[llvm] [ctx_prof] Insert the ctx prof flattener after the module inliner (PR #107499)

[Mircea Trofin via llvm-commits]

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@@ -1744,11 +1749,14 @@ ModulePassManager PassBuilder::buildThinLTODefaultPipeline(
     MPM.addPass(GlobalDCEPass());
     return MPM;
   }
-
-  // Add the core simplification pipeline.
-  MPM.addPass(buildModuleSimplificationPipeline(
-      Level, ThinOrFullLTOPhase::ThinLTOPostLink));
-
+  if (!UseCtxProfile.empty()) {
+    MPM.addPass(
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mtrofin wrote:

Right now yes, it's just to integrate. The next step plan is to run some of the module simplification after all IPO and flattened profile lowering happens, but I want to see first what the more meaningful to do that is - special case through `buildModuleSimplificationPipeline` or have them spelled out separately. I'll evaluate this experimentally.

https://github.com/llvm/llvm-project/pull/107499