llvm dev - Dec 2012 - [LLVMdev] Cannot interchange "literal" and "identified" structs

With primitive types, I can interchange literal usage and type aliases in
IR:

%mytype = type i32

define void @foo(%mytype* %ptr) {
  %t1 = load *%mytype** %ptr
  store i32 *%t1*, *i32** %ptr
  ret void
}

But for structs, I cannot:

%mytype = type { i32, i32 }

define void @foo(%mytype* %ptr) {
  %t1 = load *%mytype** %ptr
  store* { i32, i32 }* %t1, *{ i32, i32 }** %ptr
  ret void
}

bin/llvm-as: alias2.ll:6:22: error: '%t1' defined with type '%mytype
= type
{ i32, i32 }'
  store { i32, i32 } %t1, { i32, i32 }* %ptr

I don't see anything in the language reference manual that disallows such
usage, as the literal struct type and %mytype are equivalent.  Am I missing
something here, or is this just a bug in the assembly parser?

-- 

Thanks,

Justin Holewinski
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Justin,

http://llvm.org/docs/LangRef.html#structure-type
"Identified types can be recursive, can be opaqued, and are never
uniqued."
Do you think it would be less descriptive?

"Identified type, aka named llvm::StructType, is never uniqued against
other identified types nor literal types, aka unnamed StructType(s)."
?

See also; http://blog.llvm.org/2011/11/llvm-30-type-system-rewrite.html

...Takumi

2012/12/30 Justin Holewinski <justin.holewinski at
gmail.com>:
> With primitive types, I can interchange literal usage and type aliases in
> IR:
>
> %mytype = type i32
>
> define void @foo(%mytype* %ptr) {
>   %t1 = load %mytype* %ptr
>   store i32 %t1, i32* %ptr
>   ret void
> }
>
> But for structs, I cannot:
>
> %mytype = type { i32, i32 }
>
> define void @foo(%mytype* %ptr) {
>   %t1 = load %mytype* %ptr
>   store { i32, i32 } %t1, { i32, i32 }* %ptr
>   ret void
> }
>
> bin/llvm-as: alias2.ll:6:22: error: '%t1' defined with type
'%mytype = type
> { i32, i32 }'
>   store { i32, i32 } %t1, { i32, i32 }* %ptr
>
> I don't see anything in the language reference manual that disallows
such
> usage, as the literal struct type and %mytype are equivalent.  Am I missing
> something here, or is this just a bug in the assembly parser?
>
> --
>
> Thanks,
>
> Justin Holewinski
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

Alright, I misunderstood that statement then.  This does seem to be
inconsistent with llvm-link, though.  If I have two identified structs in
the same module, I cannot interchange them.  But if they are in different
modules, llvm-link will merge them:

$ cat struct1.ll
%mystruct = type { i32, i32 }

define i32 @foo(i32 %a) {
  %val = tail call %mystruct @llvm.my.intrinsic(i32 %a)
  %ret = extractvalue %mystruct %val, 0
  ret i32 %ret
}

declare %mystruct @llvm.my.intrinsic(i32)

$ cat struct2.ll
%mytype = type { i32, i32 }

define i32 @bar(i32 %a) {
  %val = tail call %mytype @llvm.my.intrinsic(i32 %a)
  %ret = extractvalue %mytype %val, 1
  ret i32 %ret
}

declare %mytype @llvm.my.intrinsic(i32)

$ bin/llvm-link struct1.ll struct2.ll -S
; ModuleID = 'struct1.ll'

%mystruct = type { i32, i32 }

define i32 @foo(i32 %a) {
  %val = tail call %mystruct @llvm.my.intrinsic(i32 %a)
  %ret = extractvalue %mystruct %val, 0
  ret i32 %ret
}

declare %mystruct @llvm.my.intrinsic(i32)

define i32 @bar(i32 %a) {
  %val = tail call %mystruct @llvm.my.intrinsic(i32 %a)
  %ret = extractvalue %mystruct %val, 1
  ret i32 %ret
}

Shouldn't llvm-link throw an error saying %mystruct and %mytype are
different structs and @llvm.my.intrinsic cannot be double-defined with both
return types?

On Sun, Dec 30, 2012 at 6:19 PM, NAKAMURA Takumi <geek4civic at
gmail.com>wrote:
> Justin,
>
> http://llvm.org/docs/LangRef.html#structure-type
> "Identified types can be recursive, can be opaqued, and are never
uniqued."
> Do you think it would be less descriptive?
>
> "Identified type, aka named llvm::StructType, is never uniqued against
> other identified types nor literal types, aka unnamed StructType(s)."
> ?
>
> See also; http://blog.llvm.org/2011/11/llvm-30-type-system-rewrite.html
>
> ...Takumi
>
> 2012/12/30 Justin Holewinski <justin.holewinski at gmail.com>:
> > With primitive types, I can interchange literal usage and type aliases
in
> > IR:
> >
> > %mytype = type i32
> >
> > define void @foo(%mytype* %ptr) {
> >   %t1 = load %mytype* %ptr
> >   store i32 %t1, i32* %ptr
> >   ret void
> > }
> >
> > But for structs, I cannot:
> >
> > %mytype = type { i32, i32 }
> >
> > define void @foo(%mytype* %ptr) {
> >   %t1 = load %mytype* %ptr
> >   store { i32, i32 } %t1, { i32, i32 }* %ptr
> >   ret void
> > }
> >
> > bin/llvm-as: alias2.ll:6:22: error: '%t1' defined with type
'%mytype > type
> > { i32, i32 }'
> >   store { i32, i32 } %t1, { i32, i32 }* %ptr
> >
> > I don't see anything in the language reference manual that
disallows such
> > usage, as the literal struct type and %mytype are equivalent.  Am I
> missing
> > something here, or is this just a bug in the assembly parser?
> >
> > --
> >
> > Thanks,
> >
> > Justin Holewinski
> >
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >
>


-- 

Thanks,

Justin Holewinski
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