[patch] Add scev_reset to cleanup_tree_cfg_loop

[Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>]

Hello,

scev info does not have to be correct when the loop structure changes
in cleanup_tree_cfg_loop.  This patch adds the call to scev_reset to the
function.  It also makes cleanup_tree_cfg_loop do the additional work
to fixup things only in the case when cleanup_tree_cfg changed cfg.

Bootstrapped & regtested on ia64.

Zdenek

	* Makefile.in (tree-cfgcleanup.o): Add SCEV_H dependency.
	* tree-cfgcleanup.c: Include tree-scalar-evolution.h.
	(cleanup_tree_cfg_loop): Call scev_reset.  Only fix up loop
	structures when cleanup_tree_cfg changed cfg.

Index: Makefile.in
===================================================================
RCS file: /cvs/gcc/gcc/gcc/Makefile.in,v
retrieving revision 1.1536
diff -c -3 -p -r1.1536 Makefile.in
*** Makefile.in	15 Aug 2005 12:26:02 -0000	1.1536
--- Makefile.in	20 Aug 2005 15:04:18 -0000
*************** tree-cfg.o : tree-cfg.c $(TREE_FLOW_H) $
*** 1824,1832 ****
  tree-cfgcleanup.o : tree-cfgcleanup.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
     $(RTL_H) $(TREE_H) $(TM_P_H) $(EXPR_H) $(GGC_H) $(FLAGS_H) output.h \
     $(DIAGNOSTIC_H) errors.h function.h $(TIMEVAR_H) $(TM_H) coretypes.h \
!    $(TREE_DUMP_H) except.h langhooks.h $(CFGLOOP_H) tree-pass.h \
!    $(CFGLAYOUT_H) $(BASIC_BLOCK_H) hard-reg-set.h $(HASHTAB_H) toplev.h \
!    tree-ssa-propagate.h
  tree-tailcall.o : tree-tailcall.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
     $(RTL_H) $(TREE_H) $(TM_P_H) function.h $(TM_H) coretypes.h \
     $(TREE_DUMP_H) $(DIAGNOSTIC_H) except.h tree-pass.h $(FLAGS_H) langhooks.h \
--- 1824,1830 ----
  tree-cfgcleanup.o : tree-cfgcleanup.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
     $(RTL_H) $(TREE_H) $(TM_P_H) $(EXPR_H) $(GGC_H) $(FLAGS_H) output.h \
     $(DIAGNOSTIC_H) errors.h function.h $(TIMEVAR_H) $(TM_H) coretypes.h \
!    tree-ssa-propagate.h $(SCEV_H)
  tree-tailcall.o : tree-tailcall.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
     $(RTL_H) $(TREE_H) $(TM_P_H) function.h $(TM_H) coretypes.h \
     $(TREE_DUMP_H) $(DIAGNOSTIC_H) except.h tree-pass.h $(FLAGS_H) langhooks.h \
Index: tree-cfgcleanup.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-cfgcleanup.c,v
retrieving revision 2.7
diff -c -3 -p -r2.7 tree-cfgcleanup.c
*** tree-cfgcleanup.c	19 Aug 2005 18:52:55 -0000	2.7
--- tree-cfgcleanup.c	20 Aug 2005 15:04:18 -0000
*************** Boston, MA 02110-1301, USA.  */
*** 44,49 ****
--- 44,50 ----
  #include "cfgloop.h"
  #include "cfglayout.h"
  #include "hashtab.h"
+ #include "tree-scalar-evolution.h"
  #include "tree-ssa-propagate.h"
  
  /* Remove any fallthru edge from EV.  Return true if an edge was removed.  */
*************** cleanup_tree_cfg (void)
*** 559,581 ****
  void
  cleanup_tree_cfg_loop (void)
  {
!   bitmap changed_bbs = BITMAP_ALLOC (NULL);
  
!   cleanup_tree_cfg ();
! 
!   fix_loop_structure (current_loops, changed_bbs);
!   calculate_dominance_info (CDI_DOMINATORS);
  
!   /* This usually does nothing.  But sometimes parts of cfg that originally
!      were inside a loop get out of it due to edge removal (since they
!      become unreachable by back edges from latch).  */
!   rewrite_into_loop_closed_ssa (changed_bbs, TODO_update_ssa);
  
!   BITMAP_FREE (changed_bbs);
  
  #ifdef ENABLE_CHECKING
!   verify_loop_structure (current_loops);
  #endif
  }
  
  /* Merge the PHI nodes at BB into those at BB's sole successor.  */
--- 560,585 ----
  void
  cleanup_tree_cfg_loop (void)
  {
!   bool changed = cleanup_tree_cfg ();
  
!   if (changed)
!     {
!       bitmap changed_bbs = BITMAP_ALLOC (NULL);
!       fix_loop_structure (current_loops, changed_bbs);
!       calculate_dominance_info (CDI_DOMINATORS);
  
!       /* This usually does nothing.  But sometimes parts of cfg that originally
! 	 were inside a loop get out of it due to edge removal (since they
! 	 become unreachable by back edges from latch).  */
!       rewrite_into_loop_closed_ssa (changed_bbs, TODO_update_ssa);
  
!       BITMAP_FREE (changed_bbs);
  
  #ifdef ENABLE_CHECKING
!       verify_loop_structure (current_loops);
  #endif
+       scev_reset ();
+     }
  }
  
  /* Merge the PHI nodes at BB into those at BB's sole successor.  */