[Webkit-unassigned] [Bug 44329] SH4 JIT SUPPORT

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Fri Sep 17 09:49:30 PDT 2010


https://bugs.webkit.org/show_bug.cgi?id=44329





--- Comment #9 from thouraya <thouraya.andolsi at st.com>  2010-09-17 09:49:30 PST ---
(In reply to comment #7)
> > Created an attachment (id=67675)
 --> (https://bugs.webkit.org/attachment.cgi?id=67675) [details] [details]
> 
> Hmmm, you have implemented your own constant/literal pool for SH4. Why? Is the AssemblerBufferWithConstantPool is not sufficent for SH4?
> 
> As I see you follow a very similar way to attach the data and pointers into the instruction stream as we have done in AssemblerBufferWithConstantPool. At first sight I did not see any reason why the SH4 should have its own pool implementation. I suggest you try to use the AssemblerBufferWithConstantPool interface for SH4. If you have any problem or question about the interface, you can contact me at IRC.
> 
> In addition, I agree with Patrick about the style issue:
> - use static const ints, enums and inline functions instead of macros
> - fix tabs, unnecessary parenthesis and other trivial style errors which are reported by the check-webkit-style script.
> 
> One more question:
> What was the problem with the generatePatternCharacterPair function? Why do you have to read a simple character? (I am not familiar with the SH4 architecture)

Hello,

I started to use the AssemblerBufferWithConstantPool :

in arm you are encoding the offset of the constant in the constant pool in the LDR instruction (offset << 1 + 1).

to know if the constant was dumped or no, you have just to see the last bit, if it's 1 the constant is not yet dumped otherwise it's dumped.

But in sh4 we are using the mov at PC-relative and the offset can be pair or impair.

that's why we added the offset of the LDR instruction in our structure. 

so, when we dump the constant Pool we patch the LDR instructions.

so to know if the constant is not yet dumped, we need just to look at the offset of the LDR instruction which shoold be 0.



Please rectify if I m wrong.

Ciao,
Thouraya.

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