reg-stack.c (struct block_info_def): Correct grammar typo.

	* reg-stack.c (struct block_info_def): Correct grammar typo.
	(compensate_edge): Clean-up.  Perform as little work as possible
	when src and dest stacks match.  Avoid modifying block_info.
	Reorder and simplify assertion checks.  Avoid unnecessary copying
	of regstack structure.
	(convert_regs_1): Set the done flag here...
	(convert_regs_2): ... instead of here.

From-SVN: r100602

gcc/ChangeLog

+2005-06-04  Roger Sayle  <roger@eyesopen.com>
+
+	* reg-stack.c (struct block_info_def): Correct grammar typo.
+	(compensate_edge): Clean-up.  Perform as little work as possible
+	when src and dest stacks match.  Avoid modifying block_info.
+	Reorder and simplify assertion checks.  Avoid unnecessary copying
+	of regstack structure.
+	(convert_regs_1): Set the done flag here...
+	(convert_regs_2): ... instead of here.
+
 2005-06-04  Dale Johannesen  <dalej@apple.com>
 
 	* config/rs6000/rs6000.c (no_global_regs_above): New.

gcc/reg-stack.c

@@ -208,7 +208,7 @@ typedef struct block_info_def
   struct stack_def stack_out;	/* Output stack configuration.  */
   HARD_REG_SET out_reg_set;	/* Stack regs live on output.  */
   int done;			/* True if block already converted.  */
-  int predecessors;		/* Number of predecessors that needs
+  int predecessors;		/* Number of predecessors that need
 				   to be visited.  */
 } *block_info;
 
@@ -2629,24 +2629,22 @@ propagate_stack (edge e)
 static bool
 compensate_edge (edge e, FILE *file)
 {
-  basic_block block = e->src, target = e->dest;
-  block_info bi = BLOCK_INFO (block);
-  struct stack_def regstack, tmpstack;
+  basic_block source = e->src, target = e->dest;
   stack target_stack = &BLOCK_INFO (target)->stack_in;
+  stack source_stack = &BLOCK_INFO (source)->stack_out;
+  struct stack_def regstack;
   int reg;
 
-  current_block = block;
-  regstack = bi->stack_out;
   if (file)
-    fprintf (file, "Edge %d->%d: ", block->index, target->index);
+    fprintf (file, "Edge %d->%d: ", source->index, target->index);
 
   gcc_assert (target_stack->top != -2);
 
   /* Check whether stacks are identical.  */
-  if (target_stack->top == regstack.top)
+  if (target_stack->top == source_stack->top)
     {
       for (reg = target_stack->top; reg >= 0; --reg)
-	if (target_stack->reg[reg] != regstack.reg[reg])
+	if (target_stack->reg[reg] != source_stack->reg[reg])
 	  break;
 
       if (reg == -1)
@@ -2663,68 +2661,56 @@ compensate_edge (edge e, FILE *file)
       print_stack (file, target_stack);
     }
 
-  /* Care for non-call EH edges specially.  The normal return path have
-     values in registers.  These will be popped en masse by the unwind
-     library.  */
-  if ((e->flags & (EDGE_EH | EDGE_ABNORMAL_CALL)) == EDGE_EH)
-    target_stack->top = -1;
-
-  /* Other calls may appear to have values live in st(0), but the
+  /* Abnormal calls may appear to have values live in st(0), but the
      abnormal return path will not have actually loaded the values.  */
-  else if (e->flags & EDGE_ABNORMAL_CALL)
+  if (e->flags & EDGE_ABNORMAL_CALL)
     {
       /* Assert that the lifetimes are as we expect -- one value
          live at st(0) on the end of the source block, and no
          values live at the beginning of the destination block.  */
-      HARD_REG_SET tmp;
-
-      CLEAR_HARD_REG_SET (tmp);
-      GO_IF_HARD_REG_EQUAL (target_stack->reg_set, tmp, eh1);
-      gcc_unreachable ();
-    eh1:
-
-      /* We are sure that there is st(0) live, otherwise we won't compensate.
-	 For complex return values, we may have st(1) live as well.  */
-      SET_HARD_REG_BIT (tmp, FIRST_STACK_REG);
-      if (TEST_HARD_REG_BIT (regstack.reg_set, FIRST_STACK_REG + 1))
-        SET_HARD_REG_BIT (tmp, FIRST_STACK_REG + 1);
-      GO_IF_HARD_REG_EQUAL (regstack.reg_set, tmp, eh2);
-      gcc_unreachable ();
-    eh2:
+      gcc_assert (source_stack->top == 0);
+      gcc_assert (target_stack->top == -1);
+      return false;
+    }
 
-      target_stack->top = -1;
+  /* Handle non-call EH edges specially.  The normal return path have
+     values in registers.  These will be popped en masse by the unwind
+     library.  */
+  if (e->flags & EDGE_EH)
+    {
+      gcc_assert (target_stack->top == -1);
+      return false;
     }
 
+  /* We don't support abnormal edges.  Global takes care to
+     avoid any live register across them, so we should never
+     have to insert instructions on such edges.  */
+  gcc_assert (! (e->flags & EDGE_ABNORMAL));
+
+  /* Make a copy of source_stack as change_stack is destructive.  */
+  regstack = *source_stack;
+
   /* It is better to output directly to the end of the block
      instead of to the edge, because emit_swap can do minimal
      insn scheduling.  We can do this when there is only one
      edge out, and it is not abnormal.  */
-  else if (EDGE_COUNT (block->succs) == 1 && !(e->flags & EDGE_ABNORMAL))
+  if (EDGE_COUNT (source->succs) == 1)
     {
-      /* change_stack kills values in regstack.  */
-      tmpstack = regstack;
-
-      change_stack (BB_END (block), &tmpstack, target_stack,
-		    (JUMP_P (BB_END (block))
-		     ? EMIT_BEFORE : EMIT_AFTER));
+      current_block = source;
+      change_stack (BB_END (source), &regstack, target_stack,
+		    (JUMP_P (BB_END (source)) ? EMIT_BEFORE : EMIT_AFTER));
     }
   else
     {
       rtx seq, after;
 
-      /* We don't support abnormal edges.  Global takes care to
-         avoid any live register across them, so we should never
-         have to insert instructions on such edges.  */
-      gcc_assert (!(e->flags & EDGE_ABNORMAL));
-
       current_block = NULL;
       start_sequence ();
 
       /* ??? change_stack needs some point to emit insns after.  */
       after = emit_note (NOTE_INSN_DELETED);
 
-      tmpstack = regstack;
-      change_stack (after, &tmpstack, target_stack, EMIT_BEFORE);
+      change_stack (after, &regstack, target_stack, EMIT_BEFORE);
 
       seq = get_insns ();
       end_sequence ();
@@ -2928,6 +2914,7 @@ convert_regs_1 (FILE *file, basic_block block)
   gcc_assert (any_malformed_asm);
  win:
   bi->stack_out = regstack;
+  bi->done = true;
 }
 
 /* Convert registers in all blocks reachable from BLOCK.  */
@@ -2975,7 +2962,6 @@ convert_regs_2 (FILE *file, basic_block block)
 	  }
 
       convert_regs_1 (file, block);
-      BLOCK_INFO (block)->done = 1;
     }
   while (sp != stack);