diff options
| -rwxr-xr-x | emcc | 3 | ||||
| -rw-r--r-- | tools/js-optimizer.js | 5 |
2 files changed, 4 insertions, 4 deletions
@@ -1621,9 +1621,6 @@ try: js_optimizer_queue += [get_eliminate(), 'simplifyExpressions'] - if shared.Settings.RELOOP and not shared.Settings.ASM_JS: - js_optimizer_queue += ['optimizeShiftsAggressive', get_eliminate()] # aggressive shifts optimization requires loops, it breaks on switches - if closure and not shared.Settings.ASM_JS: flush_js_optimizer_queue() diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js index 7d72b7b8..e61317af 100644 --- a/tools/js-optimizer.js +++ b/tools/js-optimizer.js @@ -801,7 +801,10 @@ function simplifyExpressions(ast) { // HEAP[x >> 2] // very often. We can in some cases do the shift on the variable itself when it is set, // to greatly reduce the number of shift operations. -// TODO: when shifting a variable, if there are other uses, keep an unshifted version too, to prevent slowdowns? +// XXX this optimization is deprecated and currently invalid: does not handle overflows +// or non-aligned (round numbers, x >> 2 is a multiple of 4). Both are ok to assume +// for pointers (undefined behavior otherwise), but invalid in general, and we do +// no sufficiently-well distinguish the cases. function optimizeShiftsInternal(ast, conservative) { var MAX_SHIFTS = 3; traverseGeneratedFunctions(ast, function(fun) { |