[clang] [TBAA] Emit int TBAA metadata on FP math libcalls (PR #96025)

[Eli Friedman via cfe-commits]

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@@ -707,7 +707,39 @@ static RValue emitLibraryCall(CodeGenFunction &CGF, const FunctionDecl *FD,
                               const CallExpr *E, llvm::Constant *calleeValue) {
   CodeGenFunction::CGFPOptionsRAII FPOptsRAII(CGF, E);
   CGCallee callee = CGCallee::forDirect(calleeValue, GlobalDecl(FD));
-  return CGF.EmitCall(E->getCallee()->getType(), callee, E, ReturnValueSlot());
+  RValue Call =
+      CGF.EmitCall(E->getCallee()->getType(), callee, E, ReturnValueSlot());
+
+  // Check the supported intrinsic.
+  if (unsigned BuiltinID = FD->getBuiltinID()) {
+    auto IntrinsicID = [&]() -> unsigned {
+      switch (BuiltinID) {
+      case Builtin::BIexpf:
+      case Builtin::BI__builtin_expf:
+      case Builtin::BI__builtin_expf128:
+        return true;
+      }
+      // TODO: support more FP math libcalls
+      return false;
+    }();
+
+    // Restrict to target with errno, for example, MacOS doesn't set errno.
+    if (IntrinsicID && CGF.CGM.getLangOpts().MathErrno) {
+      llvm::MDBuilder MDHelper(CGF.getLLVMContext());
+      ASTContext &Context = CGF.getContext();
+      // Emit "int" TBAA metadata on FP math libcalls.
+      clang::QualType IntTy = Context.IntTy;
+      MDNode *AliasType = CGF.CGM.getTBAATypeInfo(IntTy);
+      MDNode *MDInt = MDHelper.createTBAAStructTagNode(AliasType, AliasType, 0);
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efriedma-quic wrote:

I think you want CodeGenModule::getTBAAAccessTagInfo, not getTBAATypeInfo?  (My mistake.)

https://github.com/llvm/llvm-project/pull/96025