[llvm][Inline] Add FunctionSimplificationPipeline to module inliner pipeline

[taolq]

Summary

The FunctionSimplificationPipeline could effectively reduce the size of .text section when module inliner is enabled.

[taolq]

• add necessary file

[kazu]

Please be sure to address the clang-format issues pointed out by "Pre-merge checks".

[lebedev.ri]

Tests?
Presumably this is default-off?

[taolq]

• address clang-format

[taolq]

In D114704#3159012, @lebedev.ri wrote:

Tests?
Presumably this is default-off?

Sorry for forgetting to paste the tests.

I compiled clang to test this patch.

GCC 9.4		                              150746981	
clang -O3 default inliner		      115624552	    0.0%
clang -O3 module inliner	              253852361	 119.55%
clang -O3 module inliner + this patch         114116650	  -4.33%

llvm/include/llvm/Passes/PassBuilder.h

public:
 
   /// Construct the module pipeline that performs inlining as well as
   /// the inlining-driven cleanups.
   ModuleInlinerWrapperPass buildInlinerPipeline(OptimizationLevel Level,
                                                 ThinOrFullLTOPhase Phase);
 
   /// Construct the module pipeline that performs inlining with
   /// module inliner pass.
-  ModuleInlinerPass buildModuleInlinerPipeline(OptimizationLevel Level,
+  ModulePassManager buildModuleInlinerPipeline(OptimizationLevel Level,
                                                ThinOrFullLTOPhase Phase);
 
   /// Construct the core LLVM module optimization pipeline.
   ///
   /// This pipeline focuses on optimizing the execution speed of the IR. It
   /// uses cost modeling and thresholds to balance code growth against runtime
   /// improvements. It includes vectorization and other information destroying
   /// transformations. It also cannot generally be run repeatedly on a module

llvm/lib/Passes/PassBuilderPipelines.cpp

PassBuilder::buildInlinerPipeline(OptimizationLevel Level,
 
   if (EnableNoRerunSimplificationPipeline)
     MIWP.addLateModulePass(createModuleToFunctionPassAdaptor(
         InvalidateAnalysisPass<ShouldNotRunFunctionPassesAnalysis>()));
 
   return MIWP;
 }
 
-ModuleInlinerPass
+ModulePassManager
 PassBuilder::buildModuleInlinerPipeline(OptimizationLevel Level,
                                         ThinOrFullLTOPhase Phase) {
+  ModulePassManager MPM;
+
   InlineParams IP = getInlineParamsFromOptLevel(Level);
   if (Phase == ThinOrFullLTOPhase::ThinLTOPreLink && PGOOpt &&
       PGOOpt->Action == PGOOptions::SampleUse)
     IP.HotCallSiteThreshold = 0;
 
   if (PGOOpt)
     IP.EnableDeferral = EnablePGOInlineDeferral;
 
   // The inline deferral logic is used to avoid losing some
   // inlining chance in future. It is helpful in SCC inliner, in which
   // inlining is processed in bottom-up order.
   // While in module inliner, the inlining order is a priority-based order
   // by default. The inline deferral is unnecessary there. So we disable the
   // inline deferral logic in module inliner.
   IP.EnableDeferral = false;
 
-  return ModuleInlinerPass(IP, UseInlineAdvisor);
+  MPM.addPass(ModuleInlinerPass(IP, UseInlineAdvisor));
+
+  MPM.addPass(createModuleToFunctionPassAdaptor(
+      buildFunctionSimplificationPipeline(Level, Phase),
+      PTO.EagerlyInvalidateAnalyses));
+
+  MPM.addPass(createModuleToPostOrderCGSCCPassAdaptor(
+      CoroSplitPass(Level != OptimizationLevel::O0)));
+
+  return MPM;
 }
 
 ModulePassManager
 PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
                                                ThinOrFullLTOPhase Phase) {
   ModulePassManager MPM;
 
   // Place pseudo probe instrumentation as the first pass of the pipeline to