[Libomptarget] Do not check for valid binaries twice.

[jhuber6]

Summary

The only RTLs that get added to the UsedRTLs list have already been
checked is they were valid binaries. We shouldn't need to do this again
when we unregister all the used binaries as they wouldn't have been used
if they were invalid anyway. Let me know if I'm incorrect in this
assumption.

[tianshilei1992]

openmp/libomptarget/src/rtl.cpp

513

Is it necessary to still keep it?

[jhuber6]

openmp/libomptarget/src/rtl.cpp

513

It's only used for a debug print message at the end of the loop to say "No RTL's found for Image". We can get rid of that if necessary.

[jhuber6]

Actually, the RTL may contain more images than the ones we added. So we probably should just have a separate list of images used inside of the RTL type and just exit if it's not in that set.

[jhuber6]

Adding a set to contain the images used by the RTL instead. Should still save us time going into the plugin to check if the image is valid, espeically when we need to check runtime values like the target architecture.

[jhuber6]

Remove unneeded info value.

[jhuber6]

Ping

[jdoerfert]

LG

openmp/libomptarget/include/rtl.h

129

Documentation plz.

openmp/libomptarget/include/rtl.h

 //===------------ rtl.h - Target independent OpenMP target RTL ------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // Declarations for handling RTL plugins.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef _OMPTARGET_RTL_H
 #define _OMPTARGET_RTL_H
 
 #include "omptarget.h"
+#include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/SmallVector.h"
 
 #include <list>
 #include <map>
 #include <mutex>
 #include <string>
 
 // Forward declarations.
#endif
   destroy_event_ty *destroy_event = nullptr;
   init_async_info_ty *init_async_info = nullptr;
   init_device_into_ty *init_device_info = nullptr;
   release_async_info_ty *release_async_info = nullptr;
 
   // Are there images associated with this RTL.
   bool IsUsed = false;
 
+  llvm::DenseSet<const __tgt_device_image *> UsedImages;
+
   // Mutex for thread-safety when calling RTL interface functions.
   // It is easier to enforce thread-safety at the libomptarget level,
   // so that developers of new RTLs do not have to worry about it.
   std::mutex Mtx;
 };
 
 /// RTLs identified in the system.
 struct RTLsTy {

openmp/libomptarget/src/rtl.cpp

for (auto &R : AllRTLs) {
 
       // Retrieve translation table for this library.
       TranslationTable &TransTable =
           (PM->HostEntriesBeginToTransTable)[Desc->HostEntriesBegin];
 
       DP("Registering image " DPxMOD " with RTL %s!\n", DPxPTR(Img->ImageStart),
          R.RTLName.c_str());
       registerImageIntoTranslationTable(TransTable, R, Img);
+      R.UsedImages.insert(Img);
+
       PM->TrlTblMtx.unlock();
       FoundRTL = &R;
 
       // Load ctors/dtors for static objects
       registerGlobalCtorsDtorsForImage(Desc, Img, FoundRTL);
 
       // if an RTL was found we are done - proceed to register the next image
       break;

 void RTLsTy::unregisterLib(__tgt_bin_desc *Desc) {
   DP("Unloading target library!\n");
 
   PM->RTLsMtx.lock();
   // Find which RTL understands each image, if any.
   for (auto &ImageAndInfo : PM->Images) {
     // Obtain the image and information that was previously extracted.
     __tgt_device_image *Img = &ImageAndInfo.first;
-    __tgt_image_info *Info = &ImageAndInfo.second;
 
     RTLInfoTy *FoundRTL = NULL;
 
     // Scan the RTLs that have associated images until we find one that supports
     // the current image. We only need to scan RTLs that are already being used.
     for (auto *R : UsedRTLs) {
 
       assert(R->IsUsed && "Expecting used RTLs.");
 
-      if (R->is_valid_binary_info) {
-        if (!R->is_valid_binary_info(Img, Info)) {
-          DP("Image " DPxMOD " is NOT compatible with RTL %s!\n",
-             DPxPTR(Img->ImageStart), R->RTLName.c_str());
-          continue;
-        }
-      } else if (!R->is_valid_binary(Img)) {
-        DP("Image " DPxMOD " is NOT compatible with RTL %s!\n",
-           DPxPTR(Img->ImageStart), R->RTLName.c_str());
-        continue;
-      }
-
-      DP("Image " DPxMOD " is compatible with RTL " DPxMOD "!\n",
-         DPxPTR(Img->ImageStart), DPxPTR(R->LibraryHandler));
+      // Ensure that we do not use any unused images associated with this RTL.
+      if (!R->UsedImages.contains(Img))
 
       FoundRTL = R;
 
       // Execute dtors for static objects if the device has been used, i.e.
       // if its PendingCtors list has been emptied.
       for (int32_t I = 0; I < FoundRTL->NumberOfDevices; ++I) {
         DeviceTy &Device = *PM->Devices[FoundRTL->Idx + I];
         Device.PendingGlobalsMtx.lock();
         if (Device.PendingCtorsDtors[Desc].PendingCtors.empty()) {
           AsyncInfoTy AsyncInfo(Device);