[MLIR][OpenMP] Assert on map translation functions, NFC

This patch adds assertions to map-related MLIR to LLVM IR translation functions
and utils to explicitly document whether they are intended for host or device
compilation only.

Over time, map-related handling has increased in complexity. This is compounded
by the fact that some handling is device-specific and some is host-specific. By
explicitly asserting on these functions on the expected compilation pass, the
flow should become slighlty easier to follow.

Author: skatrak

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

@@ -3623,6 +3623,9 @@ static llvm::omp::OpenMPOffloadMappingFlags mapParentWithMembers(
     LLVM::ModuleTranslation &moduleTranslation, llvm::IRBuilderBase &builder,
     llvm::OpenMPIRBuilder &ompBuilder, DataLayout &dl, MapInfosTy &combinedInfo,
     MapInfoData &mapData, uint64_t mapDataIndex, bool isTargetParams) {
+  assert(!ompBuilder.Config.isTargetDevice() &&
+         "function only supported for host device codegen");
+
   // Map the first segment of our structure
   combinedInfo.Types.emplace_back(
       isTargetParams
@@ -3731,6 +3734,8 @@ static void processMapMembersWithParent(
     llvm::OpenMPIRBuilder &ompBuilder, DataLayout &dl, MapInfosTy &combinedInfo,
     MapInfoData &mapData, uint64_t mapDataIndex,
     llvm::omp::OpenMPOffloadMappingFlags memberOfFlag) {
+  assert(!ompBuilder.Config.isTargetDevice() &&
+         "function only supported for host device codegen");
 
   auto parentClause =
       llvm::cast<omp::MapInfoOp>(mapData.MapClause[mapDataIndex]);
@@ -3844,6 +3849,9 @@ static void processMapWithMembersOf(LLVM::ModuleTranslation &moduleTranslation,
                                     DataLayout &dl, MapInfosTy &combinedInfo,
                                     MapInfoData &mapData, uint64_t mapDataIndex,
                                     bool isTargetParams) {
+  assert(!ompBuilder.Config.isTargetDevice() &&
+         "function only supported for host device codegen");
+
   auto parentClause =
       llvm::cast<omp::MapInfoOp>(mapData.MapClause[mapDataIndex]);
 
@@ -3885,6 +3893,8 @@ static void
 createAlteredByCaptureMap(MapInfoData &mapData,
                           LLVM::ModuleTranslation &moduleTranslation,
                           llvm::IRBuilderBase &builder) {
+  assert(!moduleTranslation.getOpenMPBuilder()->Config.isTargetDevice() &&
+         "function only supported for host device codegen");
   for (size_t i = 0; i < mapData.MapClause.size(); ++i) {
     // if it's declare target, skip it, it's handled separately.
     if (!mapData.IsDeclareTarget[i]) {
@@ -3949,6 +3959,9 @@ static void genMapInfos(llvm::IRBuilderBase &builder,
                         LLVM::ModuleTranslation &moduleTranslation,
                         DataLayout &dl, MapInfosTy &combinedInfo,
                         MapInfoData &mapData, bool isTargetParams = false) {
+  assert(!moduleTranslation.getOpenMPBuilder()->Config.isTargetDevice() &&
+         "function only supported for host device codegen");
+
   // We wish to modify some of the methods in which arguments are
   // passed based on their capture type by the target region, this can
   // involve generating new loads and stores, which changes the
@@ -3960,8 +3973,7 @@ static void genMapInfos(llvm::IRBuilderBase &builder,
   // kernel arg structure. It primarily becomes relevant in cases like
   // bycopy, or byref range'd arrays. In the default case, we simply
   // pass thee pointer byref as both basePointer and pointer.
-  if (!moduleTranslation.getOpenMPBuilder()->Config.isTargetDevice())
-    createAlteredByCaptureMap(mapData, moduleTranslation, builder);
+  createAlteredByCaptureMap(mapData, moduleTranslation, builder);
 
   llvm::OpenMPIRBuilder *ompBuilder = moduleTranslation.getOpenMPBuilder();
 
@@ -3995,6 +4007,8 @@ emitUserDefinedMapper(Operation *declMapperOp, llvm::IRBuilderBase &builder,
 static llvm::Expected<llvm::Function *>
 getOrCreateUserDefinedMapperFunc(Operation *op, llvm::IRBuilderBase &builder,
                                  LLVM::ModuleTranslation &moduleTranslation) {
+  assert(!moduleTranslation.getOpenMPBuilder()->Config.isTargetDevice() &&
+         "function only supported for host device codegen");
   auto declMapperOp = cast<omp::DeclareMapperOp>(op);
   std::string mapperFuncName =
       moduleTranslation.getOpenMPBuilder()->createPlatformSpecificName(
@@ -4011,6 +4025,8 @@ static llvm::Expected<llvm::Function *>
 emitUserDefinedMapper(Operation *op, llvm::IRBuilderBase &builder,
                       LLVM::ModuleTranslation &moduleTranslation,
                       llvm::StringRef mapperFuncName) {
+  assert(!moduleTranslation.getOpenMPBuilder()->Config.isTargetDevice() &&
+         "function only supported for host device codegen");
   auto declMapperOp = cast<omp::DeclareMapperOp>(op);
   auto declMapperInfoOp = declMapperOp.getDeclareMapperInfo();
   DataLayout dl = DataLayout(declMapperOp->getParentOfType<ModuleOp>());
@@ -4500,6 +4516,8 @@ static void
 handleDeclareTargetMapVar(MapInfoData &mapData,
                           LLVM::ModuleTranslation &moduleTranslation,
                           llvm::IRBuilderBase &builder, llvm::Function *func) {
+  assert(moduleTranslation.getOpenMPBuilder()->Config.isTargetDevice() &&
+         "function only supported for target device codegen");
   for (size_t i = 0; i < mapData.MapClause.size(); ++i) {
     // In the case of declare target mapped variables, the basePointer is
     // the reference pointer generated by the convertDeclareTargetAttr
@@ -4592,6 +4610,8 @@ createDeviceArgumentAccessor(MapInfoData &mapData, llvm::Argument &arg,
                              LLVM::ModuleTranslation &moduleTranslation,
                              llvm::IRBuilderBase::InsertPoint allocaIP,
                              llvm::IRBuilderBase::InsertPoint codeGenIP) {
+  assert(ompBuilder.Config.isTargetDevice() &&
+         "function only supported for target device codegen");
   builder.restoreIP(allocaIP);
 
   omp::VariableCaptureKind capture = omp::VariableCaptureKind::ByRef;