2009-11-30 Paolo Bonzini <bonzini@gnu.org>

	PR rtl-optimization/41812
	* fwprop.c (local_md, local_lr): New globals.
	(process_defs, process_uses): Remove local_md argument.  Never
	consider dead pseudos to have singleton def-use chains.
	(single_def_use_enter_block): Perform LR simulation.
	(build_single_def_use_links): Remove local_md local variable.
	Add DF_NOTE.  Allocate local_lr.
	(fwprop_done): Do not remove DF_CHAIN, we do not use it anymore.
	* df-problems.c (df_md_scratch): New.
	(df_md_alloc, df_md_free): Allocate/free it.
	(df_md_local_compute): Only include live registers in init.
	(df_md_transfer_function): Prune the in-set computed by
	the confluence function, and the gen-set too.
	(df_simulate_one_insn_forwards): Fix typo.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@154753 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 25 insertions, 8 deletions

diff --git a/gcc/df-problems.c b/gcc/df-problems.c
index cc7ab882a36..e0ec16778f0 100644
--- a/gcc/df-problems.c
+++ b/gcc/df-problems.c
@@ -1574,10 +1574,9 @@ df_live_transfer_function (int bb_index)
   bitmap gen = bb_info->gen;
   bitmap kill = bb_info->kill;
 
-  /* We need to use a scratch set here so that the value returned from
-     this function invocation properly reflects if the sets changed in
-     a significant way; i.e. not just because the lr set was anded
-     in.  */
+  /* We need to use a scratch set here so that the value returned from this
+     function invocation properly reflects whether the sets changed in a
+     significant way; i.e. not just because the lr set was anded in.  */
   bitmap_and (df_live_scratch, gen, bb_lr_info->out);
   /* No register may reach a location where it is not used.  Thus
      we trim the rr result to the places where it is used.  */
@@ -3975,8 +3974,8 @@ df_simulate_one_insn_forwards (basic_block bb, rtx insn, bitmap live)
    MULTIPLE DEFINITIONS
 
    Find the locations in the function reached by multiple definition sites
-   for a pseudo.  In and out bitvectors are built for each basic
-   block.
+   for a live pseudo.  In and out bitvectors are built for each basic
+   block.  They are restricted for efficiency to live registers.
 
    The gen and kill sets for the problem are obvious.  Together they
    include all defined registers in a basic block; the gen set includes
@@ -4018,6 +4017,10 @@ df_simulate_one_insn_forwards (basic_block bb, rtx insn, bitmap live)
     propagating the information to BB3's successors.
    ---------------------------------------------------------------------------*/
 
+/* Scratch var used by transfer functions.  This is used to do md analysis
+   only for live registers.  */
+static bitmap df_md_scratch;
+
 /* Set basic block info.  */
 
 static void
@@ -4061,6 +4064,7 @@ df_md_alloc (bitmap all_blocks)
                                            sizeof (struct df_md_bb_info), 50);
 
   df_grow_bb_info (df_md);
+  df_md_scratch = BITMAP_ALLOC (NULL);
 
   EXECUTE_IF_SET_IN_BITMAP (all_blocks, 0, bb_index, bi)
     {
@@ -4236,8 +4240,10 @@ df_md_local_compute (bitmap all_blocks)
       bitmap kill = df_md_get_bb_info (bb_index)->kill;
       EXECUTE_IF_SET_IN_BITMAP (frontiers[bb_index], 0, df_bb_index, bi2)
 	{
+	  basic_block bb = BASIC_BLOCK (df_bb_index);
 	  if (bitmap_bit_p (all_blocks, df_bb_index))
-	    bitmap_ior_into (df_md_get_bb_info (df_bb_index)->init, kill);
+	    bitmap_ior_and_into (df_md_get_bb_info (df_bb_index)->init, kill,
+				 df_get_live_in (bb));
 	}
     }
 
@@ -4267,13 +4273,23 @@ df_md_reset (bitmap all_blocks)
 static bool
 df_md_transfer_function (int bb_index)
 {
+  basic_block bb = BASIC_BLOCK (bb_index);
   struct df_md_bb_info *bb_info = df_md_get_bb_info (bb_index);
   bitmap in = bb_info->in;
   bitmap out = bb_info->out;
   bitmap gen = bb_info->gen;
   bitmap kill = bb_info->kill;
 
-  return bitmap_ior_and_compl (out, gen, in, kill);
+  /* We need to use a scratch set here so that the value returned from this
+     function invocation properly reflects whether the sets changed in a
+     significant way; i.e. not just because the live set was anded in.  */
+  bitmap_and (df_md_scratch, gen, df_get_live_out (bb));
+
+  /* Multiple definitions of a register are not relevant if it is not
+     live.  Thus we trim the result to the places where it is live.  */
+  bitmap_and_into (in, df_get_live_in (bb));
+
+  return bitmap_ior_and_compl (out, df_md_scratch, in, kill);
 }
 
 /* Initialize the solution bit vectors for problem.  */
@@ -4336,6 +4352,7 @@ df_md_free (void)
 	}
     }
 
+  BITMAP_FREE (df_md_scratch);
   free_alloc_pool (df_md->block_pool);
 
   df_md->block_info_size = 0;