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Fix convertJsFunctionToWasm when the signature has more than 122 arguments #16658

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Merged
merged 5 commits into from
Apr 5, 2022
Merged

Fix convertJsFunctionToWasm when the signature has more than 122 arguments #16658

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0a30165
Fix convertJsFunctionToWasm when the signature has more than 122 argu…
hoodmane Apr 5, 2022
df1eadd
Apply suggestions from code review
hoodmane Apr 5, 2022
b6b2652
#ASSERTIONS ==> #if ASSERTIONS
hoodmane Apr 5, 2022
d782fcd
Update src/runtime_functions.js
kripken Apr 5, 2022
0c7fa14
Update src/runtime_functions.js
kripken Apr 5, 2022
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26 changes: 20 additions & 6 deletions src/runtime_functions.js
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,19 @@
* SPDX-License-Identifier: MIT
*/

// This gives correct answers for everything less than 2^{14} = 16384
// I hope nobody is contemplating functions with 16384 arguments...
function uleb128Encode(n) {
#if ASSERTIONS
assert(n < 16384);
#endif
if (n < 128) {
return [n];
}
return [(n % 128) | 128, n >> 7];
}


// Wraps a JS function as a wasm function with a given signature.
function convertJsFunctionToWasm(func, sig) {
#if WASM2JS
Expand Down Expand Up @@ -34,8 +47,6 @@ function convertJsFunctionToWasm(func, sig) {
// The module is static, with the exception of the type section, which is
// generated based on the signature passed in.
var typeSection = [
0x01, // id: section,
0x00, // length: 0 (placeholder)
0x01, // count: 1
0x60, // form: func
];
Expand All @@ -49,7 +60,7 @@ function convertJsFunctionToWasm(func, sig) {
};

// Parameters, length + signatures
typeSection.push(sigParam.length);
typeSection = typeSection.concat(uleb128Encode(sigParam.length));
for (var i = 0; i < sigParam.length; ++i) {
typeSection.push(typeCodes[sigParam[i]]);
}
Expand All @@ -62,9 +73,12 @@ function convertJsFunctionToWasm(func, sig) {
typeSection = typeSection.concat([0x01, typeCodes[sigRet]]);
}

// Write the overall length of the type section back into the section header
// (excepting the 2 bytes for the section id and length)
typeSection[1] = typeSection.length - 2;
// Write the section code and overall length of the type section into the
// section header
typeSection = [0x01 /* Type section code */].concat(
uleb128Encode(typeSection.length),
typeSection
);

// Rest of the module is static
var bytes = new Uint8Array([
Expand Down