Incremental compilation is the default, but each dependency unit was compiled
to its own .o with NO OPDF debug info — only the top --source unit got an
.opdf section. pdr could therefore not set breakpoints, show callstacks, or
inspect locals inside any dependency (RTL, stdlib, or a user's own units),
which makes the default pipeline effectively undebuggable.
Mirror FPC's multi-unit OPDF model (which pdr already reads): every object —
each unit AND the program — carries a complete, self-contained .opdf section
[32-byte header][records], and the linker concatenates the same-named sections.
The header's TotalRecords is written as 0 (stream-terminated): readers consume
records to section EOF and skip the embedded per-unit headers (and linker zero
padding). pdr needs NO changes — it already handles exactly this layout.
Layers:
- uDebugOPDF.pas: EmitHeader writes TotalRecords=0 (PatchTotalRecords now a
no-op); new CreateForUnit + unit-mode DoEmit that emits a unit's types /
globals / constants / function scopes / line info from its IntfBlock+ImplBlock
and the unit's symbol table, with NO program main scope and NO unit directory
(directory is program-only; pdr ignores it). Whole-program output is
unchanged apart from TotalRecords=0. MangledClassSym matches the native
backend's class-symbol naming so vtable labels resolve in unit mode.
- Blaise.pas: TCompileWorker.Execute appends a unit-mode OPDF section to each
unit's IR when --debug-opdf and the native codegen produced debug facts, so
the per-unit .o embeds its own .opdf. (QBE has no facts → no per-unit OPDF;
native is the debug backend.)
- blaise.assembler.x86_64.pas: accept `.section .opdf, "aw", @progbits`
(new eskOpdf); `.int` alias for `.long`; `.byte`/`.word` now parse
comma-separated value lists (needed for the OPDF magic + BuildID bytes).
- blaise.elfwriter.pas: emit the .opdf section as SHF_ALLOC|SHF_WRITE PROGBITS
so it lands in the loadable image where pdr finds it; the internal linker's
section merger already concatenates .opdf by name and resolves its
.quad <funclabel> relocations.
Verified: pdr breaks inside a dependency unit, shows the cross-unit callstack,
and inspects locals — under BOTH the internal toolchain (default) and external
gas/ld, incremental AND --no-incremental. Full suite OK (3742) on both build
paths; all four fixpoints pass (normal builds unaffected). Regression test
TestDebugOpdf_PerUnitSection_InDependencyObject asserts the dependency .o
carries an .opdf section.
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