Move GVNHoist to the right position in the new pass manager pipeline

[davide]

Summary

GVNHoist was moved as part of simplification passes for the current pass manager (but not for the new), so they're now out-of-sync.

[chandlerc]

LGTM, good catch!

llvm/trunk/lib/Passes/PassBuilder.cpp

PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
 
   // Form SSA out of local memory accesses after breaking apart aggregates into
   // scalars.
   FPM.addPass(SROA());
 
   // Catch trivial redundancies
   FPM.addPass(EarlyCSEPass());
 
+  // Hoisting of scalars and load expressions.
+  if (EnableGVNHoist)
+    FPM.addPass(GVNHoistPass());
+
   // Speculative execution if the target has divergent branches; otherwise nop.
   FPM.addPass(SpeculativeExecutionPass());
 
   // Optimize based on known information about branches, and cleanup afterward.
   FPM.addPass(JumpThreadingPass());
   FPM.addPass(CorrelatedValuePropagationPass());
   FPM.addPass(SimplifyCFGPass());
   FPM.addPass(InstCombinePass());
PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
 
   // Create an early function pass manager to cleanup the output of the
   // frontend.
   FunctionPassManager EarlyFPM(DebugLogging);
   EarlyFPM.addPass(SimplifyCFGPass());
   EarlyFPM.addPass(SROA());
   EarlyFPM.addPass(EarlyCSEPass());
   EarlyFPM.addPass(LowerExpectIntrinsicPass());
-  if (EnableGVNHoist)
-    EarlyFPM.addPass(GVNHoistPass());
   MPM.addPass(createModuleToFunctionPassAdaptor(std::move(EarlyFPM)));
 
   // Interprocedural constant propagation now that basic cleanup has occured
   // and prior to optimizing globals.
   // FIXME: This position in the pipeline hasn't been carefully considered in
   // years, it should be re-analyzed.
   MPM.addPass(IPSCCPPass());