Make GVN Hoisting obey optnone/bisect

[probinson]

Summary

AFAICT the new pass manager does not support this feature yet?

[davide]

This LGTM but Daniel should sign-off.
And yes, the new PM doesn't support this feature yet.

lib/Transforms/Scalar/GVNHoist.cpp

 public:
   static char ID;
 
   GVNHoistLegacyPass() : FunctionPass(ID) {
     initializeGVNHoistLegacyPassPass(*PassRegistry::getPassRegistry());
   }
 
   bool runOnFunction(Function &F) override {
+    if (skipFunction(F))
+      return false;
     auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
     auto &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
     auto &MD = getAnalysis<MemoryDependenceWrapperPass>().getMemDep();
 
     GVNHoist G(&DT, &AA, &MD, F.optForMinSize());
     return G.run(F);
   }
 

test/Feature/optnone-opt.ll

 ; Nothing that runs at -O0 gets skipped.
 ; OPT-O0-NOT: Skipping pass
 
 ; IR passes run at -O1 and higher.
 ; OPT-O1-DAG: Skipping pass 'Aggressive Dead Code Elimination'
 ; OPT-O1-DAG: Skipping pass 'Combine redundant instructions'
 ; OPT-O1-DAG: Skipping pass 'Dead Store Elimination'
 ; OPT-O1-DAG: Skipping pass 'Early CSE'
+; OPT-O1-DAG: Skipping pass 'Early GVN Hoisting of Expressions'
 ; OPT-O1-DAG: Skipping pass 'Jump Threading'
 ; OPT-O1-DAG: Skipping pass 'MemCpy Optimization'
 ; OPT-O1-DAG: Skipping pass 'Reassociate expressions'
 ; OPT-O1-DAG: Skipping pass 'Simplify the CFG'
 ; OPT-O1-DAG: Skipping pass 'Sparse Conditional Constant Propagation'
 ; OPT-O1-DAG: Skipping pass 'SROA'
 ; OPT-O1-DAG: Skipping pass 'Tail Call Elimination'
 ; OPT-O1-DAG: Skipping pass 'Value Propagation'