[llvm-dev] what is official way to determine if we are running lto 2nd stage?

[Mehdi Amini via llvm-dev]

> On Sep 12, 2016, at 11:07 AM, Konstantin Vladimirov <konstantin.vladimirov at gmail.com> wrote:
> 
> Hi,
> 
> This is really basic block level pass. It is no difference what is
> level, problem is the same.

Can you clarify what you mean? If you have a MachineFunction pass, it’ll run in the backend only.
I don’t understand why you would need to distinguish between LTO or no-LTO here.

> 
> After fixing for asm parser, assembler syntax is no more valid for
> backend, without processing with asm parser.

My understanding of Inline ASM is that it is supposed to be opaque to the backend till you reach MC.
So I don’t understand this sentence "no more valid for backend, without processing with asm parser”.

Sorry if my answers don’t make sense to you, I may still be missing a key part of your problem.

— 
Mehdi


> May be it will be solution to process inline asm on insn printer level
> to remove syntax fixes. But just switch it off without lto will make
> compiler do less job
> 
> P.S. sorry for dup, maillist CC lost on first sent.
> 
> ---
> WIth best regards, Konstantin
> 
> 
> On Mon, Sep 12, 2016 at 8:52 PM, Mehdi Amini <mehdi.amini at apple.com> wrote:
>> 
>>> On Sep 12, 2016, at 9:26 AM, Konstantin Vladimirov <konstantin.vladimirov at gmail.com> wrote:
>>> 
>>> Hi,
>>> 
>>> In LTO we have AsmParser that process inline assembler instructions to
>>> MCInst and I want to fix some inline assembler in order to conform its
>>> rules (do not start with non-identifier and so on) because asm syntax
>>> of our backend allows some incompatible patterns. In order to do this
>>> I am adding IR-level target-specific pass. But those fixes shall not
>>> be applied when there is no AsmParser later to process them. So I want
>>> to switch this pass off if we are not in 2nd lto stage.
>> 
>> This is not clear to me: how should this be different for LTO than for a non-LTO compile?
>> 
>> Also, if you’re only fixing the inline ASM, why doing it as an IR-level pass instead of MachineFunctionPass?
>> 
>> —
>> Mehdi
>> 
>> 
>>> 
>>> I think, I can make target-specific option and make user to supply it
>>> whenever he wants to run 2nd lto stage, but this is ugly.
>>> 
>>> Can I somehow ask, say, about whole string of options and then parse
>>> it to match "lto" from here?
>>> 
>>> ---
>>> With best regards, Konstantin
>>> 
>>> On Mon, Sep 12, 2016 at 6:17 PM, Mehdi Amini <mehdi.amini at apple.com> wrote:
>>>> Hi,
>>>> 
>>>> 
>>>>> On Sep 12, 2016, at 1:26 AM, Konstantin Vladimirov via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>>>>> 
>>>>> Hi,
>>>>> 
>>>>> I want to enable some target-specific functionality only if current
>>>>> build is 2nd LTO stage (i.e. optimizer called from plugin). What is
>>>>> best and recommended way to do it?
>>>> 
>>>> There is none. We can setup a different optimizer pass pipeline for LTO, but the target specific part (i.e. the backend) isn’t supposed to behave differently.
>>>> 
>>>> This is an issue in general with LTO where options from the command line (like -fno-builtins, or -fveclib=xxxx) are not correctly propagated to LTO.
>>>> 
>>>> What kind of behavior do you want to enable exactly?
>>>> 
>>>> —
>>>> Mehdi
>>>> 
>>