[mlir][LLVM] Add section attribute to LLVMFuncOp

[Dinistro]

Summary

This commit adds an optional section attribute to the LLVMFuncOp and
adds import and export functionality for it.

[gysit]

Thanks LGTM!

mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td

let arguments = (ins
     OptionalAttr<StrAttr>:$garbageCollector,
     OptionalAttr<ArrayAttr>:$passthrough,
     OptionalAttr<DictArrayAttr>:$arg_attrs,
     OptionalAttr<DictArrayAttr>:$res_attrs,
     OptionalAttr<I64Attr>:$function_entry_count,
     OptionalAttr<LLVM_MemoryEffectsAttr>:$memory,
     DefaultValuedAttr<Visibility, "mlir::LLVM::Visibility::Default">:$visibility_,
     OptionalAttr<UnitAttr>:$arm_streaming,
-    OptionalAttr<UnitAttr>:$arm_locally_streaming
+    OptionalAttr<UnitAttr>:$arm_locally_streaming,
+    OptionalAttr<StrAttr>:$section
   );
 
   let regions = (region AnyRegion:$body);
 
   let skipDefaultBuilders = 1;
 
   let builders = [
     OpBuilder<(ins "StringRef":$name, "Type":$type,

mlir/lib/Target/LLVMIR/ModuleImport.cpp

LogicalResult ModuleImport::processFunction(llvm::Function *func) {
   if (FlatSymbolRefAttr personality = getPersonalityAsAttr(func))
     funcOp.setPersonalityAttr(personality);
   else if (func->hasPersonalityFn())
     emitWarning(funcOp.getLoc(), "could not deduce personality, skipping it");
 
   if (func->hasGC())
     funcOp.setGarbageCollector(StringRef(func->getGC()));
 
+  if (func->hasSection())
+    funcOp.setSection(StringRef(func->getSection()));
+
   funcOp.setVisibility_(convertVisibilityFromLLVM(func->getVisibility()));
 
   if (func->hasComdat())
     funcOp.setComdatAttr(comdatMapping.lookup(func->getComdat()));
 
   // Handle Function attributes.
   processFunctionAttributes(func, funcOp);
 

mlir/lib/Target/LLVMIR/ModuleTranslation.cpp

if (func.getPersonality()) {
     if (llvm::Constant *pfunc = getLLVMConstant(ty, func.getPersonalityAttr(),
                                                 func.getLoc(), *this))
       llvmFunc->setPersonalityFn(pfunc);
   }
 
   if (auto gc = func.getGarbageCollector())
     llvmFunc->setGC(gc->str());
 
+  if (std::optional<StringRef> section = func.getSection())
+    llvmFunc->setSection(*section);
+
   if (auto armStreaming = func.getArmStreaming())
     llvmFunc->addFnAttr("aarch64_pstate_sm_enabled");
   else if (auto armLocallyStreaming = func.getArmLocallyStreaming())
     llvmFunc->addFnAttr("aarch64_pstate_sm_body");
 
   // First, create all blocks so we can jump to them.
   llvm::LLVMContext &llvmContext = llvmFunc->getContext();
   for (auto &bb : func) {

mlir/test/Target/LLVMIR/Import/function-attributes.ll

 
 // -----
 
 ; CHECK-LABEL: @locally_streaming_func
 ; CHECK-SAME: attributes {arm_locally_streaming}
 define void @locally_streaming_func() "aarch64_pstate_sm_body" {
   ret void
 }
+
+// -----
+
+; CHECK-LABEL: @section_func
+; CHECK-SAME: attributes {section = ".section.name"}
+define void @section_func() section ".section.name" {
+  ret void
+}

mlir/test/Target/LLVMIR/llvmir.mlir

 // -----
 
 // CHECK-LABEL: @hasGCFunction
 // CHECK-SAME: gc "statepoint-example"
 llvm.func @hasGCFunction() attributes { garbageCollector = "statepoint-example" } {
     llvm.return
 }
 
+// -----
+
+// CHECK-LABEL: @section_func
+// CHECK-SAME: section ".section.name"
+llvm.func @section_func() attributes { section = ".section.name" } {
+    llvm.return
+}
+
+// -----
+
 // CHECK-LABEL: @callFreezeOp
 llvm.func @callFreezeOp(%x : i32) {
   // CHECK: freeze i32 %{{[0-9]+}}
   %0 = llvm.freeze %x : i32
   %1 = llvm.mlir.undef : i32
   // CHECK: freeze i32 undef
   %2 = llvm.freeze %1 : i32
   %3 = llvm.mlir.poison : i32