Re-align lowering code with incubator implementation

Author: andykaylor

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp

@@ -44,48 +44,52 @@ class CIRAttrToValue {
                  const mlir::TypeConverter *converter)
       : parentOp(parentOp), rewriter(rewriter), converter(converter) {}
 
-  mlir::Value lowerCirAttrAsValue(mlir::Attribute attr) { return visit(attr); }
-
   mlir::Value visit(mlir::Attribute attr) {
     return llvm::TypeSwitch<mlir::Attribute, mlir::Value>(attr)
         .Case<cir::IntAttr, cir::FPAttr, cir::ConstPtrAttr>(
             [&](auto attrT) { return visitCirAttr(attrT); })
         .Default([&](auto attrT) { return mlir::Value(); });
   }
 
-  mlir::Value visitCirAttr(cir::IntAttr intAttr) {
-    mlir::Location loc = parentOp->getLoc();
-    return rewriter.create<mlir::LLVM::ConstantOp>(
-        loc, converter->convertType(intAttr.getType()), intAttr.getValue());
-  }
-
-  mlir::Value visitCirAttr(cir::FPAttr fltAttr) {
-    mlir::Location loc = parentOp->getLoc();
-    return rewriter.create<mlir::LLVM::ConstantOp>(
-        loc, converter->convertType(fltAttr.getType()), fltAttr.getValue());
-  }
-
-  mlir::Value visitCirAttr(cir::ConstPtrAttr ptrAttr) {
-    mlir::Location loc = parentOp->getLoc();
-    if (ptrAttr.isNullValue()) {
-      return rewriter.create<mlir::LLVM::ZeroOp>(
-          loc, converter->convertType(ptrAttr.getType()));
-    }
-    mlir::DataLayout layout(parentOp->getParentOfType<mlir::ModuleOp>());
-    mlir::Value ptrVal = rewriter.create<mlir::LLVM::ConstantOp>(
-        loc,
-        rewriter.getIntegerType(layout.getTypeSizeInBits(ptrAttr.getType())),
-        ptrAttr.getValue().getInt());
-    return rewriter.create<mlir::LLVM::IntToPtrOp>(
-        loc, converter->convertType(ptrAttr.getType()), ptrVal);
-  }
+  mlir::Value visitCirAttr(cir::IntAttr intAttr);
+  mlir::Value visitCirAttr(cir::FPAttr fltAttr);
+  mlir::Value visitCirAttr(cir::ConstPtrAttr ptrAttr);
 
 private:
   mlir::Operation *parentOp;
   mlir::ConversionPatternRewriter &rewriter;
   const mlir::TypeConverter *converter;
 };
 
+/// IntAttr visitor.
+mlir::Value CIRAttrToValue::visitCirAttr(cir::IntAttr intAttr) {
+  mlir::Location loc = parentOp->getLoc();
+  return rewriter.create<mlir::LLVM::ConstantOp>(
+      loc, converter->convertType(intAttr.getType()), intAttr.getValue());
+}
+
+/// ConstPtrAttr visitor.
+mlir::Value CIRAttrToValue::visitCirAttr(cir::ConstPtrAttr ptrAttr) {
+  mlir::Location loc = parentOp->getLoc();
+  if (ptrAttr.isNullValue()) {
+    return rewriter.create<mlir::LLVM::ZeroOp>(
+        loc, converter->convertType(ptrAttr.getType()));
+  }
+  mlir::DataLayout layout(parentOp->getParentOfType<mlir::ModuleOp>());
+  mlir::Value ptrVal = rewriter.create<mlir::LLVM::ConstantOp>(
+      loc, rewriter.getIntegerType(layout.getTypeSizeInBits(ptrAttr.getType())),
+      ptrAttr.getValue().getInt());
+  return rewriter.create<mlir::LLVM::IntToPtrOp>(
+      loc, converter->convertType(ptrAttr.getType()), ptrVal);
+}
+
+/// FPAttr visitor.
+mlir::Value CIRAttrToValue::visitCirAttr(cir::FPAttr fltAttr) {
+  mlir::Location loc = parentOp->getLoc();
+  return rewriter.create<mlir::LLVM::ConstantOp>(
+      loc, converter->convertType(fltAttr.getType()), fltAttr.getValue());
+}
+
 // This class handles rewriting initializer attributes for types that do not
 // require region initialization.
 class GlobalInitAttrRewriter {
@@ -94,8 +98,6 @@ class GlobalInitAttrRewriter {
                          mlir::ConversionPatternRewriter &rewriter)
       : llvmType(type), rewriter(rewriter) {}
 
-  mlir::Attribute rewriteInitAttr(mlir::Attribute attr) { return visit(attr); }
-
   mlir::Attribute visit(mlir::Attribute attr) {
     return llvm::TypeSwitch<mlir::Attribute, mlir::Attribute>(attr)
         .Case<cir::IntAttr, cir::FPAttr>(
@@ -137,12 +139,6 @@ struct ConvertCIRToLLVMPass
   StringRef getArgument() const override { return "cir-flat-to-llvm"; }
 };
 
-bool CIRToLLVMGlobalOpLowering::attrRequiresRegionInitialization(
-    mlir::Attribute attr) const {
-  // There will be more cases added later.
-  return isa<cir::ConstPtrAttr>(attr);
-}
-
 /// Replace CIR global with a region initialized LLVM global and update
 /// insertion point to the end of the initializer block.
 void CIRToLLVMGlobalOpLowering::setupRegionInitializedLLVMGlobalOp(
@@ -189,8 +185,8 @@ CIRToLLVMGlobalOpLowering::matchAndRewriteRegionInitializedGlobal(
   // to the appropriate value.
   const mlir::Location loc = op.getLoc();
   setupRegionInitializedLLVMGlobalOp(op, rewriter);
-  CIRAttrToValue attrVisitor(op, rewriter, typeConverter);
-  mlir::Value value = attrVisitor.lowerCirAttrAsValue(init);
+  CIRAttrToValue valueConverter(op, rewriter, typeConverter);
+  mlir::Value value = valueConverter.visit(init);
   rewriter.create<mlir::LLVM::ReturnOp>(loc, value);
   return mlir::success();
 }
@@ -201,12 +197,6 @@ mlir::LogicalResult CIRToLLVMGlobalOpLowering::matchAndRewrite(
 
   std::optional<mlir::Attribute> init = op.getInitialValue();
 
-  // If we have an initializer and it requires region initialization, handle
-  // that separately
-  if (init.has_value() && attrRequiresRegionInitialization(init.value())) {
-    return matchAndRewriteRegionInitializedGlobal(op, init.value(), rewriter);
-  }
-
   // Fetch required values to create LLVM op.
   const mlir::Type cirSymType = op.getSymType();
 
@@ -231,12 +221,31 @@ mlir::LogicalResult CIRToLLVMGlobalOpLowering::matchAndRewrite(
   SmallVector<mlir::NamedAttribute> attributes;
 
   if (init.has_value()) {
-    GlobalInitAttrRewriter initRewriter(llvmType, rewriter);
-    init = initRewriter.rewriteInitAttr(init.value());
-    // If initRewriter returned a null attribute, init will have a value but
-    // the value will be null. If that happens, initRewriter didn't handle the
-    // attribute type. It probably needs to be added to GlobalInitAttrRewriter.
-    if (!init.value()) {
+    if (mlir::isa<cir::FPAttr, cir::IntAttr>(init.value())) {
+      // If a directly equivalent attribute is available, use it.
+      init =
+          llvm::TypeSwitch<mlir::Attribute, mlir::Attribute>(init.value())
+              .Case<cir::FPAttr>([&](cir::FPAttr attr) {
+                return rewriter.getFloatAttr(llvmType, attr.getValue());
+              })
+              .Case<cir::IntAttr>([&](cir::IntAttr attr) {
+                return rewriter.getIntegerAttr(llvmType, attr.getValue());
+              })
+              .Default([&](mlir::Attribute attr) { return mlir::Attribute(); });
+      // If initRewriter returned a null attribute, init will have a value but
+      // the value will be null.
+      if (!init.value()) {
+        op.emitError() << "unsupported initializer '" << init.value() << "'";
+        return mlir::failure();
+      }
+    } else if (mlir::isa<cir::ConstPtrAttr>(init.value())) {
+      // TODO(cir): once LLVM's dialect has proper equivalent attributes this
+      // should be updated. For now, we use a custom op to initialize globals
+      // to the appropriate value.
+      return matchAndRewriteRegionInitializedGlobal(op, init.value(), rewriter);
+    } else {
+      // We will only get here if new initializer types are added and this
+      // code is not updated to handle them.
       op.emitError() << "unsupported initializer '" << init.value() << "'";
       return mlir::failure();
     }

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h

@@ -36,8 +36,6 @@ class CIRToLLVMGlobalOpLowering
                   mlir::ConversionPatternRewriter &rewriter) const override;
 
 private:
-  bool attrRequiresRegionInitialization(mlir::Attribute attr) const;
-
   mlir::LogicalResult matchAndRewriteRegionInitializedGlobal(
       cir::GlobalOp op, mlir::Attribute init,
       mlir::ConversionPatternRewriter &rewriter) const;