Workaround buggy offset debug info values

[bcardiff]

I've narrow a bit where the overflow was generated, but is more related to buggy debug information that is being generated or obtained.

This occur in def create_debug_type(type : InstanceVarContainer) only for LibC::PthreadMutexT#@__align so far.

Now instead of failing the debug info on that field is skipped. The other members of the struct were also created without debug info.

Some build where I extract additional traces of the issue:

• https://circleci.com/gh/bcardiff/crystal/38
• https://circleci.com/gh/bcardiff/crystal/45
• https://travis-ci.org/bcardiff/crystal/jobs/483895732

WARN: check_overflow src/compiler/crystal/codegen/debug.cr:126:11 in 'create_debug_type' LibC::PthreadMutexT @__align offset: 6593625271604084736
      @__data idx: 0  -- no type --
      @__size idx: 1  -- no type --
      @__align  idx: 2  offset: 6593625271604084736 size: 32

WARN: check_overflow src/compiler/crystal/codegen/debug.cr:126:11 in 'create_debug_type' LibC::PthreadMutexT @__align offset: 6593962857292369312
      @__data idx: 0  -- no type --
      @__size idx: 1  -- no type --
      @__align  idx: 2  offset: 6593962857292369312 size: 32

WARN: check_overflow src/compiler/crystal/codegen/debug.cr:126:11 in 'create_debug_type' LibC::PthreadMutexT @__align offset: 8030606727934340709
      @__data idx: 0  -- no type --
      @__size idx: 1  -- no type --
      @__align  idx: 2  offset: 8030606727934340709 size: 64

WARN: check_overflow src/compiler/crystal/codegen/debug.cr:126:11 in 'create_debug_type' LibC::PthreadMutexT @__align offset: 4611686018427387909
      @__data idx: 0  -- no type --
      @__size idx: 1  -- no type --
      @__align  idx: 2  offset: 4611686018427387909 size: 64

[asterite]

I guess we can move forward with this and investigate why it's happening later. Maybe if you have reproducible code @ysbaddaden might be able to fix it.

[bcardiff]

If only it would be deterministic :-). Maybe is scoped to the usage of llvm in the context of the codegen specs that could be processing the prelude multiple times accross the whole run.