[clang][Interp] Fix BooleanToSignedIntegral casts for IntAP(S)

We were not doing the final Neg here.

Author: tbaederr

clang/lib/AST/Interp/Compiler.cpp

@@ -480,19 +480,25 @@ bool Compiler<Emitter>::VisitCastExpr(const CastExpr *CE) {
       }
     }
 
+    auto maybeNegate = [&]() -> bool {
+      if (CE->getCastKind() == CK_BooleanToSignedIntegral)
+        return this->emitNeg(*ToT, CE);
+      return true;
+    };
+
     if (ToT == PT_IntAP)
-      return this->emitCastAP(*FromT, Ctx.getBitWidth(CE->getType()), CE);
+      return this->emitCastAP(*FromT, Ctx.getBitWidth(CE->getType()), CE) &&
+             maybeNegate();
     if (ToT == PT_IntAPS)
-      return this->emitCastAPS(*FromT, Ctx.getBitWidth(CE->getType()), CE);
+      return this->emitCastAPS(*FromT, Ctx.getBitWidth(CE->getType()), CE) &&
+             maybeNegate();
 
     if (FromT == ToT)
       return true;
     if (!this->emitCast(*FromT, *ToT, CE))
       return false;
 
-    if (CE->getCastKind() == CK_BooleanToSignedIntegral)
-      return this->emitNeg(*ToT, CE);
-    return true;
+    return maybeNegate();
   }
 
   case CK_PointerToBoolean:

clang/test/AST/Interp/vectors.cpp

@@ -91,3 +91,14 @@ namespace Temporaries {
   };
   int &&s = S().w[1];
 }
+
+#ifdef __SIZEOF_INT128__
+namespace bigint {
+  typedef __attribute__((__ext_vector_type__(4))) __int128 bigint4;
+  constexpr bigint4 A = (bigint4)true;
+  static_assert(A[0] == -1, "");
+  static_assert(A[1] == -1, "");
+  static_assert(A[2] == -1, "");
+  static_assert(A[3] == -1, "");
+}
+#endif