llvm dev - Mar 2018 - new @llvm.memcpy and @llvm.memset API in trunk - how to use alignment?

The new @llvm.memcpy API does not have an alignment parameter. Instead the
docs say to use the align <n> attribute. How is this supposed to work with
different alignments?

For example, I have one memcpy with align 4, align 4, and another with
align 1, align 1.

; Function Attrs: argmemonly nounwind
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly align 4,
i8* nocapture readonly align 4, i64, i1) #3

; Function Attrs: argmemonly nounwind
declare void @llvm.memcpy.p0i8.p0i8.i64.1(i8* nocapture writeonly align 1,
i8* nocapture readonly align 1, i64, i1) #3


When I add these multiple definitions to the module, llvm mangles the name,
adding `.1` to the second one, and I get "Intrinsic name not mangled
correctly for type arguments!"

What's the correct way to do this?

Thanks,
Andrew
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On 3/22/2018 3:15 PM, Andrew Kelley via llvm-dev wrote:
> The new @llvm.memcpy API does not have an alignment parameter. Instead 
> the docs say to use the align <n> attribute. How is this supposed to 
> work with different alignments?
>
> For example, I have one memcpy with align 4, align 4, and another with 
> align 1, align 1.
>
> ; Function Attrs: argmemonly nounwind
> declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly align 
> 4, i8* nocapture readonly align 4, i64, i1) #3
>
> ; Function Attrs: argmemonly nounwind
> declare void @llvm.memcpy.p0i8.p0i8.i64.1(i8* nocapture writeonly 
> align 1, i8* nocapture readonly align 1, i64, i1) #3
>
>
> When I add these multiple definitions to the module, llvm mangles the 
> name, adding `.1` to the second one, and I get "Intrinsic name not 
> mangled correctly for type arguments!"
>
> What's the correct way to do this?
You're not supposed to add the alignment to the function declaration; 
just add it to the call itself.  (If you're using IRBuilder, 
CreateMemCpy will take care of this for you.)

-Eli

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
Foundation Collaborative Project

IRBuilder::CreateMemCpy worked great, thanks!

On Thu, Mar 22, 2018 at 6:32 PM, Friedman, Eli <efriedma at
codeaurora.org>
wrote:
> On 3/22/2018 3:15 PM, Andrew Kelley via llvm-dev wrote:
>
>> The new @llvm.memcpy API does not have an alignment parameter. Instead
>> the docs say to use the align <n> attribute. How is this supposed
to work
>> with different alignments?
>>
>> For example, I have one memcpy with align 4, align 4, and another with
>> align 1, align 1.
>>
>> ; Function Attrs: argmemonly nounwind
>> declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly align
4,
>> i8* nocapture readonly align 4, i64, i1) #3
>>
>> ; Function Attrs: argmemonly nounwind
>> declare void @llvm.memcpy.p0i8.p0i8.i64.1(i8* nocapture writeonly align
>> 1, i8* nocapture readonly align 1, i64, i1) #3
>>
>>
>> When I add these multiple definitions to the module, llvm mangles the
>> name, adding `.1` to the second one, and I get "Intrinsic name not
mangled
>> correctly for type arguments!"
>>
>> What's the correct way to do this?
>>
>
> You're not supposed to add the alignment to the function declaration;
just
> add it to the call itself.  (If you're using IRBuilder, CreateMemCpy
will
> take care of this for you.)
>
> -Eli
>
> --
> Employee of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
> Foundation Collaborative Project
>
>
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