<p dir="ltr">We typically add options in clang only if there is a user for them. </p>
<div class="gmail_quote">On Jan 8, 2014 4:32 AM, "Bernard Ogden" <<a href="mailto:Bernard.Ogden@arm.com">Bernard.Ogden@arm.com</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I'm just stating that _if_ GCC compatibility is desired then we have to have -mcpu.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I don't think there's software that *needs* the compatibility, but it is easier for GCC projects to switch to clang if that compatibility is there - which I
think is why we go for GCC compatibility in the first place?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">(I raised
</span><a href="http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59718" target="_blank">http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59718</a><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> on the GCC docs.)<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"><u></u><u></u></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Eric Christopher [mailto:<a href="mailto:echristo@gmail.com" target="_blank">echristo@gmail.com</a>]
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<b>Sent:</b> 08 January 2014 12:23<br>
<b>To:</b> Bernard Ogden<br>
<b>Cc:</b> Renato Golin; LLVM Developers Mailing List; Clang Dev; Amara Emerson<br>
<b>Subject:</b> RE: [cfe-dev] [LLVMdev] AArch64 Clang CLI interface proposal<u></u><u></u></span></p>
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<p class="MsoNormal"><u></u> <u></u></p>
<p>I knew I'd regret leaving that option in for the MIPS port back in 99. Basically this is the only acceptable way for mcpu to exist, but should never have been added to the GCC aarch64 port at all since there's no compatibility with existing build systems
to worry about. <u></u><u></u></p>
<p>I would still like you to show this mythical piece of software that needs this compatibility.
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<p>-eric<u></u><u></u></p>
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<p class="MsoNormal">On Jan 8, 2014 3:06 AM, "Bernie Ogden" <<a href="mailto:bogden@arm.com" target="_blank">bogden@arm.com</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">I think there's an error in the example here.
<a href="http://gcc.gnu.org/onlinedocs/gcc-4.8.2/gcc/AArch64-Options.html" target="_blank">
http://gcc.gnu.org/onlinedocs/gcc-4.8.2/gcc/AArch64-Options.html</a> still documents -mcpu, and that march does not take CPUs as arguments. A local GCC developer tells me that the documentation is wrong in that -mcpu is actually a shorthand for specifying both
-mtune and -march, but that the option is certainly there.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">If we want GCC comptability then that's what we have to do, unless someone knows that GCC ARM/AArch64
is actually going to move away from this.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Do we want GCC compatibility?</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Regards,</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Bernie</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
<a href="mailto:cfe-dev-bounces@cs.uiuc.edu" target="_blank">cfe-dev-bounces@cs.uiuc.edu</a> [mailto:<a href="mailto:cfe-dev-bounces@cs.uiuc.edu" target="_blank">cfe-dev-bounces@cs.uiuc.edu</a>]
<b>On Behalf Of </b>Eric Christopher<br>
<b>Sent:</b> 07 January 2014 21:37<br>
<b>To:</b> Renato Golin; Amara Emerson; Clang Dev; LLVM Dev<br>
<b>Subject:</b> Re: [cfe-dev] [LLVMdev] AArch64 Clang CLI interface proposal</span><u></u><u></u></p>
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<p class="MsoNormal"> <u></u><u></u></p>
<p class="MsoNormal">Parsing the arch string is a bit icky, but I don't really have too much of a problem with it - and it's better than -mcpu so...<u></u><u></u></p>
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<p class="MsoNormal"> <u></u><u></u></p>
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<p class="MsoNormal">-eric<u></u><u></u></p>
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<p class="MsoNormal"> <u></u><u></u></p>
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<p class="MsoNormal">On Tue Jan 07 2014 at 9:23:43 AM, Renato Golin <<a href="mailto:renato.golin@linaro.org" target="_blank">renato.golin@linaro.org</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal">On 7 January 2014 17:05, Amara Emerson <<a href="mailto:amara.emerson@arm.com" target="_blank">amara.emerson@arm.com</a>> wrote:<u></u><u></u></p>
<p class="MsoNormal">We plan on implementing this interface for AArch64 Clang in future, and<br>
completely dropping the current support for -mfpu. This means that -march<br>
will become the preferred way to specify the target CPU/architecture.<u></u><u></u></p>
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<p class="MsoNormal"> <u></u><u></u></p>
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<p class="MsoNormal">Hi Amara,<u></u><u></u></p>
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<p class="MsoNormal"> <u></u><u></u></p>
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<p class="MsoNormal">This is something we were converging on the ARM32 world, too, and I believe other targets would probably do the same, if not before us. Hopefully, that'd also help clean up the
driver's code in the process.<u></u><u></u></p>
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<p class="MsoNormal"> <u></u><u></u></p>
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<p class="MsoNormal">cheers,<u></u><u></u></p>
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<p class="MsoNormal">--renato<u></u><u></u></p>
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