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<p class="MsoNormal" style="margin-left:36.0pt">It appears I get the same output wether I use `-fspec-constr` or not.<o:p></o:p></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">I’m afraid so. Look in simplCore/SimplCore.lhs, function getCoreToDo. This builds the main optimisation pipeline. You’ll see that it has a –O0
path and a –O1/-O2 path. The flag Opt_SpecConstr is consulted only in the latter.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">One could perhaps do it differently but that’s the way it is right now.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">I test an isolated optimisation by switching it on and off with –O1.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif""> ghc-devs [mailto:ghc-devs-bounces@haskell.org]
<b>On Behalf Of </b>Chris Heller<br>
<b>Sent:</b> 06 January 2014 02:44<br>
<b>To:</b> ghc-devs@haskell.org<br>
<b>Subject:</b> Optimisation flags at -O0<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I wanted to understand better what `-fspec-constr` does. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">So I compiled the User Guide example with `-O0 -fspec-constr` to isolate the effects of call-pattern specialization, and nothing else (I used ghc-core to pretty-print the resulting Core syntax).<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">It appears I get the same output wether I use `-fspec-constr` or not.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Does this mean that compiling with `-O0` even explicitly enabled optimizations are turned off?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">If that is the case, how does one test an isolated optimization?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-Chris<o:p></o:p></p>
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