Prefer use of Wasm signatures when building the thunk name

Author: kleisauke

clang/lib/CodeGen/Targets/WebAssembly.cpp

@@ -10,7 +10,6 @@
 #include "TargetInfo.h"
 
 #include "clang/AST/ParentMapContext.h"
-#include <sstream>
 
 using namespace clang;
 using namespace clang::CodeGen;
@@ -192,10 +191,11 @@ class WebAssemblyTargetCodeGenInfo final : public TargetCodeGenInfo {
   }
 
 private:
-  // Build the thunk name: "%s_{type1}_{type2}_..."
+  // Build the thunk name: "%s_{OrigName}_{WasmSig}"
   std::string getThunkName(std::string OrigName,
                            const FunctionProtoType *DstProto,
                            const ASTContext &Ctx) const;
+  char getTypeSig(const QualType &Ty, const ASTContext &Ctx) const;
   std::string sanitizeTypeString(const std::string &typeStr) const;
   std::string getTypeName(const QualType &qt, const ASTContext &Ctx) const;
   const DeclRefExpr *findDeclRefExpr(const Expr *E) const;
@@ -285,43 +285,49 @@ CodeGen::createWebAssemblyTargetCodeGenInfo(CodeGenModule &CGM,
   return std::make_unique<WebAssemblyTargetCodeGenInfo>(CGM.getTypes(), K);
 }
 
-// Helper to sanitize type name string for use in function name
-std::string WebAssemblyTargetCodeGenInfo::sanitizeTypeString(
-    const std::string &typeStr) const {
-  std::string s;
-  for (char c : typeStr) {
-    if (isalnum(c))
-      s += c;
-    else if (c == ' ')
-      s += '_';
-    else
-      s += '_';
+// Helper to get the type signature character for a given QualType
+// Returns a character that represents the given QualType in a wasm signature.
+// See getInvokeSig() in WebAssemblyAsmPrinter for related logic.
+char WebAssemblyTargetCodeGenInfo::getTypeSig(const QualType &Ty,
+                                              const ASTContext &Ctx) const {
+  if (Ty->isAnyPointerType()) {
+    return Ctx.getTypeSize(Ctx.VoidPtrTy) == 32 ? 'i' : 'j';
+  }
+  if (Ty->isIntegerType()) {
+    return Ctx.getTypeSize(Ty) <= 32 ? 'i' : 'j';
+  }
+  if (Ty->isFloatingType()) {
+    return Ctx.getTypeSize(Ty) <= 32 ? 'f' : 'd';
+  }
+  if (Ty->isVectorType()) {
+    return 'V';
+  }
+  if (Ty->isWebAssemblyTableType()) {
+    return 'F';
+  }
+  if (Ty->isWebAssemblyExternrefType()) {
+    return 'X';
   }
-  return s;
-}
 
-// Helper to generate the type string from QualType
-std::string
-WebAssemblyTargetCodeGenInfo::getTypeName(const QualType &qt,
-                                          const ASTContext &Ctx) const {
-  PrintingPolicy Policy(Ctx.getLangOpts());
-  Policy.SuppressTagKeyword = true;
-  Policy.SuppressScope = true;
-  Policy.AnonymousTagLocations = false;
-  std::string typeStr = qt.getAsString(Policy);
-  return sanitizeTypeString(typeStr);
+  llvm_unreachable("Unhandled QualType");
 }
 
 std::string
 WebAssemblyTargetCodeGenInfo::getThunkName(std::string OrigName,
                                            const FunctionProtoType *DstProto,
                                            const ASTContext &Ctx) const {
-  std::ostringstream oss;
-  oss << "__" << OrigName;
+
+  std::string ThunkName = "__" + OrigName + "_";
+  QualType RetTy = DstProto->getReturnType();
+  if (RetTy->isVoidType()) {
+    ThunkName += 'v';
+  } else {
+    ThunkName += getTypeSig(RetTy, Ctx);
+  }
   for (unsigned i = 0; i < DstProto->getNumParams(); ++i) {
-    oss << "_" << getTypeName(DstProto->getParamType(i), Ctx);
+    ThunkName += getTypeSig(DstProto->getParamType(i), Ctx);
   }
-  return oss.str();
+  return ThunkName;
 }
 
 /// Recursively find the first DeclRefExpr in an Expr subtree.
@@ -394,4 +400,4 @@ const DeclRefExpr *WebAssemblyTargetCodeGenInfo::findDeclRefExprForVarUp(
     cur = parentStmt;
   }
   return nullptr;
-}
+}