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Javascript:Hazard Builds: Difference between revisions
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== Static Rooting Analysis == | == Static Rooting Analysis == | ||
Tbpl can run two static analysis builds, one for the full browser (linux64-br-haz) and one for just the JS shell (linux64-sh-haz). | Tbpl can run two static analysis builds, one for the full browser (linux64-br-haz) and one for just the JS shell (linux64-sh-haz). The former shows up on tbpl as SM(Hf), the latter as SM(Hs) (f=firefox, s=shell. We intend to have an Hb in the future for B2G builds.) | ||
These builds are performed as follows: | These builds are performed as follows: | ||
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* during the resulting garbage collection, the object pointed to by ed.obj is moved to a different location. All pointers stored in the JS heap are updated automatically, as are all rooted pointers. ed.obj is not, because the GC doesn't know about it. | * during the resulting garbage collection, the object pointed to by ed.obj is moved to a different location. All pointers stored in the JS heap are updated automatically, as are all rooted pointers. ed.obj is not, because the GC doesn't know about it. | ||
* after decompilePC returns, something accesses ed.obj. This is now a stale pointer, and may refer to just about anything -- the wrong object, an invalid object, or whatever. Badness 10000, as TeX would say. | * after decompilePC returns, something accesses ed.obj. This is now a stale pointer, and may refer to just about anything -- the wrong object, an invalid object, or whatever. Badness 10000, as TeX would say. | ||
=== So you broke the analysis by adding a hazard. Now what? === | |||
Backout, fix the hazard, or (final resort) update the expected number of hazards in js/src/devtools/rootAnalysis/expect.browser.json. | |||
The most common way to fix a hazard is to change the variable to be a Rooted type, as described in http://dxr.mozilla.org/mozilla-central/source/js/public/RootingAPI.h#l21 | |||
For more complicated cases, ask on #jsapi. If you don't get a response, ping sfink, terrence, or jonco, and for the really hairy stuff, billm. | |||