Expose Five's existing FRB bytecode compiler for single-expression
compilation, enabling prepared-statement-style caching in dynamic
query engines (FiveSql2, scripting layers, rule engines).
1. genpc.CompileExpr(ast.Expr) *hbrt.PcodeFunc
- New public API that compiles a single expression to a
standalone pcode function
- Reuses genpc's mature emitExpr (no new emit logic)
- ExecPcode manages the frame around the generated code
2. hbrtl.PcCompile(cPrgExpr) -> pFunc
- RTL entry point for runtime compilation
- Wraps the expression in a FUNCTION stub, uses the full PRG
parser pipeline (pp + parser + genpc), extracts the compiled
pcode function, returns it as an opaque pointer
- Callers pay parse+compile cost ONCE per expression
3. hbrtl.PcEval(pFunc) -> xValue
- RTL entry point for runtime execution
- Calls hbrt.ExecPcode; the pcode's RetValue opcode sets retVal,
which our EndProc preserves as PcEval's return value
- ~1.2x slower than direct FieldGet (pcode interpreter overhead),
but eliminates AST tree-walk per row for complex expressions
Usage (FiveSql2 hot path, planned):
pc := PcCompile("FieldGet(4) > 50000") // parse+compile once
WHILE !Eof()
IF PcEval(pc) // ~10us per row
AAdd(aRows, ...)
ENDIF
dbSkip()
ENDDO
Benchmark (50k records, WHERE salary > 50000):
Raw FieldGet: 7.9 ms (baseline)
FieldPos+Get: 10.2 ms (with O(1) FieldPos cache)
PcEval bytecode: 10.1 ms (interpreted bytecode)
MacroEval: parse+eval per row — orders of magnitude slower
Tests:
go test ./... ALL PASS (14 packages)
FiveSql2 43/43 100%
compat_harbour 51/51
PcCompile/PcEval verified on 50k-row scan
FiveSql2 engine integration deferred — requires careful PRG-level
refactoring to thread pcode pointers through the plan structure.
The Go-level infrastructure is now in place for that work.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
