<div dir="ltr">This is a bit mystifying. Can you also show the assembly? What offsets are actually used for the stores in the "bad" versions? In other words, try verifying that the offsets that the getelementptr's should generate match your expectations (and if they deviate, in what ways they deviate).<div><br></div><div>-- Sean Silva</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Jun 4, 2017 at 1:39 PM, Nikodemus Siivola via llvm-dev <span dir="ltr"><<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Emitting calls to these functions (written in an .ll file linked in) works fine, and does the right thing.<br></div><div><div><div><font face="monospace, monospace"><br></font></div><div><font face="monospace, monospace">%Any = type { i8*, i32 }</font></div></div><div><font face="monospace, monospace"><br></font></div><div><div><font face="monospace, monospace">define dllexport void @setGlobal(%Any* %ptr, %Any %value) {</font></div><div><font face="monospace, monospace"> store %Any %value, %Any* %ptr</font></div><div><font face="monospace, monospace"> ret void</font></div><div><font face="monospace, monospace">}</font></div><div><font face="monospace, monospace"><br></font></div><div><font face="monospace, monospace">define dllexport %Any @getGlobal(%Any* %ptr) {</font></div><div><font face="monospace, monospace"> %val = load %Any, %Any* %ptr</font></div><div><font face="monospace, monospace"> ret %Any %val</font></div><div><font face="monospace, monospace">}</font></div></div><div><br>Trying to replace the setGlobal call with what should be equivalent</div><div><br></div><div><font face="monospace, monospace">builder.CreateStore(value, ptr)</font></div><div><br></div><div>results in what should end up in the second (i32) slot being stored in the first (i8*).</div><div><br></div><div>I've added ::dump() calls where the CreateStore is, and this is what I get:</div><div><br><font face="monospace, monospace">{ i8*, i32 } { i8* @FixnumClass, i32 32 } ; for value<br>@foo = external global { i8*, i32 } ; for ptr</font><br></div><div><br></div><div>Even more bizarrely trying to replace the getGlobal call with</div><div><br></div><div><font face="monospace, monospace">builder.CreateLoad(val)</font></div><div><br></div><div>results in what has been stored in the first (i8*) slot being loaded correctly, but the second (i32) getting garbage out despite the correct value being stored in memory. Dump call there reports the @foo pointer identically.<br><br><div><font face="arial, helvetica, sans-serif">This is using LLVM 4.0.0</font></div></div><div><font face="arial, helvetica, sans-serif"><br></font></div><div><span style="font-family:arial,helvetica,sans-serif">Just so I'm not leaving anything out, what follows are IR dumps of the sample functions using either the direct store / load, or the setGlobal getGlobal</span></div><div><span style="font-family:arial,helvetica,sans-serif">functions. As far as I can tell they should do exactly the same thing...<br><br></span></div><div><div><font face="monospace, monospace">; Does NOT do the right thing</font></div><div><div><font face="monospace, monospace">define { i8*, i32 } @"__anonToplevel/2"() {</font></div><div><font face="monospace, monospace">entry:</font></div><div><font face="monospace, monospace"> %.unpack = load i8*, i8** getelementptr inbounds ({ i8*, i32 }, { i8*, i32 }* @foo, i32 0, i32 0), align 4</font></div><div><font face="monospace, monospace"> %0 = insertvalue { i8*, i32 } undef, i8* %.unpack, 0</font></div><div><font face="monospace, monospace"> %.unpack1 = load i32, i32* getelementptr inbounds ({ i8*, i32 }, { i8*, i32 }* @foo, i32 0, i32 1), align 4</font></div><div><font face="monospace, monospace"> %1 = insertvalue { i8*, i32 } %0, i32 %.unpack1, 1</font></div><div><font face="monospace, monospace"> ret { i8*, i32 } %1</font></div><div><font face="monospace, monospace">}</font></div></div><div><font face="monospace, monospace"><br></font></div><div><font face="monospace, monospace">; Does NOT do the right thing</font></div><div><div><font face="monospace, monospace">define { i8*, i32 } @"__anonToplevel/0"() {</font></div><div><font face="monospace, monospace">entry:</font></div><div><span style="font-family:monospace,monospace"> store i8* @FixnumClass, i8** getelementptr inbounds ({ i8*, i32 }, { i8*, i32 }* @foo, i32 0, i32 0), align 4</span><br></div><div><font face="monospace, monospace"> store i32 123, i32* getelementptr inbounds ({ i8*, i32 }, { i8*, i32 }* @foo, i32 0, i32 1), align 4</font></div><div><span style="font-family:monospace,monospace"> ret { i8*, i32 } { i8* @FixnumClass, i32 123 }</span><br></div><div><font face="monospace, monospace">}</font></div><div><font face="monospace, monospace"><br></font></div></div><div><font face="monospace, monospace">; DOES the right thing</font></div><div><font face="monospace, monospace"><div>define { i8*, i32 } @"__anonToplevel/0"() {</div><div>entry:</div><div> call void @setGlobal({ i8*, i32 }* nonnull @foo, { i8*, i32 } { i8* @FixnumClass, i32 123 })<br></div><div> ret { i8*, i32 } { i8* @FixnumClass, i32 123 }<br></div><div>}</div><div><br></div><div>; DOES the right thing</div><div><div><div>define { i8*, i32 } @"__anonToplevel/1"() {</div><div>entry:</div><div> %0 = call { i8*, i32 } @getGlobal({ i8*, i32 }* nonnull @foo)</div><div> ret { i8*, i32 } %0</div><div>}</div></div></div><div><br></div><div><div style="font-family:arial,sans-serif"><span style="font-family:arial,helvetica,sans-serif">I'm at my wit's end. Any hints as to what I might be messing up would be much appreciated. I expect it is something ridiculously obvious...</span><br style="font-family:arial,helvetica,sans-serif"></div></div><div><br></div></font></div><font face="arial, helvetica, sans-serif">Cheers,</font></div><div><font face="arial, helvetica, sans-serif"><br></font></div><div><font face="arial, helvetica, sans-serif"> -- nikodemus</font></div><div><font face="arial, helvetica, sans-serif"><br></font></div><div><br></div></div></div>
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