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

[Andrew Kelley via llvm-dev]

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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