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<p class="MsoNormal">Hi Vangelis,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Not sure this will help you, but you can try to compare llvm::MachineInstr::getOpcode() with TargetOpcode::G_LOAD and TargetOpcode::G_STORE if you can obtain a MachineInstr instance.<o:p></o:p></p>
<p class="MsoNormal">It also may have sense to ask llvm-dev for a proper solution.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> lldb-dev <lldb-dev-bounces@lists.llvm.org> <b>On Behalf Of
</b>Vangelis Tsiatsianas via lldb-dev<br>
<b>Sent:</b> Tuesday, November 5, 2019 3:43 PM<br>
<b>To:</b> via lldb-dev <lldb-dev@lists.llvm.org><br>
<b>Cc:</b> Vangelis Tsiatsianas <vangelists@icloud.com><br>
<b>Subject:</b> Re: [lldb-dev] Identifying instructions that definitely access memory<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hello,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I decided to try once more with a follow-up email, since my previous one got no responses (I hope it’s not considered rude to send more than one message in a row for a particular question).<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">To sum up and clarify my previous question, what I need is a way to track memory stores and save both the old and the new value of the memory location being modified.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">My thinking so far:<o:p></o:p></p>
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Recognize the instructions that definitely access memory before they execute, based on their opcode.<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
Tell whether each operand is a register or a memory location.<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
If it’s a memory location, check whether it is a load or store destination.<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
In case it is a store destination, fetch and save current value from memory.<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
Execute instruction.<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
Fetch and save new value from memory.<o:p></o:p></li></ol>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">However, I was not able to find a cross-architecture API that covers all of the conditions above and more specifically <span style="font-family:"FiraCode-Regular",serif">Instruction::DoesStore()</span> and <span style="font-family:"FiraCode-Regular",serif">Operand::IsStoreDestination()</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">Last but not least, I should notice that the target is executed in single-step mode, so I do have control right before and after the execution of every instruction.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks, again, in advance! <span style="font-family:"Segoe UI Emoji",sans-serif">
🙂</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"><o:p> </o:p></p>
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<p class="MsoNormal">― Vangelis<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<br>
<o:p></o:p></p>
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<p class="MsoNormal">On 21 Oct 2019, at 08:54, Vangelis Tsiatsianas <<a href="mailto:vangelists@icloud.com">vangelists@icloud.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hello,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I am looking for a way to identify loads, stores and any other kind of instruction that
<b>definitely</b> perform memory access and extract the address operand(s), however I was not able to find a cross-architecture API. The closest I stumbled upon are "<span style="font-family:"FiraCode-Regular",serif">MCInstrDesc::mayLoad()</span>" and "<span style="font-family:"FiraCode-Regular",serif">MCInstrDesc::mayStore()</span>",
but I understand that their results are just a hint, so I would then need to examine the instruction name or opcode in order to find out whether it’s actually a load or store and which operand(s) is (are) memory address(es) and also do so for each architecture
separately, which I would really like to avoid.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Is there a way to identify such instructions either by examining them through the disassembler (e.g. "<span style="font-family:"FiraCode-Regular",serif">DoesLoad()</span>" | "<span style="font-family:"FiraCode-Regular",serif">DoesStore()</span>")
before they execute or right after they perform any kind of memory access?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thank you very much, in advance! <span style="font-family:"Segoe UI Emoji",sans-serif">
🙂</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"><o:p> </o:p></p>
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<p class="MsoNormal">― Vangelis<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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