[LLVM][TableGen] Change DAGISel code to use const RecordKeeper

[jurahul]

Change DAGISel code to use const RecordKeeper.

This is a part of effort to have better const correctness in TableGen backends:

https://discourse.llvm.org/t/psa-planned-changes-to-tablegen-getallderiveddefinitions-api-potential-downstream-breakages/81089

[llvmbot]

@llvm/pr-subscribers-llvm-selectiondag

Author: Rahul Joshi (jurahul)

Changes

Change DAGISel code to use const RecordKeeper.

This is a part of effort to have better const correctness in TableGen backends:

https://discourse.llvm.org/t/psa-planned-changes-to-tablegen-getallderiveddefinitions-api-potential-downstream-breakages/81089

---

Full diff: https://github.com/llvm/llvm-project/pull/109038.diff

2 Files Affected:

• (modified) llvm/utils/TableGen/DAGISelEmitter.cpp (+11-10)
• (modified) llvm/utils/TableGen/DAGISelMatcherGen.cpp (+10-10)

diff --git a/llvm/utils/TableGen/DAGISelEmitter.cpp b/llvm/utils/TableGen/DAGISelEmitter.cpp
index 6c72103f6251f5..c41afbf2dec40a 100644
--- a/llvm/utils/TableGen/DAGISelEmitter.cpp
+++ b/llvm/utils/TableGen/DAGISelEmitter.cpp
@@ -25,11 +25,11 @@ namespace {
 /// DAGISelEmitter - The top-level class which coordinates construction
 /// and emission of the instruction selector.
 class DAGISelEmitter {
-  RecordKeeper &Records; // Just so we can get at the timing functions.
-  CodeGenDAGPatterns CGP;
+  const RecordKeeper &Records; // Just so we can get at the timing functions.
+  const CodeGenDAGPatterns CGP;
 
 public:
-  explicit DAGISelEmitter(RecordKeeper &R) : Records(R), CGP(R) {}
+  explicit DAGISelEmitter(const RecordKeeper &R) : Records(R), CGP(R) {}
   void run(raw_ostream &OS);
 };
 } // End anonymous namespace
@@ -81,8 +81,8 @@ namespace {
 // In particular, we want to match maximal patterns first and lowest cost within
 // a particular complexity first.
 struct PatternSortingPredicate {
-  PatternSortingPredicate(CodeGenDAGPatterns &cgp) : CGP(cgp) {}
-  CodeGenDAGPatterns &CGP;
+  PatternSortingPredicate(const CodeGenDAGPatterns &cgp) : CGP(cgp) {}
+  const CodeGenDAGPatterns &CGP;
 
   bool operator()(const PatternToMatch *LHS, const PatternToMatch *RHS) {
     const TreePatternNode &LT = LHS->getSrcPattern();
@@ -132,7 +132,8 @@ struct PatternSortingPredicate {
 } // End anonymous namespace
 
 void DAGISelEmitter::run(raw_ostream &OS) {
-  Records.startTimer("Parse patterns");
+  RecordKeeper &MutableRC = const_cast<RecordKeeper &>(Records);
+  MutableRC.startTimer("Parse patterns");
   emitSourceFileHeader("DAG Instruction Selector for the " +
                            CGP.getTargetInfo().getName().str() + " target",
                        OS);
@@ -163,7 +164,7 @@ void DAGISelEmitter::run(raw_ostream &OS) {
              });
 
   // Add all the patterns to a temporary list so we can sort them.
-  Records.startTimer("Sort patterns");
+  MutableRC.startTimer("Sort patterns");
   std::vector<const PatternToMatch *> Patterns;
   for (const PatternToMatch &PTM : CGP.ptms())
     Patterns.push_back(&PTM);
@@ -173,7 +174,7 @@ void DAGISelEmitter::run(raw_ostream &OS) {
   llvm::stable_sort(Patterns, PatternSortingPredicate(CGP));
 
   // Convert each variant of each pattern into a Matcher.
-  Records.startTimer("Convert to matchers");
+  MutableRC.startTimer("Convert to matchers");
   SmallVector<Matcher *, 0> PatternMatchers;
   for (const PatternToMatch *PTM : Patterns) {
     for (unsigned Variant = 0;; ++Variant) {
@@ -187,12 +188,12 @@ void DAGISelEmitter::run(raw_ostream &OS) {
   std::unique_ptr<Matcher> TheMatcher =
       std::make_unique<ScopeMatcher>(std::move(PatternMatchers));
 
-  Records.startTimer("Optimize matchers");
+  MutableRC.startTimer("Optimize matchers");
   OptimizeMatcher(TheMatcher, CGP);
 
   // Matcher->dump();
 
-  Records.startTimer("Emit matcher table");
+  MutableRC.startTimer("Emit matcher table");
   EmitMatcherTable(TheMatcher.get(), CGP, OS);
 }
 
diff --git a/llvm/utils/TableGen/DAGISelMatcherGen.cpp b/llvm/utils/TableGen/DAGISelMatcherGen.cpp
index 5cb393ae7a538d..e159cf1bbefd33 100644
--- a/llvm/utils/TableGen/DAGISelMatcherGen.cpp
+++ b/llvm/utils/TableGen/DAGISelMatcherGen.cpp
@@ -23,7 +23,7 @@ using namespace llvm;
 /// getRegisterValueType - Look up and return the ValueType of the specified
 /// register. If the register is a member of multiple register classes, they
 /// must all have the same type.
-static MVT::SimpleValueType getRegisterValueType(Record *R,
+static MVT::SimpleValueType getRegisterValueType(const Record *R,
                                                  const CodeGenTarget &T) {
   bool FoundRC = false;
   MVT::SimpleValueType VT = MVT::Other;
@@ -91,7 +91,7 @@ class MatcherGen {
   /// PhysRegInputs - List list has an entry for each explicitly specified
   /// physreg input to the pattern.  The first elt is the Register node, the
   /// second is the recorded slot number the input pattern match saved it in.
-  SmallVector<std::pair<Record *, unsigned>, 2> PhysRegInputs;
+  SmallVector<std::pair<const Record *, unsigned>, 2> PhysRegInputs;
 
   /// Matcher - This is the top level of the generated matcher, the result.
   Matcher *TheMatcher;
@@ -220,13 +220,13 @@ void MatcherGen::EmitLeafMatchCode(const TreePatternNode &N) {
     return;
   }
 
-  DefInit *DI = dyn_cast<DefInit>(N.getLeafValue());
+  const DefInit *DI = dyn_cast<DefInit>(N.getLeafValue());
   if (!DI) {
     errs() << "Unknown leaf kind: " << N << "\n";
     abort();
   }
 
-  Record *LeafRec = DI->getDef();
+  const Record *LeafRec = DI->getDef();
 
   // A ValueType leaf node can represent a register when named, or itself when
   // unnamed.
@@ -673,7 +673,7 @@ void MatcherGen::EmitResultLeafAsOperand(const TreePatternNode &N,
 
   // If this is an explicit register reference, handle it.
   if (DefInit *DI = dyn_cast<DefInit>(N.getLeafValue())) {
-    Record *Def = DI->getDef();
+    const Record *Def = DI->getDef();
     if (Def->isSubClassOf("Register")) {
       const CodeGenRegister *Reg = CGP.getTargetInfo().getRegBank().getReg(Def);
       AddMatcher(new EmitRegisterMatcher(Reg, N.getSimpleType(0)));
@@ -690,7 +690,7 @@ void MatcherGen::EmitResultLeafAsOperand(const TreePatternNode &N,
     if (Def->getName() == "undef_tied_input") {
       MVT::SimpleValueType ResultVT = N.getSimpleType(0);
       auto IDOperandNo = NextRecordedOperandNo++;
-      Record *ImpDef = Def->getRecords().getDef("IMPLICIT_DEF");
+      const Record *ImpDef = Def->getRecords().getDef("IMPLICIT_DEF");
       CodeGenInstruction &II = CGP.getTargetInfo().getInstruction(ImpDef);
       AddMatcher(new EmitNodeMatcher(II, ResultVT, std::nullopt, false, false,
                                      false, false, -1, IDOperandNo));
@@ -907,11 +907,11 @@ void MatcherGen::EmitResultInstructionAsOperand(
   if (isRoot && !Pattern.getDstRegs().empty()) {
     // If the root came from an implicit def in the instruction handling stuff,
     // don't re-add it.
-    Record *HandledReg = nullptr;
+    const Record *HandledReg = nullptr;
     if (II.HasOneImplicitDefWithKnownVT(CGT) != MVT::Other)
       HandledReg = II.ImplicitDefs[0];
 
-    for (Record *Reg : Pattern.getDstRegs()) {
+    for (const Record *Reg : Pattern.getDstRegs()) {
       if (!Reg->isSubClassOf("Register") || Reg == HandledReg)
         continue;
       ResultVTs.push_back(getRegisterValueType(Reg, CGT));
@@ -1042,7 +1042,7 @@ void MatcherGen::EmitResultCode() {
   if (!Pattern.getDstRegs().empty()) {
     // If the root came from an implicit def in the instruction handling stuff,
     // don't re-add it.
-    Record *HandledReg = nullptr;
+    const Record *HandledReg = nullptr;
     const TreePatternNode &DstPat = Pattern.getDstPattern();
     if (!DstPat.isLeaf() && DstPat.getOperator()->isSubClassOf("Instruction")) {
       const CodeGenTarget &CGT = CGP.getTargetInfo();
@@ -1052,7 +1052,7 @@ void MatcherGen::EmitResultCode() {
         HandledReg = II.ImplicitDefs[0];
     }
 
-    for (Record *Reg : Pattern.getDstRegs()) {
+    for (const Record *Reg : Pattern.getDstRegs()) {
       if (!Reg->isSubClassOf("Register") || Reg == HandledReg)
         continue;
       ++NumSrcResults;