Fixes #168690

Prevents assertion in CGBuiltin for i1 - returns identity.
Created test file for the same.

Author: ebinjose02

clang/lib/CodeGen/CGBuiltin.cpp

@@ -3653,6 +3653,8 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
     Value *ArgValue = EmitScalarExpr(E->getArg(0));
     llvm::IntegerType *IntTy = cast<llvm::IntegerType>(ArgValue->getType());
     assert(IntTy && "LLVM's __builtin_bswapg only supports integer variants");
+    if (IntTy->getBitWidth() == 1)
+      return RValue::get(ArgValue);
     assert(((IntTy->getBitWidth() % 16 == 0 && IntTy->getBitWidth() != 0) ||
             IntTy->getBitWidth() == 8) &&
            "LLVM's __builtin_bswapg only supports integer variants that has a "

clang/test/CodeGen/builtin_bswapg.c

@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -triple x86_64 -O0 -emit-llvm -o - %s | FileCheck %s
+
+auto test_bswapg(bool c) {
+  return __builtin_bswapg(c);
+}
+
+// CHECK-LABEL: define{{.*}} i1 @_Z11test_bswapgb(
+// CHECK: ret i1 %{{.*}}