<html><head><meta http-equiv="Content-Type" content="text/html charset=iso-8859-1"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br><div><div>On Mar 27, 2013, at 4:57 PM, Måns Rullgård <<a href="mailto:mans@mansr.com">mans@mansr.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="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;">Jim Grosbach <<a href="mailto:grosbach@apple.com">grosbach@apple.com</a>> writes:<br><br><blockquote type="cite">On Mar 27, 2013, at 2:38 PM, Weiming Zhao <<a href="mailto:weimingz@codeaurora.org">weimingz@codeaurora.org</a>> wrote:<br><br><blockquote type="cite">Hi Måns<br><br>Oh, so you mean GAS will implicitly add a reg even if only one reg is<br>specified in assembly. Right?<br></blockquote><br>Both registers are required in the syntax. GAS is more lenient, but is<br>in error. We don't need to follow their bad example here.<br></blockquote><br>GAS is not *wrong*, strictly speaking. It is not forbidden for an<br>assembler to accept syntax beyond that described in the ARM ARM. In<br>fact, this is even encouraged in some places.<br><br>Since this syntax is non-standard, you are correct that there is no<br>_need_ to follow this. However, if the aim is for clang/llvm to compile<br>existing source code unmodified, this does become a requirement, like it<br>or not.</div></blockquote><br></div><div><div>We want to do the right thing, not blindly accept whatever language extensions other toolchains have adopted. Sometimes that means telling people they need to modify their source code to conform to our stricter adherence to documentation. This is one of those places. This syntax is a relic of the old divided syntax, which LLVM's assembler does not support. We should be actively deprecating what support there is for divided syntax (i.e., adding warnings when it's used, then removing it entirely in following releases), not expanding support for it.</div><div><br></div><div>-JIm</div></div></body></html>