Closed
Bug 1383828
Opened 7 years ago
Closed 4 years ago
Branch prediction issues in code produced by MLoadElementFromState inside loops.
Categories
(Core :: JavaScript Engine: JIT, enhancement, P3)
Core
JavaScript Engine: JIT
Tracking
()
RESOLVED
INVALID
People
(Reporter: nbp, Unassigned)
References
(Blocks 1 open bug)
Details
As documents under Bug 1364908 comment 21, Bug 1364908 comment 23, and Bug 1364908 comment 24.
MLoadElementFromState which produces a switch-case damage the ability of the branch predictor of the CPU to predict which branch is going to be taken.
We can solve this issue, either by using a stack-allocated array as the underlying representation for any State object used as argument of MLoadElementFromState, and/or by trying to unroll loops which have a MLoadElementFromState in their body, which which are using the length of this inlined-array as the loop boundary.
Comment 1•4 years ago
|
||
Removed in bug 1686692.
Status: NEW → RESOLVED
Closed: 4 years ago
Resolution: --- → INVALID
You need to log in
before you can comment on or make changes to this bug.
Description
•