llvm dev - Mar 2016 - Terminators in MachineBasicBlock

Hi,
Why does a MachineBasicBlock have multiple terminator instructions (unlike
BasicBlock, which can only have one) ?
Thanks,
Tom
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Hi,
> On Mar 24, 2016, at 10:58 AM, Tom Chen via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Hi,
> Why does a MachineBasicBlock have multiple terminator instructions (unlike
BasicBlock, which can only have one) ?
Think of it as predicated instructions.
E.g.,
bool = icmp
if bool : br if
br else

As for why, we could indeed have split those terminators into several basic
blocks, but it would have required more MachineBasicBlock objects.

Cheers,
-Quentin
> Thanks,
> Tom
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

So in your example there are two terminators in the basic block (`br if`
and `br else`)?

2016-03-24 14:15 GMT-04:00 Quentin Colombet <qcolombet at apple.com>:
> Hi,
>
> > On Mar 24, 2016, at 10:58 AM, Tom Chen via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >
> > Hi,
> > Why does a MachineBasicBlock have multiple terminator instructions
> (unlike BasicBlock, which can only have one) ?
>
> Think of it as predicated instructions.
> E.g.,
> bool = icmp
> if bool : br if
> br else
>
> As for why, we could indeed have split those terminators into several
> basic blocks, but it would have required more MachineBasicBlock objects.
>
> Cheers,
> -Quentin
> > Thanks,
> > Tom
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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