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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">But where is the flat set? Maybe I can debug and check what is going on.<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;mso-fareast-language: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;mso-fareast-language:EN-US">There is the possibility to be lldb usage, but it’s obtaining the disassembler as it is.<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;mso-fareast-language:EN-US">When lldb tries to instantiate the disassembler, it checks many information in<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;mso-fareast-language:EN-US">llvm/tools/lldb/source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp:1014 =<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;mso-fareast-language:EN-US">“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;mso-fareast-language:EN-US">const char *flavor_string)”,<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;mso-fareast-language:EN-US">which I couldn’t find if it’s doing correct. Is there a place that explains the “flavor” and<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;mso-fareast-language:EN-US">“features_str” variables used at DisassemblerLLVMC.cpp:1163<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;mso-fareast-language:EN-US">(“newLLVMCDisassembler(triple_str, cpu, features_str.c_str(), flavor, *this)”)?<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;mso-fareast-language: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;mso-fareast-language:EN-US">Another question that I have is, how can I compare the data it gets with the real instructions?<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;mso-fareast-language:EN-US">I found the file “PPCGenDisassemblerTables.inc”, where the table is declared, and where the it<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;mso-fareast-language:EN-US">is decoded, so the current instruction bne cr7,0x2000092c (0x409e000c) is being processed by<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;mso-fareast-language:EN-US">the case 30 in the PPCGenDisassemblerTables.inc file:<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;mso-fareast-language:EN-US"> case 30:<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;mso-fareast-language:EN-US"> tmp = fieldFromInstruction(insn, 21, 5);<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;mso-fareast-language:EN-US"> if (decodeUImmOperand<5>(MI, tmp, Address, Decoder) == MCDisassembler::Fail) { return MCDisassembler::Fail; }<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;mso-fareast-language:EN-US"> tmp = fieldFromInstruction(insn, 16, 5);<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;mso-fareast-language:EN-US"> if (DecodeCRBITRCRegisterClass(MI, tmp, Address, Decoder) == MCDisassembler::Fail) { return MCDisassembler::Fail;
}<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;mso-fareast-language:EN-US"> tmp = fieldFromInstruction(insn, 2, 14);<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;mso-fareast-language:EN-US"> MI.addOperand(MCOperand::createImm(tmp));<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;mso-fareast-language:EN-US"> return S;
<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;mso-fareast-language: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;mso-fareast-language:EN-US">Which is the correct reading for the BC instruction. What am I missing?<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;mso-fareast-language: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;mso-fareast-language:EN-US">Some additional information:<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:35.4pt"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">MCInst opcode: 0x7cb<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:35.4pt"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Decode Index: 0x1e<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;mso-fareast-language: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;mso-fareast-language: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;mso-fareast-language: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;mso-fareast-language:EN-US">Test case:<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;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Build the file “lldb/packages/Python/lldbsuite/test/functionalities/stop-hook/main.cpp”<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Run LLDB with the binary just generated<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Add the breakpoint “b main.cpp:30”<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Send the command “n”, stepping over to next line.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:18.0pt"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Result: The debugger will not stop and will execute the entire binary.<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;mso-fareast-language: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;mso-fareast-language:EN-US">Remembering I’m using a little endian Power8 machine.<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;mso-fareast-language: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;mso-fareast-language: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;mso-fareast-language:EN-US">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:#1F497D;mso-fareast-language: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;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><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:nemanja.i.ibm@gmail.com]
<br>
<b>Sent:</b> quinta-feira, 30 de novembro de 2017 07:54<br>
<b>To:</b> Sean Fertile <sd.fertile@gmail.com><br>
<b>Cc:</b> Leonardo Bianconi <leonardo.bianconi@eldorado.org.br>; llvm-dev@lists.llvm.org<br>
<b>Subject:</b> Re: [llvm-dev] PPC64 Disassembler<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal"><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?<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span lang="EN-US">Would you be able to provide a test case that reproduces the issue?<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><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:<o:p></o:p></span></p>
<blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0cm;margin-bottom:5.0pt">
<p class="MsoNormal"><span lang="EN-US">Hello Leonardo,<br>
<br>
What is the opcode of the MCInstrDesc?<br>
<br>
Sean<o:p></o:p></span></p>
<div>
<div>
<p class="MsoNormal"><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"><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>
><o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><span lang="EN-US">> _______________________________________________<br>
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><br>
_______________________________________________<br>
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</blockquote>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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