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| From | Kaz Kylheku <kaz@kylheku.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Bit-field union bug |
| Date | 2012-01-25 00:36 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <20120124163119.715@kylheku.com> (permalink) |
| References | <j3m8np$8gv$1@speranza.aioe.org> <610e0e48-76c6-476b-8303-2c0055781cdc@s35g2000prm.googlegroups.com> <gvab67hq7evufs0upu3aliat65c14bofqu@4ax.com> <kfnhazkhn3h.fsf@x-alumni2.alumni.caltech.edu> <jfnhg7$ahl$1@dont-email.me> |
On 2012-01-25, ec429 <ec429@cam.ac.uk> wrote: > On 24/01/12 20:17, Tim Rentsch wrote: >> Identical layout is not enough to make things work in >> the presence of type-sensitive optimization. In the >> past one could generally get away with such things, >> but that's becoming less true as time goes on. > Why is this? If the two struct (say) types have been defined > identically, what optimisation can the compiler possibly make that'll be > valid for one but not the other? It can assume that foo->x = 42 has no effect on the value of bar->x, continuing to use a stale cached value, because foo and bar are pointers to different declared structure types.
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Re: Bit-field union bug Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-24 12:17 -0800
Re: Bit-field union bug ec429 <ec429@cam.ac.uk> - 2012-01-25 00:13 +0000
Re: Bit-field union bug Kaz Kylheku <kaz@kylheku.com> - 2012-01-25 00:36 +0000
Re: Bit-field union bug Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 14:54 -0800
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