Track T: bench.tsv has no fpc column for mandelbrot / raytracer / sieve

• Track: T (test infra — tools/testmgr.py --bench)
• Found: 2026-07-15, wiring the pxx-vs-FPC ratio into the website's benchmarks table (Track W). The "vs FPC" column is blank for three of the six benchmark workloads because bench.tsv carries no fpc-level row for them. This ticket records why each one is missing and which is fixable.

Where it comes from

BENCH_SUITE in tools/testmgr.py (~line 1421) tags each workload with an fpc_ok flag; only fpc_ok=True workloads are also compiled+timed under fpc -O2 for the fpc level:

("mandelbrot", ..., False),   # float compute (pxx units)
("raytracer",  ..., False),   # call-heavy float
("sieve",      ..., False),   # memory-bound int
("nbody",      ..., True),    # float, FPC-comparable
("fib",        ..., True),    # call-heavy int, FPC-comparable

FPC flags used: -O2 -Tlinux -Px86_64 (no -M mode), mirroring the Makefile FPCFLAGS.

Findings — two distinct causes, verified with fpc 3.2.2

mandelbrot — pxx-only unit (structural, fpc_ok=False is correct).

mandelbrot.pas(31,26) Fatal: Can't find unit ansiterm used by Mandelbrot

uses sysutils, baseunix, ansiterm; — ansiterm is a pxx RTL unit with no FPC equivalent. Not FPC-comparable without an FPC shim.

raytracer — pxx-only units (structural, fpc_ok=False is correct).

raytracer.pas(25,22) Fatal: Can't find unit image used by RayTracer

uses sysutils, math, image, png, hashing, platform; — image, png, hashing, platform are pxx lib units. Same story as mandelbrot.

sieve — NOT structural; it is a dialect/mode gap and IS fixable.

sieve.pas(87,5) Error: range check error while evaluating constants
                       (1000000 must be between -32768 and 32767)

uses sysutils; only — no pxx-only unit. The failure is that FPC's default mode types Integer as 16-bit smallint, so the for n := 2 to LIMIT do loop (LIMIT = 1000000) overflows the loop variable's range. pxx defaults Integer to ≥32-bit, so it compiles as-is. Adding -Mobjfpc (32-bit Integer) makes FPC compile it clean:

$ fpc -Mobjfpc -O2 examples/primes/sieve.pas
102 lines compiled, 0.1 sec

Suggested fixes (Track T's call)

• sieve: give it an fpc column. Either add {$mode objfpc} to examples/primes/sieve.pas, or add -Mobjfpc to the harness FPC_FLAGS (arguably more correct — it makes the reference compiler's integer width match pxx's default, which is the point of the comparison). Then flip sieve's fpc_ok to True. Note the Makefile bootstrap gets away without -Mobjfpc only because compiler.pas carries its own mode directive.
• mandelbrot / raytracer: leave fpc_ok=False — they genuinely depend on pxx-only units. Optionally record the reason in a one-word column or a companion note so the dashboard can render "n/a (pxx units)" instead of a bare "—", making "no FPC number" visibly deliberate rather than missing data.

Why it matters

Low priority — the dashboard is honest today (blank = no data). But a reader sees three blanks and can't tell "FPC can't build this" from "we forgot to measure it". sieve in particular is a free extra FPC comparison being left on the table over a one-flag mode mismatch.

• 2026-07-19 (backlog sweep) RESOLVED. sieve fpc_ok with -Mobjfpc (c9d1c31d); portable mandelbrot-p/raytracer-p FPC-comparable variants added (421bdfe7, 750a2723) — exceeds the optional ask.

Log

• 2026-07-19 — resolved, commit 750a2723.