fix: valgrind on ARM#21
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New Rust crate (edition 2024) that reads a Callgrind .out profile and extracts call-graph topology (costs/addresses ignored), serializing to canonical index-ref JSON for stable cross-platform callgraph diffing.
Node identity is the {object,file,function} tuple so same-named statics stay distinct. Edges are emitted only on calls= lines (cl-format.xml CallSpec); name compression across three ID spaces, the cfl/cfi alias, inline fi/fe callee-context inheritance, and multi-part merge are handled. 18 integration tests; clippy and rustfmt clean.
Add testdata/*.c fixtures (recursion, chain, diamond, mutual) profiled by the in-repo Callgrind through an rstest harness that compiles each fixture and runs vg-in-place, then snapshots the canonical JSON. --instr-atstart=no plus the fixtures' client requests keep loader/libc frames out, so the JSON is stable across platforms.
The AArch64 B{L} decoder tagged the whole opcode group as Ijk_Call,
but only BL (bit 31 = 1, writes the link register) is a call; a plain
B (bit 31 = 0) is an ordinary unconditional branch.
Mislabelling B as a call made Callgrind treat every branch to a
function epilogue or tail target as a call. At -O0 a conditional like
`return n < 2 ? n : fib(...)` compiles the base case to `b <epilogue>`,
so each base case was counted as a recursive call -- inflating
recursive/cyclic call graphs and inventing phantom self-edges on arm64
(e.g. fib recursion 64 -> 98; mutual is_even/is_odd gaining self-loops).
Align plain B with B.cond and the register-indirect JMP, which already
use Ijk_Boring. Fixes the callgrind-utils recursion/mutual snapshot
failures.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Add a fixture_full_trace rstest matrix over the same four fixtures, traced with --instr-atstart=yes so the whole program (loader, libc startup, main's own entry) is captured, not just the client-request scoped region. The startup frames carry non-portable names (__libc_start_main@@GLIBC_2.34, raw loader addresses), so this asserts version-stable invariants rather than a golden snapshot: JSON round-trips, main appears as a callee (full-program capture), the fixture's own functions are present, and the per-fixture call shape matches the scoped snapshots. The recursion count (fib'2->fib'2 == 64) and mutual no-self-edge checks double as regression guards for the arm64 B-vs-BL jump-kind fix. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Profile a Python workload (recursion.py) live under the in-repo Callgrind, mirroring pytest-codspeed: a ctypes-loaded shim (clgctl.c) fires CALLGRIND_START/STOP and adds libpython + the python executable to the obj-skip list at runtime via CALLGRIND_ADD_OBJ_SKIP. Callgrind never names Python-level frames, so the test asserts structure rather than a golden snapshot: the START shim is captured and the Python runtime is folded out.
Merging this PR will degrade performance by 47.44%
Warning Please fix the performance issues or acknowledge them on CodSpeed. Performance Changes
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