Re: [PATCH 18/18] make TS_BLOCK a substructure of TS_BASE

[Nathan Froyd <froydnj@codesourcery.com>]

On Thu, Mar 10, 2011 at 11:23:26PM -0500, Nathan Froyd wrote:
> Now that we've  encapsulated all uses of BLOCK_CHAINON properly, we can
> make BLOCKs inherit from tree_base and redirect BLOCK_CHAINON to use a
> tree_block-private field instead of tree_common's chain.  Doing so saves
> the never-used TREE_TYPE field.

This patch was approved:

http://gcc.gnu.org/ml/gcc-patches/2011-03/msg00564.html
http://gcc.gnu.org/ml/gcc-patches/2011-05/msg01844.html

However, during retesting, I hit problems in find_decls_types_r; the
following bit of code doesn't work if your trees don't have TREE_TYPE:

  if (TREE_CODE (t) != IDENTIFIER_NODE)
    fld_worklist_push (TREE_TYPE (t), fld);

This didn't show up when I was developing the patch, since the
adjustments to IDENTIFIER_NODE:

http://gcc.gnu.org/ml/gcc-patches/2011-03/msg00561.html

had done:

@@ -4795,7 +4791,8 @@ find_decls_types_r (tree *tp, int *ws, void *data)
       fld_worklist_push (BLOCK_ABSTRACT_ORIGIN (t), fld);
     }
 
-  fld_worklist_push (TREE_TYPE (t), fld);
+  if (CODE_CONTAINS_STRUCT (TREE_CODE (t), TS_TYPED))
+    fld_worklist_push (TREE_TYPE (t), fld);
 
   return NULL_TREE;
 }

And the later BLOCK-adjusting made use of that bit.  Given that removing
TREE_TYPE from IDENTIFIER_NODE required more invasive surgery than I'm
qualified to do at this point, that bit (and several others) got
dropped, leading to our present situation.

Since Richi approved the IDENTIFIER_NODE changes, I feel justified in
committing the slightly tweaked patch below.  The relevant bit that
wasn't in the initial mail is:

@@ -4892,7 +4892,8 @@ find_decls_types_r (tree *tp, int *ws, void *data)
       fld_worklist_push (BLOCK_ABSTRACT_ORIGIN (t), fld);
     }
 
-  if (TREE_CODE (t) != IDENTIFIER_NODE)
+  if (TREE_CODE (t) != IDENTIFIER_NODE
+      && CODE_CONTAINS_STRUCT (TREE_CODE (t), TS_TYPED))
     fld_worklist_push (TREE_TYPE (t), fld);
 
   return NULL_TREE;

If people feel that checking TREE_CODE for BLOCK or just 'return'ing
from the BLOCK block just above would be more appropriate, I can commit
that as a followup patch.

Tested on x86_64-unknown-linux-gnu.  Committed as r174300.

-Nathan

gcc/
	* tree.c (initialize_tree_contains_struct): Mark TS_BLOCK as
	TS_BASE instead of TS_COMMON.
	* tree.h (struct tree_block): Inherit from tree_base, not tree_common.
	Add chain field.
	(BLOCK_CHAIN): Use new chain field.

gcc/c-family/
	* c-common.c (warning_candidate_p): Check for BLOCKs.

gcc/java/
	* decl.c (poplevel): Don't access TREE_TYPE of BLOCKs.
	* expr.c (build_jni_stub): Likewise.

diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 2d4e492..fa7ebc5 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -2367,6 +2367,9 @@ warning_candidate_p (tree x)
   if (DECL_P (x) && DECL_ARTIFICIAL (x))
     return 0;
 
+  if (TREE_CODE (x) == BLOCK)
+    return 0;
+
   /* VOID_TYPE_P (TREE_TYPE (x)) is workaround for cp/tree.c
      (lvalue_p) crash on TRY/CATCH. */
   if (TREE_TYPE (x) == NULL_TREE || VOID_TYPE_P (TREE_TYPE (x)))
diff --git a/gcc/java/decl.c b/gcc/java/decl.c
index 47b4ebe..e958136 100644
--- a/gcc/java/decl.c
+++ b/gcc/java/decl.c
@@ -1425,10 +1425,7 @@ poplevel (int keep, int reverse, int functionbody)
 
   block = 0;
   if (keep || functionbody)
-    {
-      block = make_node (BLOCK);
-      TREE_TYPE (block) = void_type_node;
-    }
+    block = make_node (BLOCK);
 
   if (current_binding_level->exception_range)
     expand_end_java_handler (current_binding_level->exception_range);
@@ -1456,7 +1453,7 @@ poplevel (int keep, int reverse, int functionbody)
 	    }
 	  *var = NULL;
 	    
-	  bind = build3 (BIND_EXPR, TREE_TYPE (block), BLOCK_VARS (block), 
+	  bind = build3 (BIND_EXPR, void_type_node, BLOCK_VARS (block), 
 			 BLOCK_EXPR_BODY (block), block);
 	  BIND_EXPR_BODY (bind) = current_binding_level->stmts;
 	  
diff --git a/gcc/java/expr.c b/gcc/java/expr.c
index 3be1cff..b9293e0 100644
--- a/gcc/java/expr.c
+++ b/gcc/java/expr.c
@@ -2649,7 +2649,6 @@ build_jni_stub (tree method)
   method_args = DECL_ARGUMENTS (method);
   block = build_block (env_var, NULL_TREE, method_args, NULL_TREE);
   TREE_SIDE_EFFECTS (block) = 1;
-  TREE_TYPE (block) = TREE_TYPE (TREE_TYPE (method));
 
   /* Compute the local `env' by calling _Jv_GetJNIEnvNewFrame.  */
   body = build2 (MODIFY_EXPR, ptr_type_node, env_var,
diff --git a/gcc/tree.c b/gcc/tree.c
index 1dfad04..d5b5dac 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -368,6 +368,7 @@ initialize_tree_contains_struct (void)
       switch (ts_code)
 	{
 	case TS_TYPED:
+	case TS_BLOCK:
 	  MARK_TS_BASE (code);
 	  break;
 
@@ -389,7 +390,6 @@ initialize_tree_contains_struct (void)
 	case TS_TYPE_COMMON:
 	case TS_LIST:
 	case TS_VEC:
-	case TS_BLOCK:
 	case TS_BINFO:
 	case TS_STATEMENT_LIST:
 	case TS_OMP_CLAUSE:
@@ -4892,7 +4892,8 @@ find_decls_types_r (tree *tp, int *ws, void *data)
       fld_worklist_push (BLOCK_ABSTRACT_ORIGIN (t), fld);
     }
 
-  if (TREE_CODE (t) != IDENTIFIER_NODE)
+  if (TREE_CODE (t) != IDENTIFIER_NODE
+      && CODE_CONTAINS_STRUCT (TREE_CODE (t), TS_TYPED))
     fld_worklist_push (TREE_TYPE (t), fld);
 
   return NULL_TREE;
diff --git a/gcc/tree.h b/gcc/tree.h
index 142237f..aefaea8 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -2051,9 +2051,7 @@ struct GTY(()) tree_omp_clause {
   VEC_index (tree, BLOCK_NONLOCALIZED_VARS (NODE), N)
 #define BLOCK_SUBBLOCKS(NODE) (BLOCK_CHECK (NODE)->block.subblocks)
 #define BLOCK_SUPERCONTEXT(NODE) (BLOCK_CHECK (NODE)->block.supercontext)
-/* Note: when changing this, make sure to find the places
-   that use chainon or nreverse.  */
-#define BLOCK_CHAIN(NODE) TREE_CHAIN (BLOCK_CHECK (NODE))
+#define BLOCK_CHAIN(NODE) (BLOCK_CHECK (NODE)->block.chain)
 #define BLOCK_ABSTRACT_ORIGIN(NODE) (BLOCK_CHECK (NODE)->block.abstract_origin)
 #define BLOCK_ABSTRACT(NODE) (BLOCK_CHECK (NODE)->block.abstract_flag)
 
@@ -2094,7 +2092,8 @@ struct GTY(()) tree_omp_clause {
 #define BLOCK_SOURCE_LOCATION(NODE) (BLOCK_CHECK (NODE)->block.locus)
 
 struct GTY(()) tree_block {
-  struct tree_common common;
+  struct tree_base base;
+  tree chain;
 
   unsigned abstract_flag : 1;
   unsigned block_num : 31;