<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">This thread from June: <a href="http://lists.llvm.org/pipermail/llvm-dev/2017-June/114108.html" class="">http://lists.llvm.org/pipermail/llvm-dev/2017-June/114108.html</a></div><div class=""><br class=""></div><div class="">this is about a pass that can split GEPs into multiple equivalent GEPs, without changing the overall meaning. Presumably the reverse operation of merging GEPs might also be a reasonable LLVM canonicalisation pass, though I don't think it is implemented at the moment. </div><div class=""><br class=""></div><div class="">If anyone knows why merging two GEPs is not equivalent to performing them one after the other, I'd love to know. I suppose the `inbounds` keyword may wreak havoc with the semantics. </div><div class=""><br class=""></div><div class="">Sam</div><br class=""><div><blockquote type="cite" class=""><div class="">On 2 Sep 2017, at 3:53 am, Anastasiya Ruzhanskaya via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">Is there a way to set always a defined behavior here - for example that we will always one getelemntptr with complex index?<br class=""></div><div class="gmail_extra"><br class=""><div class="gmail_quote">2017-09-02 12:53 GMT+02:00 Anastasiya Ruzhanskaya <span dir="ltr" class=""><<a href="mailto:anastasiya.ruzhanskaya@frtk.ru" target="_blank" class="">anastasiya.ruzhanskaya@frtk.ru</a>></span>:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="">Ok, thank you. I have also one question about getelementptr. In different versions of clang I see that sometimes array[i][i] is preceded by two getelementptr instructions and sometimes only by one - with an already complex index.<br class=""></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br class=""><div class="gmail_quote">2017-09-01 12:50 GMT+02:00 David Chisnall <span dir="ltr" class=""><<a href="mailto:David.Chisnall@cl.cam.ac.uk" target="_blank" class="">David.Chisnall@cl.cam.ac.uk</a>></span>:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="m_4485775279863739484HOEnZb"><div class="m_4485775279863739484h5">On 1 Sep 2017, at 11:44, Anastasiya Ruzhanskaya via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank" class="">llvm-dev@lists.llvm.org</a>> wrote:<br class="">
><br class="">
> Hello,<br class="">
> I wonder if the getelementptr can have other successors than load, store in some other cases when I directly print or directly return the result. every time I would like to assign the result - it will have a load/store successor?<br class="">
> So, basically the overall question is to clarify the possible successors of getelementptr.<br class="">
<br class="">
</div></div>Any instruction that may take a pointer operand might be a user of a GEP. For example, consider this C function:<br class="">
<br class="">
int x(struct S *s)<br class="">
{<br class="">
y(&s->field);<br class="">
}<br class="">
<br class="">
Here, there will be a GEP to get the address of the field and then the user will be a call (or possibly invoke) instruction.<br class="">
<span class="m_4485775279863739484HOEnZb"><font color="#888888" class=""><br class="">
David<br class="">
<br class="">
</font></span></blockquote></div><br class=""></div>
</div></div></blockquote></div><br class=""></div>
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