From b6df0a65f40384e70c805b2b3a62665cd14001c5 Mon Sep 17 00:00:00 2001
From: Kirill Yansitov <36601354+YazZz1k@users.noreply.github.com>
Date: Fri, 2 Feb 2024 04:46:51 +0300
Subject: [PATCH] [CIR][CIRGen] Support for section atttribute (#422)

This PR adds support for section("$name") attribute
---
 clang/include/clang/CIR/Dialect/IR/CIROps.td     |  3 ++-
 clang/lib/CIR/CodeGen/CIRGenModule.cpp           | 11 ++++-------
 .../CIR/CodeGen/UnimplementedFeatureGuarding.h   |  1 -
 .../CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp    | 16 ++++++++++++++--
 clang/test/CIR/CodeGen/attributes.c              | 14 ++++++++++++++
 5 files changed, 34 insertions(+), 11 deletions(-)
 create mode 100644 clang/test/CIR/CodeGen/attributes.c

diff --git a/clang/include/clang/CIR/Dialect/IR/CIROps.td b/clang/include/clang/CIR/Dialect/IR/CIROps.td
index 1e5145d0e15b..ea4013cb5bbd 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIROps.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIROps.td
@@ -1422,7 +1422,8 @@ def GlobalOp : CIR_Op<"global", [Symbol, DeclareOpInterfaceMethods<RegionBranchO
                        OptionalAttr<AnyAttr>:$initial_value,
                        UnitAttr:$constant,
                        OptionalAttr<I64Attr>:$alignment,
-                       OptionalAttr<ASTVarDeclInterface>:$ast
+                       OptionalAttr<ASTVarDeclInterface>:$ast,
+                       OptionalAttr<StrAttr>:$section
                        );
   let regions = (region AnyRegion:$ctorRegion, AnyRegion:$dtorRegion);
   let assemblyFormat = [{
diff --git a/clang/lib/CIR/CodeGen/CIRGenModule.cpp b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
index 59d88eafee21..40de4f53e32e 100644
--- a/clang/lib/CIR/CodeGen/CIRGenModule.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
@@ -716,10 +716,8 @@ CIRGenModule::getOrCreateCIRGlobal(StringRef MangledName, mlir::Type Ty,
 
     // Emit section information for extern variables.
     if (D->hasExternalStorage()) {
-      if (const SectionAttr *SA = D->getAttr<SectionAttr>()) {
-        assert(!UnimplementedFeature::setGlobalVarSection());
-        llvm_unreachable("section info for extern vars is NYI");
-      }
+      if (const SectionAttr *SA = D->getAttr<SectionAttr>())
+        GV.setSectionAttr(builder.getStringAttr(SA->getName()));
     }
 
     // Handle XCore specific ABI requirements.
@@ -1019,9 +1017,8 @@ void CIRGenModule::buildGlobalVarDefinition(const clang::VarDecl *D,
   //                 isTypeConstant(D->getType(), true));
 
   // If it is in a read-only section, mark it 'constant'.
-  if (const SectionAttr *SA = D->getAttr<SectionAttr>()) {
-    assert(0 && "not implemented");
-  }
+  if (const SectionAttr *SA = D->getAttr<SectionAttr>())
+    GV.setSectionAttr(builder.getStringAttr(SA->getName()));
 
   // TODO(cir):
   // GV->setAlignment(getContext().getDeclAlign(D).getAsAlign());
diff --git a/clang/lib/CIR/CodeGen/UnimplementedFeatureGuarding.h b/clang/lib/CIR/CodeGen/UnimplementedFeatureGuarding.h
index 89a336146f68..bf894fe53acf 100644
--- a/clang/lib/CIR/CodeGen/UnimplementedFeatureGuarding.h
+++ b/clang/lib/CIR/CodeGen/UnimplementedFeatureGuarding.h
@@ -41,7 +41,6 @@ struct UnimplementedFeature {
   // Unhandled global/linkage information.
   static bool unnamedAddr() { return false; }
   static bool setComdat() { return false; }
-  static bool setGlobalVarSection() { return false; }
   static bool setDSOLocal() { return false; }
   static bool threadLocal() { return false; }
   static bool setDLLStorageClass() { return false; }
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
index 8f07d47684be..12548f8b5af9 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
@@ -1505,12 +1505,21 @@ class CIRGlobalOpLowering
     const auto linkage = convertLinkage(op.getLinkage());
     const auto symbol = op.getSymName();
     const auto loc = op.getLoc();
+    std::optional<mlir::StringRef> section = op.getSection();
     std::optional<mlir::Attribute> init = op.getInitialValue();
 
+    SmallVector<mlir::NamedAttribute> attributes;
+    if (section.has_value())
+      attributes.push_back(rewriter.getNamedAttr(
+          "section", rewriter.getStringAttr(section.value())));
+
     // Check for missing funcionalities.
     if (!init.has_value()) {
       rewriter.replaceOpWithNewOp<mlir::LLVM::GlobalOp>(
-          op, llvmType, isConst, linkage, symbol, mlir::Attribute());
+          op, llvmType, isConst, linkage, symbol, mlir::Attribute(),
+          /*alignment*/ 0, /*addrSpace*/ 0,
+          /*dsoLocal*/ false, /*threadLocal*/ false,
+          /*comdat*/ mlir::SymbolRefAttr(), attributes);
       return mlir::success();
     }
 
@@ -1584,7 +1593,10 @@ class CIRGlobalOpLowering
 
     // Rewrite op.
     rewriter.replaceOpWithNewOp<mlir::LLVM::GlobalOp>(
-        op, llvmType, isConst, linkage, symbol, init.value());
+        op, llvmType, isConst, linkage, symbol, init.value(),
+        /*alignment*/ 0, /*addrSpace*/ 0,
+        /*dsoLocal*/ false, /*threadLocal*/ false,
+        /*comdat*/ mlir::SymbolRefAttr(), attributes);
     return mlir::success();
   }
 };
diff --git a/clang/test/CIR/CodeGen/attributes.c b/clang/test/CIR/CodeGen/attributes.c
new file mode 100644
index 000000000000..67b625c11520
--- /dev/null
+++ b/clang/test/CIR/CodeGen/attributes.c
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o -  | FileCheck %s -check-prefix=CIR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -S -emit-llvm %s -o - | FileCheck %s -check-prefix=LLVM
+// XFAIL: *
+
+extern int __attribute__((section(".shared"))) ext;
+int getExt() {
+  return ext;
+}
+// CIR:   cir.global "private" external @ext : !s32i {section = ".shared"}
+// LLVM:  @ext = external global i32, section ".shared"
+
+int __attribute__((section(".shared"))) glob = 42;
+// CIR:   cir.global external @glob = #cir.int<42> : !s32i {section = ".shared"}
+// LLVM   @glob = global i32 42, section ".shared"