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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Sean,<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">Why a map instead of just a vector?<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">Why do you think it should be set up to do stuff in parallel with threads? I’ve run the existing version over a fairly large group of headers and it just took
a few seconds.<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">-John<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"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Sean Silva [mailto:silvas@purdue.edu]
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<b>Sent:</b> Monday, June 24, 2013 2:42 PM<br>
<b>To:</b> Thompson, John<br>
<b>Cc:</b> Argyrios Kyrtzidis; cfe-dev@cs.uiuc.edu<br>
<b>Subject:</b> Re: [cfe-dev] macro-expanded/preprocessed string (clangLex) question<o:p></o:p></span></p>
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<p class="MsoNormal">On Fri, Jun 21, 2013 at 1:28 PM, Thompson, John <<a href="mailto:John_Thompson@playstation.sony.com" target="_blank">John_Thompson@playstation.sony.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Argyrios,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span 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 style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Yeah, your comment made me think that perhaps I should just track macro expansions in general, not
limiting it to conditional directives, as macro instances anywhere with different values could be problematic as well for modules. Is that what you meant as well?</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span 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 style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">What do you think, Sean?</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span 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 style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The program structure doesn’t change a whole lot. Instead of storing the condition location and
values, I store the macro information.</span><o:p></o:p></p>
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<p class="MsoNormal">I think the program structure will have to change a good amount anyway in order to make it clear what the algorithm is doing. Unless it is unable to express the check that is desired (but I think it can), I strongly believe that the pseudocode
I suggested is the right approach, which nicely models the problem as:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">1) Defining an equivalence relation on macro expansions or preprocessor conditions or whatever (call this type T)<o:p></o:p></p>
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<p class="MsoNormal">2) Maintaining a map keyed on the physical source file location of the T and having T as values, and using that to ensure that all physical source locations expand to the same thing across TU's.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">This approach should work for either of the scenarios. Moreover, it has obvious time and space complexity and it's easy to see how to parallelize it (operate on independent maps in independent threads and at the end perform a "union" operation
on the maps).<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-- Sean Silva<o:p></o:p></p>
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