Bug 152923 – Fixed compilation of JavaScriptCore with GCC 4.8 on 32-bit platforms

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

[Konstantin Tokarev]

This small patch restores compilation of JSC with GCC 4.8 on 32-bit platforms.

[Konstantin Tokarev]

Created attachment 268578 [details]
Patch

[Michael Saboff]

What is the error that GCC 4.8 reports?  Aggregate initialization is a c++11 feature and should be in GCC 4.8.

[Konstantin Tokarev]

I hit this GCC bug which is fixed in 4.9.0:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50025

Exact message is:

In file included from ../../Source/JavaScriptCore/dfg/DFGSpeculativeJIT32_64.cpp:33:0:
../../Source/JavaScriptCore/jit/CallFrameShuffler.h: In member function ‘void JSC::CallFrameShuffler::assumeCalleeIsCell()’:
../../Source/JavaScriptCore/jit/CallFrameShuffler.h:144:90: error: invalid initialization of non-const reference of type ‘JSC::CachedRecovery&’ from an rvalue of type ‘<brace-enclosed initializer list>’
         CachedRecovery& calleeCachedRecovery { *getNew(VirtualRegister(JSStack::Callee)) };

[Alex Christensen]

This seems like it is completely unrelated to whether it is being compiled on a 32-bit platform.

[Csaba Osztrogonác]

(In reply to comment #4)
> This seems like it is completely unrelated to whether it is being compiled
> on a 32-bit platform.

It is in JSVALUE32_64 block.

[Michael Catanzaro]

Frankly, if a one-line change is all that's needed to support a particular compiler, I would just take it.

For openSUSE I got the latest stable WebKitGTK+ building and running fine with GCC 4.8 using -DENABLE_INDEXED_DATABASE=OFF and -DENABLE_DATABASE_PROCESS=OFF, in order to provide them the option of upgrading. (It built fine without running into this issue.) We will need to be more conservative with increasing our GCC requirement in the future.

[Konstantin Tokarev]

Many vendor-supplied cross-toolchains don't have GCC 4.9 yet, but provide 4.8.x.

And many other Linux distributions, e.g. Ubuntu 14.04 LTS, provide GCC 4.8 in their repos, but not newer versions.

[Csaba Osztrogonác]

Just a note, once we would like to use B3 as FTL JIT backend, GCC 5.2 
will be the minimum required version. See bug151624 for details.

[Konstantin Tokarev]

That's sad, I hoped I will be able to fix FTL compilation with 4.8 in local branch.

However, right now I'm mostly interested in supporting GCC 4.8 for targeting MIPS with vendor-supplied toolchain, and it has no B3 yet.

[Alex Christensen]

(In reply to comment #5)
> (In reply to comment #4)
> > This seems like it is completely unrelated to whether it is being compiled
> > on a 32-bit platform.
> 
> It is in JSVALUE32_64 block.
Oh, duh.

(In reply to comment #6)
> Frankly, if a one-line change is all that's needed to support a particular compiler, I would just take it.
I agree.  I see no harm in accepting this change right now.

[WebKit Commit Bot]

Comment on attachment 268578 [details]
Patch

Clearing flags on attachment: 268578

Committed r194861: <http://trac.webkit.org/changeset/194861>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.