Bug 40231 – Add native call support for ARM and Thumb-2 JIT with JSValue32

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Gabor Loki]

Currently the native call enhancement is available on x86 with JSValue32_64 and on x86_64 with JSValue64.

I am going to upload a patch which adds this call support for ARM and Thumb-2 JIT as well.

[Gabor Loki]

Created attachment 58020 [details]
Add native call support for ARM and Thumb-2 JIT with JSValue32.

Same technique was used as on x86_64 with some limitations.
- we cannot use regT0 for the new callframe, because r0 (=regT0) should be the first argument of the host function.
- a callee preserved register should be used to hold the return address instead of the stack.
- preserveReturnAddressAfterCall/restoreReturnAddressBeforeReturn functions should be used to work with return address (instead of peek/poke on stack).

[WebKit Review Bot]

Attachment 58020 [details] did not pass style-queue:

Failed to run "['WebKitTools/Scripts/check-webkit-style', '--no-squash']" exit_code: 1
JavaScriptCore/jit/JITOpcodes.cpp:249:  Extra space before ( in function call  [whitespace/parens] [4]
JavaScriptCore/wtf/Platform.h:973:  More than one command on the same line in if  [whitespace/parens] [4]
Total errors found: 2 in 3 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Gabor Loki]

Created attachment 58025 [details]
Add native call support for ARM and Thumb-2 JIT

It was easy to add the native call support for JSValue32_64 as well.

So, this patch contains the native call enhancement for each ARM JIT and for each supported JSValue representations.

[WebKit Review Bot]

Attachment 58025 [details] did not pass style-queue:

Failed to run "['WebKitTools/Scripts/check-webkit-style', '--no-squash']" exit_code: 1
JavaScriptCore/wtf/Platform.h:973:  More than one command on the same line in if  [whitespace/parens] [4]
Total errors found: 1 in 4 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Geoffrey Garen]

Comment on attachment 58025 [details]
Add native call support for ARM and Thumb-2 JIT

JavaScriptCore/jit/JITOpcodes.cpp:226
 +      restoreReturnAddressBeforeReturn(regT3);
This implies that the link register is caller save. Is it? I thought it was callee save.

r=me

[Gabor Loki]

>  +      restoreReturnAddressBeforeReturn(regT3);
> This implies that the link register is caller save. Is it? I thought it was callee save.

The link register (r14) is caller-save.
The callee-save registers are: r4-r11.

[Gabor Loki]

Committed revision 61614.