This way, tracking segment-to-section mapping becomes a lot easier
since it's effectively just start index plus number of sections
defined within the segment. If a section becomes empty however
care needs to be taken to remove the header upon committing to the
final binary.
Fix incorrect writing of symtab and strtab in dSYM bundle in incremental
context.
Fix incorrectly navigating unnamed consts (freeing) in incremental context.
This is currently hard-coded to require all consts to land in `__TEXT,__const`,
which is wrong and needs a rewrite.
Instead of generating sections upfront, allow generation by scanning
the object files for input -> output sections mapping. Next, always
strive to keep output sections in the final container sorted as they
appear in the final binary. This makes the linker less messy wrt
handling of output sections sort order for dyld/macOS not to complain.
There's still more work to be done for incremental context though
to make this work but looks promising already.
As part of the Opaque Pointers upgrade documentation, LLVM says that the
function LLVMGetGEPSourceElementType() can be used to obtain element
type information in lieu of LLVMGetElementType(), however, this function
actually returns the struct type, not the field type. The GEP
instruction does store the information we need, however, this is not
exposed in the C API. It seems like they accidentally exposed the wrong
field, because one would never need the struct type since one must
already pass it directly to the GEP instruction, so one will always have
it handy, whereas one will usually not have the field type handy.
This change provides a basic implementation of #2349 for stage2. There's
still quite a lot of work before this logic is as complete as what's in
Clang (b364535304/clang/lib/CodeGen/CGStmt.cpp (L2304-L2795)),
particularly considering the diversity of constraints across targets.
It's probably not worth doing the complete work until there's a clearer
picture for constraints in Zig's future dedicated ASM syntax, but at
least this gives us a small improvement for now.
As a bonus, this also fixes a bug with how we were handling `_`
identifiers.
