[llvm-dev] (Thin)LTO llvm build

Carsten Mattner via llvm-dev llvm-dev at lists.llvm.org
Fri Sep 16 14:19:08 PDT 2016

On Fri, Sep 16, 2016 at 10:57 PM, Teresa Johnson <tejohnson at google.com> wrote:
> On Fri, Sep 16, 2016 at 1:48 PM, Carsten Mattner <carstenmattner at gmail.com> wrote:
>> On Fri, Sep 16, 2016 at 10:18 PM, Teresa Johnson <tejohnson at google.com> wrote:
>> >
>> > Cc'ing llvm-dev again in case someone knows what is going on.
>> >
>> > That error is coming from a polly configure script, which I don't
>> > have cloned into my own tree. Not sure why polly would behave
>> > differently when configuring for ThinLTO. Does polly configure ok
>> > when configuring the same way, but for regular LTO?
>> Yes it does, and I don't remember when I've added it, meaning it's
>> been working when bootstrapping llvm with the host gcc toolchain, for
>> a long time.
> You mentioned in your original email:
> > I first tried to rebuild llvm with llvm-3.9, which has ThinLTO, by
> > providing -DLLVM_ENABLE_LTO=Thin, but that failed very quickly, so I
> > fell back to building with -DLLVM_ENABLE_LTO=On and using the system
> > CC/CXX (gcc 6.1).
> I assume this error when you try to bootstrap using llvm-3.9 and ThinLTO then?
> What about bootstrapping with llvm-3.9 and -DLLVM_ENABLE_LTO=On?
> If the latter works, I'll have to clone polly and see if I can reproduce it and
> see what is different between a -DLLVM_ENABLE_LTO=Thin and
> -DLLVM_ENABLE_LTO=On build then.

Same error, and as mentioned in reply to Mehdi, I'll have to verify it there
isn't an underlying issue of my local llvm install.

However, I would certainly welcome a success report and binary size info.

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