[ia64-improvements] Moved Superblock formation to Tree-SSA

[ia64-improvements] Moved Superblock formation to Tree-SSA

[Robert Kidd]

I checked a patch into the ia64-improvements branch to move  
Superblock formation to the Tree-SSA level.  This patch also brings  
an update to the trace formation pass.  When building a trace inside  
a loop, we now follow the backedge once to add the loop header to the  
trace.  This allows tail duplication to form a superblock loop that  
can be processed by the loop unroller later on.

2006-02-17  Robert Kidd  <rkidd@crhc.uiuc.edu>

         * tracer.c (mark_bb_seen): New function.
         (bb_seen_p): New function.
         (count_insns): Use estimate_num_insns instead of counting RTL
         instructions.
         (find_trace): Tracing a loop now traverses the back edge once
         to duplicate the loop header.
         (tail_duplicate): Phi nodes are fixed after duplicating
         blocks.
         (layout_superblocks): Remove function.
         (execute_tracer): CFG layout stuff is not needed at the tree
         level.
         (rest_of_handle_tracer): Remove function.
         * bb-reorder.c (rest_of_handle_reorder_blocks): Removed call
         to RTL level tracer.
         * passes.c (init_optimization_passes): Moved pass_tracer from
         after pass_rtl_ifcvt to after pass_build_ssa.

Robert Kidd
rkidd@crhc.uiuc.edu