[CIR] Upstream initial attribute support

clang/include/clang/CIR/Dialect/Builder/CIRBaseBuilder.h

@@ -9,7 +9,11 @@
 #ifndef LLVM_CLANG_CIR_DIALECT_BUILDER_CIRBASEBUILDER_H
 #define LLVM_CLANG_CIR_DIALECT_BUILDER_CIRBASEBUILDER_H
 
+#include "clang/CIR/Dialect/IR/CIRAttrs.h"
+
 #include "mlir/IR/Builders.h"
+#include "mlir/IR/BuiltinTypes.h"
+#include "mlir/IR/Types.h"
 
 namespace cir {
 
@@ -26,6 +30,13 @@ class CIRBaseBuilderTy : public mlir::OpBuilder {
   cir::PointerType getVoidPtrTy() {
     return getPointerTo(cir::VoidType::get(getContext()));
   }
+
+  mlir::TypedAttr getConstPtrAttr(mlir::Type type, int64_t value) {
+    auto valueAttr = mlir::IntegerAttr::get(
+        mlir::IntegerType::get(type.getContext(), 64), value);
+    return cir::ConstPtrAttr::get(
+        getContext(), mlir::cast<cir::PointerType>(type), valueAttr);
+  }
 };
 
 } // namespace cir

clang/include/clang/CIR/Dialect/IR/CIRAttrs.h

@@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the attributes in the CIR dialect.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_CIR_DIALECT_IR_CIRATTRS_H
+#define LLVM_CLANG_CIR_DIALECT_IR_CIRATTRS_H
+
+#include "clang/CIR/Dialect/IR/CIRTypes.h"
+
+#include "mlir/IR/Attributes.h"
+#include "mlir/IR/BuiltinAttributeInterfaces.h"
+
+#include "llvm/ADT/SmallVector.h"
+
+//===----------------------------------------------------------------------===//
+// CIR Dialect Attrs
+//===----------------------------------------------------------------------===//
+
+namespace clang {
+class FunctionDecl;
+class VarDecl;
+class RecordDecl;
+} // namespace clang
+
+#define GET_ATTRDEF_CLASSES
+#include "clang/CIR/Dialect/IR/CIROpsAttributes.h.inc"
+
+#endif // LLVM_CLANG_CIR_DIALECT_IR_CIRATTRS_H

clang/include/clang/CIR/Dialect/IR/CIRAttrs.td

@@ -0,0 +1,142 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the CIR dialect attributes.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_CIR_DIALECT_IR_CIRATTRS_TD
+#define LLVM_CLANG_CIR_DIALECT_IR_CIRATTRS_TD
+
+include "mlir/IR/BuiltinAttributeInterfaces.td"
+include "mlir/IR/EnumAttr.td"
+
+include "clang/CIR/Dialect/IR/CIRDialect.td"
+
+//===----------------------------------------------------------------------===//
+// CIR Attrs
+//===----------------------------------------------------------------------===//
+
+class CIR_Attr<string name, string attrMnemonic, list<Trait> traits = []>
+    : AttrDef<CIR_Dialect, name, traits> {
+  let mnemonic = attrMnemonic;
+}
+
+class CIRUnitAttr<string name, string attrMnemonic, list<Trait> traits = []>
+    : CIR_Attr<name, attrMnemonic, traits> {
+  let returnType = "bool";
+  let defaultValue = "false";
+  let valueType = NoneType;
+  let isOptional = 1;
+}
+
+//===----------------------------------------------------------------------===//
+// IntegerAttr
+//===----------------------------------------------------------------------===//
+
+def IntAttr : CIR_Attr<"Int", "int", [TypedAttrInterface]> {
+  let summary = "An attribute containing an integer value";
+  let description = [{
+    An integer attribute is a literal attribute that represents an integral
+    value of the specified integer type.
+  }];
+  let parameters = (ins AttributeSelfTypeParameter<"">:$type,
+                        "llvm::APInt":$value);
+  let builders = [
+    AttrBuilderWithInferredContext<(ins "mlir::Type":$type,
+                                        "const llvm::APInt &":$value), [{
+      return $_get(type.getContext(), type, value);
+    }]>,
+    AttrBuilderWithInferredContext<(ins "mlir::Type":$type,
+                                        "int64_t":$value), [{
+      IntType intType = mlir::cast<IntType>(type);
+      mlir::APInt apValue(intType.getWidth(), value, intType.isSigned());
+      return $_get(intType.getContext(), intType, apValue);
+    }]>,
+  ];
+  let extraClassDeclaration = [{
+    int64_t getSInt() const { return getValue().getSExtValue(); }
+    uint64_t getUInt() const { return getValue().getZExtValue(); }
+    bool isNullValue() const { return getValue() == 0; }
+    uint64_t getBitWidth() const {
+      return mlir::cast<IntType>(getType()).getWidth();
+    }
+  }];
+  let genVerifyDecl = 1;
+  let hasCustomAssemblyFormat = 1;
+}
+
+//===----------------------------------------------------------------------===//
+// FPAttr
+//===----------------------------------------------------------------------===//
+
+def FPAttr : CIR_Attr<"FP", "fp", [TypedAttrInterface]> {
+  let summary = "An attribute containing a floating-point value";
+  let description = [{
+    An fp attribute is a literal attribute that represents a floating-point
+    value of the specified floating-point type. Supporting only CIR FP types.
+  }];
+  let parameters = (ins
+    AttributeSelfTypeParameter<"", "::cir::CIRFPTypeInterface">:$type,
+    APFloatParameter<"">:$value
+  );
+  let builders = [
+    AttrBuilderWithInferredContext<(ins "mlir::Type":$type,
+                                        "const llvm::APFloat &":$value), [{
+      return $_get(type.getContext(), mlir::cast<CIRFPTypeInterface>(type),
+                   value);
+    }]>,
+    AttrBuilder<(ins "mlir::Type":$type,
+                     "const llvm::APFloat &":$value), [{
+      return $_get($_ctxt, mlir::cast<CIRFPTypeInterface>(type), value);
+    }]>,
+  ];
+  let extraClassDeclaration = [{
+    static FPAttr getZero(mlir::Type type);
+  }];
+  let genVerifyDecl = 1;
+
+  let assemblyFormat = [{
+    `<` custom<FloatLiteral>($value, ref($type)) `>`
+  }];
+}
+
+//===----------------------------------------------------------------------===//
+// ConstPtrAttr
+//===----------------------------------------------------------------------===//
+
+def ConstPtrAttr : CIR_Attr<"ConstPtr", "ptr", [TypedAttrInterface]> {
+  let summary = "Holds a constant pointer value";
+  let parameters = (ins
+    AttributeSelfTypeParameter<"", "::cir::PointerType">:$type,
+    "mlir::IntegerAttr":$value);
+  let description = [{
+    A pointer attribute is a literal attribute that represents an integral
+    value of a pointer type.
+  }];
+  let builders = [
+    AttrBuilderWithInferredContext<(ins "mlir::Type":$type,
+                                        "mlir::IntegerAttr":$value), [{
+      return $_get(type.getContext(), mlir::cast<cir::PointerType>(type),
+                   value);
+    }]>,
+    AttrBuilder<(ins "mlir::Type":$type,
+                     "mlir::IntegerAttr":$value), [{
+      return $_get($_ctxt, mlir::cast<cir::PointerType>(type), value);
+    }]>,
+  ];
+  let extraClassDeclaration = [{
+    bool isNullValue() const { return getValue().getInt() == 0; }
+  }];
+
+  let assemblyFormat = [{
+    `<` custom<ConstPtr>($value) `>`
+  }];
+}
+
+#endif // LLVM_CLANG_CIR_DIALECT_IR_CIRATTRS_TD

clang/include/clang/CIR/Dialect/IR/CIRDialect.h

@@ -26,6 +26,7 @@
 #include "mlir/Interfaces/MemorySlotInterfaces.h"
 #include "mlir/Interfaces/SideEffectInterfaces.h"
 
+#include "clang/CIR/Dialect/IR/CIRAttrs.h"
 #include "clang/CIR/Dialect/IR/CIROpsDialect.h.inc"
 
 // TableGen'erated files for MLIR dialects require that a macro be defined when

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -16,6 +16,7 @@
 
 include "clang/CIR/Dialect/IR/CIRDialect.td"
 include "clang/CIR/Dialect/IR/CIRTypes.td"
+include "clang/CIR/Dialect/IR/CIRAttrs.td"
 
 include "mlir/IR/BuiltinAttributeInterfaces.td"
 include "mlir/IR/EnumAttr.td"
@@ -75,6 +76,45 @@ class LLVMLoweringInfo {
 class CIR_Op<string mnemonic, list<Trait> traits = []> :
     Op<CIR_Dialect, mnemonic, traits>, LLVMLoweringInfo;
 
+//===----------------------------------------------------------------------===//
+// ConstantOp
+//===----------------------------------------------------------------------===//
+
+def ConstantOp : CIR_Op<"const",
+                        [ConstantLike, Pure, AllTypesMatch<["value", "res"]>]> {
+  let summary = "Defines a CIR constant";
+  let description = [{
+    The `cir.const` operation turns a literal into an SSA value. The data is
+    attached to the operation as an attribute.
+
+    ```mlir
+      %0 = cir.const 42 : i32
+      %1 = cir.const 4.2 : f32
+      %2 = cir.const nullptr : !cir.ptr<i32>
+    ```
+  }];
+
+  // The constant operation takes an attribute as the only input.
+  let arguments = (ins TypedAttrInterface:$value);
+
+  // The constant operation returns a single value of CIR_AnyType.
+  let results = (outs CIR_AnyType:$res);
+
+  let assemblyFormat = "attr-dict $value";
+
+  let hasVerifier = 1;
+
+  let extraClassDeclaration = [{
+    bool isNullPtr() {
+      if (const auto ptrAttr = mlir::dyn_cast<cir::ConstPtrAttr>(getValue()))
+        return ptrAttr.isNullValue();
+      return false;
+    }
+  }];
+
+  let hasFolder = 1;
+}
+
 //===----------------------------------------------------------------------===//
 // GlobalOp
 //===----------------------------------------------------------------------===//
@@ -92,9 +132,19 @@ def GlobalOp : CIR_Op<"global"> {
     described by the type of the variable.
   }];
 
-  let arguments = (ins SymbolNameAttr:$sym_name, TypeAttr:$sym_type);
+  let arguments = (ins SymbolNameAttr:$sym_name, TypeAttr:$sym_type,
+                       OptionalAttr<AnyAttr>:$initial_value);
+
+  let assemblyFormat = [{
+    $sym_name
+    custom<GlobalOpTypeAndInitialValue>($sym_type, $initial_value)
+    attr-dict
+  }];
 
-  let assemblyFormat = [{ $sym_name `:` $sym_type attr-dict }];
+  let extraClassDeclaration = [{
+    bool isDeclaration() { return !getInitialValue(); }
+    bool hasInitializer() { return !isDeclaration(); }
+  }];
 
   let skipDefaultBuilders = 1;
 

clang/include/clang/CIR/Dialect/IR/CIRTypes.td

@@ -220,8 +220,8 @@ def CIR_LongDouble : CIR_FloatType<"LongDouble", "long_double"> {
 
 // Constraints
 
-def CIR_AnyFloat: AnyTypeOf<[CIR_Single, CIR_Double, CIR_FP80, CIR_FP128, CIR_LongDouble,
-    CIR_FP16, CIR_BFloat16]>;
+def CIR_AnyFloat: AnyTypeOf<[CIR_Single, CIR_Double, CIR_FP80, CIR_FP128,
+                             CIR_LongDouble, CIR_FP16, CIR_BFloat16]>;
 def CIR_AnyIntOrFloat: AnyTypeOf<[CIR_AnyFloat, CIR_IntType]>;
 
 //===----------------------------------------------------------------------===//
@@ -350,4 +350,12 @@ def VoidPtr : Type<
       "cir::VoidType::get($_builder.getContext()))"> {
 }
 
+//===----------------------------------------------------------------------===//
+// Global type constraints
+//===----------------------------------------------------------------------===//
+
+def CIR_AnyType : AnyTypeOf<[
+  CIR_VoidType, CIR_IntType, CIR_AnyFloat, CIR_PointerType, CIR_FuncType
+]>;
+
 #endif // MLIR_CIR_DIALECT_CIR_TYPES

clang/include/clang/CIR/Dialect/IR/CMakeLists.txt

@@ -14,3 +14,6 @@ mlir_tablegen(CIROpsDialect.cpp.inc -gen-dialect-defs)
 add_public_tablegen_target(MLIRCIROpsIncGen)
 add_dependencies(mlir-headers MLIRCIROpsIncGen)
 
+mlir_tablegen(CIROpsAttributes.h.inc -gen-attrdef-decls)
+mlir_tablegen(CIROpsAttributes.cpp.inc -gen-attrdef-defs)
+add_public_tablegen_target(MLIRCIRAttrsEnumsGen)

clang/lib/CIR/CodeGen/CIRGenModule.cpp

@@ -115,6 +115,48 @@ void CIRGenModule::emitGlobalVarDefinition(const clang::VarDecl *vd,
   if (clang::IdentifierInfo *identifier = vd->getIdentifier()) {
     auto varOp = builder.create<cir::GlobalOp>(getLoc(vd->getSourceRange()),
                                                identifier->getName(), type);
+    // TODO(CIR): This code for processing initial values is a placeholder
+    // until class ConstantEmitter is upstreamed and the code for processing
+    // constant expressions is filled out.  Only the most basic handling of
+    // certain constant expressions is implemented for now.
+    const VarDecl *initDecl;
+    const Expr *initExpr = vd->getAnyInitializer(initDecl);
+    if (initExpr) {
+      mlir::Attribute initializer;
+      if (APValue *value = initDecl->evaluateValue()) {
+        switch (value->getKind()) {
+        case APValue::Int: {
+          initializer = builder.getAttr<cir::IntAttr>(type, value->getInt());
+          break;
+        }
+        case APValue::Float: {
+          initializer = builder.getAttr<cir::FPAttr>(type, value->getFloat());
+          break;
+        }
+        case APValue::LValue: {
+          if (value->getLValueBase()) {
+            errorNYI(initExpr->getSourceRange(),
+                     "non-null pointer initialization");
+          } else {
+            if (auto ptrType = mlir::dyn_cast<cir::PointerType>(type)) {
+              initializer = builder.getConstPtrAttr(
+                  ptrType, value->getLValueOffset().getQuantity());
+            } else {
+              llvm_unreachable(
+                  "non-pointer variable initialized with a pointer");
+            }
+          }
+          break;
+        }
+        default:
+          errorNYI(initExpr->getSourceRange(), "unsupported initializer kind");
+          break;
+        }
+      } else {
+        errorNYI(initExpr->getSourceRange(), "non-constant initializer");
+      }
+      varOp.setInitialValueAttr(initializer);
+    }
     theModule.push_back(varOp);
   } else {
     errorNYI(vd->getSourceRange().getBegin(),