This patch implements generic type query and conversion functions,

and applies them to the use of cgraph_node, varpool_node, and symtab_node.

The functions are:

bool is_a <TYPE> (pointer)
  Tests whether the pointer actually points to a more derived TYPE.

TYPE *as_a <TYPE> (pointer)
  Converts pointer to a TYPE*.

TYPE *dyn_cast <TYPE> (pointer)
  Converts pointer to TYPE* if and only if "is_a <TYPE> pointer".
  Otherwise, returns NULL.
  This function is essentially a checked down cast.

These functions reduce compile time and increase type safety when treating a
generic item as a more specific item.  In essence, the code change is from

  if (symtab_function_p (node))
    {
      struct cgraph_node *cnode = cgraph (node);
      ....
    }

to

  if (cgraph_node *cnode = dyn_cast <cgraph_node> (node))
    {
      ....
    }

The necessary conditional test defines a variable that holds a known good
pointer to the specific item and avoids subsequent conversion calls and
the assertion checks that may come with them.

When, the property test is embedded within a larger condition, the variable
declaration gets pulled out of the condition.  (This leaves some room for
using the variable inappropriately.)

  if (symtab_variable_p (node)
      && varpool (node)->finalized)
    varpool_analyze_node (varpool (node));

becomes

  varpool_node *vnode = dyn_cast <varpool_node> (node);
  if (vnode && vnode->finalized)
    varpool_analyze_node (vnode);

Note that we have converted two sets of assertions in the calls to varpool
into safe and efficient use of a variable.


There are remaining calls to symtab_function_p and symtab_variable_p that
do not involve a pointer to a more specific type.  These have been converted
to calls to a functions is_a <cgraph_node> and is_a <varpool_node>.  The
original predicate functions have been removed.

The cgraph.h header defined both a struct and a function with the name
varpool_node.  This name overloading can cause some unintuitive error messages
when, as is common in C++, one omits the struct keyword when using the type.
I have renamed the function to varpool_node_for_decl.

Tested on x86_64.


Index: gcc/ChangeLog

2012-10-31  Lawrence Crowl  <crowl@google.com>

	* is-a.h: New.
	(is_a <T> (U*)): New.  Test for is-a relationship.
	(as_a <T> (U*)): New.  Treat as a derived type.
	(dyn_cast <T> (U*)): New.  Conditionally cast based on is_a.
	* cgraph.h (varpool_node): Rename to varpool_node_for_decl.
	Adjust callers to match.
	(is_a_helper <cgraph_node>::test (symtab_node_def *)): New.
	(is_a_helper <varpool_node>::test (symtab_node_def *)): New.
	(symtab_node_def::try_function): New.  Change most calls to
	symtab_function_p with calls to dyn_cast <cgraph_node> (p).
	(symtab_node_def::try_variable): New.  Change most calls to
	symtab_variable_p with calls to dyn_cast <varpool_node> (p).
	(symtab_function_p): Remove.  Change callers to use
        is_a <cgraph_node> (p) instead.
	(symtab_variable_p): Remove.  Change callers to use
        is_a <varpool_node> (p) instead.
	* cgraph.c (cgraph_node_for_asm): Remove redundant call to
	symtab_node_for_asm.
	* cgraphunit.c (symbol_finalized_and_needed): New.
	(symbol_finalized): New.
	(cgraph_analyze_functions): Split complicated conditionals out into
	above new functions.
	* Makefile.in (CGRAPH_H): Add is-a.h as used by cgraph.h.

From-SVN: r193051

1 files changed, 11 insertions, 8 deletions

diff --git a/gcc/ipa-inline-analysis.c b/gcc/ipa-inline-analysis.c
index 8baaced..3de1439 100644
--- a/gcc/ipa-inline-analysis.c
+++ b/gcc/ipa-inline-analysis.c
@@ -3855,22 +3855,25 @@ void
 inline_write_summary (void)
 {
   struct cgraph_node *node;
-  symtab_node snode;
   struct output_block *ob = create_output_block (LTO_section_inline_summary);
   lto_symtab_encoder_t encoder = ob->decl_state->symtab_node_encoder;
   unsigned int count = 0;
   int i;
 
   for (i = 0; i < lto_symtab_encoder_size (encoder); i++)
-    if (symtab_function_p (snode = lto_symtab_encoder_deref (encoder, i))
-	&& cgraph (snode)->analyzed)
-      count++;
+    {
+      symtab_node snode = lto_symtab_encoder_deref (encoder, i);
+      cgraph_node *cnode = dyn_cast <cgraph_node> (snode);
+      if (cnode && cnode->analyzed)
+	count++;
+    }
   streamer_write_uhwi (ob, count);
 
   for (i = 0; i < lto_symtab_encoder_size (encoder); i++)
     {
-      if (symtab_function_p (snode = lto_symtab_encoder_deref (encoder, i))
-	  && (node = cgraph (snode))->analyzed)
+      symtab_node snode = lto_symtab_encoder_deref (encoder, i);
+      cgraph_node *cnode = dyn_cast <cgraph_node> (snode);
+      if (cnode && (node = cnode)->analyzed)
 	{
 	  struct inline_summary *info = inline_summary (node);
 	  struct bitpack_d bp;
@@ -3878,7 +3881,7 @@ inline_write_summary (void)
 	  int i;
 	  size_time_entry *e;
 	  struct condition *c;
-
+  
 	  streamer_write_uhwi (ob, lto_symtab_encoder_encode (encoder, (symtab_node)node));
 	  streamer_write_hwi (ob, info->estimated_self_stack_size);
 	  streamer_write_hwi (ob, info->self_size);
@@ -3897,7 +3900,7 @@ inline_write_summary (void)
 	      bp_pack_value (&bp, c->by_ref, 1);
 	      streamer_write_bitpack (&bp);
 	      if (c->agg_contents)
-		streamer_write_uhwi (ob, c->offset);
+	        streamer_write_uhwi (ob, c->offset);
 	    }
 	  streamer_write_uhwi (ob, VEC_length (size_time_entry, info->entry));
 	  for (i = 0;