[wasm] Add a thunk cache

Author: turran

clang/lib/CodeGen/Targets/WebAssembly.cpp

@@ -8,6 +8,7 @@
 
 #include "ABIInfoImpl.h"
 #include "TargetInfo.h"
+#include "llvm/ADT/StringMap.h"
 
 #include "clang/AST/ParentMapContext.h"
 
@@ -56,6 +57,7 @@ class WebAssemblyTargetCodeGenInfo final : public TargetCodeGenInfo {
       : TargetCodeGenInfo(std::make_unique<WebAssemblyABIInfo>(CGT, K)) {
     SwiftInfo =
         std::make_unique<SwiftABIInfo>(CGT, /*SwiftErrorInRegister=*/false);
+    ThunkCache = llvm::StringMap<llvm::Function *>();
   }
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
@@ -151,6 +153,16 @@ class WebAssemblyTargetCodeGenInfo final : public TargetCodeGenInfo {
     // Construct the Thunk function with the Target (destination) signature
     std::string ThunkName = getThunkName(OriginalFnPtr->getName().str(),
                                          DstProtoType, CGM.getContext());
+    // Check if we already have a thunk for this function
+    if (auto It = ThunkCache.find(ThunkName); It != ThunkCache.end()) {
+      LLVM_DEBUG(llvm::dbgs() << "getOrCreateWasmFunctionPointerThunk: "
+                              << "found existing thunk for "
+                              << OriginalFnPtr->getName().str() << " as "
+                              << ThunkName << "\n");
+      return It->second;
+    }
+
+    // Create the thunk function
     llvm::Module &M = CGM.getModule();
     llvm::Function *Thunk = llvm::Function::Create(
         DstFunctionType, llvm::Function::InternalLinkage, ThunkName, M);
@@ -187,10 +199,14 @@ class WebAssemblyTargetCodeGenInfo final : public TargetCodeGenInfo {
     LLVM_DEBUG(llvm::dbgs() << "getOrCreateWasmFunctionPointerThunk:"
                             << " from " << OriginalFnPtr->getName().str()
                             << " to " << ThunkName << "\n");
+    // Cache the thunk
+    ThunkCache[ThunkName] = Thunk;
     return Thunk;
   }
 
 private:
+  // The thunk cache
+  mutable llvm::StringMap<llvm::Function *> ThunkCache;
   // Build the thunk name: "%s_{OrigName}_{WasmSig}"
   std::string getThunkName(std::string OrigName,
                            const FunctionProtoType *DstProto,