Bug 149031 – Implement global variables in WebAssembly

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Sukolsak Sakshuwong]

Implement global variables in WebAssembly

[Sukolsak Sakshuwong]

Created attachment 260911 [details]
Patch

[Sukolsak Sakshuwong]

Created attachment 260912 [details]
Patch

[Geoffrey Garen]

Comment on attachment 260912 [details]
Patch

r=me

[WebKit Commit Bot]

Comment on attachment 260912 [details]
Patch

Clearing flags on attachment: 260912

Committed r189584: <http://trac.webkit.org/changeset/189584>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Sukolsak Sakshuwong]

Global variables have been removed from the MVP.

"Mutable global variables

In the MVP, there are no global variables; C/C++ global variables are stored in linear memory and thus accessed through normal linear memory operations. Dynamic linking will add some form of immutable global variable analogous to "symbols" in native binaries. In some cases, though, it may be useful to have a fully mutable global variable which lives outside linear memory. This would allow more aggressive compiler optimizations (due to better alias information). If globals are additionally allowed array types, significant portions of memory could be moved out of linear memory which could reduce fragmentation issues. Langauges like FORTRAN which limit aliasing would be one use case. C/C++ compilers could also determine that some global variables never have their address taken." (https://github.com/WebAssembly/design/blob/master/FutureFeatures.md#mutable-global-variables)

"Postpone adding globals until dynamic linking" (https://github.com/WebAssembly/design/issues/154)