Implement __builtin_return_address

clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp

@@ -1462,8 +1462,19 @@ RValue CIRGenFunction::buildBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
     llvm_unreachable("BI__builtin_wmemcmp NYI");
   case Builtin::BI__builtin_dwarf_cfa:
     llvm_unreachable("BI__builtin_dwarf_cfa NYI");
-  case Builtin::BI__builtin_return_address:
-    llvm_unreachable("BI__builtin_return_address NYI");
+  case Builtin::BI__builtin_return_address: {
+    mlir::Location loc = getLoc(E->getExprLoc());
+    mlir::Attribute frameAttr = ConstantEmitter(*this).emitAbstract(
+        E->getArg(0), E->getArg(0)->getType());
+    int64_t frame = mlir::cast<mlir::cir::IntAttr>(frameAttr).getSInt();
+    // The intrinsic call is expecting unsigned int arg type, void* return type
+    return RValue::get(builder
+                           .create<mlir::cir::IntrinsicCallOp>(
+                               loc, builder.getStringAttr("llvm.returnaddress"),
+                               VoidPtrTy,
+                               builder.getUInt32(frame, loc).getRes())
+                           .getResult());
+  }
   case Builtin::BI_ReturnAddress:
     llvm_unreachable("BI_ReturnAddress NYI");
   case Builtin::BI__builtin_frame_address:

clang/test/CIR/CodeGen/builtins-memory.c

@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck %s --check-prefix=CIR --input-file=%t.cir
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o %t.ll
+// RUN: FileCheck %s --check-prefix=LLVM --input-file=%t.ll
+
+void *test_return_address(void) {
+  return __builtin_return_address(1);
+
+  // CIR-LABEL: test_return_address
+  // [[ARG:%.*]] = cir.const #cir.int<1> : !u32i
+  // {{%.*}} = cir.llvm.intrinsic "llvm.returnaddress" [[ARG]] : (!u32i) -> !cir.ptr<!void>
+
+  // LLVM-LABEL: @test_return_address
+  // LLVM: {{%.*}} = call ptr @llvm.returnaddress(i32 1)
+}