[InstCombine] Remove ExpensiveCombines option

[nikic]

Summary

D75801 removed the last and only user of this option, so we can drop it now. The original idea behind this was to only run expensive transforms under -O3, but apart from the one known bits transform, this has never really taken off. I believe nowadays the recommendation is to put expensive transforms in AggressiveInstCombine instead, though that isn't terribly popular either :)

[spatel]

LGTM - thanks for the cleanup!

include/llvm/Transforms/IPO/PassManagerBuilder.h

 private:
   void addExtensionsToPM(ExtensionPointTy ETy,
                          legacy::PassManagerBase &PM) const;
   void addInitialAliasAnalysisPasses(legacy::PassManagerBase &PM) const;
   void addLTOOptimizationPasses(legacy::PassManagerBase &PM);
   void addLateLTOOptimizationPasses(legacy::PassManagerBase &PM);
   void addPGOInstrPasses(legacy::PassManagerBase &MPM, bool IsCS);
   void addFunctionSimplificationPasses(legacy::PassManagerBase &MPM);
-  void addInstructionCombiningPass(legacy::PassManagerBase &MPM) const;
 
 public:
   /// populateFunctionPassManager - This fills in the function pass manager,
   /// which is expected to be run on each function immediately as it is
   /// generated.  The idea is to reduce the size of the IR in memory.
   void populateFunctionPassManager(legacy::FunctionPassManager &FPM);
 
   /// populateModulePassManager - This sets up the primary pass manager.

include/llvm/Transforms/InstCombine/InstCombine.h

 #include "llvm/IR/Function.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/Transforms/InstCombine/InstCombineWorklist.h"
 
 namespace llvm {
 
 class InstCombinePass : public PassInfoMixin<InstCombinePass> {
   InstCombineWorklist Worklist;
-  const bool ExpensiveCombines;
   const unsigned MaxIterations;
 
 public:
   static StringRef name() { return "InstCombinePass"; }
 
-  explicit InstCombinePass(bool ExpensiveCombines = true);
-  explicit InstCombinePass(bool ExpensiveCombines, unsigned MaxIterations);
+  explicit InstCombinePass();
+  explicit InstCombinePass(unsigned MaxIterations);
 
   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
 };
 
 /// The legacy pass manager's instcombine pass.
 ///
 /// This is a basic whole-function wrapper around the instcombine utility. It
 /// will try to combine all instructions in the function.
 class InstructionCombiningPass : public FunctionPass {
   InstCombineWorklist Worklist;
-  const bool ExpensiveCombines;
   const unsigned MaxIterations;
 
 public:
   static char ID; // Pass identification, replacement for typeid
 
-  explicit InstructionCombiningPass(bool ExpensiveCombines = true);
-  explicit InstructionCombiningPass(bool ExpensiveCombines,
-                                    unsigned MaxIterations);
+  explicit InstructionCombiningPass();
+  explicit InstructionCombiningPass(unsigned MaxIterations);
 
   void getAnalysisUsage(AnalysisUsage &AU) const override;
   bool runOnFunction(Function &F) override;
 };
 
 //===----------------------------------------------------------------------===//
 //
 // InstructionCombining - Combine instructions to form fewer, simple
 // instructions. This pass does not modify the CFG, and has a tendency to make
 // instructions dead, so a subsequent DCE pass is useful.
 //
 // This pass combines things like:
 //    %Y = add int 1, %X
 //    %Z = add int 1, %Y
 // into:
 //    %Z = add int 2, %X
 //
-FunctionPass *createInstructionCombiningPass(bool ExpensiveCombines = true);
-FunctionPass *createInstructionCombiningPass(bool ExpensiveCombines,
-                                             unsigned MaxIterations);
+FunctionPass *createInstructionCombiningPass();
+FunctionPass *createInstructionCombiningPass(unsigned MaxIterations);
 }
 
 #endif

lib/Transforms/IPO/PassManagerBuilder.cpp

void PassManagerBuilder::addInitialAliasAnalysisPasses(
 
   // Add TypeBasedAliasAnalysis before BasicAliasAnalysis so that
   // BasicAliasAnalysis wins if they disagree. This is intended to help
   // support "obvious" type-punning idioms.
   PM.add(createTypeBasedAAWrapperPass());
   PM.add(createScopedNoAliasAAWrapperPass());
 }
 
-void PassManagerBuilder::addInstructionCombiningPass(
-    legacy::PassManagerBase &PM) const {
-  bool ExpensiveCombines = OptLevel > 2;
-  PM.add(createInstructionCombiningPass(ExpensiveCombines));
-}
-
 void PassManagerBuilder::populateFunctionPassManager(
     legacy::FunctionPassManager &FPM) {
   addExtensionsToPM(EP_EarlyAsPossible, FPM);
   FPM.add(createEntryExitInstrumenterPass());
 
   // Add LibraryInfo if we have some.
   if (LibraryInfo)
     FPM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
if (OptLevel > 1) {
 
     MPM.add(createJumpThreadingPass());         // Thread jumps.
     MPM.add(createCorrelatedValuePropagationPass()); // Propagate conditionals
   }
   MPM.add(createCFGSimplificationPass());     // Merge & remove BBs
   // Combine silly seq's
   if (OptLevel > 2)
     MPM.add(createAggressiveInstCombinerPass());
-  addInstructionCombiningPass(MPM);
+  MPM.add(createInstructionCombiningPass());
   if (SizeLevel == 0 && !DisableLibCallsShrinkWrap)
     MPM.add(createLibCallsShrinkWrapPass());
   addExtensionsToPM(EP_Peephole, MPM);
 
   // Optimize memory intrinsic calls based on the profiled size information.
   if (SizeLevel == 0)
     MPM.add(createPGOMemOPSizeOptLegacyPass());
 
void PassManagerBuilder::addFunctionSimplificationPasses(
   if (EnableSimpleLoopUnswitch)
     MPM.add(createSimpleLoopUnswitchLegacyPass());
   else
     MPM.add(createLoopUnswitchPass(SizeLevel || OptLevel < 3, DivergentTarget));
   // FIXME: We break the loop pass pipeline here in order to do full
   // simplify-cfg. Eventually loop-simplifycfg should be enhanced to replace the
   // need for this.
   MPM.add(createCFGSimplificationPass());
-  addInstructionCombiningPass(MPM);
+  MPM.add(createInstructionCombiningPass());
   // We resume loop passes creating a second loop pipeline here.
   MPM.add(createIndVarSimplifyPass());        // Canonicalize indvars
   MPM.add(createLoopIdiomPass());             // Recognize idioms like memset.
   addExtensionsToPM(EP_LateLoopOptimizations, MPM);
   MPM.add(createLoopDeletionPass());          // Delete dead loops
 
   if (EnableLoopInterchange)
     MPM.add(createLoopInterchangePass()); // Interchange loops
void PassManagerBuilder::addFunctionSimplificationPasses(
 
   // Delete dead bit computations (instcombine runs after to fold away the dead
   // computations, and then ADCE will run later to exploit any new DCE
   // opportunities that creates).
   MPM.add(createBitTrackingDCEPass());        // Delete dead bit computations
 
   // Run instcombine after redundancy elimination to exploit opportunities
   // opened up by them.
-  addInstructionCombiningPass(MPM);
+  MPM.add(createInstructionCombiningPass());
   addExtensionsToPM(EP_Peephole, MPM);
   if (OptLevel > 1) {
     MPM.add(createJumpThreadingPass());         // Thread jumps
     MPM.add(createCorrelatedValuePropagationPass());
     MPM.add(createDeadStoreEliminationPass());  // Delete dead stores
     MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
   }
 
   addExtensionsToPM(EP_ScalarOptimizerLate, MPM);
 
   if (RerollLoops)
     MPM.add(createLoopRerollPass());
 
   // TODO: Investigate if this is too expensive at O1.
   MPM.add(createAggressiveDCEPass());         // Delete dead instructions
   MPM.add(createCFGSimplificationPass()); // Merge & remove BBs
   // Clean up after everything.
-  addInstructionCombiningPass(MPM);
+  MPM.add(createInstructionCombiningPass());
   addExtensionsToPM(EP_Peephole, MPM);
 
   if (EnableCHR && OptLevel >= 3 &&
       (!PGOInstrUse.empty() || !PGOSampleUse.empty() || EnablePGOCSInstrGen))
     MPM.add(createControlHeightReductionLegacyPass());
 }
 
 void PassManagerBuilder::populateModulePassManager(
void PassManagerBuilder::populateModulePassManager(
   MPM.add(createCalledValuePropagationPass());
 
   MPM.add(createGlobalOptimizerPass()); // Optimize out global vars
   // Promote any localized global vars.
   MPM.add(createPromoteMemoryToRegisterPass());
 
   MPM.add(createDeadArgEliminationPass()); // Dead argument elimination
 
-  addInstructionCombiningPass(MPM); // Clean up after IPCP & DAE
+  MPM.add(createInstructionCombiningPass()); // Clean up after IPCP & DAE
   addExtensionsToPM(EP_Peephole, MPM);
   MPM.add(createCFGSimplificationPass()); // Clean up after IPCP & DAE
 
   // For SamplePGO in ThinLTO compile phase, we do not want to do indirect
   // call promotion as it will change the CFG too much to make the 2nd
   // profile annotation in backend more difficult.
   // PGO instrumentation is added during the compile phase for ThinLTO, do
   // not run it a second time
void PassManagerBuilder::populateModulePassManager(
   // of the current iteration.
   MPM.add(createLoopLoadEliminationPass());
 
   // FIXME: Because of #pragma vectorize enable, the passes below are always
   // inserted in the pipeline, even when the vectorizer doesn't run (ex. when
   // on -O1 and no #pragma is found). Would be good to have these two passes
   // as function calls, so that we can only pass them when the vectorizer
   // changed the code.
-  addInstructionCombiningPass(MPM);
+  MPM.add(createInstructionCombiningPass());
   if (OptLevel > 1 && ExtraVectorizerPasses) {
     // At higher optimization levels, try to clean up any runtime overlap and
     // alignment checks inserted by the vectorizer. We want to track correllated
     // runtime checks for two inner loops in the same outer loop, fold any
     // common computations, hoist loop-invariant aspects out of any outer loop,
     // and unswitch the runtime checks if possible. Once hoisted, we may have
     // dead (or speculatable) control flows or more combining opportunities.
     MPM.add(createCorrelatedValuePropagationPass());
-    addInstructionCombiningPass(MPM);
+    MPM.add(createInstructionCombiningPass());
     MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
     MPM.add(createLoopUnswitchPass(SizeLevel || OptLevel < 3, DivergentTarget));
     MPM.add(createCFGSimplificationPass());
-    addInstructionCombiningPass(MPM);
+    MPM.add(createInstructionCombiningPass());
   }
 
   // Cleanup after loop vectorization, etc. Simplification passes like CVP and
   // GVN, loop transforms, and others have already run, so it's now better to
   // convert to more optimized IR using more aggressive simplify CFG options.
   // The extra sinking transform can create larger basic blocks, so do this
   // before SLP vectorization.
   MPM.add(createCFGSimplificationPass(1, true, true, false, true));
 
   if (SLPVectorize) {
     MPM.add(createSLPVectorizerPass()); // Vectorize parallel scalar chains.
     if (OptLevel > 1 && ExtraVectorizerPasses) {
       MPM.add(createEarlyCSEPass());
     }
   }
 
   addExtensionsToPM(EP_Peephole, MPM);
-  addInstructionCombiningPass(MPM);
+  MPM.add(createInstructionCombiningPass());
 
   if (EnableUnrollAndJam && !DisableUnrollLoops) {
     // Unroll and Jam. We do this before unroll but need to be in a separate
     // loop pass manager in order for the outer loop to be processed by
     // unroll and jam before the inner loop is unrolled.
     MPM.add(createLoopUnrollAndJamPass(OptLevel));
   }
 
   // Unroll small loops
   MPM.add(createLoopUnrollPass(OptLevel, DisableUnrollLoops,
                                ForgetAllSCEVInLoopUnroll));
 
   if (!DisableUnrollLoops) {
     // LoopUnroll may generate some redundency to cleanup.
-    addInstructionCombiningPass(MPM);
+    MPM.add(createInstructionCombiningPass());
 
     // Runtime unrolling will introduce runtime check in loop prologue. If the
     // unrolled loop is a inner loop, then the prologue will be inside the
     // outer loop. LICM pass can help to promote the runtime check out if the
     // checked value is loop invariant.
     MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap));
   }
 
void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
   PM.add(createDeadArgEliminationPass());
 
   // Reduce the code after globalopt and ipsccp.  Both can open up significant
   // simplification opportunities, and both can propagate functions through
   // function pointers.  When this happens, we often have to resolve varargs
   // calls, etc, so let instcombine do this.
   if (OptLevel > 2)
     PM.add(createAggressiveInstCombinerPass());
-  addInstructionCombiningPass(PM);
+  PM.add(createInstructionCombiningPass());
   addExtensionsToPM(EP_Peephole, PM);
 
   // Inline small functions
   bool RunInliner = Inliner;
   if (RunInliner) {
     PM.add(Inliner);
     Inliner = nullptr;
   }
if (RunInliner)
     PM.add(createGlobalOptimizerPass());
   PM.add(createGlobalDCEPass()); // Remove dead functions.
 
   // If we didn't decide to inline a function, check to see if we can
   // transform it to pass arguments by value instead of by reference.
   PM.add(createArgumentPromotionPass());
 
   // The IPO passes may leave cruft around.  Clean up after them.
-  addInstructionCombiningPass(PM);
+  PM.add(createInstructionCombiningPass());
   addExtensionsToPM(EP_Peephole, PM);
   PM.add(createJumpThreadingPass());
 
   // Break up allocas
   PM.add(createSROAPass());
 
   // LTO provides additional opportunities for tailcall elimination due to
   // link-time inlining, and visibility of nocapture attribute.
PM.add(createLoopUnrollPass(OptLevel, DisableUnrollLoops,
                               ForgetAllSCEVInLoopUnroll));
 
   PM.add(createWarnMissedTransformationsPass());
 
   // Now that we've optimized loops (in particular loop induction variables),
   // we may have exposed more scalar opportunities. Run parts of the scalar
   // optimizer again at this point.
   PM.add(createVectorCombinePass());
-  addInstructionCombiningPass(PM); // Initial cleanup
+  PM.add(createInstructionCombiningPass()); // Initial cleanup
   PM.add(createCFGSimplificationPass()); // if-convert
   PM.add(createSCCPPass()); // Propagate exposed constants
-  addInstructionCombiningPass(PM); // Clean up again
+  PM.add(createInstructionCombiningPass()); // Clean up again
   PM.add(createBitTrackingDCEPass());
 
   // More scalar chains could be vectorized due to more alias information
   if (SLPVectorize) {
     PM.add(createSLPVectorizerPass()); // Vectorize parallel scalar chains.
     PM.add(createVectorCombinePass()); // Clean up partial vectorization.
   }
 
   // After vectorization, assume intrinsics may tell us more about pointer
   // alignments.
   PM.add(createAlignmentFromAssumptionsPass());
 
   // Cleanup and simplify the code after the scalar optimizations.
-  addInstructionCombiningPass(PM);
+  PM.add(createInstructionCombiningPass());
   addExtensionsToPM(EP_Peephole, PM);
 
   PM.add(createJumpThreadingPass());
 }
 
 void PassManagerBuilder::addLateLTOOptimizationPasses(
     legacy::PassManagerBase &PM) {
   // See comment in the new PM for justification of scheduling splitting at

lib/Transforms/InstCombine/InstCombineInternal.h

public:
   /// worklist.
   using BuilderTy = IRBuilder<TargetFolder, IRBuilderCallbackInserter>;
   BuilderTy &Builder;
 
 private:
   // Mode in which we are running the combiner.
   const bool MinimizeSize;
 
-  /// Enable combines that trigger rarely but are costly in compiletime.
-  const bool ExpensiveCombines;
-
   AliasAnalysis *AA;
 
   // Required analyses.
   AssumptionCache &AC;
   TargetLibraryInfo &TLI;
   DominatorTree &DT;
   const DataLayout &DL;
   const SimplifyQuery SQ;
   OptimizationRemarkEmitter &ORE;
   BlockFrequencyInfo *BFI;
   ProfileSummaryInfo *PSI;
 
   // Optional analyses. When non-null, these can both be used to do better
   // combining and will be updated to reflect any changes.
   LoopInfo *LI;
 
   bool MadeIRChange = false;
 
 public:
   InstCombiner(InstCombineWorklist &Worklist, BuilderTy &Builder,
-               bool MinimizeSize, bool ExpensiveCombines, AliasAnalysis *AA,
+               bool MinimizeSize, AliasAnalysis *AA,
                AssumptionCache &AC, TargetLibraryInfo &TLI, DominatorTree &DT,
                OptimizationRemarkEmitter &ORE, BlockFrequencyInfo *BFI,
                ProfileSummaryInfo *PSI, const DataLayout &DL, LoopInfo *LI)
       : Worklist(Worklist), Builder(Builder), MinimizeSize(MinimizeSize),
-        ExpensiveCombines(ExpensiveCombines), AA(AA), AC(AC), TLI(TLI), DT(DT),
+        AA(AA), AC(AC), TLI(TLI), DT(DT),
         DL(DL), SQ(DL, &TLI, &DT, &AC), ORE(ORE), BFI(BFI), PSI(PSI), LI(LI) {}
 
   /// Run the combiner over the entire worklist until it is empty.
   ///
   /// \returns true if the IR is changed.
   bool run();
 
   AssumptionCache &getAssumptionCache() const { return AC; }

lib/Transforms/InstCombine/InstructionCombining.cpp

 
 static constexpr unsigned InstCombineDefaultMaxIterations = 1000;
 static constexpr unsigned InstCombineDefaultInfiniteLoopThreshold = 1000;
 
 static cl::opt<bool>
 EnableCodeSinking("instcombine-code-sinking", cl::desc("Enable code sinking"),
                                               cl::init(true));
 
-// FIXME: This option is no longer used for anything and may be removed.
-static cl::opt<bool>
-EnableExpensiveCombines("expensive-combines",
-                        cl::desc("Enable expensive instruction combines"));
-
 static cl::opt<unsigned> LimitMaxIterations(
     "instcombine-max-iterations",
     cl::desc("Limit the maximum number of instruction combining iterations"),
     cl::init(InstCombineDefaultMaxIterations));
 
 static cl::opt<unsigned> InfiniteLoopDetectionThreshold(
     "instcombine-infinite-loop-threshold",
     cl::desc("Number of instruction combining iterations considered an "
static bool prepareICWorklistFromFunction(Function &F, const DataLayout &DL,
 
   return MadeIRChange;
 }
 
 static bool combineInstructionsOverFunction(
     Function &F, InstCombineWorklist &Worklist, AliasAnalysis *AA,
     AssumptionCache &AC, TargetLibraryInfo &TLI, DominatorTree &DT,
     OptimizationRemarkEmitter &ORE, BlockFrequencyInfo *BFI,
-    ProfileSummaryInfo *PSI, bool ExpensiveCombines, unsigned MaxIterations,
-    LoopInfo *LI) {
+    ProfileSummaryInfo *PSI, unsigned MaxIterations, LoopInfo *LI) {
   auto &DL = F.getParent()->getDataLayout();
-  if (EnableExpensiveCombines.getNumOccurrences())
-    ExpensiveCombines = EnableExpensiveCombines;
   MaxIterations = std::min(MaxIterations, LimitMaxIterations.getValue());
 
   /// Builder - This is an IRBuilder that automatically inserts new
   /// instructions into the worklist when they are created.
   IRBuilder<TargetFolder, IRBuilderCallbackInserter> Builder(
       F.getContext(), TargetFolder(DL),
       IRBuilderCallbackInserter([&Worklist, &AC](Instruction *I) {
         Worklist.add(I);
if (Iteration > MaxIterations) {
       break;
     }
 
     LLVM_DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
                       << F.getName() << "\n");
 
     MadeIRChange |= prepareICWorklistFromFunction(F, DL, &TLI, Worklist);
 
-    InstCombiner IC(Worklist, Builder, F.hasMinSize(), ExpensiveCombines, AA,
+    InstCombiner IC(Worklist, Builder, F.hasMinSize(), AA,
                     AC, TLI, DT, ORE, BFI, PSI, DL, LI);
     IC.MaxArraySizeForCombine = MaxArraySize;
 
     if (!IC.run())
       break;
 
     MadeIRChange = true;
   }
 
   return MadeIRChange;
 }
 
-InstCombinePass::InstCombinePass(bool ExpensiveCombines)
-    : ExpensiveCombines(ExpensiveCombines), MaxIterations(LimitMaxIterations) {}
+InstCombinePass::InstCombinePass() : MaxIterations(LimitMaxIterations) {}
 
-InstCombinePass::InstCombinePass(bool ExpensiveCombines, unsigned MaxIterations)
-    : ExpensiveCombines(ExpensiveCombines), MaxIterations(MaxIterations) {}
+InstCombinePass::InstCombinePass(unsigned MaxIterations)
+    : MaxIterations(MaxIterations) {}
 
 PreservedAnalyses InstCombinePass::run(Function &F,
                                        FunctionAnalysisManager &AM) {
   auto &AC = AM.getResult<AssumptionAnalysis>(F);
   auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
   auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
   auto &ORE = AM.getResult<OptimizationRemarkEmitterAnalysis>(F);
 
   auto *LI = AM.getCachedResult<LoopAnalysis>(F);
 
   auto *AA = &AM.getResult<AAManager>(F);
   const ModuleAnalysisManager &MAM =
       AM.getResult<ModuleAnalysisManagerFunctionProxy>(F).getManager();
   ProfileSummaryInfo *PSI =
       MAM.getCachedResult<ProfileSummaryAnalysis>(*F.getParent());
   auto *BFI = (PSI && PSI->hasProfileSummary()) ?
       &AM.getResult<BlockFrequencyAnalysis>(F) : nullptr;
 
   if (!combineInstructionsOverFunction(F, Worklist, AA, AC, TLI, DT, ORE, BFI,
-                                       PSI, ExpensiveCombines, MaxIterations,
-                                       LI))
+                                       PSI, MaxIterations, LI))
     // No changes, all analyses are preserved.
     return PreservedAnalyses::all();
 
   // Mark all the analyses that instcombine updates as preserved.
   PreservedAnalyses PA;
   PA.preserveSet<CFGAnalyses>();
   PA.preserve<AAManager>();
   PA.preserve<BasicAA>();
bool InstructionCombiningPass::runOnFunction(Function &F) {
   ProfileSummaryInfo *PSI =
       &getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
   BlockFrequencyInfo *BFI =
       (PSI && PSI->hasProfileSummary()) ?
       &getAnalysis<LazyBlockFrequencyInfoPass>().getBFI() :
       nullptr;
 
   return combineInstructionsOverFunction(F, Worklist, AA, AC, TLI, DT, ORE, BFI,
-                                         PSI, ExpensiveCombines, MaxIterations,
-                                         LI);
+                                         PSI, MaxIterations, LI);
 }
 
 char InstructionCombiningPass::ID = 0;
 
-InstructionCombiningPass::InstructionCombiningPass(bool ExpensiveCombines)
-    : FunctionPass(ID), ExpensiveCombines(ExpensiveCombines),
-      MaxIterations(InstCombineDefaultMaxIterations) {
+InstructionCombiningPass::InstructionCombiningPass()
+    : FunctionPass(ID), MaxIterations(InstCombineDefaultMaxIterations) {
   initializeInstructionCombiningPassPass(*PassRegistry::getPassRegistry());
 }
 
-InstructionCombiningPass::InstructionCombiningPass(bool ExpensiveCombines,
-                                                   unsigned MaxIterations)
-    : FunctionPass(ID), ExpensiveCombines(ExpensiveCombines),
-      MaxIterations(MaxIterations) {
+InstructionCombiningPass::InstructionCombiningPass(unsigned MaxIterations)
+    : FunctionPass(ID), MaxIterations(MaxIterations) {
   initializeInstructionCombiningPassPass(*PassRegistry::getPassRegistry());
 }
 
 INITIALIZE_PASS_BEGIN(InstructionCombiningPass, "instcombine",
                       "Combine redundant instructions", false, false)
 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)

 void llvm::initializeInstCombine(PassRegistry &Registry) {
   initializeInstructionCombiningPassPass(Registry);
 }
 
 void LLVMInitializeInstCombine(LLVMPassRegistryRef R) {
   initializeInstructionCombiningPassPass(*unwrap(R));
 }
 
-FunctionPass *llvm::createInstructionCombiningPass(bool ExpensiveCombines) {
-  return new InstructionCombiningPass(ExpensiveCombines);
+FunctionPass *llvm::createInstructionCombiningPass() {
+  return new InstructionCombiningPass();
 }
 
-FunctionPass *llvm::createInstructionCombiningPass(bool ExpensiveCombines,
-                                                   unsigned MaxIterations) {
-  return new InstructionCombiningPass(ExpensiveCombines, MaxIterations);
+FunctionPass *llvm::createInstructionCombiningPass(unsigned MaxIterations) {
+  return new InstructionCombiningPass(MaxIterations);
 }
 
 void LLVMAddInstructionCombiningPass(LLVMPassManagerRef PM) {
   unwrap(PM)->add(createInstructionCombiningPass());
 }

test/Transforms/InstCombine/all-bits-shift.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -instcombine -expensive-combines=0 < %s | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-OFF
-; RUN: opt -S -instcombine -expensive-combines=1 < %s | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-ON
+; RUN: opt -S -instcombine < %s | FileCheck %s
 target datalayout = "E-m:e-i64:64-n32:64"
 target triple = "powerpc64-unknown-linux-gnu"
 
 @d = global i32 15, align 4
 @b = global i32* @d, align 8
 @a = common global i32 0, align 4
 
 ; Check that both InstCombine and InstSimplify can use computeKnownBits to

test/Transforms/InstCombine/assume.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -instcombine -S | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-ON
-; RUN: opt < %s -instcombine -expensive-combines=0 -S | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-OFF
+; RUN: opt < %s -instcombine -S | FileCheck %s
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 define i32 @foo1(i32* %a) #0 {
 ; CHECK-LABEL: @foo1(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[TMP0:%.*]] = load i32, i32* [[A:%.*]], align 32
 ; CHECK-NEXT:    [[PTRINT:%.*]] = ptrtoint i32* [[A]] to i64

test/Transforms/InstCombine/call-returned.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -instcombine -expensive-combines=0 < %s | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-OFF
-; RUN: opt -S -instcombine -expensive-combines=1 < %s | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-ON
+; RUN: opt -S -instcombine < %s | FileCheck %s
 
 declare i32 @passthru_i32(i32 returned)
 declare i8* @passthru_p8(i8* returned)
 
 define i32 @returned_const_int_arg() {
 ; CHECK-LABEL: @returned_const_int_arg(
 ; CHECK-NEXT:    [[X:%.*]] = call i32 @passthru_i32(i32 42)
 ; CHECK-NEXT:    ret i32 42

test/Transforms/InstCombine/expensive-combines.ll

-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -instcombine < %s | FileCheck %s --check-prefix=DEFAULT
-; RUN: opt -S -instcombine -expensive-combines=1 < %s | FileCheck %s --check-prefix=EXPENSIVE-ON
-; RUN: opt -S -instcombine -expensive-combines=0 < %s | FileCheck %s --check-prefix=EXPENSIVE-OFF
-
-define void @test() {
-; DEFAULT-LABEL: @test(
-; DEFAULT-NEXT:    [[CALL:%.*]] = call i32 @passthru(i32 0)
-; DEFAULT-NEXT:    call void @sink(i32 0)
-; DEFAULT-NEXT:    ret void
-;
-; EXPENSIVE-ON-LABEL: @test(
-; EXPENSIVE-ON-NEXT:    [[CALL:%.*]] = call i32 @passthru(i32 0)
-; EXPENSIVE-ON-NEXT:    call void @sink(i32 0)
-; EXPENSIVE-ON-NEXT:    ret void
-;
-; EXPENSIVE-OFF-LABEL: @test(
-; EXPENSIVE-OFF-NEXT:    [[CALL:%.*]] = call i32 @passthru(i32 0)
-; EXPENSIVE-OFF-NEXT:    call void @sink(i32 0)
-; EXPENSIVE-OFF-NEXT:    ret void
-;
-  %call = call i32 @passthru(i32 0)
-  call void @sink(i32 %call)
-  ret void
-}
-
-declare i32 @passthru(i32 returned)
-declare void @sink(i32)

test/Transforms/InstCombine/known-bits.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -instcombine -expensive-combines=0 < %s | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-OFF
-; RUN: opt -S -instcombine -expensive-combines=1 < %s | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-ON
+; RUN: opt -S -instcombine < %s | FileCheck %s
 
 define void @test_shl(i1 %x) {
 ; CHECK-LABEL: @test_shl(
 ; CHECK-NEXT:    call void @sink(i8 0)
 ; CHECK-NEXT:    ret void
 ;
   %y = zext i1 %x to i8
   %z = shl i8 64, %y

test/Transforms/InstCombine/known-signbit-shift.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -instcombine -expensive-combines=0 -S | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-OFF
-; RUN: opt < %s -instcombine -expensive-combines=1 -S | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-ON
+; RUN: opt < %s -instcombine -S | FileCheck %s
 
 ; Result of left shifting a non-negative integer
 ; with nsw flag should also be non-negative
 define i1 @test_shift_nonnegative(i32 %a) {
 ; CHECK-LABEL: @test_shift_nonnegative(
 ; CHECK-NEXT:    ret i1 true
 ;
   %b = lshr i32 %a, 2

test/Transforms/InstCombine/out-of-bounds-indexes.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -instcombine -expensive-combines=0 < %s | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-OFF
-; RUN: opt -S -instcombine -expensive-combines=1 < %s | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-ON
+; RUN: opt -S -instcombine < %s | FileCheck %s
 ; Check that we don't crash on unreasonable constant indexes
 
 define i32 @test_out_of_bounds(i32 %a, i1 %x, i1 %y) {
 ; CHECK-LABEL: @test_out_of_bounds(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[AND1:%.*]] = and i32 [[A:%.*]], 3
 ; CHECK-NEXT:    tail call void @llvm.assume(i1 undef)
 ; CHECK-NEXT:    ret i32 [[AND1]]

test/Transforms/InstCombine/phi-shifts.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -instcombine -expensive-combines=0 < %s | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-OFF
-; RUN: opt -S -instcombine -expensive-combines=1 < %s | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-ON
+; RUN: opt -S -instcombine < %s | FileCheck %s
 
 ; OSS Fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15217
 define i64 @fuzz15217(i1 %cond, i8* %Ptr, i64 %Val) {
 ; CHECK-LABEL: @fuzz15217(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br i1 [[COND:%.*]], label [[END:%.*]], label [[TWO:%.*]]
 ; CHECK:       two:
 ; CHECK-NEXT:    br label [[END]]

test/Transforms/InstCombine/pr44541.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -instcombine -expensive-combines=0 -instcombine-infinite-loop-threshold=2 < %s | FileCheck %s
+; RUN: opt -S -instcombine -instcombine-infinite-loop-threshold=2 < %s | FileCheck %s
 
 ; This test used to cause an infinite combine loop.
 
 define i16 @passthru(i16 returned %x) {
 ; CHECK-LABEL: @passthru(
 ; CHECK-NEXT:    ret i16 [[X:%.*]]
 ;
   ret i16 %x