[LLVMdev] Is addrspacecast implemented on Windows?

[Kai Nacke]

Thanks! This works for me, too.

Regards,
Kai

On 27.01.2014 21:42, David Majnemer wrote:
> I believe the following does what you would like:
>
> define i64 @getStackBottom(i64 %addr) {
>    %0 = inttoptr i64 %addr to i64 addrspace(256)*
>    %1 = load i64 addrspace(256)* %0, align 1
>    ret i64 %1
> }
>
> My build of llvm generates the following code with -O3:
> getStackBottom:
>          movq    %gs:(%rdi), %rax
>          retq
>
>
>
>
> On Mon, Jan 27, 2014 at 12:04 PM, Kai Nacke <kai.nacke at redstar.de
> <mailto:kai.nacke at redstar.de>> wrote:
>
>     Hi all!
>
>     On x86_64, segment prefix fs: is in address space 257 and gs: in
>     address space 256. (BTW: are there constants for these magic
>     values?) How can I use this in IR? I want to express this assembler
>     code in IR:
>
>                       mov RAX, 8;
>                       mov RAX, GS:[RAX];
>                       ret;
>
>     I tried the following:
>
>     define i64 @getStackBottom(i64 %addr) {
>     entry:
>        %ptr = inttoptr i64 %addr to i64*
>        %fs_ptr = addrspacecast i64* %ptr to i64 addrspace(256)*
>        %bottom = load i64 addrspace(256)* %fs_ptr, align 1
>        ret i64 %bottom
>     }
>
>     but this results in
>
>     LLVM ERROR: Cannot select: 0xcc6c60: i64 = addrspacecast 0xcc6b60[0
>     -> 256] [ORD=3] [ID=6]
>        0xcc6b60: i64,ch = CopyFromReg 0xc95e38, 0xcc6a60 [ORD=1] [ID=5]
>          0xcc6a60: i64 = Register %vreg0 [ID=1]
>     In function: getStackBottom
>     Stack dump:
>     0.      Program arguments: llc thr_ll.ll
>     1.      Running pass 'Function Pass Manager' on module 'thr_ll.ll'.
>     2.      Running pass 'X86 DAG->DAG Instruction Selection' on
>     function '@getStackBottom'
>
>     Do I miss something here? Or is this simply not yet implemented?
>
>     Regards,
>     Kai
>
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