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* [PATCH 1/4] add utility to poison globals that should not be used
@ 2021-06-30  5:35 Trevor Saunders
  2021-06-30  5:35 ` [PATCH 2/4] allow poisoning input_location in ranges it " Trevor Saunders
                   ` (2 more replies)
  0 siblings, 3 replies; 25+ messages in thread
From: Trevor Saunders @ 2021-06-30  5:35 UTC (permalink / raw)
  To: gcc-patches; +Cc: Trevor Saunders

This provides a class to wrap globals like input_location or cfun that should
not be used directly and will ideally go away.  This class tracks if access to
the global is currently blocked and asserts if accessed when that is not
allowed.  It also adds a class to mark access as blocked for the lifetime of the
scope.

bootstrapped and regtested on x86_64-linux-gnu, ok?

Trev

gcc/ChangeLog:

	* poison.h: New file.
---
 gcc/poison.h | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 gcc/poison.h

diff --git a/gcc/poison.h b/gcc/poison.h
new file mode 100644
index 00000000000..239ab1cb91a
--- /dev/null
+++ b/gcc/poison.h
@@ -0,0 +1,88 @@
+/* Simple utility to poison globals that should be avoided.
+
+   Copyright (C) 2021 the GNU Toolchain Authors
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#ifndef GCC_POISON_H
+#define GCC_POISON_H
+
+template<typename T> class auto_poison;
+
+/* This class is intended to be used as a transparent wrapper around the type of
+   a global object that we would like to stop using.  */
+template<typename T>
+class poisonable
+{
+public:
+  poisonable () : m_val (), m_poisoned (false) {}
+  explicit poisonable (T val) : m_val (val), m_poisoned (false) {}
+
+  operator T& ()
+    {
+      gcc_assert (!m_poisoned);
+      return m_val;
+    }
+
+  poisonable &operator= (T val)
+    {
+      gcc_assert (!m_poisoned);
+      m_val = val;
+      return *this;
+    }
+
+  T *operator& ()
+    {
+      gcc_assert (!m_poisoned);
+      return &m_val;
+    }
+
+  poisonable (const poisonable &) = delete;
+  poisonable (poisonable &&) = delete;
+  poisonable &operator= (const poisonable &) = delete;
+  poisonable &operator= (poisonable &&) = delete;
+
+private:
+  friend class auto_poison<T>;
+
+  T m_val;
+  bool m_poisoned;
+  };
+
+/* This class provides a way to make a global inaccessible in the given scope,
+   and any functions called within that scope.  */
+template<typename T>
+class auto_poison
+{
+public:
+  auto_poison (poisonable<T> &p) : m_target (p)
+  {
+    gcc_assert (!p.m_poisoned);
+    p.m_poisoned = true;
+  }
+  ~auto_poison () { m_target.m_poisoned = false; }
+
+  auto_poison (const auto_poison &) = delete;
+  auto_poison (auto_poison &&) = delete;
+  auto_poison &operator= (const auto_poison &) = delete;
+  auto_poison &operator= (auto_poison &&) = delete;
+
+private:
+  poisonable<T> &m_target;
+};
+
+#endif
-- 
2.20.1


^ permalink raw reply	[flat|nested] 25+ messages in thread
end of thread, other threads:[~2021-07-14 22:53 UTC | newest]

Thread overview: 25+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-06-30  5:35 [PATCH 1/4] add utility to poison globals that should not be used Trevor Saunders
2021-06-30  5:35 ` [PATCH 2/4] allow poisoning input_location in ranges it " Trevor Saunders
2021-06-30  9:00   ` Richard Biener
2021-06-30 12:33     ` Trevor Saunders
2021-06-30 19:09       ` Richard Biener
2021-07-01 10:23         ` Trevor Saunders
2021-07-01 12:48           ` Richard Biener
2021-06-30 15:13   ` David Malcolm
2021-06-30 19:34     ` Jason Merrill
2021-07-01 10:16     ` Trevor Saunders
2021-07-01 12:53       ` Richard Biener
2021-07-01 15:40         ` David Malcolm
2021-07-01 16:04           ` David Malcolm
2021-07-01 21:51             ` [committed] input.c: move file caching globals to a new file_cache class David Malcolm
2021-07-11 16:58               ` Lewis Hyatt
2021-07-14 22:53                 ` David Malcolm
2021-07-02  0:44           ` [PATCH 2/4] allow poisoning input_location in ranges it should not be used Trevor Saunders
2021-07-02 15:46       ` Jason Merrill
2021-07-02 23:23         ` Trevor Saunders
2021-07-02 19:20   ` Martin Sebor
2021-07-02 23:47     ` Trevor Saunders
2021-07-06 20:53       ` Martin Sebor
2021-06-30  5:35 ` [PATCH 3/4] allow poisoning cfun Trevor Saunders
2021-06-30  5:35 ` [PATCH 4/4] poison input_location and cfun in one spot Trevor Saunders
2021-06-30  9:02   ` Richard Biener

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