[PATCH] D65478: Create unique, but identically-named ELF sections for explicitly-sectioned functions and globals when using -function-sections and -data-sections.

Peter Collingbourne via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Aug 7 15:24:15 PDT 2019


pcc added a comment.

In D65478#1619990 <https://reviews.llvm.org/D65478#1619990>, @rahmanl wrote:

> In D65478#1619713 <https://reviews.llvm.org/D65478#1619713>, @inglorion wrote:
>
> > Unfortunately, this causes some problems. It looks like the sections are created with different attributes than the original. This causes problems such as sections being writable when the original was read-only, including https://crbug.com/990942 where that causes program crashes. There is some more discussion on that bug report.
> >
> > I'll revert this to unbreak the Chromium build, and we can come up with a way forward from there.
>
>
> Hi Bob, 
>  We plan to gate this feature behind a condition: D65837 <https://reviews.llvm.org/D65837> 
>  I think in the Chromium case, what it needs is the -funique-section-names. More precisely, Chromium needs this flag only for the explicitly defined section "protected_memory", but I don't think it hurts to do it globally ( Chromium build may actually be using this flag anyways. Please confirm.)
>  If you think that the chromium build could use this flag, I will change D65837 <https://reviews.llvm.org/D65837> to do the check.


Chromium is depending on an implementation detail here and the revert is temporary until we can land a compiler feature that will let us avoid the implementation detail dependence. It doesn't seem necessary to change the condition that you've already implemented in D65837 <https://reviews.llvm.org/D65837>.


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https://reviews.llvm.org/D65478





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