* cse.c (cse_insn): Mostly remove first hunk of code which collapsed

        a computed jump into an unconditional jump.
        In second hunk of code for collapsing computed and conditional jumps
        into unconditional jumps, reemit the jump in additional cases.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@41953 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 15 insertions, 30 deletions

diff --git a/gcc/cse.c b/gcc/cse.c
index 85716533792..f3978e4b257 100644
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -5518,31 +5518,17 @@ cse_insn (insn, libcall_insn)
 	     check for this separately here.  We will delete such an
 	     insn below.
 
-	     Tablejump insns contain a USE of the table, so simply replacing
-	     the operand with the constant won't match.  This is simply an
-	     unconditional branch, however, and is therefore valid.  Just
-	     insert the substitution here and we will delete and re-emit
-	     the insn later.  */
-
+	     For other cases such as a table jump or conditional jump
+	     where we know the ultimate target, go ahead and replace the
+	     operand.  While that may not make a valid insn, we will
+	     reemit the jump below (and also insert any necessary
+	     barriers).  */
 	  if (n_sets == 1 && dest == pc_rtx
 	      && (trial == pc_rtx
 		  || (GET_CODE (trial) == LABEL_REF
 		      && ! condjump_p (insn))))
 	    {
-	      if (trial == pc_rtx)
-		{
-		  SET_SRC (sets[i].rtl) = trial;
-		  cse_jumps_altered = 1;
-		  break;
-		}
-
-	      PATTERN (insn) = gen_jump (XEXP (trial, 0));
-	      INSN_CODE (insn) = -1;
-
-	      if (NEXT_INSN (insn) != 0
-		  && GET_CODE (NEXT_INSN (insn)) != BARRIER)
-		emit_barrier_after (insn);
-
+	      SET_SRC (sets[i].rtl) = trial;
 	      cse_jumps_altered = 1;
 	      break;
 	    }
@@ -5804,13 +5790,17 @@ cse_insn (insn, libcall_insn)
 	}
 
       /* If this SET is now setting PC to a label, we know it used to
-	 be a conditional or computed branch.  So we see if we can follow
-	 it.  If it was a computed branch, delete it and re-emit.  */
+	 be a conditional or computed branch.  */
       else if (dest == pc_rtx && GET_CODE (src) == LABEL_REF)
 	{
-	  /* If this is not in the format for a simple branch and
-	     we are the only SET in it, re-emit it.  */
-	  if (! simplejump_p (insn) && n_sets == 1)
+	  /* We reemit the jump in as many cases as possible just in
+	     case the form of an unconditional jump is significantly
+	     different than a computed jump or conditional jump.
+
+	     If this insn has multiple sets, then reemitting the
+	     jump is nontrivial.  So instead we just force rerecognition
+	     and hope for the best.  */
+	  if (n_sets == 1)
 	    {
 	      rtx new = emit_jump_insn_before (gen_jump (XEXP (src, 0)), insn);
 	      JUMP_LABEL (new) = XEXP (src, 0);
@@ -5818,11 +5808,6 @@ cse_insn (insn, libcall_insn)
 	      insn = new;
 	    }
 	  else
-	    /* Otherwise, force rerecognition, since it probably had
-	       a different pattern before.
-	       This shouldn't really be necessary, since whatever
-	       changed the source value above should have done this.
-	       Until the right place is found, might as well do this here.  */
 	    INSN_CODE (insn) = -1;
 
 	  never_reached_warning (insn);