[PATCH] D68115: Zero initialize padding in unions

Wed Jan 8 16:14:59 PST 2020

lebedev.ri added a subscriber: aaron.ballman.
lebedev.ri added a comment.

In D68115#1811089 <https://reviews.llvm.org/D68115#1811089>, @hubert.reinterpretcast wrote:

> In D68115#1810891 <https://reviews.llvm.org/D68115#1810891>, @lebedev.ri wrote:
>
> > Does this have to be an unilateral change,
> >  likely penalizing non-`-ftrivial-auto-var-init=` cases,
> >  i.e. [why] can't it be **only** done for when `-ftrivial-auto-var-init=` is enabled?
>
>
> We left off near that conclusion (https://reviews.llvm.org/D68115#1686887);

Would be great if @rsmith / @aaron.ballman could comment on that

> however, `-ftrivial-auto-var-init=` merely increases the chance that code expecting the zeroing to occur would break. A separate option to control zeroing for union padding would help in cases where the zeroing does not happen for reasons other than `-ftrivial-auto-var-init`.

Repository:
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https://reviews.llvm.org/D68115