Hi all,
I've been making some changes in GDC that will eventually be made
updated to be specially handled in GDB when it comes to non-local
symbol lookup, completion, etc.
Here's the current implementation in a brief nutshell. It's a
bit rough, but hopefully someone with knowledge of DMD's
internals may understand it well enough to update the DMD backend
to produce the correct debug code.
The the debug generation of 'module foo' emits a DW_TAG_module at
the file name and location of the module foo. If there is no
module declaration in the file, then the location defaults to
line 1 in the source file.
/* module foo; */
<1><2d>: Abbrev Number: 2 (DW_TAG_module)
<2e> DW_AT_name : foo
<32> DW_AT_decl_file : 1
<33> DW_AT_decl_line : 2
Packages are handled by emitting the parent tags first, then the
sub-modules in order. Children of parent modules are referenced
using DW_AT_sibling.
/* module std.foo; */
<1><2d>: Abbrev Number: 2 (DW_TAG_module)
<2e> DW_AT_name : std
<32> DW_AT_decl_file : 1
<33> DW_AT_decl_line : 2
<2><38>: Abbrev Number: 3 (DW_TAG_module)
<39> DW_AT_name : (indirect string, offset: 0xe0):
foo
<3d> DW_AT_decl_file : 1
<3e> DW_AT_decl_line : 2
...
/* module std.bar; */
<1><4d>: Abbrev Number: 2 (DW_TAG_module)
<4e> DW_AT_name : std
<52> DW_AT_decl_file : 2
<53> DW_AT_decl_line : 3
<2><58>: Abbrev Number: 3 (DW_TAG_module)
<59> DW_AT_name : (indirect string, offset: 0x4b):
bar
<5d> DW_AT_decl_file : 2
<5e> DW_AT_decl_line : 3
The DW_TAG_module being emitted twice isn't intentional here.
And more a side effect of the front-end sending two different
instantiations of the same 'std' package to the backend. If it
is genuinely needed, then expect this to change when I come round
to it.
Imported modules are tagged with DW_TAG_imported_module, and the
DW_AT_import points to the external module declaration.
/* import object.d. */
<3><3f>: Abbrev Number: 4 (DW_TAG_imported_module)
<40> DW_AT_decl_file : 1
<41> DW_AT_decl_line : 1
<42> DW_AT_import : <0x53> [Abbrev Number: 6
(DW_TAG_module)]
...
<1><53>: Abbrev Number: 6 (DW_TAG_module)
<54> DW_AT_name : (indirect string, offset: 0x0):
object
<58> DW_AT_declaration : 1
Renamed imports are identical, but with the addition of
DW_AT_name to reference the alias.
/* import simd = core.simd; */
<3><46>: Abbrev Number: 5 (DW_TAG_imported_module)
<47> DW_AT_decl_file : 1
<48> DW_AT_decl_line : 4
<49> DW_AT_name : (indirect string, offset: 0x81):
simd
<4d> DW_AT_import : <0x63> [Abbrev Number: 6
(DW_TAG_module)]
...
<1><58>: Abbrev Number: 7 (DW_TAG_module)
<59> DW_AT_name : (indirect string, offset: 0x8d):
core
<5d> DW_AT_decl_file : 2
<5e> DW_AT_decl_line : 13
<5f> DW_AT_sibling : <0x69>
<2><63>: Abbrev Number: 6 (DW_TAG_module)
<64> DW_AT_name : (indirect string, offset: 0x81):
simd
<68> DW_AT_declaration : 1
And currently I'm testing selective imports to be represented as
DW_TAG_imported_declaration. Don't have any examples for yet,
but it looks like it would be the imported declaration tag
pointing to the real declaration.
Regards
Iain.
