cont-stack-limit.js

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// |jit-test| skip-if: !wasmStackSwitchingEnabled(); --setpref=wasm_cont_stack_max_vmem=1

// Tests the cap on the virtual memory used by continuation stacks. A cap of one

// byte is too small for even a single stack, and we always allow one, so exactly

// one continuation may be live at a time.

const { makeA, makeB, clear, recur } = wasmEvalText(`(module

  (type $ft (func))

  (type $ct (cont $ft))

  (func $g (type $ft))

  (global $a (mut (ref null $ct)) (ref.null $ct))

  (global $b (mut (ref null $ct)) (ref.null $ct))

  (elem declare func $g $recur)

  (func (export "makeA")

    (global.set $a (cont.new $ct (ref.func $g))))

  (func (export "makeB")

    (global.set $b (cont.new $ct (ref.func $g))))

  (func (export "clear")

    (global.set $a (ref.null $ct))

    (global.set $b (ref.null $ct)))

  (func $recur (type $ft)

    (resume $ct (cont.new $ct (ref.func $recur))))

  (func (export "recur") (call $recur))

)`).exports;

makeA();

assertErrorMessage(() => makeB(), WebAssembly.RuntimeError,

                   /too many continuation stacks/);

// Dropping the continuation returns its stack, so the next one succeeds.

clear();

gc();

makeB();

// Unbounded `resume (cont.new ...)` recursion traps instead of mapping stacks

// until the process runs out of kernel mappings (bug 2058605).

clear();

gc();

assertErrorMessage(() => recur(), WebAssembly.RuntimeError,

                   /too many continuation stacks/);