[CIR][NFC] Add Symbol Table to CIRGenFunction (#153625)

This patchs adds a symbol table to CIRGenFunction plus scopes and
insertions to the table where we were missing them previously.

Author: mmha

clang/include/clang/CIR/MissingFeatures.h

@@ -27,9 +27,6 @@ struct MissingFeatures {
   // Address space related
   static bool addressSpace() { return false; }
 
-  // CIRGenFunction implementation details
-  static bool cgfSymbolTable() { return false; }
-
   // Unhandled global/linkage information.
   static bool opGlobalThreadLocal() { return false; }
   static bool opGlobalConstant() { return false; }

clang/lib/CIR/CodeGen/CIRGenExpr.cpp

@@ -591,6 +591,12 @@ LValue CIRGenFunction::emitDeclRefLValue(const DeclRefExpr *e) {
             ? emitLoadOfReferenceLValue(addr, getLoc(e->getSourceRange()),
                                         vd->getType(), AlignmentSource::Decl)
             : makeAddrLValue(addr, ty, AlignmentSource::Decl);
+
+    // Statics are defined as globals, so they are not include in the function's
+    // symbol table.
+    assert((vd->isStaticLocal() || symbolTable.count(vd)) &&
+           "non-static locals should be already mapped");
+
     return lv;
   }
 

clang/lib/CIR/CodeGen/CIRGenFunction.cpp

@@ -215,7 +215,7 @@ void CIRGenFunction::declare(mlir::Value addrVal, const Decl *var, QualType ty,
                              mlir::Location loc, CharUnits alignment,
                              bool isParam) {
   assert(isa<NamedDecl>(var) && "Needs a named decl");
-  assert(!cir::MissingFeatures::cgfSymbolTable());
+  assert(!symbolTable.count(var) && "not supposed to be available just yet");
 
   auto allocaOp = addrVal.getDefiningOp<cir::AllocaOp>();
   assert(allocaOp && "expected cir::AllocaOp");
@@ -224,6 +224,8 @@ void CIRGenFunction::declare(mlir::Value addrVal, const Decl *var, QualType ty,
     allocaOp.setInitAttr(mlir::UnitAttr::get(&getMLIRContext()));
   if (ty->isReferenceType() || ty.isConstQualified())
     allocaOp.setConstantAttr(mlir::UnitAttr::get(&getMLIRContext()));
+
+  symbolTable.insert(var, allocaOp);
 }
 
 void CIRGenFunction::LexicalScope::cleanup() {
@@ -485,6 +487,9 @@ void CIRGenFunction::finishFunction(SourceLocation endLoc) {
 }
 
 mlir::LogicalResult CIRGenFunction::emitFunctionBody(const clang::Stmt *body) {
+  // We start with function level scope for variables.
+  SymTableScopeTy varScope(symbolTable);
+
   auto result = mlir::LogicalResult::success();
   if (const CompoundStmt *block = dyn_cast<CompoundStmt>(body))
     emitCompoundStmtWithoutScope(*block);
@@ -531,6 +536,8 @@ cir::FuncOp CIRGenFunction::generateCode(clang::GlobalDecl gd, cir::FuncOp fn,
   FunctionArgList args;
   QualType retTy = buildFunctionArgList(gd, args);
 
+  // Create a scope in the symbol table to hold variable declarations.
+  SymTableScopeTy varScope(symbolTable);
   {
     LexicalScope lexScope(*this, fusedLoc, entryBB);
 

clang/lib/CIR/CodeGen/CIRGenFunction.h

@@ -31,6 +31,7 @@
 #include "clang/CIR/Dialect/IR/CIRDialect.h"
 #include "clang/CIR/MissingFeatures.h"
 #include "clang/CIR/TypeEvaluationKind.h"
+#include "llvm/ADT/ScopedHashTable.h"
 
 namespace {
 class ScalarExprEmitter;
@@ -103,6 +104,14 @@ class CIRGenFunction : public CIRGenTypeCache {
   /// Sanitizers enabled for this function.
   clang::SanitizerSet sanOpts;
 
+  /// The symbol table maps a variable name to a value in the current scope.
+  /// Entering a function creates a new scope, and the function arguments are
+  /// added to the mapping. When the processing of a function is terminated,
+  /// the scope is destroyed and the mappings created in this scope are
+  /// dropped.
+  using SymTableTy = llvm::ScopedHashTable<const clang::Decl *, mlir::Value>;
+  SymTableTy symbolTable;
+
   /// Whether or not a Microsoft-style asm block has been processed within
   /// this fuction. These can potentially set the return value.
   bool sawAsmBlock = false;
@@ -325,6 +334,9 @@ class CIRGenFunction : public CIRGenTypeCache {
     ~SourceLocRAIIObject() { restore(); }
   };
 
+  using SymTableScopeTy =
+      llvm::ScopedHashTableScope<const clang::Decl *, mlir::Value>;
+
   /// Hold counters for incrementally naming temporaries
   unsigned counterRefTmp = 0;
   unsigned counterAggTmp = 0;
@@ -499,7 +511,11 @@ class CIRGenFunction : public CIRGenTypeCache {
   void setAddrOfLocalVar(const clang::VarDecl *vd, Address addr) {
     assert(!localDeclMap.count(vd) && "Decl already exists in LocalDeclMap!");
     localDeclMap.insert({vd, addr});
-    // TODO: Add symbol table support
+
+    // Add to the symbol table if not there already.
+    if (symbolTable.count(vd))
+      return;
+    symbolTable.insert(vd, addr.getPointer());
   }
 
   bool shouldNullCheckClassCastValue(const CastExpr *ce);

clang/lib/CIR/CodeGen/CIRGenStmt.cpp

@@ -33,6 +33,8 @@ void CIRGenFunction::emitCompoundStmtWithoutScope(const CompoundStmt &s) {
 }
 
 void CIRGenFunction::emitCompoundStmt(const CompoundStmt &s) {
+  // Add local scope to track new declared variables.
+  SymTableScopeTy varScope(symbolTable);
   mlir::Location scopeLoc = getLoc(s.getSourceRange());
   mlir::OpBuilder::InsertPoint scopeInsPt;
   builder.create<cir::ScopeOp>(