1277148 - [Static Analysis][Logically dead code] numIfEnd==0 in CheckIf() never succeeds

Status: RESOLVED FIXED

(Core :: JavaScript Engine: JIT, defect)

Description

[Nicholas Nethercote [inactive]]

Coverity detected that this code in CheckIf() never succeeds:

> if (numIfEnd == 0)
>   return false;

because numIfEnd is initialized to 1 and then is only incremented after that.

sunfish, can you take a look? Maybe the test should just be removed, or maybe something bigger needs to be done.

Comment 1

[Benjamin Bouvier [:bbouvier] (inactive)]

For more context, this is in AsmJS.cpp. Probably testing for overflow? Could be rewritten to be made more explicit, I guess...

Comment 2

[Benjamin Bouvier [:bbouvier] (inactive)]

Attachment: overflow.patch

Comment 3

[Nicholas Nethercote [inactive]]

Comment on attachment 8759088 [details] [diff] [review]
overflow.patch

Review of attachment 8759088 [details] [diff] [review]:
-----------------------------------------------------------------

Your patch has r?sunfish in it but you asked me for review. I'm guessing you just typed the wrong name into the review request field...

Comment 4

[Dan Gohman [:sunfish]]

Comment on attachment 8759088 [details] [diff] [review]
overflow.patch

Review of attachment 8759088 [details] [diff] [review]:
-----------------------------------------------------------------

Yes, that code is testing for overflow. The proposed change looks ok.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/55bd2af31d62
Make overflow testing more explicit in CheckIf; r=sunfish

Comment 6

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/55bd2af31d62