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9d2559e75d
Replace the legacy direct-opcode compiler with an SSA pipeline that
emits per-function amd64.s and arm64.s for every wasm function. A
pure-Go body is also emitted (build-constrained on other GOOS/GOARCH)
and shares the same New() / exported-method surface, so callers never
see the path distinction.
Asm pipeline
- SSA always on; unsupported wasm features are now hard errors.
Translate now drives Parse -> SSA build -> passes (Simplify, DCE,
CSE) -> arch-specific emit.
- Per-arch block-local linear-scan regalloc with slot reuse and
m-pointer caching (the *Module pointer is pinned in a reserved
register across the function body — R11 on amd64, R4 on arm64 —
so per-access reloads from the FP frame are gone).
- Cross-block stack allocation via interference-graph slot sharing
reduces the typical per-function frame to 8-16 bytes.
- Peephole + branch fusion: drop dead spills, elide empty else
fall-through, fold constant displacement into indexed load/store,
fuse AND+NE+BlockIf into BTL+JCC.
- A new cross-block linear-scan allocator with Belady eviction
lives in internal/regalloc/ and is gated behind
WASM2GO_NEWREGALLOC for measurement.
Output shape
- Bulk-dispatch exports: when -bulk-export-prefix matches at least
one export, each <prefix><svc>_<mt> becomes a standalone
Inv_<svc>_<mt> function with inlined trap-recovery (defer +
recover + mutable-global snapshot/restore). The Go linker drops
whichever Inv_* the consumer never calls.
- Cross-package asm CALL: when every byte of an import path maps to
a plan-9 identifier rune ("/" -> U+2215, "." -> U+00B7), the CALL
target emits the direct cross-package symbol; otherwise asm falls
back to a per-chunk Go-body trampoline.
- Multi-package layout for large modules: bodies split across
p0..p<N> with go:linkname bridges in alias.go and per-chunk
amd64.s / arm64.s sidecars. Single-file mode remains supported
for modules under the internal multi-file threshold.
Coverage and tests
- internal/asmgen, internal/codegen, internal/regalloc, internal/ssa,
internal/wasm pass with -race. Total cross-package statement
coverage 85.8%, above the enforced 85% threshold.
- A new TestRecoverTrapsAreSurfacedAsErrors end-to-end test
(testdata/cg_recover.wat) pins the Inv_<svc>_<mt> trap-recovery
contract: wasm traps surface as errors (no Go panic), mutable
globals restore to wrapper-entry values, and 5000 trap+recover
cycles leak no goroutines and keep the Go heap delta under 1 MiB
after a forced GC.
Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>
10 lines
330 B
WebAssembly Text Format
10 lines
330 B
WebAssembly Text Format
;; Reachable unreachable: trap path is in the control-flow graph,
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;; so SSA's DCE keeps the BlockUnreachable terminator.
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(module
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(func (export "trap_if_zero") (param $x i32) (result i32)
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(if (i32.eqz (local.get $x))
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(then (unreachable)))
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(i32.const 42))
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(func (export "always_42") (result i32) (i32.const 42))
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)
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