_apply_generic at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:3072
low_level_caller_rng at /home/datastore/lorenz/software/julia/Singular.jl/src/caller.jl:378
primdecGTZ at /home/datastore/lorenz/software/julia/Singular.jl/src/Meta.jl:45
unknown function (ip: 0x14dcb5dadb69)
_jl_invoke at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:2875 [inlined]
ijl_apply_generic at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:3076
#_compute_primary_decomposition#320 at /home/datastore/lorenz/software/julia/Oscar.jl/src/Rings/mpoly-ideals.jl:578
_compute_primary_decomposition at /home/datastore/lorenz/software/julia/Oscar.jl/src/Rings/mpoly-ideals.jl:566 [inlined]
#313 at /home/datastore/lorenz/software/julia/Oscar.jl/src/Rings/mpoly-ideals.jl:541 [inlined]
get! at ./dict.jl:479
get_attribute! at /home/datastore/lorenz/software/julia/depot/packages/AbstractAlgebra/R29qD/src/Attributes.jl:230 [inlined]
#primary_decomposition#312 at /home/datastore/lorenz/software/julia/Oscar.jl/src/Rings/mpoly-ideals.jl:540 [inlined]
primary_decomposition at /home/datastore/lorenz/software/julia/Oscar.jl/src/Rings/mpoly-ideals.jl:538 [inlined]
connected_components at /home/datastore/lorenz/software/julia/Oscar.jl/src/AlgebraicGeometry/Schemes/AffineSchemes/Objects/Methods.jl:183
#_is_projective_without_denominators#7140 at /home/datastore/lorenz/software/julia/Oscar.jl/experimental/Schemes/ProjectiveModules.jl:95
_is_projective_without_denominators at /home/datastore/lorenz/software/julia/Oscar.jl/experimental/Schemes/ProjectiveModules.jl:71 [inlined]
__compute_is_smooth__ at /home/datastore/lorenz/software/julia/Oscar.jl/src/AlgebraicGeometry/Schemes/AffineSchemes/Objects/Properties.jl:705
#3793 at /home/datastore/lorenz/software/julia/depot/packages/AbstractAlgebra/R29qD/src/Attributes.jl:357
get! at ./dict.jl:479
unknown function (ip: 0x14dcb5d2b200)
_jl_invoke at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:2875 [inlined]
ijl_invoke at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:2901
unknown function (ip: 0x14dcd8ffe839)
unknown function (ip: 0x14dcd8ffe80b)
get_attribute! at /home/datastore/lorenz/software/julia/depot/packages/AbstractAlgebra/R29qD/src/Attributes.jl:230 [inlined]
is_smooth at /home/datastore/lorenz/software/julia/Oscar.jl/src/AlgebraicGeometry/Schemes/AffineSchemes/Objects/Properties.jl:699
unknown function (ip: 0x14dcd8ffe745)
_jl_invoke at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:2875 [inlined]
ijl_apply_generic at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:3076
jl_apply at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/julia.h:1982 [inlined]
do_call at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/interpreter.c:126
eval_value at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/interpreter.c:223
eval_stmt_value at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/interpreter.c:174 [inlined]
eval_body at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/interpreter.c:621
eval_body at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/interpreter.c:544
eval_body at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/interpreter.c:544
eval_body at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/interpreter.c:544
eval_body at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/interpreter.c:544
eval_body at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/interpreter.c:544
jl_interpret_toplevel_thunk at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/interpreter.c:775
jl_toplevel_eval_flex at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/toplevel.c:934
jl_toplevel_eval_flex at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/toplevel.c:877
ijl_toplevel_eval_in at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/toplevel.c:985
eval at ./boot.jl:385 [inlined]
include_string at ./loading.jl:2070
_jl_invoke at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:2875 [inlined]
ijl_apply_generic at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:3076
_include at ./loading.jl:2130
include at ./Base.jl:496 [inlined]
macro expansion at ./timing.jl:503 [inlined]
#_timed_include#21 at /home/datastore/lorenz/software/julia/Oscar.jl/src/utils/tests.jl:5
_timed_include at /home/datastore/lorenz/software/julia/Oscar.jl/src/utils/tests.jl:1 [inlined]
_timed_include at /home/datastore/lorenz/software/julia/Oscar.jl/src/utils/tests.jl:1 [inlined]
#test_module#27 at /home/datastore/lorenz/software/julia/Oscar.jl/src/utils/tests.jl:151
test_module at /home/datastore/lorenz/software/julia/Oscar.jl/src/utils/tests.jl:119 [inlined]
#29 at /home/datastore/lorenz/software/julia/Oscar.jl/test/runtests.jl:134 [inlined]
#1023 at ./asyncmap.jl:94
unknown function (ip: 0x14dcd8f50979)
_jl_invoke at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:2875 [inlined]
ijl_apply_generic at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:3076
jl_apply at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/julia.h:1982 [inlined]
do_apply at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/builtins.c:768
#1039 at ./asyncmap.jl:228
unknown function (ip: 0x14dcd8f4cd62)
_jl_invoke at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:2875 [inlined]
ijl_apply_generic at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/gf.c:3076
jl_apply at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/julia.h:1982 [inlined]
start_task at /home/datastore/lorenz/software/julia/jv/julia-110-assert/src/task.c:1238
Allocations: 134206885 (Pool: 134090342; Big: 116543); GC: 73

[fingolfin]

Great catch

[benlorenz]

So far I haven't seen any further crashes in about 100 iterations. I will let it continue for a while but from my point of view we can merge (+build) this now. Either with a new libsingular_julia version, or just as a rebuild (+1) of the previous build.