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<p class="MsoNormal"><span lang="EN-US">Hi!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">In order to not overburden the previous discussion about Analyzer and Tooling, I would like to ask you opinions on a related but slightly orthogonal matter.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Gabor and I had a brainstorming session about the issues CTU analysis and compilation command handling (previous topic) brought up recently.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Note that these points are to be regarded as cursory expeditions into the hypothetical (at best).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">The train of thought regarding CTU analysis had the following outline:<o:p></o:p></span></p>
<ul type="disc">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
<span lang="EN-US">We need a tool that gets a `FunctionDecl` (the function which we would like to inline) and returns with an AST to its TU.<o:p></o:p></span></li><ul type="circle">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level2 lfo1">
<span lang="EN-US">the fitting abstraction level of the result seems to be the TU level<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level2 lfo1">
<span lang="EN-US">`externalDefMapping.txt` is just an implementation detail, actually we don't need that.<o:p></o:p></span></li></ul>
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
<span lang="EN-US">Let's call this tool `<b>ASTServer</b>`.<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
<span lang="EN-US">ASTServer has some resemblance to `clangd`.<o:p></o:p></span></li><ul type="circle">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level2 lfo1">
<span lang="EN-US">Works on the whole project<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level2 lfo1">
<span lang="EN-US">Uses compilation DB<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level2 lfo1">
<span lang="EN-US">Persists already parsed ASTs in its memory (up to a limit)<o:p></o:p></span></li><ul type="square">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level3 lfo1">
<span lang="EN-US">(Cache eviction strategies? LRU?)<o:p></o:p></span></li></ul>
</ul>
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
<span lang="EN-US">The AST would be returned on a socket and in a serialized form (ASTReader/Writer).<o:p></o:p></span></li><ul type="circle">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level2 lfo1">
<span lang="EN-US">could also work over the network, promoting distribution<o:p></o:p></span></li></ul>
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
<span lang="EN-US">We need another tool: `<b>clang-analyzer</b>` !!!<o:p></o:p></span></li><ul type="circle">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level2 lfo1">
<span lang="EN-US">Actually we should have done this earlier<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level2 lfo1">
<span lang="EN-US">Utilizes clang for analysis purposes<o:p></o:p></span></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level2 lfo1">
<span lang="EN-US">Handles comm with `ASTServer`<o:p></o:p></span></li><ul type="square">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level3 lfo1">
<span lang="EN-US">Caches ASTs from the server<o:p></o:p></span></li></ul>
</ul>
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo1">
<span lang="EN-US">external orchestrator tool CodeChecker tool would launch ASTServer and then would call clang-analyzer tool for each TU, thus conducting the analysis.<o:p></o:p></span></li></ul>
<p class="MsoNormal"><span lang="EN-US">The reasoning behind the separation:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">The analyzer is a complex subsystem of Clang. The valid concern of clang binary growing out of proportion, and the increasing need for<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">tooling dependencies surfacing due to CTU analysis indicate the need reorganizing facilities.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">The point is further backed by the argument that a complex functionality of interprocess communication (over sockets in our example)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">is even less desirable inside the clang binary than binary size bloat.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Also the complexity of the whole solution could be distributed, and concerns of build system management, build configuration formats<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">can be separated from the analyzer itself (but allows for a wide variety of build-system vs analysis cooperation schemes to be implemented).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Again, the scope of these ideas is not trivial to assess, and would probably require a considerable amount of effort,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">but I hope an open discussion would outline a solution that benefits the structure of the whole project.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Cheers,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Endre<o:p></o:p></span></p>
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