[Flang][MLIR][OpenMP] Remove the early outlining interface (#78450)

After the removal of the OpenMP early outlining MLIR pass in #67319, the
`EarlyOutliningInterface` stopped doing any useful work. It used to be
necessary to tie the name of the function from which a target region was
outlined to that new function, so it would be used when translating to
LLVM IR in place of the outlined function's name.

This is not necessary anymore, so this patch removes all references to
this interface and uses of the `omp.outline_parent_name` discardable
attribute in tests.

Author: skatrak

flang/lib/Optimizer/Transforms/ExternalNameConversion.cpp

@@ -44,20 +44,6 @@ mangleExternalName(const std::pair<fir::NameUniquer::NameKind,
                                                   appendUnderscore);
 }
 
-/// Update the early outlining parent name
-void updateEarlyOutliningParentName(mlir::func::FuncOp funcOp,
-                                    bool appendUnderscore) {
-  if (auto earlyOutlineOp = llvm::dyn_cast<mlir::omp::EarlyOutliningInterface>(
-          funcOp.getOperation())) {
-    auto oldName = earlyOutlineOp.getParentName();
-    if (oldName != "") {
-      auto dName = fir::NameUniquer::deconstruct(oldName);
-      std::string newName = mangleExternalName(dName, appendUnderscore);
-      earlyOutlineOp.setParentName(newName);
-    }
-  }
-}
-
 //===----------------------------------------------------------------------===//
 // Rewrite patterns
 //===----------------------------------------------------------------------===//
@@ -93,8 +79,6 @@ struct MangleNameOnFuncOp : public mlir::OpRewritePattern<mlir::func::FuncOp> {
       op->setAttr(fir::getInternalFuncNameAttrName(),
                   mlir::StringAttr::get(op->getContext(), oldName));
     }
-
-    updateEarlyOutliningParentName(op, appendUnderscore);
     rewriter.finalizeOpModification(op);
     return ret;
   }

flang/test/Fir/external-mangling.fir

@@ -89,12 +89,3 @@ func.func @_QPcaller() {
 
 // LLVMIR-NOUNDER: llvm.call @callee() : () -> ()
 // LLVMIR-NOUNDER: llvm.call @callee() : () -> ()
-
-// -----
-
-func.func @_QPwriteindex_omp_outline_0() attributes {omp.outline_parent_name = "_QPwriteindex"} {
-   return
-}
-
-// CHECK-UNDER: attributes {fir.internal_name = "_QPwriteindex_omp_outline_0", omp.outline_parent_name = "writeindex_"}
-// CHECK-NOUNDER: attributes {fir.internal_name = "_QPwriteindex_omp_outline_0", omp.outline_parent_name = "writeindex"}

mlir/include/mlir/Dialect/OpenMP/OpenMPInterfaces.h

@@ -36,11 +36,6 @@ struct DeclareTargetDefaultModel
     : public DeclareTargetInterface::ExternalModel<DeclareTargetDefaultModel<T>,
                                                    T> {};
 
-template <typename T>
-struct EarlyOutliningDefaultModel
-    : public EarlyOutliningInterface::ExternalModel<
-          EarlyOutliningDefaultModel<T>, T> {};
-
 } // namespace mlir::omp
 
 #endif // MLIR_DIALECT_OPENMP_OPENMPINTERFACES_H_

mlir/include/mlir/Dialect/OpenMP/OpenMPOpsInterfaces.td

@@ -288,44 +288,4 @@ def OffloadModuleInterface : OpInterface<"OffloadModuleInterface"> {
   ];
 }
 
-def EarlyOutliningInterface : OpInterface<"EarlyOutliningInterface"> {
-  let description = [{
-    FuncOps that are a result of early outlining should have this interface.
-  }];
-
-  let cppNamespace = "::mlir::omp";
-
-  let methods = [
-    InterfaceMethod<
-      /*description=*/[{
-        Set a StringAttr on an outlined target region function containing the
-        name of the parent function where the target region was outlined
-        from. The parent name is used to construct the kernel names for target
-        regions.
-      }],
-      /*retTy=*/"void",
-      /*methodName=*/"setParentName",
-      (ins "std::string":$parentName), [{}], [{
-        $_op->setAttr(
-          mlir::StringAttr::get($_op->getContext(),
-                                llvm::Twine{"omp.outline_parent_name"}),
-          mlir::StringAttr::get($_op->getContext(), parentName));
-       }]>,
-
-    InterfaceMethod<
-      /*description=*/[{
-        Returns the parent function name from where the target op was outlined
-        from. If it doesn't exist it returns an empty string.
-      }],
-      /*retTy=*/"llvm::StringRef",
-      /*methodName=*/"getParentName",
-      (ins), [{}], [{
-        if (Attribute parentName = $_op->getAttr("omp.outline_parent_name"))
-          if (::llvm::isa<mlir::StringAttr>(parentName))
-            return ::llvm::dyn_cast<mlir::StringAttr>(parentName).getValue();
-        return {};
-      }]>
-  ];
-}
-
 #endif // OpenMP_OPS_INTERFACES

mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp

@@ -98,13 +98,6 @@ void OpenMPDialect::initialize() {
       *getContext());
   mlir::func::FuncOp::attachInterface<
       mlir::omp::DeclareTargetDefaultModel<mlir::func::FuncOp>>(*getContext());
-
-  // Attach default early outlining interface to func ops.
-  mlir::func::FuncOp::attachInterface<
-      mlir::omp::EarlyOutliningDefaultModel<mlir::func::FuncOp>>(*getContext());
-  mlir::LLVM::LLVMFuncOp::attachInterface<
-      mlir::omp::EarlyOutliningDefaultModel<mlir::LLVM::LLVMFuncOp>>(
-      *getContext());
 }
 
 //===----------------------------------------------------------------------===//

mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp

@@ -2362,13 +2362,6 @@ convertOmpTarget(Operation &opInst, llvm::IRBuilderBase &builder,
   llvm::OpenMPIRBuilder::LocationDescription ompLoc(builder);
   StringRef parentName = opInst.getParentOfType<LLVM::LLVMFuncOp>().getName();
 
-  // Override parent name if early outlining function
-  if (auto earlyOutlineOp = llvm::dyn_cast<mlir::omp::EarlyOutliningInterface>(
-          opInst.getParentOfType<LLVM::LLVMFuncOp>().getOperation())) {
-    llvm::StringRef outlineParentName = earlyOutlineOp.getParentName();
-    parentName = outlineParentName.empty() ? parentName : outlineParentName;
-  }
-
   llvm::TargetRegionEntryInfo entryInfo;
 
   if (!getTargetEntryUniqueInfo(entryInfo, targetOp, parentName))

mlir/test/Dialect/OpenMP/attr.mlir

@@ -181,11 +181,3 @@ llvm.mlir.global external @omp_decl_tar_data_any_enter() {omp.declare_target = #
   %0 = llvm.mlir.constant(1 : i32) : i32
   llvm.return %0 : i32
 }
-
-// ----
-
-// CHECK-LABEL: func @_QPwriteindex_omp_outline_0
-// CHECK-SAME: {{.*}} attributes {omp.outline_parent_name = "QPwriteindex"} {
-func.func @_QPwriteindex_omp_outline_0() attributes {omp.outline_parent_name = "QPwriteindex"} {
-   return
-}

mlir/test/Target/LLVMIR/omptarget-parallel-llvm.mlir

@@ -4,7 +4,7 @@
 // for omp target parallel construct
 
 module attributes {dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<"dlti.alloca_memory_space", 5 : ui32>>, llvm.data_layout = "e-p:64:64-p1:64:64-p2:32:32-p3:32:32-p4:64:64-p5:32:32-p6:32:32-p7:160:256:256:32-p8:128:128-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64-S32-A5-G1-ni:7:8:9", llvm.target_triple = "amdgcn-amd-amdhsa", omp.is_gpu = true, omp.is_target_device = true, omp.target = #omp.target<target_cpu = "gfx90a", target_features = "">} {
-  llvm.func @_QQmain_omp_outline_1(%arg0: !llvm.ptr) attributes {omp.declare_target = #omp.declaretarget<device_type = (host), capture_clause = (to)>, omp.outline_parent_name = "_QQmain"} {
+  llvm.func @_QQmain_omp_outline_1(%arg0: !llvm.ptr) attributes {omp.declare_target = #omp.declaretarget<device_type = (host), capture_clause = (to)>} {
     %0 = omp.map_info var_ptr(%arg0 : !llvm.ptr, i32) map_clauses(from) capture(ByRef) -> !llvm.ptr {name = "d"}
     omp.target map_entries(%0 -> %arg2 : !llvm.ptr) {
     ^bb0(%arg2: !llvm.ptr):
@@ -18,7 +18,7 @@ module attributes {dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<"dlti.alloca_memo
   llvm.return
   }
 
-  llvm.func @_test_num_threads(%arg0: !llvm.ptr) attributes {omp.declare_target = #omp.declaretarget<device_type = (host), capture_clause = (to)>, omp.outline_parent_name = "_QQmain"} {
+  llvm.func @_test_num_threads(%arg0: !llvm.ptr) attributes {omp.declare_target = #omp.declaretarget<device_type = (host), capture_clause = (to)>} {
     %0 = omp.map_info var_ptr(%arg0 : !llvm.ptr, i32) map_clauses(from) capture(ByRef) -> !llvm.ptr {name = "d"}
     omp.target map_entries(%0 -> %arg2 : !llvm.ptr) {
     ^bb0(%arg2: !llvm.ptr):