Source code
Revision control
Copy as Markdown
Other Tools
// Once we exhaust the register arguments this will alternately grow and then
// shrink the stack frame across tail call boundaries because the increment of
// stack allocation is 16 bytes and our variability exceeds that.
//
// (This is not redundant with eg litmus2, because in that case all the
// functions have the same ballast. Here we have different ballast, so we get
// growing and shrinking.)
//
// See litmus11 for the direct-call case.
// See litmus16 for the cross-module call_indirect case.
function ntimes(n, v) {
if (typeof v == "function")
return iota(n).map(v).join(' ');
return iota(n).map(_ => v).join(' ');
}
function get_local(n) {
return `(local.get ${n})`
}
function compute(ballast) {
return iota(ballast).reduce((p,g,n) => `(i32.or ${p} (local.get ${n}))`,
`(i32.const ${1 << ballast})`)
}
function build(n, ballast) {
switch (n) {
case 0:
return `
(func $f0 (export "f") (result i32)
(return_call_indirect (type $ty1) (i32.const ${1 << n}) (i32.const 1)))
`;
case ballast:
return `
(func $f${ballast} (param ${ntimes(ballast, 'i32')}) (result i32)
(if (result i32) (i32.eqz (global.get $glob))
(then (return ${compute(ballast)}))
(else (block (result i32)
(global.set $glob (i32.sub (global.get $glob) (i32.const 1)))
(return_call_indirect (type $ty0) (i32.const 0))))))
`;
default:
return `
(func $f${n} (param ${ntimes(n, 'i32')}) (result i32)
(return_call_indirect (type $ty${n+1}) (i32.const ${1 << n}) ${ntimes(n, get_local)} (i32.const ${n+1})))
`
}
}
function types(n) {
var ps = n == 0 ? '' : `(param ${ntimes(n, 'i32')})`;
return `
(type $ty${n} (func ${ps} (result i32)))`;
}
function funcnames(n) {
return ntimes(n, n => `$f${n}`)
}
for ( let ballast=1; ballast < TailCallBallast; ballast++ ) {
let vals = iota(ballast+1).map(v => 1 << v);
let sumv = vals.reduce((p,c) => p|c);
let text = `
(module
${ntimes(ballast+1, n => types(n))}
(table $t ${ballast+1} ${ballast+1} funcref)
(elem (table $t) (i32.const 0) func ${funcnames(ballast+1)})
(global $glob (mut i32) (i32.const ${TailCallIterations}))
${ntimes(ballast, n => build(n, ballast))}
${build(ballast, ballast)})
`;
let ins = wasmEvalText(text);
assertEq(ins.exports.f(), sumv);
}