Poison XNEW and friends for types that should use new/delete

This patch (finally!) makes it so that trying to use XNEW with a type that requires "new" will cause a compilation error. The criterion I initially used to allow a type to use XNEW (which calls malloc in the end) was std::is_trivially_constructible, but then realized that gcc 4.8 did not have it. Instead, I went with: using IsMallocatable = std::is_pod<T>; which is just a bit more strict, which doesn't hurt. A similar thing is done for macros that free instead of allocated, the criterion is: using IsFreeable = gdb::Or<std::is_trivially_destructible<T>, std::is_void<T>>; Trying to use XNEW on a type that requires new will result in an error like this: In file included from /home/simark/src/binutils-gdb/gdb/common/common-utils.h:26:0, from /home/simark/src/binutils-gdb/gdb/common/common-defs.h:78, from /home/simark/src/binutils-gdb/gdb/defs.h:28, from /home/simark/src/binutils-gdb/gdb/lala.c:1: /home/simark/src/binutils-gdb/gdb/common/poison.h: In instantiation of ‘T* xnew() [with T = bar]’: /home/simark/src/binutils-gdb/gdb/lala.c:13:3: required from here /home/simark/src/binutils-gdb/gdb/common/poison.h:103:3: error: static assertion failed: Trying to use XNEW with a non-POD data type. Use operator new instead. static_assert (IsMallocatable<T>::value, "Trying to use XNEW with a non-POD\ ^~~~~~~~~~~~~ Generated-code-wise, it adds one more function call (xnew<T>) when using XNEW and building with -O0, but it all goes away with optimizations enabled. gdb/ChangeLog: * common/common-utils.h: Include poison.h. (xfree): Remove declaration, add definition with static_assert. * common/common-utils.c (xfree): Remove. * common/poison.h (IsMallocatable): Define. (IsFreeable): Define. (free): Delete for non-freeable types. (xnew): New. (XNEW): Undef and redefine. (xcnew): New. (XCNEW): Undef and redefine. (xdelete): New. (XDELETE): Undef and redefine. (xnewvec): New. (XNEWVEC): Undef and redefine. (xcnewvec): New. (XCNEWVEC): Undef and redefine. (xresizevec): New. (XRESIZEVEC): Undef and redefine. (xdeletevec): New. (XDELETEVEC): Undef and redefine. (xnewvar): New. (XNEWVAR): Undef and redefine. (xcnewvar): New. (XCNEWVAR): Undef and redefine. (xresizevar): New. (XRESIZEVAR): Undef and redefine.
2017-11-24 10:42:01 -05:00 · 2017-11-24 10:42:01 -05:00 · 8172f16b5b
parent 7aabaf9d4a
commit 8172f16b5b
4 changed files with 174 additions and 8 deletions
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@ -1,3 +1,32 @@
+2017-11-24  Simon Marchi  <simon.marchi@polymtl.ca>
+
+	* common/common-utils.h: Include poison.h.
+	(xfree): Remove declaration, add definition with static_assert.
+	* common/common-utils.c (xfree): Remove.
+	* common/poison.h (IsMallocatable): Define.
+	(IsFreeable): Define.
+	(free): Delete for non-freeable types.
+	(xnew): New.
+	(XNEW): Undef and redefine.
+	(xcnew): New.
+	(XCNEW): Undef and redefine.
+	(xdelete): New.
+	(XDELETE): Undef and redefine.
+	(xnewvec): New.
+	(XNEWVEC): Undef and redefine.
+	(xcnewvec): New.
+	(XCNEWVEC): Undef and redefine.
+	(xresizevec): New.
+	(XRESIZEVEC): Undef and redefine.
+	(xdeletevec): New.
+	(XDELETEVEC): Undef and redefine.
+	(xnewvar): New.
+	(XNEWVAR): Undef and redefine.
+	(xcnewvar): New.
+	(XCNEWVAR): Undef and redefine.
+	(xresizevar): New.
+	(XRESIZEVAR): Undef and redefine.
+
 2017-11-24  Simon Marchi  <simon.marchi@polymtl.ca>

 	* gdbthread.h (private_thread_info): Define structure type, add
--- a/gdb/common/common-utils.c
+++ b/gdb/common/common-utils.c
@ -94,13 +94,6 @@ xzalloc (size_t size)
  return xcalloc (1, size);
 }

-void
-xfree (void *ptr)
-{
-  if (ptr != NULL)
-    free (ptr);		/* ARI: free */
-}
-
 void
 xmalloc_failed (size_t size)
 {
--- a/gdb/common/common-utils.h
+++ b/gdb/common/common-utils.h
@ -23,6 +23,8 @@
 #include <string>
 #include <vector>

+#include "poison.h"
+
 /* If possible, define FUNCTION_NAME, a macro containing the name of
   the function being defined.  Since this macro may not always be
   defined, all uses must be protected by appropriate macro definition
@ -47,7 +49,17 @@
 /* Like xmalloc, but zero the memory.  */
 void *xzalloc (size_t);

-void xfree (void *);
+template <typename T>
+static void
+xfree (T *ptr)
+{
+  static_assert (IsFreeable<T>::value, "Trying to use xfree with a non-POD \
+data type.  Use operator delete instead.");
+
+  if (ptr != NULL)
+    free (ptr);		/* ARI: free */
+}
+

 /* Like asprintf and vasprintf, but return the string, throw an error
   if no memory.  */
--- a/gdb/common/poison.h
+++ b/gdb/common/poison.h
@ -84,4 +84,136 @@ void *memmove (D *dest, const S *src, size_t n) = delete;

 #endif /* HAVE_IS_TRIVIALLY_COPYABLE */

+/* Poison XNEW and friends to catch usages of malloc-style allocations on
+   objects that require new/delete.  */
+
+template<typename T>
+using IsMallocable = std::is_pod<T>;
+
+template<typename T>
+using IsFreeable = gdb::Or<std::is_trivially_destructible<T>, std::is_void<T>>;
+
+template <typename T, typename = gdb::Requires<gdb::Not<IsFreeable<T>>>>
+void free (T *ptr) = delete;
+
+template<typename T>
+static T *
+xnew ()
+{
+  static_assert (IsMallocable<T>::value, "Trying to use XNEW with a non-POD \
+data type.  Use operator new instead.");
+  return XNEW (T);
+}
+
+#undef XNEW
+#define XNEW(T) xnew<T>()
+
+template<typename T>
+static T *
+xcnew ()
+{
+  static_assert (IsMallocable<T>::value, "Trying to use XCNEW with a non-POD \
+data type.  Use operator new instead.");
+  return XCNEW (T);
+}
+
+#undef XCNEW
+#define XCNEW(T) xcnew<T>()
+
+template<typename T>
+static void
+xdelete (T *p)
+{
+  static_assert (IsFreeable<T>::value, "Trying to use XDELETE with a non-POD \
+data type.  Use operator delete instead.");
+  XDELETE (p);
+}
+
+#undef XDELETE
+#define XDELETE(P) xdelete (p)
+
+template<typename T>
+static T *
+xnewvec (size_t n)
+{
+  static_assert (IsMallocable<T>::value, "Trying to use XNEWVEC with a \
+non-POD data type.  Use operator new[] (or std::vector) instead.");
+  return XNEWVEC (T, n);
+}
+
+#undef XNEWVEC
+#define XNEWVEC(T, N) xnewvec<T> (N)
+
+template<typename T>
+static T *
+xcnewvec (size_t n)
+{
+  static_assert (IsMallocable<T>::value, "Trying to use XCNEWVEC with a \
+non-POD data type.  Use operator new[] (or std::vector) instead.");
+  return XCNEWVEC (T, n);
+}
+
+#undef XCNEWVEC
+#define XCNEWVEC(T, N) xcnewvec<T> (N)
+
+template<typename T>
+static T *
+xresizevec (T *p, size_t n)
+{
+  static_assert (IsMallocable<T>::value, "Trying to use XRESIZEVEC with a \
+non-POD data type.");
+  return XRESIZEVEC (T, p, n);
+}
+
+#undef XRESIZEVEC
+#define XRESIZEVEC(T, P, N) xresizevec<T> (P, N)
+
+template<typename T>
+static void
+xdeletevec (T *p)
+{
+  static_assert (IsFreeable<T>::value, "Trying to use XDELETEVEC with a \
+non-POD data type.  Use operator delete[] (or std::vector) instead.");
+  XDELETEVEC (p);
+}
+
+#undef XDELETEVEC
+#define XDELETEVEC(P) xdeletevec (P)
+
+template<typename T>
+static T *
+xnewvar (size_t s)
+{
+  static_assert (IsMallocable<T>::value, "Trying to use XNEWVAR with a \
+non-POD data type.");
+  return XNEWVAR (T, s);;
+}
+
+#undef XNEWVAR
+#define XNEWVAR(T, S) xnewvar<T> (S)
+
+template<typename T>
+static T *
+xcnewvar (size_t s)
+{
+  static_assert (IsMallocable<T>::value, "Trying to use XCNEWVAR with a \
+non-POD data type.");
+  return XCNEWVAR (T, s);
+}
+
+#undef XCNEWVAR
+#define XCNEWVAR(T, S) xcnewvar<T> (S)
+
+template<typename T>
+static T *
+xresizevar (T *p, size_t s)
+{
+  static_assert (IsMallocable<T>::value, "Trying to use XRESIZEVAR with a \
+non-POD data type.");
+  return XRESIZEVAR (T, p, s);
+}
+
+#undef XRESIZEVAR
+#define XRESIZEVAR(T, P, S) xresizevar<T> (P, S)
+
 #endif /* COMMON_POISON_H */