cgen: restore -trace-calls in the new compiler

[medvednikov]

Summary

Restore V1-compatible -trace-calls in the new C backend, without routing through -old-compiler.

• Reuse the existing tracing runtime and tid/ns/ssize/name output for function entries, module/function names and arity, C.main, _vinit, and _vcleanup. Traces go to stderr; program stdout is unchanged.
• Restore -trace-fns selection by function/module names and glob patterns, independently of the existing -d trace custom call-site hooks.
• Propagate instrumentation into parallel generation and bypass uninstrumented module caches and literal-output shortcuts.
• Prevent _vinit from resetting the trace clock/stack baseline, which caused address-sized negative stack deltas. Exclude the tracing runtime from tracing/profiling recursion.
• Parse the trace prelude separately before user files, preserving implicit imports such as $embed_file's runtime.
• Add codegen and end-to-end regression coverage, require -new-compiler in trace tests, and document the flags and stack-delta limitations.

./v -trace-calls examples/hello_world.v
./examples/hello_world
./v -trace-calls -trace-fns 'main.*,println,_vcleanup' run examples/hello_world.v

The os.join_path fixture uses a spread argument so it remains an actual join_path call rather than being lowered to join_path_single by the new compiler.

Upstream integration

Merged master 2b99da47ea7268c152d8b90aae18517b39c1f788, resolving the _vinit conflict by preserving both the trace hook and upstream gc_runtime_init(). The implicit embed-import fix is committed, not pending.

Published integration commit: 6415933439171a6da708b5c87e881ca1070ac4c6. Its complete tree, 77a709228fd6a4dfcbad1ee6ec1d32369314d8c1, exactly matches the tree rebuilt and tested locally. No temporary workflows, patch-transport files, or synthetic assembly history are included in this PR.

Validation

Rebuilt the integrated compiler on Linux with VJOBS=2, then passed all three focused suites using the new compiler explicitly:

VJOBS=2 ./v -new-compiler vlib/v/gen/c/trace_calls_test.v
VJOBS=2 ./v -new-compiler vlib/v/tests/trace_calls_test.v
VJOBS=2 ./v -new-compiler vlib/v/gen/c/parallel_worker_test.v

The end-to-end suite covers filtering, recursive calls, normal dead-code elimination, serial/parallel generation, -prod, combined profiling/tracing, and implicit embed imports. The final hello-world smoke test also passed, with stdout exactly Hello, World!\n and tracing on stderr, including builtin calls and cleanup without address-sized negative stack values. git diff --check and formatting verification of the new tracing code/tests and modified tracing runtime passed.

The pre-integration feature and implicit-import fix also passed the focused Linux Actions validation in run https://github.com/vlang/v/actions/runs/35445012768.

Validation limits

This is not a claim that the full repository CI is green. An earlier upstream-integration Actions attempt built successfully but exited 139 on its first codegen test (https://github.com/vlang/v/actions/runs/35445429442); that failure was not reproduced in the final local integrated build with VJOBS=2. Fresh PR CI still needs to complete.

Earlier broader validation reported the same 12 failing / 41 passing skip-unused compiler-error fixtures with both the modified and original unpatched compiler; the full C-generator directory run exceeded the local execution timeout. The 32-bit cases were skipped because 32-bit headers are unavailable. macOS/Windows were not executed locally.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-19T14:38:02.003538Z	6415933	Draft marked ready

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