The VM call path (PushSymbol → Function → Frame) is traversed by every
PRG function call. Three changes together cut per-call overhead across
the entire bench suite.
Changes
- hbrt/call.go Function(): replace pop-push dance with a single slice
shift (N+2 pops + N pushes → 1 copy of N slots + sp adjust). Kills
the per-call `make([]Value, nArgs)` heap alloc. Resolved function
pointer is cached back into sym.Func so subsequent calls on the
same Symbol skip the VM lookup entirely.
- hbrt/vm.go GetSym(): new helper. Generated code calls it with a
pointer to a package-level `*Symbol` slot so FindSymbol (which takes
the VM RWMutex + map lookup) runs at most once per symbol per
process. Nil results are intentionally NOT cached — an init-order
miss becomes a retry on the next call instead of a permanent sticky
failure.
- hbrt/thread.go pushPendingSym(): scalar fast slot for depth=1 call
nesting (common case). Nil syms still go through the slice so the
"empty vs stored nil" ambiguity can't produce a false pop.
- compiler/gengo/gengo.go: emit `t.PushSymbol(t.GetSym(&_sym_<file>_<NAME>, "NAME"))`
for every function call site, with a per-file prefix so multi-PRG
builds don't collide on identical symbol names.
Bugs fixed during bring-up
- pendingSymFast == nil was ambiguous ("unused" vs "nil stored"). Nil
syms now spill to the slice, preserving distinguishability.
- The old varName-reuse branch at the PushSymbol emit site skipped
the GetSym wrapper, emitting a raw `t.PushSymbol(varName)` against
an uninitialized package-level *Symbol. Every call path now funnels
through emitPushSymbol.
bench_sql deltas vs prior build
- B1 SELECT * 114 → 97 µs (15%)
- B4 GROUP_HAVING 584 → 554 µs (5%)
- B8 RECURSIVE CTE 150 → 141 µs (6%)
- B10 RANK PARTITION 310 → 296 µs (5%)
- B11 SUM OVER 335 → 320 µs (4%)
- B14 COUNT 295 → 281 µs (5%)
- B15 CTE+WIN+JOIN 1891 → 1826 µs (3%)
Verification
- go test ./... ALL PASS
- FiveSql2 test_sql1999 43/43
- tests/compat_harbour 56/56
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
