<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hi,<div class=""><br class=""></div><div class="">LLVM allows to work with arbitrary bit sizes (see <a href="https://llvm.org/docs/LangRef.html#integer-type" class="">https://llvm.org/docs/LangRef.html#integer-type</a>), but please bear in mind that working with unusual sizes might expose bugs, as the corresponding code paths are less tested.</div><div class=""><br class=""></div><div class="">Answering your specific question: yes, it’s definitely possible, however you need to define how to add 3-bit operand to 5-bit operand in terms of operations supported by LLVM. One way is to, for instance, zero-extend both operands to 6-bits and then add:</div><div class=""><div class=""><div class=""><br class=""></div><div class="">define i6 @foo(i5 %a, i3 %b) {</div><div class="">entry:</div><div class=""> %a_zext = zext i5 %a to i6</div><div class=""> %b_zext = zext i3 %b to i6</div><div class=""> %c = add i6 %a_zext, %b_zext</div><div class=""> ret i6 %c</div><div class="">}</div></div></div><div class=""><br class=""></div><div class="">Thanks,</div><div class="">Michael</div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Jul 28, 2017, at 1:32 PM, 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=""><div class=""><div class="">Hello,<br class=""></div>I wanted to ask one general question ( for now it is hard to check it manually, maybe there is a fast answer):<br class=""></div>can I construct an operation, say, addition, from operand_0 - 5 bits size and operand_1 - 3 bit size -> receive result as 6 bit size . I am basically reducing these sizes in the whole IR, so I want that all operands can have arbitrary sizes ( llvm pass is not really good because it converts sizes only to some predefined sizes). However , I am not sure if there will be internal checks on these sizes after I will transform the tree. Or is it better to create some my own attributes, that can describe the sizes? <br class=""></div>
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