Backport from mysql-trunk of:

------------------------------------------------------------
revno: 3258
committer: Jon Olav Hauglid <jon.hauglid@oracle.com>
branch nick: mysql-trunk-bug12663165
timestamp: Thu 2011-07-14 10:05:12 +0200
message:
  Bug#12663165 SP DEAD CODE REMOVAL DOESN'T UNDERSTAND CONTINUE HANDLERS
  
  When stored routines are loaded, a simple optimizer tries to locate
  and remove dead code. The problem was that this dead code removal
  did not work correctly with CONTINUE handlers.
  
  If a statement triggers a CONTINUE handler, the following statement
  will be executed after the handler statement has completed. This
  means that the following statement is not dead code even if the
  previous statement unconditionally alters control flow. This fact
  was lost on the dead code removal routine, which ended up with
  removing instructions that could have been executed. This could
  then lead to assertions, crashes and generally bad behavior when
  the stored routine was executed.
  
  This patch fixes the problem by marking as live code all stored
  routine instructions that are in the same scope as a CONTINUE handler.
  
  Test case added to sp.test.

1 files changed, 11 insertions, 1 deletions

diff --git a/sql/sp_head.h b/sql/sp_head.h
index da490527f42..a026ac47221 100644
--- a/sql/sp_head.h
+++ b/sql/sp_head.h
@@ -1000,7 +1000,7 @@ class sp_instr_hpush_jump : public sp_instr_jump
 public:
 
   sp_instr_hpush_jump(uint ip, sp_pcontext *ctx, int htype, uint fp)
-    : sp_instr_jump(ip, ctx), m_type(htype), m_frame(fp)
+    : sp_instr_jump(ip, ctx), m_type(htype), m_frame(fp), m_opt_hpop(0)
   {
     m_cond.empty();
   }
@@ -1022,6 +1022,15 @@ public:
     return m_ip;
   }
 
+  virtual void backpatch(uint dest, sp_pcontext *dst_ctx)
+  {
+    DBUG_ASSERT(!m_dest || !m_opt_hpop);
+    if (!m_dest)
+      m_dest= dest;
+    else
+      m_opt_hpop= dest;
+  }
+
   inline void add_condition(struct sp_cond_type *cond)
   {
     m_cond.push_front(cond);
@@ -1031,6 +1040,7 @@ private:
 
   int m_type;			///< Handler type
   uint m_frame;
+  uint m_opt_hpop;              // hpop marking end of handler scope.
   List<struct sp_cond_type> m_cond;
 
 }; // class sp_instr_hpush_jump : public sp_instr_jump