llvm dev - Jan 2017 - Problems with tbaa in llvm 4.0

Hi all,

I do a little work on the GHC haskell compiler. One of the things I
do is compile current GHC git HEAD against the next release of LLVM
to find issues and adapt the GHC code as early as possible.

A recent modification to LLVM is now rejecting GHC generated LLVM
IR that was previously accepted. I discussed this on IRC with
sanjoyd who explained what had changed and gave me some hints about
trying to fix it. Basically the issue (as I understood it) was that
no statements should reference the root tbaa node directly.

With that in mind, I came up with a fix to GHC llvm codegen so the
the tbaa metadata is now:

    !0 = !{!"root", null}
    !1 = !{!"top", !0}
    !2 = !{!"stack", !1}
    !3 = !{!"heap", !1}
    !4 = !{!"rx", !3}
    !5 = !{!"base", !1}

However, with this fix I get basically the same set of error messages
A couple of the errors are:

    Access type node must be a valid scalar type
      %ln59 = load i64, i64* %ln58, !tbaa !6
    !6 = !{!2, !2, i64 0}
    !2 = !{!"top", !3}

    Access type node must be a valid scalar type
      %ln5d = load i64, i64* %ln5c, !tbaa !4
    !4 = !{!5, !5, i64 0}
    !5 = !{!"base", !2}

    Access type node must be a valid scalar type
      %ln5i = load i64, i64* %ln5h, !tbaa !0
    !0 = !{!1, !1, i64 0}
    !1 = !{!"stack", !2}

I would appreciate any clues that might help me solve this.

Cheers,
Erik
-- 
----------------------------------------------------------------------
Erik de Castro Lopo
http://www.mega-nerd.com/

[+Sanjoy]


On 01/13/2017 06:57 PM, Erik de Castro Lopo via llvm-dev
wrote:
> Hi all,
>
> I do a little work on the GHC haskell compiler. One of the things I
> do is compile current GHC git HEAD against the next release of LLVM
> to find issues and adapt the GHC code as early as possible.
>
> A recent modification to LLVM is now rejecting GHC generated LLVM
> IR that was previously accepted. I discussed this on IRC with
> sanjoyd who explained what had changed and gave me some hints about
> trying to fix it. Basically the issue (as I understood it) was that
> no statements should reference the root tbaa node directly.
>
> With that in mind, I came up with a fix to GHC llvm codegen so the
> the tbaa metadata is now:
>
>      !0 = !{!"root", null}
>      !1 = !{!"top", !0}
>      !2 = !{!"stack", !1}
>      !3 = !{!"heap", !1}
>      !4 = !{!"rx", !3}
>      !5 = !{!"base", !1}
>
> However, with this fix I get basically the same set of error messages
> A couple of the errors are:
>
>      Access type node must be a valid scalar type
>        %ln59 = load i64, i64* %ln58, !tbaa !6
>      !6 = !{!2, !2, i64 0}
>      !2 = !{!"top", !3}
>
>      Access type node must be a valid scalar type
>        %ln5d = load i64, i64* %ln5c, !tbaa !4
>      !4 = !{!5, !5, i64 0}
>      !5 = !{!"base", !2}
>
>      Access type node must be a valid scalar type
>        %ln5i = load i64, i64* %ln5h, !tbaa !0
>      !0 = !{!1, !1, i64 0}
>      !1 = !{!"stack", !2}
>
> I would appreciate any clues that might help me solve this.
>
> Cheers,
> Erik
-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory

Hi Erik,

(I've already replied on IRC, but echoing that here for others)

Hal Finkel wrote:
> [+Sanjoy]
>
>
> On 01/13/2017 06:57 PM, Erik de Castro Lopo via llvm-dev wrote:
>> Hi all,
>>
>> I do a little work on the GHC haskell compiler. One of the things I
>> do is compile current GHC git HEAD against the next release of LLVM
>> to find issues and adapt the GHC code as early as possible.
>>
>> A recent modification to LLVM is now rejecting GHC generated LLVM
>> IR that was previously accepted. I discussed this on IRC with
>> sanjoyd who explained what had changed and gave me some hints about
>> trying to fix it. Basically the issue (as I understood it) was that
>> no statements should reference the root tbaa node directly.
>>
>> With that in mind, I came up with a fix to GHC llvm codegen so the
>> the tbaa metadata is now:
>>
>> !0 = !{!"root", null}
You need to change !0 to !{!"root"}.  Root nodes must have a single
operand.

-- Sanjoy
>> !1 = !{!"top", !0}
>> !2 = !{!"stack", !1}
>> !3 = !{!"heap", !1}
>> !4 = !{!"rx", !3}
>> !5 = !{!"base", !1}
>>
>> However, with this fix I get basically the same set of error messages
>> A couple of the errors are:
>>
>> Access type node must be a valid scalar type
>> %ln59 = load i64, i64* %ln58, !tbaa !6
>> !6 = !{!2, !2, i64 0}
>> !2 = !{!"top", !3}
>>
>> Access type node must be a valid scalar type
>> %ln5d = load i64, i64* %ln5c, !tbaa !4
>> !4 = !{!5, !5, i64 0}
>> !5 = !{!"base", !2}
>>
>> Access type node must be a valid scalar type
>> %ln5i = load i64, i64* %ln5h, !tbaa !0
>> !0 = !{!1, !1, i64 0}
>> !1 = !{!"stack", !2}
>>
>> I would appreciate any clues that might help me solve this.
>>
>> Cheers,
>> Erik
>