[C] Remove dead code related to type compatibility across TUs.

Message ID f44ec2bb791d05c69636b8d881d74edb4b57234f.camel@tugraz.at
State Accepted
Headers
Series [C] Remove dead code related to type compatibility across TUs. |

Checks

Context Check Description
snail/gcc-patch-check success Github commit url

Commit Message

Martin Uecker May 19, 2023, 8:38 p.m. UTC
  Repost for stage 1.


    C: Remove dead code related to type compatibility across TUs.
    
    Code to detect struct/unions across the same TU is not needed
    anymore. Code for determining compatibility of tagged types is
    preserved as it will be used for C2X. Some errors in the unused
    code are fixed.
    
    Bootstrapped with no regressions for x86_64-pc-linux-gnu.
    
    gcc/c/
            * c-decl.cc (set_type_context): Remove.
            (pop_scope, diagnose_mismatched_decls, pushdecl):
            Remove dead code.
            * c-typeck.cc (comptypes_internal): Remove dead code.
            (same_translation_unit_p): Remove.
            (tagged_types_tu_compatible_p): Some fixes.
  

Comments

Joseph Myers May 19, 2023, 9:07 p.m. UTC | #1
On Fri, 19 May 2023, Martin Uecker via Gcc-patches wrote:

> Repost for stage 1.
> 
> 
>     C: Remove dead code related to type compatibility across TUs.
>     
>     Code to detect struct/unions across the same TU is not needed
>     anymore. Code for determining compatibility of tagged types is
>     preserved as it will be used for C2X. Some errors in the unused
>     code are fixed.
>     
>     Bootstrapped with no regressions for x86_64-pc-linux-gnu.
>     
>     gcc/c/
>             * c-decl.cc (set_type_context): Remove.
>             (pop_scope, diagnose_mismatched_decls, pushdecl):
>             Remove dead code.
>             * c-typeck.cc (comptypes_internal): Remove dead code.
>             (same_translation_unit_p): Remove.
>             (tagged_types_tu_compatible_p): Some fixes.

OK.
  

Patch

diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index f63c1108ab5..70345b4b019 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -1155,16 +1155,6 @@  update_label_decls (struct c_scope *scope)
     }
 }
 
-/* Set the TYPE_CONTEXT of all of TYPE's variants to CONTEXT.  */
-
-static void
-set_type_context (tree type, tree context)
-{
-  for (type = TYPE_MAIN_VARIANT (type); type;
-       type = TYPE_NEXT_VARIANT (type))
-    TYPE_CONTEXT (type) = context;
-}
-
 /* Exit a scope.  Restore the state of the identifier-decl mappings
    that were in effect when this scope was entered.  Return a BLOCK
    node containing all the DECLs in this scope that are of interest
@@ -1253,7 +1243,6 @@  pop_scope (void)
 	case ENUMERAL_TYPE:
 	case UNION_TYPE:
 	case RECORD_TYPE:
-	  set_type_context (p, context);
 
 	  /* Types may not have tag-names, in which case the type
 	     appears in the bindings list with b->id NULL.  */
@@ -1364,12 +1353,7 @@  pop_scope (void)
 	     the TRANSLATION_UNIT_DECL.  This makes same_translation_unit_p
 	     work.  */
 	  if (scope == file_scope)
-	    {
 	      DECL_CONTEXT (p) = context;
-	      if (TREE_CODE (p) == TYPE_DECL
-		  && TREE_TYPE (p) != error_mark_node)
-		set_type_context (TREE_TYPE (p), context);
-	    }
 
 	  gcc_fallthrough ();
 	  /* Parameters go in DECL_ARGUMENTS, not BLOCK_VARS, and have
@@ -2318,21 +2302,18 @@  diagnose_mismatched_decls (tree newdecl, tree olddecl,
 	{
 	  if (DECL_INITIAL (olddecl))
 	    {
-	      /* If both decls are in the same TU and the new declaration
-		 isn't overriding an extern inline reject the new decl.
-		 In c99, no overriding is allowed in the same translation
-		 unit.  */
-	      if ((!DECL_EXTERN_INLINE (olddecl)
-		   || DECL_EXTERN_INLINE (newdecl)
-		   || (!flag_gnu89_inline
-		       && (!DECL_DECLARED_INLINE_P (olddecl)
-			   || !lookup_attribute ("gnu_inline",
-						 DECL_ATTRIBUTES (olddecl)))
-		       && (!DECL_DECLARED_INLINE_P (newdecl)
-			   || !lookup_attribute ("gnu_inline",
-						 DECL_ATTRIBUTES (newdecl))))
-		  )
-		  && same_translation_unit_p (newdecl, olddecl))
+	      /* If the new declaration isn't overriding an extern inline
+		 reject the new decl. In c99, no overriding is allowed
+		 in the same translation unit.  */
+	      if (!DECL_EXTERN_INLINE (olddecl)
+		  || DECL_EXTERN_INLINE (newdecl)
+		  || (!flag_gnu89_inline
+		      && (!DECL_DECLARED_INLINE_P (olddecl)
+			  || !lookup_attribute ("gnu_inline",
+						DECL_ATTRIBUTES (olddecl)))
+		      && (!DECL_DECLARED_INLINE_P (newdecl)
+			  || !lookup_attribute ("gnu_inline",
+						DECL_ATTRIBUTES (newdecl)))))
 		{
 		  auto_diagnostic_group d;
 		  error ("redefinition of %q+D", newdecl);
@@ -3360,18 +3341,11 @@  pushdecl (tree x)
 	 type to the composite of all the types of that declaration.
 	 After the consistency checks, it will be reset to the
 	 composite of the visible types only.  */
-      if (b && (TREE_PUBLIC (x) || same_translation_unit_p (x, b->decl))
-	  && b->u.type)
+      if (b && b->u.type)
 	TREE_TYPE (b->decl) = b->u.type;
 
-      /* The point of the same_translation_unit_p check here is,
-	 we want to detect a duplicate decl for a construct like
-	 foo() { extern bar(); } ... static bar();  but not if
-	 they are in different translation units.  In any case,
-	 the static does not go in the externals scope.  */
-      if (b
-	  && (TREE_PUBLIC (x) || same_translation_unit_p (x, b->decl))
-	  && duplicate_decls (x, b->decl))
+      /* the static does not go in the externals scope.  */
+      if (b && duplicate_decls (x, b->decl))
 	{
 	  tree thistype;
 	  if (vistype)
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index f619e2a67e7..9a5d6e003ca 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -1259,7 +1259,7 @@  comptypes_internal (const_tree type1, const_tree type2, bool *enum_and_int_p,
     case ENUMERAL_TYPE:
     case RECORD_TYPE:
     case UNION_TYPE:
-      if (val != 1 && !same_translation_unit_p (t1, t2))
+      if (val != 1 && false)
 	{
 	  tree a1 = TYPE_ATTRIBUTES (t1);
 	  tree a2 = TYPE_ATTRIBUTES (t2);
@@ -1268,11 +1268,11 @@  comptypes_internal (const_tree type1, const_tree type2, bool *enum_and_int_p,
 	      && ! attribute_list_contained (a2, a1))
 	    break;
 
-	  if (attrval != 2)
-	    return tagged_types_tu_compatible_p (t1, t2, enum_and_int_p,
-						 different_types_p);
 	  val = tagged_types_tu_compatible_p (t1, t2, enum_and_int_p,
 					      different_types_p);
+
+	  if (attrval != 2)
+	    return val;
 	}
       break;
 
@@ -1347,40 +1347,7 @@  comp_target_types (location_t location, tree ttl, tree ttr)
 
 /* Subroutines of `comptypes'.  */
 
-/* Determine whether two trees derive from the same translation unit.
-   If the CONTEXT chain ends in a null, that tree's context is still
-   being parsed, so if two trees have context chains ending in null,
-   they're in the same translation unit.  */
-
-bool
-same_translation_unit_p (const_tree t1, const_tree t2)
-{
-  while (t1 && TREE_CODE (t1) != TRANSLATION_UNIT_DECL)
-    switch (TREE_CODE_CLASS (TREE_CODE (t1)))
-      {
-      case tcc_declaration:
-	t1 = DECL_CONTEXT (t1); break;
-      case tcc_type:
-	t1 = TYPE_CONTEXT (t1); break;
-      case tcc_exceptional:
-	t1 = BLOCK_SUPERCONTEXT (t1); break;  /* assume block */
-      default: gcc_unreachable ();
-      }
 
-  while (t2 && TREE_CODE (t2) != TRANSLATION_UNIT_DECL)
-    switch (TREE_CODE_CLASS (TREE_CODE (t2)))
-      {
-      case tcc_declaration:
-	t2 = DECL_CONTEXT (t2); break;
-      case tcc_type:
-	t2 = TYPE_CONTEXT (t2); break;
-      case tcc_exceptional:
-	t2 = BLOCK_SUPERCONTEXT (t2); break;  /* assume block */
-      default: gcc_unreachable ();
-      }
-
-  return t1 == t2;
-}
 
 /* Allocate the seen two types, assuming that they are compatible. */
 
@@ -1531,6 +1498,7 @@  tagged_types_tu_compatible_p (const_tree t1, const_tree t2,
     case UNION_TYPE:
       {
 	struct tagged_tu_seen_cache *tu = alloc_tagged_tu_seen_cache (t1, t2);
+
 	if (list_length (TYPE_FIELDS (t1)) != list_length (TYPE_FIELDS (t2)))
 	  {
 	    tu->val = 0;
@@ -1609,7 +1577,7 @@  tagged_types_tu_compatible_p (const_tree t1, const_tree t2,
 		return 0;
 	      }
 	  }
-	tu->val = needs_warning ? 2 : 10;
+	tu->val = needs_warning ? 2 : 1;
 	return tu->val;
       }
 
@@ -1617,6 +1585,12 @@  tagged_types_tu_compatible_p (const_tree t1, const_tree t2,
       {
 	struct tagged_tu_seen_cache *tu = alloc_tagged_tu_seen_cache (t1, t2);
 
+	if (list_length (TYPE_FIELDS (t1)) != list_length (TYPE_FIELDS (t2)))
+	  {
+	    tu->val = 0;
+	    return 0;
+	  }
+
 	for (s1 = TYPE_FIELDS (t1), s2 = TYPE_FIELDS (t2);
 	     s1 && s2;
 	     s1 = DECL_CHAIN (s1), s2 = DECL_CHAIN (s2))