diff options
Diffstat (limited to 'src/settings.js')
| -rw-r--r-- | src/settings.js | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/src/settings.js b/src/settings.js index a9a72425..3289eace 100644 --- a/src/settings.js +++ b/src/settings.js @@ -124,13 +124,20 @@ var PRECISE_I32_MUL = 1; // If enabled, i32 multiplication is done with full pre var PRECISE_F32 = 0; // 0: Use JS numbers for floating-point values. These are 64-bit and do not model C++ // floats exactly, which are 32-bit. // 1: Model C++ floats precisely, using Math.fround, polyfilling when necessary. This - // can be slow if the polyfill is used on heavy float32 computation. + // can be slow if the polyfill is used on heavy float32 computation. See note on + // browser support below. // 2: Model C++ floats precisely using Math.fround if available in the JS engine, otherwise // use an empty polyfill. This will have much less of a speed penalty than using the full // polyfill in cases where engine support is not present. In addition, we can // remove the empty polyfill calls themselves on the client when generating html, // which should mean that this gives you the best of both worlds of 0 and 1, and is // therefore recommended. + // XXX Note: To optimize float32-using code, we use the 'const' keyword in the emitted + // code. This allows us to avoid unnecessary calls to Math.fround, which would + // slow down engines not yet supporting that function. 'const' is present in + // all modern browsers, including Firefox, Chrome and Safari, but in IE is only + // present in IE11 and above. Therefore if you need to support legacy versions of + // IE, you should not enable PRECISE_F32 1 or 2. var SIMD = 0; // Whether to emit SIMD code ( https://github.com/johnmccutchan/ecmascript_simd ) var CLOSURE_COMPILER = 0; // Whether closure compiling is being run on this output |