<div><div dir="auto">Hi John,</div><div dir="auto">What targer are you trying to compile this for? I imagine this is just a case of using an X86 intrinsic on a non-X86 back end. Or is this an intrinsic you added and didn't provide a selection pattern for?</div><div dir="auto"><br></div><div dir="auto">In any case, this intrinsic makes it into the selection DAG and the instruction selector tries to select a sequence of instructions for it. However, it fails to find a pattern that it can match in your back end, so you get this error.</div><div dir="auto"><br></div><div dir="auto">As far as learning LLVM, The documentation at <a href="http://llvm.org">llvm.org</a> is the best place to start. However, it is a huge project so you probably want to be a bit more specific in terms of what it is you want to learn. Based on your question, I imagine you want to learn how code generation works, so you might want to check out <a href="http://llvm.org/docs/CodeGenerator.html">http://llvm.org/docs/CodeGenerator.html</a></div><div dir="auto"><br></div><div dir="auto">Hope this helps.</div><br><div class="gmail_quote"><div>On Sun, Jan 7, 2018 at 4:21 PM John Ky via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="m_5729780129323471537markdown-here-wrapper"><p style="margin:0px 0px 1.2em!important">Hello,</p>
<p style="margin:0px 0px 1.2em!important">I’m not sure if this is the right place to ask beginner questions.</p>
<p style="margin:0px 0px 1.2em!important">If not, please direct me to the appropriate place.</p>
<p style="margin:0px 0px 1.2em!important">I’m writing my first <code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-radius:3px;display:inline">llvm</code> program and I’m trying to call an intrinsic, but failing.</p>
<p style="margin:0px 0px 1.2em!important">So far this is what I have:</p>
<pre style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;font-size:1em;line-height:1.2em;margin:1.2em 0px"><code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-radius:3px;display:inline;white-space:pre-wrap;overflow:auto;border-radius:3px;border:1px solid rgb(204,204,204);padding:0.5em 0.7em;display:block!important">declare ccc i32 @llvm.x86.bmi.pdep.32(i32, i32)
@.str2 = private unnamed_addr constant [4 x i8] c"%d\0A\00", align 1
declare i32 @printf(i8*, ...) nounwind
; Definition of main function
define i32 @main() {
%res = call ccc i32 (i32, i32) @llvm.x86.bmi.pdep.32( i32 1, i32 1 )
%a = alloca i32, align 8
%1 = load i32, i32* %a, align 8
%ss = getelementptr inbounds [4 x i8], [4 x i8]* @.str2, i32 0, i32 0
call i32 (i8*, ...) @printf( i8* %ss, i32 %res)
ret i32 0
}
</code></pre><p style="margin:0px 0px 1.2em!important">When I run this code, I get the following error:</p>
<pre style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;font-size:1em;line-height:1.2em;margin:1.2em 0px"><code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-radius:3px;display:inline;white-space:pre-wrap;overflow:auto;border-radius:3px;border:1px solid rgb(204,204,204);padding:0.5em 0.7em;display:block!important">$ lli helloWorld.ll
LLVM ERROR: Cannot select: intrinsic %llvm.x86.bmi.pdep.32
</code></pre><p style="margin:0px 0px 1.2em!important">Where am I going wrong?</p>
<p style="margin:0px 0px 1.2em!important">Also, what’s the best resource for learning <code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-radius:3px;display:inline">llvm</code>?</p>
<p style="margin:0px 0px 1.2em!important">Cheers,</p>
<p style="margin:0px 0px 1.2em!important">-John</p>
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</blockquote></div></div>