llvm dev - Sep 2014 - [LLVMdev] '___ltsf2' could not be resolved - iOS/ARM cross compile

Hi there,

I’m building llvm for my iOS devices, and all seems to work well, until I try to
execute the results:

LLVM ERROR: Program used external function '___ltsf2' which could not be
resolved!

This appears to be part of compiler-rt which as far as I can see should be built
/ linked automatically when installed correctly? Am I missing something obvious?

Thanks,

.m

On 5 September 2014 12:32, mondi <mondi at dyskinetic.com>
wrote:
> I’m building llvm for my iOS devices, and all seems to work well, until I
try to execute the results:
>
> LLVM ERROR: Program used external function '___ltsf2' which could
not be resolved!
That's the software floating-point less-than operator. It shouldn't be
used if you're compiling for iOS since there are real instructions to
do the job.

If this is for a custom front-end, you're going to have to set the
triple and CPU features manually. You might get away with just setting
the triple to something like "thumbv7s-apple-ios7.0", at least for
initial experiments. But longer term, there are quite a few subtleties
you're likely to have to contend with.

Cheers.

Tim.

It is indeed for a custom frontend, and given that I’m compiling with the very
generic “arm-apple-darwin” at the moment, that makes a lot of sense. I’ll try
some more specific targets and see what difference it makes

Thanks.

.m
> On 05 Sep 2014, at 14:11, Tim Northover <t.p.northover at gmail.com>
wrote:
> 
> On 5 September 2014 12:32, mondi <mondi at dyskinetic.com> wrote:
>> I’m building llvm for my iOS devices, and all seems to work well, until
I try to execute the results:
>> 
>> LLVM ERROR: Program used external function '___ltsf2' which
could not be resolved!
> 
> That's the software floating-point less-than operator. It shouldn't
be
> used if you're compiling for iOS since there are real instructions to
> do the job.
> 
> If this is for a custom front-end, you're going to have to set the
> triple and CPU features manually. You might get away with just setting
> the triple to something like "thumbv7s-apple-ios7.0", at least
for
> initial experiments. But longer term, there are quite a few subtleties
> you're likely to have to contend with.
> 
> Cheers.
> 
> Tim.