[LoopVectorize] Rename pass options. NFC.

[Meinersbur]

Summary

Rename:
NoUnrolling to InterleaveOnlyWhenForced
and
AlwaysVectorize to !VectorizeOnlyWhenForced

Contrary to what the name 'AlwaysVectorize' suggests, it does not unconditionally vectorize all loops, but applies a cost model to determine whether vectorization is profitable to all loops. Hence, passing false will disable the cost model, except when a loop is marked with llvm.loop.vectorize.enable. The 'OnlyWhenForced' suffix (suggested by @hfinkel in D55716) better matches this behavior.

Similarly, 'NoUnrolling' disables the profitability cost model for interleaving (a term to distinguish it from unrolling by the LoopUnrollPass); rename it for consistency.

Note that LoopVectorize'rs vectorize and interleaving transformations are not entirely independent. For instance, {!"llvm.loop.vectorize.enable", i32 0} disables interleaving as well.

[hfinkel]

LGTM. Thanks, I think this naming is more accurate and useful.

[Meinersbur]

• Rebase after commit of D55716

include/llvm/Transforms/Vectorize.h

struct VectorizeConfig {
   /// Initialize the VectorizeConfig from command line options.
   VectorizeConfig();
 };
 
 //===----------------------------------------------------------------------===//
 //
 // LoopVectorize - Create a loop vectorization pass.
 //
-Pass *createLoopVectorizePass(bool NoUnrolling = false,
-                              bool AlwaysVectorize = true);
+Pass *createLoopVectorizePass(bool InterleaveOnlyWhenForced = false,
+                              bool VectorizeOnlyWhenForced = false);
 
 //===----------------------------------------------------------------------===//
 //
 // SLPVectorizer - Create a bottom-up SLP vectorizer pass.
 //
 Pass *createSLPVectorizerPass();
 
 //===----------------------------------------------------------------------===//

include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h

 
 public:
   enum ForceKind {
     FK_Undefined = -1, ///< Not selected.
     FK_Disabled = 0,   ///< Forcing disabled.
     FK_Enabled = 1,    ///< Forcing enabled.
   };
 
-  LoopVectorizeHints(const Loop *L, bool DisableInterleaving,
+  LoopVectorizeHints(const Loop *L, bool InterleaveOnlyWhenForced,
                      OptimizationRemarkEmitter &ORE);
 
   /// Mark the loop L as already vectorized by setting the width to 1.
   void setAlreadyVectorized() {
     IsVectorized.Value = 1;
     Hint Hints[] = {IsVectorized};
     writeHintsToMetadata(Hints);
   }
 
-  bool allowVectorization(Function *F, Loop *L, bool AlwaysVectorize) const;
+  bool allowVectorization(Function *F, Loop *L,
+                          bool VectorizeOnlyWhenForced) const;
 
   /// Dumps all the hint information.
   void emitRemarkWithHints() const;
 
   unsigned getWidth() const { return Width.Value; }
   unsigned getInterleave() const { return Interleave.Value; }
   unsigned getIsVectorized() const { return IsVectorized.Value; }
   enum ForceKind getForce() const {

include/llvm/Transforms/Vectorize/LoopVectorize.h

 class LoopInfo;
 class OptimizationRemarkEmitter;
 class ScalarEvolution;
 class TargetLibraryInfo;
 class TargetTransformInfo;
 
 /// The LoopVectorize Pass.
 struct LoopVectorizePass : public PassInfoMixin<LoopVectorizePass> {
-  bool DisableUnrolling = false;
-
-  /// If true, consider all loops for vectorization.
-  /// If false, only loops that explicitly request vectorization are
-  /// considered.
-  bool AlwaysVectorize = true;
+  /// If false, consider all loops for interleaving.
+  /// If true, only loops that explicitly request interleaving are considered.
+  bool InterleaveOnlyWhenForced = false;
+
+  /// If false, consider all loops for vectorization.
+  /// If true, only loops that explicitly request vectorization are considered.
+  bool VectorizeOnlyWhenForced = false;
 
   ScalarEvolution *SE;
   LoopInfo *LI;
   TargetTransformInfo *TTI;
   DominatorTree *DT;
   BlockFrequencyInfo *BFI;
   TargetLibraryInfo *TLI;
   DemandedBits *DB;

lib/Transforms/IPO/PassManagerBuilder.cpp

void PassManagerBuilder::populateModulePassManager(
   MPM.add(createLoopRotatePass(SizeLevel == 2 ? 0 : -1));
 
   // Distribute loops to allow partial vectorization.  I.e. isolate dependences
   // into separate loop that would otherwise inhibit vectorization.  This is
   // currently only performed for loops marked with the metadata
   // llvm.loop.distribute=true or when -enable-loop-distribute is specified.
   MPM.add(createLoopDistributePass());
 
-  MPM.add(createLoopVectorizePass(DisableUnrollLoops, LoopVectorize));
+  MPM.add(createLoopVectorizePass(DisableUnrollLoops, !LoopVectorize));
 
   // Eliminate loads by forwarding stores from the previous iteration to loads
   // 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
void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
   // More loops are countable; try to optimize them.
   PM.add(createIndVarSimplifyPass());
   PM.add(createLoopDeletionPass());
   if (EnableLoopInterchange)
     PM.add(createLoopInterchangePass());
 
   if (!DisableUnrollLoops)
     PM.add(createSimpleLoopUnrollPass(OptLevel));   // Unroll small loops
-  PM.add(createLoopVectorizePass(true, LoopVectorize));
+  PM.add(createLoopVectorizePass(true, !LoopVectorize));
   // The vectorizer may have significantly shortened a loop body; unroll again.
   if (!DisableUnrollLoops)
     PM.add(createLoopUnrollPass(OptLevel));
 
   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

lib/Transforms/Vectorize/LoopVectorizationLegality.cpp

bool LoopVectorizeHints::Hint::validate(unsigned Val) {
   case HK_FORCE:
     return (Val <= 1);
   case HK_ISVECTORIZED:
     return (Val == 0 || Val == 1);
   }
   return false;
 }
 
-LoopVectorizeHints::LoopVectorizeHints(const Loop *L, bool DisableInterleaving,
+LoopVectorizeHints::LoopVectorizeHints(const Loop *L,
+                                       bool InterleaveOnlyWhenForced,
                                        OptimizationRemarkEmitter &ORE)
     : Width("vectorize.width", VectorizerParams::VectorizationFactor, HK_WIDTH),
-      Interleave("interleave.count", DisableInterleaving, HK_UNROLL),
+      Interleave("interleave.count", InterleaveOnlyWhenForced, HK_UNROLL),
       Force("vectorize.enable", FK_Undefined, HK_FORCE),
       IsVectorized("isvectorized", 0, HK_ISVECTORIZED), TheLoop(L), ORE(ORE) {
   // Populate values with existing loop metadata.
   getHintsFromMetadata();
 
   // force-vector-interleave overrides DisableInterleaving.
   if (VectorizerParams::isInterleaveForced())
     Interleave.Value = VectorizerParams::VectorizationInterleave;
 
   if (IsVectorized.Value != 1)
     // If the vectorization width and interleaving count are both 1 then
     // consider the loop to have been already vectorized because there's
     // nothing more that we can do.
     IsVectorized.Value = Width.Value == 1 && Interleave.Value == 1;
-  LLVM_DEBUG(if (DisableInterleaving && Interleave.Value == 1) dbgs()
+  LLVM_DEBUG(if (InterleaveOnlyWhenForced && Interleave.Value == 1) dbgs()
              << "LV: Interleaving disabled by the pass manager\n");
 }
 
-bool LoopVectorizeHints::allowVectorization(Function *F, Loop *L,
-                                            bool AlwaysVectorize) const {
+bool LoopVectorizeHints::allowVectorization(
+    Function *F, Loop *L, bool VectorizeOnlyWhenForced) const {
   if (getForce() == LoopVectorizeHints::FK_Disabled) {
     LLVM_DEBUG(dbgs() << "LV: Not vectorizing: #pragma vectorize disable.\n");
     emitRemarkWithHints();
     return false;
   }
 
-  if (!AlwaysVectorize && getForce() != LoopVectorizeHints::FK_Enabled) {
+  if (VectorizeOnlyWhenForced && getForce() != LoopVectorizeHints::FK_Enabled) {
     LLVM_DEBUG(dbgs() << "LV: Not vectorizing: No #pragma vectorize enable.\n");
     emitRemarkWithHints();
     return false;
   }
 
   if (getIsVectorized() == 1) {
     LLVM_DEBUG(dbgs() << "LV: Not vectorizing: Disabled/already vectorized.\n");
     // FIXME: Add interleave.disable metadata. This will allow

lib/Transforms/Vectorize/LoopVectorize.cpp

static bool isExplicitVecOuterLoop(Loop *OuterLp,
   LoopVectorizeHints Hints(OuterLp, true /*DisableInterleaving*/, *ORE);
 
   // Only outer loops with an explicit vectorization hint are supported.
   // Unannotated outer loops are ignored.
   if (Hints.getForce() == LoopVectorizeHints::FK_Undefined)
     return false;
 
   Function *Fn = OuterLp->getHeader()->getParent();
-  if (!Hints.allowVectorization(Fn, OuterLp, false /*AlwaysVectorize*/)) {
+  if (!Hints.allowVectorization(Fn, OuterLp,
+                                true /*VectorizeOnlyWhenForced*/)) {
     LLVM_DEBUG(dbgs() << "LV: Loop hints prevent outer loop vectorization.\n");
     return false;
   }
 
   if (!Hints.getWidth()) {
     LLVM_DEBUG(dbgs() << "LV: Not vectorizing: No user vector width.\n");
     Hints.emitRemarkWithHints();
     return false;

 
 /// The LoopVectorize Pass.
 struct LoopVectorize : public FunctionPass {
   /// Pass identification, replacement for typeid
   static char ID;
 
   LoopVectorizePass Impl;
 
-  explicit LoopVectorize(bool NoUnrolling = false, bool AlwaysVectorize = true)
+  explicit LoopVectorize(bool InterleaveOnlyWhenForced = false,
+                         bool VectorizeOnlyWhenForced = false)
       : FunctionPass(ID) {
-    Impl.DisableUnrolling = NoUnrolling;
-    Impl.AlwaysVectorize = AlwaysVectorize;
+    Impl.InterleaveOnlyWhenForced = InterleaveOnlyWhenForced;
+    Impl.VectorizeOnlyWhenForced = VectorizeOnlyWhenForced;
     initializeLoopVectorizePass(*PassRegistry::getPassRegistry());
   }
 
   bool runOnFunction(Function &F) override {
     if (skipFunction(F))
       return false;
 
     auto *SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();

 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopAccessLegacyAnalysis)
 INITIALIZE_PASS_DEPENDENCY(DemandedBitsWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(OptimizationRemarkEmitterWrapperPass)
 INITIALIZE_PASS_END(LoopVectorize, LV_NAME, lv_name, false, false)
 
 namespace llvm {
 
-Pass *createLoopVectorizePass(bool NoUnrolling, bool AlwaysVectorize) {
-  return new LoopVectorize(NoUnrolling, AlwaysVectorize);
+Pass *createLoopVectorizePass(bool InterleaveOnlyWhenForced,
+                              bool VectorizeOnlyWhenForced) {
+  return new LoopVectorize(InterleaveOnlyWhenForced, VectorizeOnlyWhenForced);
 }
 
 } // end namespace llvm
 
 bool LoopVectorizationCostModel::isConsecutiveLoadOrStore(Instruction *Inst) {
   // Check if the pointer operand of a load or store instruction is
   // consecutive.
   if (auto *Ptr = getLoadStorePointerOperand(Inst))

 #ifndef NDEBUG
   const std::string DebugLocStr = getDebugLocString(L);
 #endif /* NDEBUG */
 
   LLVM_DEBUG(dbgs() << "\nLV: Checking a loop in \""
                     << L->getHeader()->getParent()->getName() << "\" from "
                     << DebugLocStr << "\n");
 
-  LoopVectorizeHints Hints(L, DisableUnrolling, *ORE);
+  LoopVectorizeHints Hints(L, InterleaveOnlyWhenForced, *ORE);
 
   LLVM_DEBUG(
       dbgs() << "LV: Loop hints:"
              << " force="
              << (Hints.getForce() == LoopVectorizeHints::FK_Disabled
                      ? "disabled"
                      : (Hints.getForce() == LoopVectorizeHints::FK_Enabled
                             ? "enabled"
                             : "?"))
              << " width=" << Hints.getWidth()
              << " unroll=" << Hints.getInterleave() << "\n");
 
   // Function containing loop
   Function *F = L->getHeader()->getParent();
 
   // Looking at the diagnostic output is the only way to determine if a loop
   // was vectorized (other than looking at the IR or machine code), so it
   // is important to generate an optimization remark for each loop. Most of
   // these messages are generated as OptimizationRemarkAnalysis. Remarks
   // generated as OptimizationRemark and OptimizationRemarkMissed are
   // less verbose reporting vectorized loops and unvectorized loops that may
   // benefit from vectorization, respectively.
 
-  if (!Hints.allowVectorization(F, L, AlwaysVectorize)) {
+  if (!Hints.allowVectorization(F, L, VectorizeOnlyWhenForced)) {
     LLVM_DEBUG(dbgs() << "LV: Loop hints prevent vectorization.\n");
     return false;
   }
 
   PredicatedScalarEvolution PSE(*SE, *L);
 
   // Check if it is legal to vectorize the loop.
   LoopVectorizationRequirements Requirements(*ORE);