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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">One possible approach is to use the instruction mapping infrastructure: <a href="http://llvm.org/docs/HowToUseInstrMappings.html">http://llvm.org/docs/HowToUseInstrMappings.html</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">This provides a simple 1:1 mapping between the same instruction in two ISAs. For MIPS we use this to map the base MIPS ISA<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">to the microMIPS ISA, and allows us to write the bulk of our .cpp files without multiple switches on ISA.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></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""> llvm-dev [mailto:llvm-dev-bounces@lists.llvm.org]
<b>On Behalf Of </b>Martin J. O'Riordan via llvm-dev<br>
<b>Sent:</b> 08 July 2016 12:58<br>
<b>To:</b> 'Bruce Hoult'<br>
<b>Cc:</b> 'LLVM Developers'<br>
<b>Subject:</b> Re: [llvm-dev] Dynamic selection of assembly mnemonic strings<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US">Thanks for the quick answer Bruce.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US">So far as I can tell (from a quick read), this is really for integrated assemblers/disassemblers - but we use an external assembler. When
invoking clang we would provide ‘</span><span lang="EN-IE" style="font-family:"Courier New";color:black;mso-fareast-language:EN-US">-mcpu=chip_v1</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US">’ or
‘</span><span lang="EN-IE" style="font-family:"Courier New";color:black;mso-fareast-language:EN-US">-mcpu=chip_v2</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US">’, and the mnemonic ‘</span><span lang="EN-IE" style="font-family:"Courier New";color:black;mso-fareast-language:EN-US">LD32</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US">’
is only valid when compiling for ‘</span><span lang="EN-IE" style="font-family:"Courier New";color:black;mso-fareast-language:EN-US">chip_v1</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US">’, while
‘</span><span lang="EN-IE" style="font-family:"Courier New";color:black;mso-fareast-language:EN-US">LD.32</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US">’ is only valid when compiling for ‘</span><span lang="EN-IE" style="font-family:"Courier New";color:black;mso-fareast-language:EN-US">chip_v2</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US">’.
But I will study the mnemonic aliasing carefully to see if it does provide what I need.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US">All the best,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:black;mso-fareast-language:EN-US"> MartinO<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE" style="font-family:"Book Antiqua","serif";color:#943634;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif"">
<a href="mailto:bruce.hoult@gmail.com">bruce.hoult@gmail.com</a> [<a href="mailto:bruce.hoult@gmail.com">mailto:bruce.hoult@gmail.com</a>]
<b>On Behalf Of </b>Bruce Hoult<br>
<b>Sent:</b> 08 July 2016 12:32<br>
<b>To:</b> Martin J. O'Riordan <<a href="mailto:Martin.ORiordan@movidius.com">Martin.ORiordan@movidius.com</a>><br>
<b>Cc:</b> LLVM Developers <<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>><br>
<b>Subject:</b> Re: [llvm-dev] Dynamic selection of assembly mnemonic strings<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-IE">Do instruction aliases do the job?<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-IE"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-IE"><a href="http://llvm.org/docs/CodeGenerator.html#instruction-alias-processing">http://llvm.org/docs/CodeGenerator.html#instruction-alias-processing</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-IE"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-IE">Is it ok to have the same source file use LD32 in one instruction but LD.32 in the next one, or do you want different modes?<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-IE"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-IE"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-IE">On Fri, Jul 8, 2016 at 2:24 PM, Martin J. O'Riordan via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>> wrote:<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">Hi LLVM Dev,</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> </span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">I have an old problem that I’ve wanted to clean-up for some time. Our chip has gone through a number of iterations
in the past few years, but with each revision there have been changes to some of the mnemonics for instructions. These are mostly very simple, for example we had a 32-bit load from memory instruction named ‘</span><span lang="EN-IE" style="font-family:"Courier New"">LD32</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">’
in one version of the chip, but for a later version this was changed to ‘</span><span lang="EN-IE" style="font-family:"Courier New"">LD.32</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">’.</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> </span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">The semantics and schedule remained the same, but in the TD file I had to introduce two ‘</span><span lang="EN-IE" style="font-family:"Courier New"">def</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">’s
for this (actually, I abstract a bit more and use a ‘</span><span lang="EN-IE" style="font-family:"Courier New"">defm</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">’):</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> </span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:36.0pt">
<span lang="EN-IE" style="font-family:"Courier New"">def LD32_v1 : Instr<... “LD32” ...>, Requires<[isV1]>;</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:36.0pt">
<span lang="EN-IE" style="font-family:"Courier New"">def LD32_v2 : Instr<... “LD.32” ...>, Requires<[isV2]>;</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> </span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">This all works fine, but there is a large number of them which makes maintenance difficult. This also adds to the
burden of selection when using ‘</span><span lang="EN-IE" style="font-family:"Courier New"">BuildMI</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">’ in the C++ code, as I have to do things like:</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> </span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:36.0pt">
<span lang="EN-IE" style="font-family:"Courier New"">if (isV1())</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:36.0pt">
<span lang="EN-IE" style="font-family:"Courier New""> BuildMI(..., TII->get(SHAVE::LD32_v1)</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:36.0pt">
<span lang="EN-IE" style="font-family:"Courier New"">else if (isV2())</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:36.0pt">
<span lang="EN-IE" style="font-family:"Courier New""> BuildMI(..., TII->get(SHAVE::LD32_v2)</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> </span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">What I would like, is for some mechanism that can substitute the version specific mnemonic dynamically (perhaps using
a lookup table), and I could reduce the above to just:</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> </span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:36.0pt">
<span lang="EN-IE" style="font-family:"Courier New"">def LD32 : Instr<... “??MetaMnemonic??” ...>;</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">and:</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:36.0pt">
<span lang="EN-IE" style="font-family:"Courier New"">BuildMI(..., TII->get(SHAVE::LD32)</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> </span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">Does anyone know how this can be achieved without resort to placing some Meta-Mnemonic for ‘</span><span lang="EN-IE" style="font-family:"Courier New"">??MetaMnemonic??</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">’
and replacing this with the version specific value during AsmPrinting?</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> </span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">Some instructions have more elaborate substitutions, but the general principle is the same and there are a large number
of instructions that are affected which makes the TD files very large, and the conditional ‘</span><span lang="EN-IE" style="font-family:"Courier New"">BuildMI</span><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">’ code overcomplicated.</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> </span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif"">Thanks,</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> </span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> MartinO</span><span lang="EN-IE"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-IE" style="font-family:"Book Antiqua","serif""> </span><span lang="EN-IE"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-IE"><br>
_______________________________________________<br>
LLVM Developers mailing list<br>
<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a><br>
<a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev" target="_blank">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-IE"><o:p> </o:p></span></p>
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