Revert "[MLIR][Target/Cpp] Natural induction variable naming. (llvm#136102)"

This reverts commit dcc692a.

Author: Max191

mlir/lib/Target/Cpp/TranslateToCpp.cpp

@@ -186,10 +186,6 @@ struct CppEmitter {
   /// Return the existing or a new name for a Value.
   StringRef getOrCreateName(Value val);
 
-  /// Return the existing or a new name for a loop induction variable of an
-  /// emitc::ForOp.
-  StringRef getOrCreateInductionVarName(Value val);
-
   // Returns the textual representation of a subscript operation.
   std::string getSubscriptName(emitc::SubscriptOp op);
 
@@ -205,39 +201,23 @@ struct CppEmitter {
   /// Whether to map an mlir integer to a unsigned integer in C++.
   bool shouldMapToUnsigned(IntegerType::SignednessSemantics val);
 
-  /// Abstract RAII helper function to manage entering/exiting C++ scopes.
+  /// RAII helper function to manage entering/exiting C++ scopes.
   struct Scope {
-    ~Scope() { emitter.labelInScopeCount.pop(); }
-
-  private:
-    llvm::ScopedHashTableScope<Value, std::string> valueMapperScope;
-    llvm::ScopedHashTableScope<Block *, std::string> blockMapperScope;
-
-  protected:
     Scope(CppEmitter &emitter)
         : valueMapperScope(emitter.valueMapper),
           blockMapperScope(emitter.blockMapper), emitter(emitter) {
+      emitter.valueInScopeCount.push(emitter.valueInScopeCount.top());
       emitter.labelInScopeCount.push(emitter.labelInScopeCount.top());
     }
-    CppEmitter &emitter;
-  };
-
-  /// RAII helper function to manage entering/exiting functions, while re-using
-  /// value names.
-  struct FunctionScope : Scope {
-    FunctionScope(CppEmitter &emitter) : Scope(emitter) {
-      // Re-use value names.
-      emitter.resetValueCounter();
+    ~Scope() {
+      emitter.valueInScopeCount.pop();
+      emitter.labelInScopeCount.pop();
     }
-  };
 
-  /// RAII helper function to manage entering/exiting emitc::forOp loops and
-  /// handle induction variable naming.
-  struct LoopScope : Scope {
-    LoopScope(CppEmitter &emitter) : Scope(emitter) {
-      emitter.increaseLoopNestingLevel();
-    }
-    ~LoopScope() { emitter.decreaseLoopNestingLevel(); }
+  private:
+    llvm::ScopedHashTableScope<Value, std::string> valueMapperScope;
+    llvm::ScopedHashTableScope<Block *, std::string> blockMapperScope;
+    CppEmitter &emitter;
   };
 
   /// Returns wether the Value is assigned to a C++ variable in the scope.
@@ -273,15 +253,6 @@ struct CppEmitter {
     return operandExpression == emittedExpression;
   };
 
-  // Resets the value counter to 0.
-  void resetValueCounter();
-
-  // Increases the loop nesting level by 1.
-  void increaseLoopNestingLevel();
-
-  // Decreases the loop nesting level by 1.
-  void decreaseLoopNestingLevel();
-
 private:
   using ValueMapper = llvm::ScopedHashTable<Value, std::string>;
   using BlockMapper = llvm::ScopedHashTable<Block *, std::string>;
@@ -303,19 +274,11 @@ struct CppEmitter {
   /// Map from block to name of C++ label.
   BlockMapper blockMapper;
 
-  /// Default values representing outermost scope.
-  llvm::ScopedHashTableScope<Value, std::string> defaultValueMapperScope;
-  llvm::ScopedHashTableScope<Block *, std::string> defaultBlockMapperScope;
-
+  /// The number of values in the current scope. This is used to declare the
+  /// names of values in a scope.
+  std::stack<int64_t> valueInScopeCount;
   std::stack<int64_t> labelInScopeCount;
 
-  /// Keeps track of the amount of nested loops the emitter currently operates
-  /// in.
-  uint64_t loopNestingLevel{0};
-
-  /// Emitter-level count of created values to enable unique identifiers.
-  unsigned int valueCount{0};
-
   /// State of the current expression being emitted.
   ExpressionOp emittedExpression;
   SmallVector<int> emittedExpressionPrecedence;
@@ -897,6 +860,7 @@ static LogicalResult printOperation(CppEmitter &emitter,
 }
 
 static LogicalResult printOperation(CppEmitter &emitter, emitc::ForOp forOp) {
+
   raw_indented_ostream &os = emitter.ostream();
 
   // Utility function to determine whether a value is an expression that will be
@@ -915,12 +879,12 @@ static LogicalResult printOperation(CppEmitter &emitter, emitc::ForOp forOp) {
           emitter.emitType(forOp.getLoc(), forOp.getInductionVar().getType())))
     return failure();
   os << " ";
-  os << emitter.getOrCreateInductionVarName(forOp.getInductionVar());
+  os << emitter.getOrCreateName(forOp.getInductionVar());
   os << " = ";
   if (failed(emitter.emitOperand(forOp.getLowerBound())))
     return failure();
   os << "; ";
-  os << emitter.getOrCreateInductionVarName(forOp.getInductionVar());
+  os << emitter.getOrCreateName(forOp.getInductionVar());
   os << " < ";
   Value upperBound = forOp.getUpperBound();
   bool upperBoundRequiresParentheses = requiresParentheses(upperBound);
@@ -931,15 +895,13 @@ static LogicalResult printOperation(CppEmitter &emitter, emitc::ForOp forOp) {
   if (upperBoundRequiresParentheses)
     os << ")";
   os << "; ";
-  os << emitter.getOrCreateInductionVarName(forOp.getInductionVar());
+  os << emitter.getOrCreateName(forOp.getInductionVar());
   os << " += ";
   if (failed(emitter.emitOperand(forOp.getStep())))
     return failure();
   os << ") {\n";
   os.indent();
 
-  CppEmitter::LoopScope lScope(emitter);
-
   Region &forRegion = forOp.getRegion();
   auto regionOps = forRegion.getOps();
 
@@ -1026,6 +988,8 @@ static LogicalResult printOperation(CppEmitter &emitter,
 }
 
 static LogicalResult printOperation(CppEmitter &emitter, ModuleOp moduleOp) {
+  CppEmitter::Scope scope(emitter);
+
   for (Operation &op : moduleOp) {
     if (failed(emitter.emitOperation(op, /*trailingSemicolon=*/false)))
       return failure();
@@ -1034,6 +998,7 @@ static LogicalResult printOperation(CppEmitter &emitter, ModuleOp moduleOp) {
 }
 
 static LogicalResult printOperation(CppEmitter &emitter, ClassOp classOp) {
+  CppEmitter::Scope classScope(emitter);
   raw_indented_ostream &os = emitter.ostream();
   os << "class " << classOp.getSymName();
   if (classOp.getFinalSpecifier())
@@ -1079,6 +1044,8 @@ static LogicalResult printOperation(CppEmitter &emitter, FileOp file) {
   if (!emitter.shouldEmitFile(file))
     return success();
 
+  CppEmitter::Scope scope(emitter);
+
   for (Operation &op : file) {
     if (failed(emitter.emitOperation(op, /*trailingSemicolon=*/false)))
       return failure();
@@ -1194,7 +1161,7 @@ static LogicalResult printOperation(CppEmitter &emitter,
     return functionOp.emitOpError() << "cannot emit array type as result type";
   }
 
-  CppEmitter::FunctionScope scope(emitter);
+  CppEmitter::Scope scope(emitter);
   raw_indented_ostream &os = emitter.ostream();
   if (failed(emitter.emitTypes(functionOp.getLoc(),
                                functionOp.getFunctionType().getResults())))
@@ -1222,7 +1189,7 @@ static LogicalResult printOperation(CppEmitter &emitter,
         "with multiple blocks needs variables declared at top");
   }
 
-  CppEmitter::FunctionScope scope(emitter);
+  CppEmitter::Scope scope(emitter);
   raw_indented_ostream &os = emitter.ostream();
   if (functionOp.getSpecifiers()) {
     for (Attribute specifier : functionOp.getSpecifiersAttr()) {
@@ -1256,6 +1223,7 @@ static LogicalResult printOperation(CppEmitter &emitter,
 
 static LogicalResult printOperation(CppEmitter &emitter,
                                     DeclareFuncOp declareFuncOp) {
+  CppEmitter::Scope scope(emitter);
   raw_indented_ostream &os = emitter.ostream();
 
   auto functionOp = SymbolTable::lookupNearestSymbolFrom<emitc::FuncOp>(
@@ -1287,8 +1255,8 @@ static LogicalResult printOperation(CppEmitter &emitter,
 CppEmitter::CppEmitter(raw_ostream &os, bool declareVariablesAtTop,
                        StringRef fileId)
     : os(os), declareVariablesAtTop(declareVariablesAtTop),
-      fileId(fileId.str()), defaultValueMapperScope(valueMapper),
-      defaultBlockMapperScope(blockMapper) {
+      fileId(fileId.str()) {
+  valueInScopeCount.push(0);
   labelInScopeCount.push(0);
 }
 
@@ -1329,26 +1297,7 @@ StringRef CppEmitter::getOrCreateName(Value val) {
     assert(!hasDeferredEmission(val.getDefiningOp()) &&
            "cacheDeferredOpResult should have been called on this value, "
            "update the emitOperation function.");
-
-    valueMapper.insert(val, formatv("v{0}", ++valueCount));
-  }
-  return *valueMapper.begin(val);
-}
-
-/// Return the existing or a new name for a loop induction variable Value.
-/// Loop induction variables follow natural naming: i, j, k, ..., t, uX.
-StringRef CppEmitter::getOrCreateInductionVarName(Value val) {
-  if (!valueMapper.count(val)) {
-
-    int64_t identifier = 'i' + loopNestingLevel;
-
-    if (identifier >= 'i' && identifier <= 't') {
-      valueMapper.insert(val,
-                         formatv("{0}{1}", (char)identifier, ++valueCount));
-    } else {
-      // If running out of letters, continue with uX.
-      valueMapper.insert(val, formatv("u{0}", ++valueCount));
-    }
+    valueMapper.insert(val, formatv("v{0}", ++valueInScopeCount.top()));
   }
   return *valueMapper.begin(val);
 }
@@ -1889,12 +1838,6 @@ LogicalResult CppEmitter::emitTupleType(Location loc, ArrayRef<Type> types) {
   return success();
 }
 
-void CppEmitter::resetValueCounter() { valueCount = 0; }
-
-void CppEmitter::increaseLoopNestingLevel() { loopNestingLevel++; }
-
-void CppEmitter::decreaseLoopNestingLevel() { loopNestingLevel--; }
-
 LogicalResult emitc::translateToCpp(Operation *op, raw_ostream &os,
                                     bool declareVariablesAtTop,
                                     StringRef fileId) {