On Thu, Jan 10, 2019 at 6:11 PM Yu, Jennifer <jennifer...@intel.com> wrote:
>
> Syntax for asm goto:
> Syntax:
>   asm [volatile] goto ( AssemblerTemplate
>                       :
>                       : InputOperands
>                       : Clobbers
>                       : GotoLabels)
>
> Only input is allowed.  Output is not allowed

To match parity with GCC, yes.  Support for output is requested by
kernel developers, but it can understandably be left out of v1.

> Thanks.
> Jennifer
>
> -----Original Message-----
> From: Eli Friedman via Phabricator [mailto:revi...@reviews.llvm.org]
> Sent: Thursday, January 10, 2019 5:58 PM
> To: craig.top...@gmail.com; Keane, Erich <erich.ke...@intel.com>; 
> ndesaulni...@google.com; chandl...@gmail.com; Yu, Jennifer 
> <jennifer...@intel.com>; syaghm...@apple.com
> Cc: efrie...@codeaurora.org; srhi...@google.com; era...@google.com; 
> cfe-commits@lists.llvm.org
> Subject: [PATCH] D56571: [RFC prototype] Implementation of asm-goto support 
> in LLVM
>
> efriedma added a comment.
>
> Missing changes to lib/Analysis/CFG.cpp.
>
>
>
> ================
> Comment at: lib/Sema/SemaStmtAsm.cpp:470
> +    if (NS->isGCCAsmGoto() &&
> +        Exprs[ConstraintIdx]->getStmtClass() == Stmt::AddrLabelExprClass)
> +      break;
> ----------------
> This looks suspicious; an AddrLabelExpr could be an input or output, e.g. 
> `"r"(&&foo)`.
>
>
> CHANGES SINCE LAST ACTION
>   https://reviews.llvm.org/D56571/new/
>
> https://reviews.llvm.org/D56571
>
>
>


-- 
Thanks,
~Nick Desaulniers
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