You want to look for uses of the `MCBoundaryAlignFragment` class in the
X86AsmBackend. This should provide some hints for how to insert
alignment-specific fragments.
Sam
> On 10 Aug 2020, at 11:36 am, 郑晗 via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
>
> Hi:
> I'm trying to implement something similar to sandbox(Software fault
isolation).I put the protect instruction
> and danger instruction(such as call) in a basicblock and use the
MachineBasicBlock::setAlignment to align it
> to 32B.The results is the picture above.but i'm wondering if it's
possible to insert the no-op before the call
> instruction like the picture below.
> 0B
32B
> | some protect instruction | call instruction | no-ops |
> | some protect instruction | no-ops | call instruction |
> So is it possible to modify llvm's X86 backend to set the layout
like this?(I guess google's native client achieve
> this goal, but i can't find any document.) I know there is no pass in
MC layer, i just want to know if i modify
> the source code, can i achieve this goal?
> The second question, does function EmitNops in
'llvm/lib/Target/X86/MCInstLower' insert all no-ops to the binary?
> if not, which function does?
> Thanks for your help.
> Regards,
> zheng han
> <alignment.png>_______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
--
Sam Elliott
Software Team Lead
Senior Software Developer - LLVM and OpenTitan
lowRISC CIC
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20200820/c7fcdc81/attachment.html>