Debugging, targets, and build tracing

Choose the inspection boundary that can still reproduce the failure.

Targets

--target and --sysroot control cross-target compilation when the LLVM target, SDK, linker inputs, and runtime bitcode for that triple exist under lib/runtime/<triple>/. A successful IR emission does not prove that the toolchain ships everything needed to link or run that target; a missing module is reported by name rather than as a generic link failure.

Failure isolation

Emit textual IR to separate frontend/codegen success from object and link configuration. The library bitcode merge has no bypass — there is no supported build that skips it, and the obsolete PRISMIO_INLINE_RUNTIME is ignored — so isolate that boundary by reading the merged module (-o out.ll before the merge, PRISMIO_BUILD_TRACE=1 for the stage timing) rather than by turning it off. Use the exact compiler path and target triple in reports.

For memory bugs, combine value assertions, the verifier ledger, AIF explanation, and a native sanitizer. Each observes a different class of failure.

Target selection

common/target.psm owns the selected triple, data layout, pointer width, and explicit/default state. ir_target_select asks LLVM to validate a triple and derive its layout. ir_target_triple, ir_target_data_layout, ir_target_pointer_bits, and ir_target_is_explicit expose the result. ir_module_set_target stamps both strings on every generated module.

compiler_set_sysroot records an explicit SDK root. target_clang_flags converts target and sysroot into native compiler arguments. find_llvm_paths resolves the LLVM installation used to build/link backend and runtime support. Diagnose these layers separately: frontend acceptance, IR triple/layout, object generation, runtime bitcode availability for the triple, and final link.

Build tracing

build_trace_enabled reads the supported trace switch. build_trace_ms provides monotonic timestamps, and build_trace_stage(name, start) reports the elapsed stage. Instrumented stages include runtime discovery/curation, IR-to-object compilation, cache lookup, native runtime objects, linking, debug-symbol output, publish, and execution.

Object-cache tracing is separate. object_cache_trace reports the computed key and hit/miss decision; object_cache_disabled forces a real rebuild. A suspicious performance or correctness result should be reproduced with caching disabled.

Compiler inspection boundaries

• prismio check isolates lexer/parser/import/sema.
• prismio dump-ast exposes the resolved AST before AIF/backend.
• prismio aif --why <site> explains memory facts and placement.
• prismio build file.psm -o file.ll stops at textual LLVM IR.
• Native build tracing exposes object/runtime/link steps.
• --verify instruments runtime memory actions.
• ASan and TSan cover native memory/race behavior outside the verifier's model.

When filing a target failure, include prismio --version, host OS/architecture, requested triple, sysroot, compiler path, runtime hashes, complete command, first failing stage, emitted IR/object availability, and the relevant trace. “Cross compilation failed” is not enough to identify whether LLVM, the runtime, SDK, linker, or manifest owns the problem.