[PATCH] D114895: [SelectionDagBuilder] improve CallBrInst BlockAddress constraint handling

[Bill Wendling via Phabricator via llvm-commits]

void added a comment.

In D114895#3178108 <https://reviews.llvm.org/D114895#3178108>, @nickdesaulniers wrote:

> In D114895#3177794 <https://reviews.llvm.org/D114895#3177794>, @efriedma wrote:
>
>> In D114895#3170282 <https://reviews.llvm.org/D114895#3170282>, @nickdesaulniers wrote:
>>
>>> Unless you can tie a block address. Hopefully `"+r"(&&goto_label)` isn't a valid output constraint...
>>>
>>>   void x(void) {
>>>       asm goto ("":"+r"(&&foo):::foo);
>>>       //                ^ error: lvalue required in 'asm' statement
>>>       foo:;
>>>   }
>>
>> I think you meant to write something like this:
>>
>>   void *x(void) {
>>       void *p = &&foo;
>>       asm goto ("":"+r"(p):::foo);
>>       foo:;
>>       return p;
>>   }
>
> Damn! Then yeah, this approach (Diff 392533) is still broken.

I must be missing something. Isn't that just simply reassigning the variable `p` and not using the label `foo` for output?


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