[gcc r8-10470] c: Handle C_TYPE_INCOMPLETE_VARS even for ENUMERAL_TYPEs [PR94172]

[gcc r8-10470] c: Handle C_TYPE_INCOMPLETE_VARS even for ENUMERAL_TYPEs [PR94172]

[Jakub Jelinek]

https://gcc.gnu.org/g:cac1949a51e25360a7fd7dc8f473997b7ca048a9

commit r8-10470-gcac1949a51e25360a7fd7dc8f473997b7ca048a9
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Mar 17 22:32:34 2020 +0100

    c: Handle C_TYPE_INCOMPLETE_VARS even for ENUMERAL_TYPEs [PR94172]
    
    The following testcases ICE, because they contain extern variable
    declarations with incomplete enum types that is later completed and after
    that those variables are accessed.  The ICEs are because the vars then may have
    incorrect DECL_MODE etc., e.g. in the first case the var has SImode
    DECL_MODE (the guessed mode for the enum), but the enum then actually has
    DImode because its enumerators don't fit into unsigned int.
    
    The following patch fixes it by using C_TYPE_INCOMPLETE_VARS not just on
    incomplete struct/union types, but also incomplete enum types.
    TYPE_VFIELD can't be used as it is TYPE_MIN_VALUE on ENUMERAL_TYPE,
    thankfully TYPE_LANG_SLOT_1 has been used in the C FE only on
    FUNCTION_TYPEs.
    
    2020-03-17  Jakub Jelinek  <jakub@redhat.com>
    
            PR c/94172
            * c-tree.h (C_TYPE_INCOMPLETE_VARS): Define to TYPE_LANG_SLOT_1
            instead of TYPE_VFIELD, and support it on {RECORD,UNION,ENUMERAL}_TYPE.
            (TYPE_ACTUAL_ARG_TYPES): Check that it is only used on FUNCTION_TYPEs.
            * c-decl.c (pushdecl): Push C_TYPE_INCOMPLETE_VARS also to
            ENUMERAL_TYPEs.
            (finish_incomplete_vars): New function, moved from finish_struct.  Use
            relayout_decl instead of layout_decl.
            (finish_struct): Remove obsolete comment about C_TYPE_INCOMPLETE_VARS
            being TYPE_VFIELD.  Use finish_incomplete_vars.
            (finish_enum): Clear C_TYPE_INCOMPLETE_VARS.  Call
            finish_incomplete_vars.
            * c-typeck.c (c_build_qualified_type): Clear C_TYPE_INCOMPLETE_VARS
            also on ENUMERAL_TYPEs.
    
            * gcc.dg/pr94172-1.c: New test.
            * gcc.dg/pr94172-2.c: New test.
    
    (cherry picked from commit 87ce34fa00cd6b87452d747235da40dfe5b6e00f)

Diff:
---
 gcc/c/c-decl.c                   | 50 ++++++++++++++++++++++------------------
 gcc/c/c-tree.h                   | 12 ++++++----
 gcc/c/c-typeck.c                 |  3 ++-
 gcc/testsuite/gcc.dg/pr94172-1.c | 12 ++++++++++
 gcc/testsuite/gcc.dg/pr94172-2.c | 19 +++++++++++++++
 5 files changed, 68 insertions(+), 28 deletions(-)

diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
index c566f765899..2cdbff1a960 100644
--- a/gcc/c/c-decl.c
+++ b/gcc/c/c-decl.c
@@ -3111,7 +3111,8 @@ pushdecl (tree x)
 	element = TREE_TYPE (element);
       element = TYPE_MAIN_VARIANT (element);
 
-      if (RECORD_OR_UNION_TYPE_P (element)
+      if ((RECORD_OR_UNION_TYPE_P (element)
+	   || TREE_CODE (element) == ENUMERAL_TYPE)
 	  && (TREE_CODE (x) != TYPE_DECL
 	      || TREE_CODE (TREE_TYPE (x)) == ARRAY_TYPE)
 	  && !COMPLETE_TYPE_P (element))
@@ -7999,6 +8000,26 @@ field_decl_cmp (const void *x_p, const void *y_p)
   return 1;
 }
 
+/* If this structure or union completes the type of any previous
+   variable declaration, lay it out and output its rtl.  */
+static void
+finish_incomplete_vars (tree incomplete_vars, bool toplevel)
+{
+  for (tree x = incomplete_vars; x; x = TREE_CHAIN (x))
+    {
+      tree decl = TREE_VALUE (x);
+      if (TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE)
+	layout_array_type (TREE_TYPE (decl));
+      if (TREE_CODE (decl) != TYPE_DECL)
+	{
+	  relayout_decl (decl);
+	  if (c_dialect_objc ())
+	    objc_check_decl (decl);
+	  rest_of_decl_compilation (decl, toplevel, 0);
+	}
+    }
+}
+
 /* Fill in the fields of a RECORD_TYPE or UNION_TYPE node, T.
    LOC is the location of the RECORD_TYPE or UNION_TYPE's definition.
    FIELDLIST is a chain of FIELD_DECL nodes for the fields.
@@ -8247,13 +8268,6 @@ finish_struct (location_t loc, tree t, tree fieldlist, tree attributes,
       }
   }
 
-  /* Note: C_TYPE_INCOMPLETE_VARS overloads TYPE_VFIELD which is used
-     in dwarf2out via rest_of_decl_compilation below and means
-     something totally different.  Since we will be clearing
-     C_TYPE_INCOMPLETE_VARS shortly after we iterate through them,
-     clear it ahead of time and avoid problems in dwarf2out.  Ideally,
-     C_TYPE_INCOMPLETE_VARS should use some language specific
-     node.  */
   tree incomplete_vars = C_TYPE_INCOMPLETE_VARS (TYPE_MAIN_VARIANT (t));
   for (x = TYPE_MAIN_VARIANT (t); x; x = TYPE_NEXT_VARIANT (x))
     {
@@ -8283,21 +8297,7 @@ finish_struct (location_t loc, tree t, tree fieldlist, tree attributes,
   /* Finish debugging output for this type.  */
   rest_of_type_compilation (t, toplevel);
 
-  /* If this structure or union completes the type of any previous
-     variable declaration, lay it out and output its rtl.  */
-  for (x = incomplete_vars; x; x = TREE_CHAIN (x))
-    {
-      tree decl = TREE_VALUE (x);
-      if (TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE)
-	layout_array_type (TREE_TYPE (decl));
-      if (TREE_CODE (decl) != TYPE_DECL)
-	{
-	  layout_decl (decl, 0);
-	  if (c_dialect_objc ())
-	    objc_check_decl (decl);
-	  rest_of_decl_compilation (decl, toplevel, 0);
-	}
-    }
+  finish_incomplete_vars (incomplete_vars, toplevel);
 
   /* If we're inside a function proper, i.e. not file-scope and not still
      parsing parameters, then arrange for the size of a variable sized type
@@ -8576,8 +8576,10 @@ finish_enum (tree enumtype, tree values, tree attributes)
   TYPE_LANG_SPECIFIC (enumtype) = lt;
 
   /* Fix up all variant types of this enum type.  */
+  tree incomplete_vars = C_TYPE_INCOMPLETE_VARS (TYPE_MAIN_VARIANT (enumtype));
   for (tem = TYPE_MAIN_VARIANT (enumtype); tem; tem = TYPE_NEXT_VARIANT (tem))
     {
+      C_TYPE_INCOMPLETE_VARS (tem) = NULL_TREE;
       if (tem == enumtype)
 	continue;
       TYPE_VALUES (tem) = TYPE_VALUES (enumtype);
@@ -8596,6 +8598,8 @@ finish_enum (tree enumtype, tree values, tree attributes)
   /* Finish debugging output for this type.  */
   rest_of_type_compilation (enumtype, toplevel);
 
+  finish_incomplete_vars (incomplete_vars, toplevel);
+
   /* If this enum is defined inside a struct, add it to
      struct_types.  */
   if (warn_cxx_compat
diff --git a/gcc/c/c-tree.h b/gcc/c/c-tree.h
index bd7d396c67d..fb99cc7acd2 100644
--- a/gcc/c/c-tree.h
+++ b/gcc/c/c-tree.h
@@ -38,9 +38,12 @@ along with GCC; see the file COPYING3.  If not see
    nonzero if the definition of the type has already started.  */
 #define C_TYPE_BEING_DEFINED(TYPE) TYPE_LANG_FLAG_0 (TYPE)
 
-/* In an incomplete RECORD_TYPE or UNION_TYPE, a list of variable
-   declarations whose type would be completed by completing that type.  */
-#define C_TYPE_INCOMPLETE_VARS(TYPE) TYPE_VFIELD (TYPE)
+/* In an incomplete RECORD_TYPE, UNION_TYPE or ENUMERAL_TYPE, a list of
+   variable declarations whose type would be completed by completing
+   that type.  */
+#define C_TYPE_INCOMPLETE_VARS(TYPE) \
+  TYPE_LANG_SLOT_1 (TREE_CHECK4 (TYPE, RECORD_TYPE, UNION_TYPE, \
+				 QUAL_UNION_TYPE, ENUMERAL_TYPE))
 
 /* In an IDENTIFIER_NODE, nonzero if this identifier is actually a
    keyword.  C_RID_CODE (node) is then the RID_* value of the keyword.  */
@@ -107,7 +110,8 @@ along with GCC; see the file COPYING3.  If not see
 /* For FUNCTION_TYPE, a hidden list of types of arguments.  The same as
    TYPE_ARG_TYPES for functions with prototypes, but created for functions
    without prototypes.  */
-#define TYPE_ACTUAL_ARG_TYPES(NODE) TYPE_LANG_SLOT_1 (NODE)
+#define TYPE_ACTUAL_ARG_TYPES(NODE) \
+  TYPE_LANG_SLOT_1 (FUNCTION_TYPE_CHECK (NODE))
 
 /* For a CONSTRUCTOR, whether some initializer contains a
    subexpression meaning it is not a constant expression.  */
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 8c4a1939f3d..eb4886b7289 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -14268,7 +14268,8 @@ c_build_qualified_type (tree type, int type_quals, tree orig_qual_type,
 		   : build_qualified_type (type, type_quals));
   /* A variant type does not inherit the list of incomplete vars from the
      type main variant.  */
-  if (RECORD_OR_UNION_TYPE_P (var_type)
+  if ((RECORD_OR_UNION_TYPE_P (var_type)
+       || TREE_CODE (var_type) == ENUMERAL_TYPE)
       && TYPE_MAIN_VARIANT (var_type) != var_type)
     C_TYPE_INCOMPLETE_VARS (var_type) = 0;
   return var_type;
diff --git a/gcc/testsuite/gcc.dg/pr94172-1.c b/gcc/testsuite/gcc.dg/pr94172-1.c
new file mode 100644
index 00000000000..12f84af42dd
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr94172-1.c
@@ -0,0 +1,12 @@
+/* PR c/94172 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+extern enum E e;
+enum E { l = 0x100000000ULL };
+
+unsigned long long
+foo (void)
+{
+  return e;
+}
diff --git a/gcc/testsuite/gcc.dg/pr94172-2.c b/gcc/testsuite/gcc.dg/pr94172-2.c
new file mode 100644
index 00000000000..bb7b060d7b2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr94172-2.c
@@ -0,0 +1,19 @@
+/* PR c/94172 */
+/* { dg-do compile } */
+/* { dg-options "-Os -g -fshort-enums" } */
+
+extern enum E e;
+extern void bar (int a);
+enum E { F };
+
+void
+foo (int a)
+{
+  int l = e;
+  if (a)
+    {
+      __asm volatile ("nop");
+      l = 0;
+    }
+  bar (l);
+}