Revert last change until I figure out what's wrong with it.

From-SVN: r28592

gcc/global.c

@@ -271,7 +271,7 @@ static void set_preference	PROTO((rtx, rtx));
 static void dump_conflicts	PROTO((FILE *));
 static void reg_becomes_live	PROTO((rtx, rtx));
 static void reg_dies		PROTO((int, enum machine_mode));
-static void build_insn_chain	PROTO((void));
+static void build_insn_chain	PROTO((rtx));
 
 /* Perform allocation of pseudo-registers not allocated by local_alloc.
    FILE is a file to output debugging information on,
@@ -578,7 +578,7 @@ global_alloc (file)
   if (n_basic_blocks > 0)
 #endif
     {
-      build_insn_chain ();
+      build_insn_chain (get_insns ());
       retval = reload (get_insns (), 1, file);
     }
 
@@ -1667,88 +1667,96 @@ reg_dies (regno, mode)
 /* Walk the insns of the current function and build reload_insn_chain,
    and record register life information.  */
 static void
-build_insn_chain ()
+build_insn_chain (first)
+     rtx first;
 {
   struct insn_chain **p = &reload_insn_chain;
   struct insn_chain *prev = 0;
-  int b;
+  int b = 0;
 
   live_relevant_regs = ALLOCA_REG_SET ();
 
-  for (b = n_basic_blocks - 1; b >= 0; --b)
+  for (; first; first = NEXT_INSN (first))
     {
-      basic_block bb = BASIC_BLOCK (b);
-      rtx insn, end;
-      int i;
-
-      CLEAR_REG_SET (live_relevant_regs);
+      struct insn_chain *c;
 
-      EXECUTE_IF_SET_IN_REG_SET (bb->global_live_at_start, 0, i,
+      if (first == BLOCK_HEAD (b))
 	{
-	  if ((i < FIRST_PSEUDO_REGISTER
+	  int i;
+	  CLEAR_REG_SET (live_relevant_regs);
+	  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
+	    if (REGNO_REG_SET_P (BASIC_BLOCK (b)->global_live_at_start, i)
 		&& ! TEST_HARD_REG_BIT (eliminable_regset, i))
-	      || (i >= FIRST_PSEUDO_REGISTER
-		  && reg_renumber[i] >= 0))
 	      SET_REGNO_REG_SET (live_relevant_regs, i);
-	});
 
-      insn = bb->head, end = bb->end;
-      while (1)
-	{
-	  struct insn_chain *c;
+	  for (; i < max_regno; i++)
+	    if (reg_renumber[i] >= 0
+		&& REGNO_REG_SET_P (BASIC_BLOCK (b)->global_live_at_start, i))
+	      SET_REGNO_REG_SET (live_relevant_regs, i);
+	}
 
-	  if (GET_CODE (insn) != NOTE)
+      if (GET_CODE (first) != NOTE && GET_CODE (first) != BARRIER)
 	{
 	  c = new_insn_chain ();
 	  c->prev = prev;
 	  prev = c;
 	  *p = c;
 	  p = &c->next;
-	      c->insn = insn;
+	  c->insn = first;
 	  c->block = b;
 
 	  COPY_REG_SET (c->live_before, live_relevant_regs);
 
-	      if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
+	  if (GET_RTX_CLASS (GET_CODE (first)) == 'i')
 	    {
 	      rtx link;
 
-		  /* Mark the death of everything that dies in this
-		     instruction.  */
-		  for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
+	      /* Mark the death of everything that dies in this instruction.  */
+
+	      for (link = REG_NOTES (first); link; link = XEXP (link, 1))
 		if (REG_NOTE_KIND (link) == REG_DEAD
 		    && GET_CODE (XEXP (link, 0)) == REG)
-		      reg_dies (REGNO (XEXP (link, 0)),
-				GET_MODE (XEXP (link, 0)));
+		  reg_dies (REGNO (XEXP (link, 0)), GET_MODE (XEXP (link, 0)));
 
 	      /* Mark everything born in this instruction as live.  */
-		  note_stores (PATTERN (insn), reg_becomes_live);
+
+	      note_stores (PATTERN (first), reg_becomes_live);
 	    }
 
-	      /* Remember which registers are live at the end of the insn,
-		 before killing those with REG_UNUSED notes.  */
+	  /* Remember which registers are live at the end of the insn, before
+	     killing those with REG_UNUSED notes.  */
 	  COPY_REG_SET (c->live_after, live_relevant_regs);
 
-	      if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
+	  if (GET_RTX_CLASS (GET_CODE (first)) == 'i')
 	    {
 	      rtx link;
 
-		  /* Mark anything that is set in this insn and then unused
-		     as dying.  */
-		  for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
+	      /* Mark anything that is set in this insn and then unused as dying.  */
+
+	      for (link = REG_NOTES (first); link; link = XEXP (link, 1))
 		if (REG_NOTE_KIND (link) == REG_UNUSED
 		    && GET_CODE (XEXP (link, 0)) == REG)
-		      reg_dies (REGNO (XEXP (link, 0)),
-				GET_MODE (XEXP (link, 0)));
+		  reg_dies (REGNO (XEXP (link, 0)), GET_MODE (XEXP (link, 0)));
 	    }
 	}
 
-	  if (insn == end)
+      if (first == BLOCK_END (b))
+	b++;
+
+      /* Stop after we pass the end of the last basic block.  Verify that
+	 no real insns are after the end of the last basic block.
+
+	 We may want to reorganize the loop somewhat since this test should
+	 always be the right exit test.  */
+      if (b == n_basic_blocks)
+	{
+	  for (first = NEXT_INSN (first) ; first; first = NEXT_INSN (first))
+	    if (GET_RTX_CLASS (GET_CODE (first)) == 'i'
+		&& GET_CODE (PATTERN (first)) != USE)
+	      abort ();
 	  break;
-	  insn = NEXT_INSN (insn);
 	}
     }
-
   FREE_REG_SET (live_relevant_regs);
   *p = 0;
 }