Re: [C++ PATCH] Stash bitfield width into DECL_BIT_FIELD_REPRESENTATIVE instead of DECL_INITIAL

[Nathan Sidwell]

On 09/28/2017 11:49 AM, Jakub Jelinek wrote:


The following patch is the D_B_F_R part of the above.
Bootstrapped/regtested on top of the patch I've just posted, ok for trunk?


Looks good, a couple of nits.  I think the bits out of the cp FE are 
sufficiently obvious given the cp changes.




c/
* c-decl.c (grokfield): Use SET_DECL_C_BIT_FIELD here if
with is non-NULL.

/with/width


--- gcc/c-family/c-attribs.c.jj 2017-09-18 20:48:53.731871226 +0200
+++ gcc/c-family/c-attribs.c2017-09-19 09:51:21.928612658 +0200
@@ -426,7 +426,7 @@ handle_packed_attribute (tree *node, tre



--- gcc/cp/class.c.jj   2017-09-18 20:48:53.509873991 +0200
+++ gcc/cp/class.c  2017-09-19 10:31:35.435961690 +0200
@@ -3231,12 +3231,12 @@ check_bitfield_decl (tree field)
tree w;
  
/* Extract the declared width of the bitfield, which has been

- temporarily stashed in DECL_INITIAL.  */
-  w = DECL_INITIAL (field);
+ temporarily stashed in DECL_BIT_FIELD_REPRESENTATIVE.  */


While you're here, could you point the comment at grokbitfield?



+++ gcc/cp/decl2.c  2017-09-19 10:31:45.066839694 +0200
@@ -1042,7 +1047,8 @@ grokbitfield (const cp_declarator *decla
   TREE_TYPE (width));
else
{
- DECL_INITIAL (value) = width;
+ /* Temporarily stash the width in DECL_BIT_FIELD_REPRESENTATIVE.  */


And likewise here point at ceheck_bitfield_decl? (answering the 
temporarily 'til when? question)



+++ gcc/objc/objc-act.c 2017-09-19 13:01:06.917412755 +0200
@@ -4602,8 +4602,14 @@ check_ivars (tree inter, tree imp)
t1 = TREE_TYPE (intdecls); t2 = TREE_TYPE (impdecls);
  
if (!comptypes (t1, t2)

+#ifdef OBJCPLUS
+ || !tree_int_cst_equal (DECL_BIT_FIELD_REPRESENTATIVE (intdecls),
+ DECL_BIT_FIELD_REPRESENTATIVE (impdecls))
+#else
  || !tree_int_cst_equal (DECL_INITIAL (intdecls),
- DECL_INITIAL (impdecls)))
+ DECL_INITIAL (impdecls))
+#endif


This is a little unfortunate.  Feel like adding a cleanup task to the 
easy-projects wiki?  You'll see I added a few I've been spotting.


ok for trunk.

nathan

--
Nathan Sidwell

[C++ PATCH] Stash bitfield width into DECL_BIT_FIELD_REPRESENTATIVE instead of DECL_INITIAL

[Jakub Jelinek]

Hi!

On Wed, Sep 27, 2017 at 07:55:20AM -0700, Nathan Sidwell wrote:
>   1) fix the parsing bug you found and move to (ab)using
> DECL_BIT_FIELD_REPRESENTATIVE

The following patch is the D_B_F_R part of the above.
Bootstrapped/regtested on top of the patch I've just posted, ok for trunk?

2017-09-28  Jakub Jelinek  

c-family/
* c-attribs.c (handle_packed_attribute): Test DECL_C_BIT_FIELD
rather than DECL_INITIAL.
(common_handle_aligned_attribute): Likewise.
c/
* c-decl.c (grokfield): Use SET_DECL_C_BIT_FIELD here if
with is non-NULL.
(finish_struct): Test DECL_C_BIT_FIELD instead of DECL_INITIAL,
don't SET_DECL_C_BIT_FIELD here.
cp/
* class.c (check_bitfield_decl): Retrieve and clear width from
DECL_BIT_FIELD_REPRESENTATIVE rather than DECL_INITIAL.
(check_field_decls): Test DECL_BIT_FIELD_REPRESENTATIVE rather than
DECL_INITIAL.
(remove_zero_width_bit_fields): Adjust comment.
* decl2.c (grokbitfield): Stash width into
DECL_BIT_FIELD_REPRESENTATIVE rather than DECL_INITIAL.
* pt.c (tsubst_decl): For DECL_C_BIT_FIELD, tsubst_expr
DECL_BIT_FIELD_REPRESENTATIVE rather than DECL_INITIAL for width.
objc/
* objc-act.c (check_ivars, gen_declaration): For OBJCPLUS look at
DECL_BIT_FIELD_REPRESENTATIVE rather than DECL_INITIAL.

--- gcc/c-family/c-attribs.c.jj 2017-09-18 20:48:53.731871226 +0200
+++ gcc/c-family/c-attribs.c2017-09-19 09:51:21.928612658 +0200
@@ -426,7 +426,7 @@ handle_packed_attribute (tree *node, tre
 {
   if (TYPE_ALIGN (TREE_TYPE (*node)) <= BITS_PER_UNIT
  /* Still pack bitfields.  */
- && ! DECL_INITIAL (*node))
+ && ! DECL_C_BIT_FIELD (*node))
warning (OPT_Wattributes,
 "%qE attribute ignored for field of type %qT",
 name, TREE_TYPE (*node));
@@ -1773,7 +1773,7 @@ common_handle_aligned_attribute (tree *n
 {
   if (warn_if_not_aligned_p)
{
- if (TREE_CODE (decl) == FIELD_DECL && !DECL_INITIAL (decl))
+ if (TREE_CODE (decl) == FIELD_DECL && !DECL_C_BIT_FIELD (decl))
{
  SET_DECL_WARN_IF_NOT_ALIGN (decl, (1U << i) * BITS_PER_UNIT);
  warn_if_not_aligned_p = false;
--- gcc/c/c-decl.c.jj   2017-09-12 21:57:59.0 +0200
+++ gcc/c/c-decl.c  2017-09-19 10:43:30.898898784 +0200
@@ -7602,6 +7602,8 @@ grokfield (location_t loc,
 
   finish_decl (value, loc, NULL_TREE, NULL_TREE, NULL_TREE);
   DECL_INITIAL (value) = width;
+  if (width)
+SET_DECL_C_BIT_FIELD (value);
 
   if (warn_cxx_compat && DECL_NAME (value) != NULL_TREE)
 {
@@ -7946,12 +7948,11 @@ finish_struct (location_t loc, tree t, t
   if (C_DECL_VARIABLE_SIZE (x))
C_TYPE_VARIABLE_SIZE (t) = 1;
 
-  if (DECL_INITIAL (x))
+  if (DECL_C_BIT_FIELD (x))
{
  unsigned HOST_WIDE_INT width = tree_to_uhwi (DECL_INITIAL (x));
  DECL_SIZE (x) = bitsize_int (width);
  DECL_BIT_FIELD (x) = 1;
- SET_DECL_C_BIT_FIELD (x);
}
 
   if (TYPE_PACKED (t)
--- gcc/cp/class.c.jj   2017-09-18 20:48:53.509873991 +0200
+++ gcc/cp/class.c  2017-09-19 10:31:35.435961690 +0200
@@ -3231,12 +3231,12 @@ check_bitfield_decl (tree field)
   tree w;
 
   /* Extract the declared width of the bitfield, which has been
- temporarily stashed in DECL_INITIAL.  */
-  w = DECL_INITIAL (field);
+ temporarily stashed in DECL_BIT_FIELD_REPRESENTATIVE.  */
+  w = DECL_BIT_FIELD_REPRESENTATIVE (field);
   gcc_assert (w != NULL_TREE);
   /* Remove the bit-field width indicator so that the rest of the
- compiler does not treat that value as an initializer.  */
-  DECL_INITIAL (field) = NULL_TREE;
+ compiler does not treat that value as a qualifier.  */
+  DECL_BIT_FIELD_REPRESENTATIVE (field) = NULL_TREE;
 
   /* Detect invalid bit-field type.  */
   if (!INTEGRAL_OR_ENUMERATION_TYPE_P (type))
@@ -3571,7 +3571,8 @@ check_field_decls (tree t, tree *access_
DECL_PACKED (x) = 1;
}
 
-  if (DECL_C_BIT_FIELD (x) && integer_zerop (DECL_INITIAL (x)))
+  if (DECL_C_BIT_FIELD (x)
+ && integer_zerop (DECL_BIT_FIELD_REPRESENTATIVE (x)))
/* We don't treat zero-width bitfields as making a class
   non-empty.  */
;
@@ -5268,9 +5269,9 @@ remove_zero_width_bit_fields (tree t)
 {
   if (TREE_CODE (*fieldsp) == FIELD_DECL
  && DECL_C_BIT_FIELD (*fieldsp)
-  /* We should not be confused by the fact that grokbitfield
+ /* We should not be confused by the fact that grokbitfield
 temporarily sets the width of the bit field into
-DECL_INITIAL (*fieldsp).
+DECL_BIT_FIELD_REPRESENTATIVE (*fieldsp).
 check_bitfield_decl eventually sets DECL_SIZE (*fieldsp)
 to that width.  */
  && (DECL_SIZE (*fieldsp) == NULL_TREE
--- gcc/cp/decl2.c.jj