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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">But where is the flat set? Maybe I can debug and check what is going on.</span><o:p></o:p></p>
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<p class="MsoNormal"> The MCInstrDesc are in a table in lib/Target/PowerPC/PPCGenInstrInfo.inc of your build directory.<o:p></o:p></p>
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<p class="gmail-msonormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Some additional information:</span><o:p></o:p></p>
<p class="gmail-msonormal" style="text-indent:35.4pt"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">MCInst opcode: 0x7cb</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Decode Index: 0x1e</span><o:p></o:p></p>
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<p class="MsoNormal">I had assumed this would have dissembled to '// Inst #234 = BC' which does have the branch flag set, but I think that opcode is for XXLNOR instruction.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Could it be disassembling to `// Inst #2014 = gBC` instead which does not have the branch flag set? Adding Hal and Ulrich in case they have some extra insight here.<span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#385723;mso-style-textfill-fill-color:#385723;mso-style-textfill-fill-alpha:100.0%">This code is new for me, I will make some
more debugging to check this, and if I find more information, I let you know.</span><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p></o:p></span></p>
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<p class="gmail-msonormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Remembering I’m using a little endian Power8 machine.</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Are there any outstanding patches or workarounds I need to build lldb on Power8?<o:p></o:p></p>
</div>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#385723;mso-style-textfill-fill-color:#385723;mso-style-textfill-fill-alpha:100.0%">This “https://github.com/PPC64/lldb” is the
repository we are using to development (using “next” branch).<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#385723;mso-style-textfill-fill-color:#385723;mso-style-textfill-fill-alpha:100.0%">Also there are “https://github.com/PPC64/clang”
and “https://github.com/PPC64/llvm” as fixed references to avoid, for example, use lldb with the llvm from upstream repository in a different version.<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#385723;mso-style-textfill-fill-color:#385723;mso-style-textfill-fill-alpha:100.0%">Using these versions it should build.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#385723;mso-style-textfill-fill-color:#385723;mso-style-textfill-fill-alpha:100.0%">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#385723;mso-style-textfill-fill-color:#385723;mso-style-textfill-fill-alpha:100.0%">Leonardo.<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Thanks<o:p></o:p></span></p>
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<div>
<p class="MsoNormal">Sean<br>
<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Thu, Nov 30, 2017 at 10:09 AM, Leonardo Bianconi <<a href="mailto:leonardo.bianconi@eldorado.org.br" target="_blank">leonardo.bianconi@eldorado.org.br</a>> wrote:<o:p></o:p></p>
<blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm">
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">But where is the flat set? Maybe I can debug and check what is going on.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">There is the possibility to be lldb usage, but it’s obtaining the disassembler as it is.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">When lldb tries to instantiate the disassembler, it checks many information in</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">llvm/tools/lldb/source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp:1014 =</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">“DisassemblerLLVMC::DisassemblerLLVMC(const ArchSpec &arch,</span><span lang="EN-US">
</span><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">const char *flavor_string)”,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">which I couldn’t find if it’s doing correct. Is there a place that explains the “flavor”
and</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">“features_str” variables used at DisassemblerLLVMC.cpp:1163</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">(“newLLVMCDisassembler(triple_str, cpu, features_str.c_str(), flavor, *this)”)?</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Another question that I have is, how can I compare the data it gets with the real instructions?</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I found the file “PPCGenDisassemblerTables.inc”, where the table is declared, and where
the it</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">is decoded, so the current instruction bne cr7,0x2000092c (0x409e000c) is being processed
by</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">the case 30 in the PPCGenDisassemblerTables.inc file:</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> case 30:</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> tmp = fieldFromInstruction(insn, 21, 5);</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> if (decodeUImmOperand<5>(MI, tmp, Address, Decoder) == MCDisassembler::Fail) {
return MCDisassembler::Fail; }</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> tmp = fieldFromInstruction(insn, 16, 5);</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> if (DecodeCRBITRCRegisterClass(MI, tmp, Address, Decoder) == MCDisassembler::Fail)
{ return MCDisassembler::Fail; }</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> tmp = fieldFromInstruction(insn, 2, 14);</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> MI.addOperand(MCOperand::createImm(tmp));</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> return S;
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Which is the correct reading for the BC instruction. What am I missing?</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Some additional information:</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;text-indent:35.4pt">
<span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">MCInst opcode: 0x7cb</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;text-indent:35.4pt">
<span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Decode Index: 0x1e</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">=================
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Test case:</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="m1959917323803839692msolistparagraph"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">-</span><span lang="EN-US" style="font-size:7.0pt;color:#1F497D">
</span><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Build the file “lldb/packages/Python/lldbsuite/test/functionalities/stop-hook/main.cpp”</span><o:p></o:p></p>
<p class="m1959917323803839692msolistparagraph"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">-</span><span lang="EN-US" style="font-size:7.0pt;color:#1F497D">
</span><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Run LLDB with the binary just generated</span><o:p></o:p></p>
<p class="m1959917323803839692msolistparagraph"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">-</span><span lang="EN-US" style="font-size:7.0pt;color:#1F497D">
</span><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Add the breakpoint “b main.cpp:30”</span><o:p></o:p></p>
<p class="m1959917323803839692msolistparagraph"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">-</span><span lang="EN-US" style="font-size:7.0pt;color:#1F497D">
</span><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Send the command “n”, stepping over to next line.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;text-indent:18.0pt">
<span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Result: The debugger will not stop and will execute the entire binary.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Remembering I’m using a little endian Power8 machine.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Thanks!</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Nemanja Ivanovic [mailto:<a href="mailto:nemanja.i.ibm@gmail.com" target="_blank">nemanja.i.ibm@gmail.com</a>]
<br>
<b>Sent:</b> quinta-feira, 30 de novembro de 2017 07:54<br>
<b>To:</b> Sean Fertile <<a href="mailto:sd.fertile@gmail.com" target="_blank">sd.fertile@gmail.com</a>><br>
<b>Cc:</b> Leonardo Bianconi <<a href="mailto:leonardo.bianconi@eldorado.org.br" target="_blank">leonardo.bianconi@eldorado.org.br</a>>;
<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a><br>
<b>Subject:</b> Re: [llvm-dev] PPC64 Disassembler</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">The `isBranch` flag is already set on the branch instructions. Furthermore, we do use the `isBranch()` query in a few places in the PPC back end, so this does
work. Perhaps there's something specific about the lldb usage? Is it somehow possible that the `isBranch()` query is called on the wrong instruction?</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">Would you be able to provide a test case that reproduces the issue?</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">On Thu, Nov 30, 2017 at 2:30 AM, Sean Fertile via llvm-dev <</span><a href="mailto:llvm-dev@lists.llvm.org" target="_blank"><span lang="EN-US">llvm-dev@lists.llvm.org</span></a><span lang="EN-US">>
wrote:</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">Hello Leonardo,<br>
<br>
What is the opcode of the MCInstrDesc?<br>
<br>
Sean</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"><br>
On Wed, Nov 29, 2017 at 1:48 PM, Leonardo Bianconi via llvm-dev<br>
<</span><a href="mailto:llvm-dev@lists.llvm.org" target="_blank"><span lang="EN-US">llvm-dev@lists.llvm.org</span></a><span lang="EN-US">> wrote:<br>
> Hi all,<br>
><br>
><br>
><br>
> I’m working on lldb to make it available to ppc64le, but the “step over”<br>
><br>
> is not working for some cases.<br>
><br>
><br>
><br>
> When debugging, I can see that the disassembler analyze some instructions<br>
><br>
> forward, looking for a branch instruction<br>
><br>
> (llvm/tools/lldb/source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp:87<br>
><br>
> – “const bool can_branch = mc_disasm_ptr->CanBranch(inst);”), while<br>
><br>
> trying to set the next breakpoint.<br>
><br>
><br>
><br>
> On this case, the instruction is the “bne cr7,0x2000092c”, which is a<br>
> branch,<br>
><br>
> but at llvm/lib/MC/MCInstrDesc.cpp:35 –<br>
><br>
> “if (isBranch() || isCall() || isReturn() || isIndirectBranch())” it returns<br>
> false,<br>
><br>
> making lldb do not set the correct breakpoint, so the execution does not<br>
> stop<br>
><br>
> at next line, which should be the “step over” behavior.<br>
><br>
><br>
><br>
> The variable “Flags” for the disassembled instruction does not have the<br>
> branch<br>
><br>
> flag.<br>
><br>
><br>
><br>
> I have tried to change the file “/lib/Target/PowerPC/PPCInstrInfo.td”,<br>
> adding<br>
><br>
> “isBranch = 1” for the instruction "bc 4, $bi, $dst", but had not effect.<br>
><br>
><br>
><br>
> Comparing with x86_64, building the same cpp file, the instruction<br>
><br>
> “jne 0x4005eb” has the branch flag, which identifies it as a branch<br>
> instruction.<br>
><br>
><br>
><br>
> Where is the definition that an instruction is a branch? Is it a bug?<br>
><br>
><br>
><br>
> Thanks!<br>
><br>
></span><o:p></o:p></p>
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