Second pcode peephole to match the one added for FieldGet(literal).
SqlExprToPrg auto-wraps CHAR column references with AllTrim() to
match SqlCmpEq's CHAR-padding trim semantics, so every string WHERE
predicate evaluates `AllTrim(FieldGet(n)) == 'literal'` per row.
Before this commit each of those per-row evaluations did:
1. PushSymbol ALLTRIM
2. PushSymbol FIELDGET → Function(1) [1 RTL Frame]
3. parseCharField → MakeString [alloc: copies raw bytes]
4. Function(1) → AllTrim RTL [1 RTL Frame]
5. strings.TrimSpace [alloc: new string]
6. Return, continue
New opcode `PcOpFieldTrim <idx>` (0x47) fuses the two RTL calls into
a single opcode that:
1. Calls FastFieldGetter directly (no Frame/Function dispatch).
2. Walks the returned string with ASCII-space trim in place.
3. Pushes `s[lo:hi]` — a sub-slice, no new allocation.
4. Short-circuits back to the same string if no trim needed.
genpc recognizes the shape `AllTrim(FieldGet(<int-literal>))` in
emitCall and emits the fused opcode automatically — no SQL-side
API change. Matches the existing FieldGet peephole's shape.
Bench impact (50k rows, 3-run steady state, vs raw RDD baseline 6.2ms):
String WHERE before 7.9ms → after 6.2ms 1.00x (parity!)
Numeric WHERE 6.9ms (unchanged) 1.11x
No WHERE 9.1ms (unchanged) 1.47x
String WHERE is now at parity with the raw Harbour-style RDD scan.
Compared to session start (119ms), that's a 19x speedup.
Validation:
- FiveSql2 43/43
- Harbour compat 51/51
- go test ./... ALL PASS
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>