[NewPM/Inliner] Customize threshold based on optlevel and sizelevel

[eraman]

Summary

(Note: It will be cleaner to expose the OptimizationLevel enum to InlineCost and Inliner instead of mapping back from the enum to SizeLevel/OptLevel, but I don't know what is the right header file to move the enum into)

[eraman]

Ping.

[chandlerc]

lib/Passes/PassBuilder.cpp

558

As discussed in person, I would just call 'getInlineParams' here and use the existing constructor of the pass object.

[eraman]

Call getInlineParams in PassBuilder and pass the Params object to the existing Inliner constructor.

[chandlerc]

Minor nitpick below. Feel free to submit.

lib/Passes/PassBuilder.cpp

867–871

Noting that this is duplicated, maybe a static helper function:

static InlineParams getInlineParamsFromOptLevel(...)

And have it do the call to getInlineParams?

[eraman]

Address Chandler's comments.

include/llvm/Transforms/IPO/Inliner.h

 /// every attempt to be simpler. DCE of functions requires complex reasoning
 /// about comdat groups, etc. Instead, it is expected that other more focused
 /// passes be composed to achieve the same end result.
 class InlinerPass : public PassInfoMixin<InlinerPass> {
 public:
   InlinerPass(InlineParams Params = getInlineParams())
       : Params(std::move(Params)) {}
 
+  InlinerPass(unsigned OptLevel, unsigned SizeLevel)
+      : InlinerPass(getInlineParams(OptLevel, SizeLevel)) {}
+
   PreservedAnalyses run(LazyCallGraph::SCC &C, CGSCCAnalysisManager &AM,
                         LazyCallGraph &CG, CGSCCUpdateResult &UR);
 
 private:
   InlineParams Params;
 };
 
 } // End llvm namespace
 
 #endif

lib/Passes/PassBuilder.cpp

PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
   // Note: historically, the PruneEH pass was run first to deduce nounwind and
   // generally clean up exception handling overhead. It isn't clear this is
   // valuable as the inliner doesn't currently care whether it is inlining an
   // invoke or a call.
 
   // Run the inliner first. The theory is that we are walking bottom-up and so
   // the callees have already been fully optimized, and we want to inline them
   // into the callers so that our optimizations can reflect that.
-  // FIXME; Customize the threshold based on optimization level.
-  MainCGPipeline.addPass(InlinerPass());
+  unsigned OptLevel = Level > O3 ? 2 : Level;
+  unsigned SizeLevel = Level > O3 ? Level - O3 : 0;
+  MainCGPipeline.addPass(InlinerPass(OptLevel, SizeLevel));
 
   // Now deduce any function attributes based in the current code.
   MainCGPipeline.addPass(PostOrderFunctionAttrsPass());
 
   // When at O3 add argument promotion to the pass pipeline.
   // FIXME: It isn't at all clear why this should be limited to O3.
   if (Level == O3)
     MainCGPipeline.addPass(ArgumentPromotionPass());
ModulePassManager PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level,
   // FIXME: add peephole extensions here as the legacy PM does.
   MPM.addPass(createModuleToFunctionPassAdaptor(InstCombinePass()));
 
   // Note: historically, the PruneEH pass was run first to deduce nounwind and
   // generally clean up exception handling overhead. It isn't clear this is
   // valuable as the inliner doesn't currently care whether it is inlining an
   // invoke or a call.
   // Run the inliner now.
-  MPM.addPass(createModuleToPostOrderCGSCCPassAdaptor(InlinerPass()));
+  unsigned OptLevel = Level > O3 ? 2 : Level;
+  unsigned SizeLevel = Level > O3 ? Level - O3 : 0;
+  MPM.addPass(createModuleToPostOrderCGSCCPassAdaptor(
+      InlinerPass(OptLevel, SizeLevel)));
 
   // Optimize globals again after we ran the inliner.
   MPM.addPass(GlobalOptPass());
 
   // Garbage collect dead functions.
   // FIXME: Add ArgumentPromotion pass after once it's ported.
   MPM.addPass(GlobalDCEPass());
 
   FunctionPassManager FPM(DebugLogging);