[NFC][TableGen] Use ArrayRef instead of const vector reference

llvm/include/llvm/CodeGen/SelectionDAGISel.h

@@ -435,9 +435,9 @@ class SelectionDAGISel {
   /// It runs node predicate number PredNo and returns true if it succeeds or
   /// false if it fails.  The number is a private implementation detail to the
   /// code tblgen produces.
-  virtual bool CheckNodePredicateWithOperands(
-      SDValue Op, unsigned PredNo,
-      const SmallVectorImpl<SDValue> &Operands) const {
+  virtual bool
+  CheckNodePredicateWithOperands(SDValue Op, unsigned PredNo,
+                                 ArrayRef<SDValue> Operands) const {
     llvm_unreachable("Tblgen should generate the implementation of this!");
   }
 

llvm/lib/TableGen/StringMatcher.cpp

@@ -11,7 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/TableGen/StringMatcher.h"
-#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cassert>
@@ -23,14 +23,15 @@
 using namespace llvm;
 
 /// FindFirstNonCommonLetter - Find the first character in the keys of the
-/// string pairs that is not shared across the whole set of strings.  All
+/// string pairs that is not shared across the whole set of strings. All
 /// strings are assumed to have the same length.
 static unsigned
 FindFirstNonCommonLetter(ArrayRef<const StringMatcher::StringPair *> Matches) {
   assert(!Matches.empty());
   for (auto [Idx, Letter] : enumerate(Matches[0]->first)) {
-    // Check to see if `Letter` is the same across the set.
-    for (const StringMatcher::StringPair *Match : Matches)
+    // Check to see if `Letter` is the same across the set. Since the letter is
+    // from `Matches[0]`, we can skip `Matches[0]` in the loop below.
+    for (const StringMatcher::StringPair *Match : Matches.drop_front())
       if (Match->first[Idx] != Letter)
         return Idx;
   }

llvm/lib/TableGen/StringToOffsetTable.cpp

@@ -44,8 +44,8 @@ void StringToOffsetTable::EmitStringTableDef(raw_ostream &OS, const Twine &Name,
   bool UseChars = !EmitLongStrLiterals && AggregateString.size() > (64 * 1024);
   OS << (UseChars ? "{\n" : "\n");
 
-  llvm::ListSeparator LineSep(UseChars ? ",\n" : "\n");
-  llvm::SmallVector<StringRef> Strings(split(AggregateString, '\0'));
+  ListSeparator LineSep(UseChars ? ",\n" : "\n");
+  SmallVector<StringRef> Strings(split(AggregateString, '\0'));
   // We should always have an empty string at the start, and because these are
   // null terminators rather than separators, we'll have one at the end as
   // well. Skip the end one.
@@ -63,7 +63,7 @@ void StringToOffsetTable::EmitStringTableDef(raw_ostream &OS, const Twine &Name,
       continue;
     }
 
-    llvm::ListSeparator CharSep(", ");
+    ListSeparator CharSep(", ");
     for (char C : Str) {
       OS << CharSep << "'";
       OS.write_escaped(StringRef(&C, 1));

llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp

@@ -3187,7 +3187,7 @@ bool TreePattern::InferAllTypes(
           return true;
         }
 
-        const SmallVectorImpl<TreePatternNode *> &InNodes = InIter->second;
+        ArrayRef<TreePatternNode *> InNodes = InIter->second;
 
         // The input types should be fully resolved by now.
         for (TreePatternNode *Node : Nodes) {

llvm/utils/TableGen/Common/CodeGenSchedule.cpp

@@ -1292,8 +1292,8 @@ class PredTransitions {
 
   PredTransitions(CodeGenSchedModels &sm) : SchedModels(sm) {}
 
-  bool substituteVariantOperand(const SmallVectorImpl<unsigned> &RWSeq,
-                                bool IsRead, unsigned StartIdx);
+  bool substituteVariantOperand(ArrayRef<unsigned> RWSeq, bool IsRead,
+                                unsigned StartIdx);
 
   bool substituteVariants(const PredTransition &Trans);
 
@@ -1526,8 +1526,8 @@ void PredTransitions::pushVariant(const TransVariant &VInfo, bool IsRead) {
 // operand. StartIdx is an index into TransVec where partial results
 // starts. RWSeq must be applied to all transitions between StartIdx and the end
 // of TransVec.
-bool PredTransitions::substituteVariantOperand(
-    const SmallVectorImpl<unsigned> &RWSeq, bool IsRead, unsigned StartIdx) {
+bool PredTransitions::substituteVariantOperand(ArrayRef<unsigned> RWSeq,
+                                               bool IsRead, unsigned StartIdx) {
   bool Subst = false;
   // Visit each original RW within the current sequence.
   for (unsigned int RWI : RWSeq) {
@@ -1591,7 +1591,7 @@ bool PredTransitions::substituteVariants(const PredTransition &Trans) {
 }
 
 static void addSequences(CodeGenSchedModels &SchedModels,
-                         const SmallVectorImpl<SmallVector<unsigned, 4>> &Seqs,
+                         ArrayRef<SmallVector<unsigned, 4>> Seqs,
                          IdxVec &Result, bool IsRead) {
   for (const auto &S : Seqs)
     if (!S.empty())

llvm/utils/TableGen/DAGISelMatcherEmitter.cpp

@@ -1158,7 +1158,7 @@ void MatcherTableEmitter::EmitPredicateFunctions(raw_ostream &OS) {
   EmitNodePredicatesFunction(
       NodePredicatesWithOperands,
       "CheckNodePredicateWithOperands(SDValue Op, unsigned PredNo, "
-      "const SmallVectorImpl<SDValue> &Operands) const",
+      "ArrayRef<SDValue> Operands) const",
       OS);
 
   // Emit CompletePattern matchers.

llvm/utils/TableGen/DAGISelMatcherOpt.cpp

@@ -282,8 +282,8 @@ static void ContractNodes(std::unique_ptr<Matcher> &InputMatcherPtr,
 #endif
 
         if (ResultsMatch) {
-          const SmallVectorImpl<MVT::SimpleValueType> &VTs = EN->getVTList();
-          const SmallVectorImpl<unsigned> &Operands = EN->getOperandList();
+          ArrayRef<MVT::SimpleValueType> VTs = EN->getVTList();
+          ArrayRef<unsigned> Operands = EN->getOperandList();
           MatcherPtr->reset(new MorphNodeToMatcher(
               EN->getInstruction(), VTs, Operands, EN->hasChain(),
               EN->hasInGlue(), EN->hasOutGlue(), EN->hasMemRefs(),