jit(wasm): size CA callee frames with per-token compact geometry#505
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jit(wasm): size CA callee frames with per-token compact geometry#505youknowone wants to merge 4 commits into
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…shots Remove state_field_identity_const and the identity_const parameter chain: build_vable_snapshot_boxes now always emits the identity as SnapshotTagged::Box. The identity is a live input box; rewriting it to TAGCONST excluded it from liveboxes/failarg numbering, baking a trace-time object address into resume data. next_ref() now decodes the identity from the failing frame's failarg slot (resume.py:1566-1578). Assisted-by: Claude
…e pointer after collecting calls wasm_jit_ca_alloc_frame switches from the malloc+LIFO pool to a collecting nursery allocation (rewrite.py gen_malloc_nursery_varsize_frame), retiring the CA_FRAMES pool. Because a minor collection can now move the running frame and the collector cannot update wasm locals, trace bodies reload local 0 from the jitframe shadow-stack top before every post-collection home reload (_reload_frame_if_necessary, assembler.py:1369), and the CA arm reloads the caller frame via the new jf_under_top_ptr() accessor after its callee push. Trampoline fallback paths keep the documented non-moving-frame assumption. fib32 via CA: gc_majors 262 (oldgen variant) -> 4. Synthetic suite 151/151 on wasm, dynasm, cranelift. Assisted-by: Claude
Assisted-by: Claude
Replace the fixed MIN_FRAME_BYTES frame layout for CA-allocated callee frames with a per-token FrameGeometry frozen at the token's first compile: value region sized from the token's actual slot needs, then call area, dispatch key, and Ref homes at per-token offsets (jitframe.py sizes frames by the regalloc frame_depth). Arena execute_token frames keep the fixed floor. compile_bridge declines a chained bridge whose slot needs exceed the frozen geometry. Host-side frame readers and per-bridge gcmap building take the token geometry instead of the global constants. fib32 via CA: gc_minors 5034 -> 1243, wall 1.20s -> 0.66-0.69s (malloc-pool baseline 0.83s). Synthetic suite 151/151 on wasm, dynasm, cranelift. Assisted-by: Claude
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Summary
Stacked on #501. Removes the fixed
MIN_FRAME_BYTES(2152B) layout floor for CA-allocated callee jitframes: each token freezes a compactFrameGeometryat its first compile (value region sized from the token's actual slot needs, then call area, dispatch key, and Ref homes at per-token offsets), matching how native jitframes are sized by the regalloc's actual frame depth (jitframe.pyJITFRAME_FIXED_SIZE + frame_depth).execute_tokenframes keep the fixed floor (they are shared across tokens).compile_bridgedeclines a bridge whose slot needs exceed it (safe fallback, no miscompile).Motivation / measurements (fib32 via CALL_ASSEMBLER, interleaved ×5)
#501 moved CA callee frames from a malloc+LIFO pool to nursery GC allocation, which regressed fib32 0.83s → 1.20s purely from minor-GC frequency (gc_minors 262 → 5034): every CA call allocated a ~2.3KB fixed-layout frame. A 32MB-nursery probe (0.77s, minors 629) confirmed the cost is per-minor overhead × count; native dynasm shows only 146 minors with its frame-depth-sized frames.
With compact geometry:
Output stays 2178309/exit 0. Synthetic suite 151/151 on wasm, dynasm, cranelift;
i64envandmajit-backend-wasmtests green.🤖 Generated with Claude Code