Extend GCMole with poor man's data flow analysis to catch dead raw pointer vars.

tools/gcmole/gccause.lua

Index: tools/gcmole/gccause.lua
diff --git a/tools/gcmole/gccause.lua b/tools/gcmole/gccause.lua
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+++ b/tools/gcmole/gccause.lua
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+-- Copyright 2011 the V8 project authors. All rights reserved.
+-- Redistribution and use in source and binary forms, with or without
+-- modification, are permitted provided that the following conditions are
+-- met:
+--
+--     * Redistributions of source code must retain the above copyright
+--       notice, this list of conditions and the following disclaimer.
+--     * Redistributions in binary form must reproduce the above
+--       copyright notice, this list of conditions and the following
+--       disclaimer in the documentation and/or other materials provided
+--       with the distribution.
+--     * Neither the name of Google Inc. nor the names of its
+--       contributors may be used to endorse or promote products derived
+--       from this software without specific prior written permission.
+--
+-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+-- "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+-- LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+-- A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+-- OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+-- SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+-- LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+-- DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+-- THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+-- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+-- OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+-- This is an auxiliary tool that reads gccauses file generated by
+-- gcmole.lua and prints tree of the calls that can potentially cause a GC
+-- inside a given function.
+--
+-- Usage: lua tools/gcmole/gccause.lua <function-name-pattern>
+--
+
+assert(loadfile "gccauses")()
+
+local P = ...
+
+local T = {}
+
+local function TrackCause(name, lvl)
+   io.write(("  "):rep(lvl or 0), name, "\n")
+   if GC[name] then
+      local causes = GC[name]
+      for i = 1, #causes do
+	 local f = causes[i]
+	 if not T[f] then
+	    T[f] = true
+	    TrackCause(f, (lvl or 0) + 1)
+	 end
+      end
+   end
+end
+
+for name, _ in pairs(GC) do
+   if name:match(P) then
+      T = {}
+      TrackCause(name)
+   end
+end