Commit Graph

2 Commits

Author SHA1 Message Date
mvstanton
0a36b5cd2c [Turbofan] Make the -0 deopt case more efficient in multiplication.
After multiplying two integers we emit code like:

  if (result == 0) {
    if (OR_OPERATION(rhs, lhs) < 0) {
      DEOPT;
    }
  }

This CL allows us to eliminate the OR and comparison if either rhs or
lhs is a negative number, reducing the code to:

  if (result == 0) DEOPT;

BUG=

Review-Url: https://codereview.chromium.org/2167643002
Cr-Commit-Position: refs/heads/master@{#38016}
2016-07-25 12:15:22 +00:00
mvstanton
47aaac6442 [Turbofan]: Eliminate the check for -0 if it's not possible/observable.
In int32 multiplication, if we have a positive integer as input, then we know we can't produce a -0 answer. The same is true if truncation is applied (x * y | 0). Without this information, we have to rather annoyingly check if the result of multiplication is 0, then OR the inputs to check for negativity, and possibly return -0. In TurboFan, we'll deopt in this case.

BUG=

Review-Url: https://codereview.chromium.org/2154073002
Cr-Commit-Position: refs/heads/master@{#37831}
2016-07-18 11:37:23 +00:00