[PATCH] D20144: Fix constant folding of addrspacecast

[Matt Arsenault via llvm-commits]

arsenm added a comment.

In http://reviews.llvm.org/D20144#436115, @majnemer wrote:

> Er, I'm still very confused here.  Let's take your example `@constant_fold_inttoptr`.
>
> trunk turns this into:
>
>   define void @constant_fold_inttoptr() {
>     store i32 7, i32 addrspace(4)* addrspacecast (i32 addrspace(3)* inttoptr (i32 -1 to i32 addrspace(3)*) to i32 addrspace(4)*)
>     ret void
>   }
>
>
> I'm not seeing an argument as to why this is not desirable.  The target should still have all the information it needs, the only difference I see is that contains an additional `ConstantExpr` instead of an additional `Instruction`.


The constant value for a pointer in one address space may not match the value in another address space, so constant folding it to the same constant is incorrect


http://reviews.llvm.org/D20144