Rollup merge of rust-lang#129749 - krasimirgg:llvm-20-lto, r=nikic

llvm-wrapper: adapt for LLVM API changes

No functional changes intended.

Updates the wrapper for 5c4lar/llvm-project@21eddfa.

````@rustbot```` label: +llvm-main
r? ````@nikic````

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -1212,7 +1212,11 @@ struct LLVMRustThinLTOData {
   // Not 100% sure what these are, but they impact what's internalized and
   // what's inlined across modules, I believe.
 #if LLVM_VERSION_GE(18, 0)
+#if LLVM_VERSION_GE(20, 0)
+  FunctionImporter::ImportListsTy ImportLists;
+#else
   DenseMap<StringRef, FunctionImporter::ImportMapTy> ImportLists;
+#endif
   DenseMap<StringRef, FunctionImporter::ExportSetTy> ExportLists;
   DenseMap<StringRef, GVSummaryMapTy> ModuleToDefinedGVSummaries;
 #else
@@ -1421,13 +1425,13 @@ LLVMRustPrepareThinLTOInternalize(const LLVMRustThinLTOData *Data,
   return true;
 }
 
-extern "C" bool LLVMRustPrepareThinLTOImport(const LLVMRustThinLTOData *Data,
+extern "C" bool LLVMRustPrepareThinLTOImport(LLVMRustThinLTOData *Data,
                                              LLVMModuleRef M,
                                              LLVMTargetMachineRef TM) {
   Module &Mod = *unwrap(M);
   TargetMachine &Target = *unwrap(TM);
 
-  const auto &ImportList = Data->ImportLists.lookup(Mod.getModuleIdentifier());
+  const auto &ImportList = Data->ImportLists[Mod.getModuleIdentifier()];
   auto Loader = [&](StringRef Identifier) {
     const auto &Memory = Data->ModuleMap.lookup(Identifier);
     auto &Context = Mod.getContext();
@@ -1610,7 +1614,7 @@ extern "C" void LLVMRustComputeLTOCacheKey(RustStringRef KeyOut,
                                            LLVMRustThinLTOData *Data) {
   SmallString<40> Key;
   llvm::lto::Config conf;
-  const auto &ImportList = Data->ImportLists.lookup(ModId);
+  const auto &ImportList = Data->ImportLists[ModId];
   const auto &ExportList = Data->ExportLists.lookup(ModId);
   const auto &ResolvedODR = Data->ResolvedODR.lookup(ModId);
   const auto &DefinedGlobals = Data->ModuleToDefinedGVSummaries.lookup(ModId);