litmus2.js - mozsearch

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// Mutually recursive functions implement a multi-entry loop using indirect tail

// calls.  The functions do not have the same signatures, so if all arguments

// are stack arguments then these use different amounts of stack space.

//

// The variable ballast is intended to test that we handle various combinations

// of stack and register arguments properly.

for ( let ballast=1; ballast < TailCallBallast; ballast++ ) {

    let vals = iota(ballast,1);

    let ps = vals.map(_ => 'i32').join(' ')

    let es = vals.map(i => `(local.get ${i})`).join(' ')

    let sum = vals.reduceRight((p,c) => `(i32.add (local.get ${c}) ${p})`, `(i32.const 0)`)

    let sumv = vals.reduce((p,c) => p+c);

    let text = `

(module

  (table 2 2 funcref)

  (elem (i32.const 0) $even $odd)

  (type $t (func (param i32 ${ps}) (result i32)))

  (type $q (func (param i32 ${ps} i32) (result i32)))

  (func $odd (export "odd") (param $n i32) (param ${ps}) (param $dummy i32) (result i32)

    (if (result i32) (i32.eqz (local.get $n))

        (then (return (i32.or (i32.shl ${sum} (i32.const 1)) (i32.const 0))))

        (else (return_call_indirect (type $t) (i32.sub (local.get $n) (i32.const 1)) ${es} (i32.const 0)))))

  (func $even (export "even") (param $n i32) (param ${ps}) (result i32)

    (if (result i32) (i32.eqz (local.get $n))

        (then (return (i32.or (i32.shl ${sum} (i32.const 1)) (i32.const 1))))

        (else (return_call_indirect (type $q) (i32.sub (local.get $n) (i32.const 1)) ${es} (i32.const 33) (i32.const 1))))))`

    let ins = wasmEvalText(text);

    assertEq(ins.exports.even(TailCallIterations, ...vals), (sumv*2) + 1);

    assertEq(ins.exports.odd(TailCallIterations, ...vals, 33), (sumv*2) + 0);