[Openmp-commits] [PATCH] D95530: [libomptarget] Load images in order of registration

[Manoel Roemmer via Phabricator via Openmp-commits]

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This makes sure that images are loaded in the order in which they are registered with libomptarget.

If a target can load multiple images and these images depend on each other (for example if one image contains the programs target regions and one image contains library code), then the order in which images are loaded can be important for symbol resolution (for example, in the VE plugin).
In this case: because the same code exist in the host binaries, the order in which the host linker loads them (which is also the order in which images are registered with libomptarget) is the order in which the images have to be loaded onto the device.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D95530

Files:
  openmp/libomptarget/src/device.h
  openmp/libomptarget/src/omptarget.cpp
  openmp/libomptarget/src/rtl.cpp
  openmp/libomptarget/src/rtl.h


Index: openmp/libomptarget/src/rtl.h
===================================================================
--- openmp/libomptarget/src/rtl.h
+++ openmp/libomptarget/src/rtl.h
@@ -67,6 +67,11 @@
   std::string RTLName;
 #endif
 
+  // Can this image handle images which do not contain target regions or global
+  // variables, but might only contain #declare target functions.
+  // These images will have an empty target table.
+  bool handles_library_images = false;
+
   // Functions implemented in the RTL.
   is_valid_binary_ty *is_valid_binary = nullptr;
   is_data_exchangable_ty *is_data_exchangable = nullptr;
Index: openmp/libomptarget/src/rtl.cpp
===================================================================
--- openmp/libomptarget/src/rtl.cpp
+++ openmp/libomptarget/src/rtl.cpp
@@ -148,6 +148,10 @@
     R.RTLName = Name;
 #endif
 
+    if (strcmp(Name, "libomptarget.rtl.ve.so") == 0) {
+      R.handles_library_images = true;
+    }
+
     DP("Registering RTL %s supporting %d devices!\n", R.RTLName.c_str(),
        R.NumberOfDevices);
 
@@ -331,6 +335,7 @@
       // Initialize (if necessary) translation table for this library.
       PM->TrlTblMtx.lock();
       if (!PM->HostEntriesBeginToTransTable.count(desc->HostEntriesBegin)) {
+        PM->HostEntriesBeginRegistrationOrder.push_back(desc->HostEntriesBegin);
         TranslationTable &TransTable =
             (PM->HostEntriesBeginToTransTable)[desc->HostEntriesBegin];
         TransTable.HostTable.EntriesBegin = desc->HostEntriesBegin;
Index: openmp/libomptarget/src/omptarget.cpp
===================================================================
--- openmp/libomptarget/src/omptarget.cpp
+++ openmp/libomptarget/src/omptarget.cpp
@@ -60,15 +60,16 @@
 
   Device.PendingGlobalsMtx.lock();
   PM->TrlTblMtx.lock();
-  for (HostEntriesBeginToTransTableTy::iterator entry_it =
-           PM->HostEntriesBeginToTransTable.begin();
-       entry_it != PM->HostEntriesBeginToTransTable.end(); ++entry_it) {
-    TranslationTable *TransTable = &entry_it->second;
+  for (auto *HostEntriesBegin : PM->HostEntriesBeginRegistrationOrder) {
+    TranslationTable *TransTable =
+      &PM->HostEntriesBeginToTransTable[HostEntriesBegin];
     if (TransTable->HostTable.EntriesBegin ==
-        TransTable->HostTable.EntriesEnd) {
+        TransTable->HostTable.EntriesEnd && 
+        !Device.RTL->handles_library_images) {
       // No host entry so no need to proceed
       continue;
     }
+
     if (TransTable->TargetsTable[device_id] != 0) {
       // Library entries have already been processed
       continue;
Index: openmp/libomptarget/src/device.h
===================================================================
--- openmp/libomptarget/src/device.h
+++ openmp/libomptarget/src/device.h
@@ -245,6 +245,8 @@
   /// Translation table retreived from the binary
   HostEntriesBeginToTransTableTy HostEntriesBeginToTransTable;
   std::mutex TrlTblMtx; ///< For Translation Table
+  /// Host offload entries in order of image registration
+  std::vector<__tgt_offload_entry *> HostEntriesBeginRegistrationOrder;
 
   /// Map from ptrs on the host to an entry in the Translation Table
   HostPtrToTableMapTy HostPtrToTableMap;


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