<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">I have not chimed in on the general signed/unsigned discussion, but my experience porting software to various embedded systems and game consoles over the years has taught me to always prefer using explicitly sized integer types except where size_t should be used.<div class=""><br class=""></div><div class="">While it is generally true that most modern 64-bit architectures all agree on the meanings of `short`, `long`, `unsigned`, `int`, and others. There is no guarantee of that. I would strongly support a coding standard that suggested preferring explicitly sized integer types (i.e. int64_t) over `int`.</div><div class=""><br class=""></div><div class="">-Chris <br class=""><div class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Jun 14, 2019, at 6:40 AM, 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=""><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none;" class="">-----Original Message-----<br class="">From: llvm-dev [<a href="mailto:llvm-dev-bounces@lists.llvm.org" class="">mailto:llvm-dev-bounces@lists.llvm.org</a>] On Behalf Of JF<br class="">Bastien via llvm-dev<br class="">Sent: Thursday, June 13, 2019 12:25 PM<br class="">To: John Reagan<br class="">Cc:<span class="Apple-converted-space"> </span><a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a><br class="">Subject: Re: [llvm-dev] [RFC] Coding Standards: "prefer `int` for, regular<br class="">arithmetic, use `unsigned` only for bitmask and when you, intend to rely<br class="">on wrapping behavior."<br class=""><br class=""><br class=""><br class=""><blockquote type="cite" class="">On Jun 13, 2019, at 9:19 AM, John Reagan <<a href="mailto:john.reagan@vmssoftware.com" class="">john.reagan@vmssoftware.com</a>><br class=""></blockquote>wrote:<br class=""><blockquote type="cite" class=""><br class="">Yes. We currently build LLVM 3.4.2 on our OpenVMS Itanium box with an<br class="">older EDG/Intel C++03 compiler to create legacy cross-compilers to our<br class="">OpenVMS x86 box (well, VirtualBox). We do have a few tweaks to the<br class="">relocations to access static data always through the GOT (including<br class="">CodeGen's static data). Our linker sees references to code (which might<br class="">be in 64-bit space) and creates trampolines in 32-bit space. That lets<br class="">any legacy code from the VAX-days to continue to take the address of a<br class="">routine and save it into some INTEGER*4 Fortran variable.<br class=""><br class="">So mostly a small memory model with a few things from medium/large.<br class=""><br class="">I've been unable to build the companion clang 3.4.2 however as its use<br class="">of templates seems to push our old compiler over the edge of sanity.<br class=""><br class="">We're working on bootstrapping 8.0.0. Compile 8.0.0 on Linux, move<br class="">objects to our OpenVMS Itanium box to use the cross-linker (which can<br class="">handle Linux objects as well as our own), move the resulting image to<br class="">our OpenVMS x86 box... (and the same thing for libcxx, compiler-rt,<br class="">libcxxabi, etc.) and with a wave of a magic wand, we end up with a<br class="">native clang. And with a little more waving, our other legacy compilers<br class="">(our C, BLISS, Pascal, COBOL, BASIC, and Fortran)<br class=""><br class="">I'm planning on submitting a lightning talk for this fall on "When 3<br class="">memory models isn't enough.”<br class=""></blockquote><br class="">This is a rare occurrence… but you leave me speechless. I don’t even know<br class="">where to start.<br class=""></blockquote><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">The word-size migration is rare but not unique. The HP/Tandem NonStop</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">line has moved from 16-bit to 32-bit to 64-bit over the decades, and we</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">needed to handle mixed-size pointers and "int" weirdness at each stage. </span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">OpenVMS is a special snowflake in terms of its LLVM bootstrapping process,<span class="Apple-converted-space"> </span></span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">and the mind just boggles at what John and his team have had to contend<span class="Apple-converted-space"> </span></span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">with. But the size part is certainly familiar to me, and actually simpler</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">than what NonStop had to deal with. (We weren't using LLVM, clearly, but</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">container size etc. is not a particularly LLVM-specific issue.)</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">--paulr</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><br class=""><br class=""><blockquote type="cite" class="">On 6/13/19 12:00 PM, JF Bastien wrote:<br class=""><blockquote type="cite" class=""><br class=""><br class=""><blockquote type="cite" class="">On Jun 12, 2019, at 2:01 PM, John Reagan via llvm-dev <llvm-<br class=""></blockquote></blockquote></blockquote><a href="mailto:dev@lists.llvm.org" class="">dev@lists.llvm.org</a>> wrote:<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><br class="">On Tue, Jun 11, 2019 at 12:26 PM Michael Kruse <<a href="mailto:llvmdev@meinersbur.de" class="">llvmdev@meinersbur.de</a>><br class="">wrote:<br class=""><br class="">vector.size() returns a size_t, which on 64-bit platforms can<br class=""></blockquote></blockquote></blockquote>represent<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">types values larger than those that can fit into an int64_t. So to<br class=""></blockquote></blockquote></blockquote>turn<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">your argument around, since it's theoretically possible to have a<br class=""></blockquote></blockquote></blockquote>vector<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">with more items than an int64_t can represent, isn't it already worth<br class=""></blockquote></blockquote></blockquote>it<br class=""><blockquote type="cite" class=""><blockquote type="cite" class=""><blockquote type="cite" class="">to use size_t, which is an unsigned type?<br class=""><br class=""><br class="">That's not true on my platform. I have 64-bit pointers so intptr_t is<br class="">64-bits, but the largest thing you can allocate is only 32-bits big so<br class="">size_t (and ptrdiff_t) are 32-bits.<br class=""></blockquote><br class="">It runs LLVM?<br class=""><br class=""></blockquote><br class=""></blockquote><br class="">_______________________________________________<br class="">LLVM Developers mailing list<br class=""><a href="mailto:llvm-dev@lists.llvm.org" class="">llvm-dev@lists.llvm.org</a><br class="">https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev<br class=""></blockquote><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">_______________________________________________</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">LLVM Developers mailing list</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><a href="mailto:llvm-dev@lists.llvm.org" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">llvm-dev@lists.llvm.org</a><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a></div></blockquote></div><br class=""></div></div></body></html>