[llvm] [Offload] add 'olIterateSymbols' runtime function (PR #213036)

[Joseph Huber via llvm-commits]

================
@@ -1314,19 +1313,61 @@ Error olGetSymbol_impl(ol_program_handle_t Program, const char *Name,
                   Device, *Program->Image, GlobalObj))
         return Res;
 
-      Global = std::make_unique<ol_symbol_impl_t>(GlobalObj.getName().c_str(),
-                                                  std::move(GlobalObj));
+      Global = std::make_unique<ol_symbol_impl_t>(std::move(GlobalObj));
     }
 
-    *Symbol = Global.get();
-    return Error::success();
+    return Global.get();
   }
   default:
     return createOffloadError(ErrorCode::INVALID_ENUMERATION,
                               "getSymbol kind enum '%i' is invalid", Kind);
   }
 }
 
+Error olGetSymbol_impl(ol_program_handle_t Program, const char *Name,
+                       ol_symbol_kind_t Kind, ol_symbol_handle_t *Symbol) {
+  std::lock_guard<std::mutex> Lock(Program->SymbolListMutex);
+
+  auto SymbolOrErr = getSymbolImplDetail(Program, Name, Kind);
+  if (!SymbolOrErr)
+    return SymbolOrErr.takeError();
+
+  *Symbol = *SymbolOrErr;
+  return Error::success();
+}
+
+Error olIterateSymbols_impl(ol_program_handle_t Program, ol_symbol_kind_t Kind,
+                            ol_symbol_iterate_cb_t Callback, void *UserData) {
+  SymbolKindTy PluginKind;
+  switch (Kind) {
+  case OL_SYMBOL_KIND_KERNEL:
+    PluginKind = SymbolKindTy::Kernel;
+    break;
+  case OL_SYMBOL_KIND_GLOBAL_VARIABLE:
+    PluginKind = SymbolKindTy::GlobalVariable;
+    break;
+  default:
+    return createOffloadError(ErrorCode::INVALID_ENUMERATION,
+                              "iterateSymbols kind enum '%i' is invalid", Kind);
+  }
+
+  auto &Device = Program->Image->getDevice();
+  std::lock_guard<std::mutex> Lock(Program->SymbolListMutex);
+
+  Error SymbolErr = Error::success();
+  Error IterateErr = Device.Plugin.getGlobalHandler().iterateSymbols(
+      *Program->Image, PluginKind, [&](StringRef Name) {
+        auto SymbolOrErr = getSymbolImplDetail(Program, Name, Kind);
----------------
jhuber6 wrote:

Symbol lookup is relatively cheap, but I was torn on how to keep the interface 'generic'. The problem is that liboffload defines a symbol as a specific thing, and the plugins could potentially use something that isn't an ELF, hence the tradeoff. For what it's worth, scanning through all the symbols is *never* gonig to be on a hot path. It's always going to be a configuration step.

https://github.com/llvm/llvm-project/pull/213036