[Polly][CodegenCleanup] Update cleanup passes according (old) PassManagerBuilder.

[Meinersbur]

Summary

Update CodegenCleanup using the function-level passes added by populatePassManager that run between EP_EarlyAsPossible and EP_VectorizerStart in -O3.

The changes in particular are:

• Added pass create arguments, e.g. ExpensiveCombines for InstCombine.
• Remove reroll pass. The option -reroll-loops is disabled by default.
• Add passes run with UnitAtATime, which is the default.
• Add instances of LibCallsShrinkWrap, TailCallElimination, SCCP (sparse conditional constant propagation), Float2Int that did not run before.
• Add instances of GVN as in the default pipeline.

Notes:

• GVNHoist, GVNSink, NewGVN are still disabled in the -O3 pipeline.
• The optimization level and other optimization parameters are not accessible outside of PassManagerBuilder, hence we cannot add passes depending on these.

[Meinersbur]

Add ExpensiveCombines argument.

[philip.pfaffe]

LGTM. It would be great to actually have a testcase for this, so we'd be able to see any changes earlier.

[Meinersbur]

In D37571#865787, @philip.pfaffe wrote:

LGTM. It would be great to actually have a testcase for this, so we'd be able to see any changes earlier.

What do you think should be tested?

Testing end-to-end full-pipeline optimizations are purposefully not done in LLVM. These would be fragile tests that potentially break with any change in the cleanup passes.

[philip.pfaffe]

In D37571#865835, @Meinersbur wrote:

What do you think should be tested?

Not the actual optimizations of course, but the sequence of optimization passes that are being run. Take a look at the new-pm-defaults.ll testcase for an example.

lib/CodeGen/CodegenCleanup.cpp

virtual bool doInitialization(Module &M) override {
     // TODO: These are non-conditional passes that run between
     // EP_ModuleOptimizerEarly and EP_VectorizerStart just to ensure we do not
     // miss any optimization that would have run after Polly with
     // -polly-position=early. This can probably be reduced to a more compact set
     // of passes.
     FPM->add(createCFGSimplificationPass());
     FPM->add(createSROAPass());
     FPM->add(createEarlyCSEPass());
+
+    FPM->add(createPromoteMemoryToRegisterPass());
     FPM->add(createInstructionCombiningPass());
+    FPM->add(createCFGSimplificationPass());
+    FPM->add(createSROAPass());
+    FPM->add(createEarlyCSEPass(true));
+    FPM->add(createSpeculativeExecutionIfHasBranchDivergencePass());
     FPM->add(createJumpThreadingPass());
     FPM->add(createCorrelatedValuePropagationPass());
     FPM->add(createCFGSimplificationPass());
-    FPM->add(createInstructionCombiningPass());
+    FPM->add(createInstructionCombiningPass(true));
+    FPM->add(createLibCallsShrinkWrapPass());
+    FPM->add(createTailCallEliminationPass());
     FPM->add(createCFGSimplificationPass());
     FPM->add(createReassociatePass());
-    FPM->add(createLoopRotatePass());
+    FPM->add(createLoopRotatePass(-1));
     FPM->add(createGVNPass());
     FPM->add(createLICMPass());
     FPM->add(createLoopUnswitchPass());
     FPM->add(createCFGSimplificationPass());
-    FPM->add(createInstructionCombiningPass());
+    FPM->add(createInstructionCombiningPass(true));
     FPM->add(createIndVarSimplifyPass());
     FPM->add(createLoopIdiomPass());
     FPM->add(createLoopDeletionPass());
     FPM->add(createCFGSimplificationPass());
-    FPM->add(createSimpleLoopUnrollPass());
+    FPM->add(createSimpleLoopUnrollPass(3));
     FPM->add(createMergedLoadStoreMotionPass());
+    FPM->add(createGVNPass());
     FPM->add(createMemCpyOptPass());
+    FPM->add(createSCCPPass());
     FPM->add(createBitTrackingDCEPass());
-    FPM->add(createInstructionCombiningPass());
+    FPM->add(createInstructionCombiningPass(true));
     FPM->add(createJumpThreadingPass());
     FPM->add(createCorrelatedValuePropagationPass());
     FPM->add(createDeadStoreEliminationPass());
     FPM->add(createLICMPass());
-    FPM->add(createLoopRerollPass());
     FPM->add(createAggressiveDCEPass());
     FPM->add(createCFGSimplificationPass());
-    FPM->add(createInstructionCombiningPass());
+    FPM->add(createInstructionCombiningPass(true));
+    FPM->add(createFloat2IntPass());
 
     return FPM->doInitialization();
   }
 
   virtual bool doFinalization(Module &M) override {
     bool Result = FPM->doFinalization();
 
     delete FPM;