This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
[PATCH] Fix Ada bitfield issue No. 1
- From: Richard Guenther <rguenther at suse dot de>
- To: gcc-patches at gcc dot gnu dot org
- Date: Fri, 16 Mar 2012 12:45:49 +0100 (CET)
- Subject: [PATCH] Fix Ada bitfield issue No. 1
This fixes issue No. 1, easy.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2012-03-16 Richard Guenther <rguenther@suse.de>
* stor-layout.c (finish_bitfield_representative): Fall back
to the conservative maximum size if we cannot compute the
size of the tail padding.
* gnat.dg/specs/pack7.ads: New testcase.
Index: gcc/stor-layout.c
===================================================================
--- gcc/stor-layout.c (revision 185461)
+++ gcc/stor-layout.c (working copy)
@@ -1765,6 +1765,9 @@ finish_bitfield_representative (tree rep
- tree_low_cst (DECL_FIELD_BIT_OFFSET (repr), 1)
+ tree_low_cst (DECL_SIZE (field), 1));
+ /* Round up bitsize to multiples of BITS_PER_UNIT. */
+ bitsize = (bitsize + BITS_PER_UNIT - 1) & ~(BITS_PER_UNIT - 1);
+
/* Now nothing tells us how to pad out bitsize ... */
nextf = DECL_CHAIN (field);
while (nextf && TREE_CODE (nextf) != FIELD_DECL)
@@ -1787,12 +1790,16 @@ finish_bitfield_representative (tree rep
{
/* ??? If you consider that tail-padding of this struct might be
re-used when deriving from it we cannot really do the following
- and thus need to set maxsize to bitsize? */
+ and thus need to set maxsize to bitsize? Also we cannot
+ generally rely on maxsize to fold to an integer constant, so
+ use bitsize as fallback for this case. */
tree maxsize = size_diffop (TYPE_SIZE_UNIT (DECL_CONTEXT (field)),
DECL_FIELD_OFFSET (repr));
- gcc_assert (host_integerp (maxsize, 1));
- maxbitsize = (tree_low_cst (maxsize, 1) * BITS_PER_UNIT
- - tree_low_cst (DECL_FIELD_BIT_OFFSET (repr), 1));
+ if (host_integerp (maxsize, 1))
+ maxbitsize = (tree_low_cst (maxsize, 1) * BITS_PER_UNIT
+ - tree_low_cst (DECL_FIELD_BIT_OFFSET (repr), 1));
+ else
+ maxbitsize = bitsize;
}
/* Only if we don't artificially break up the representative in
@@ -1801,9 +1808,6 @@ finish_bitfield_representative (tree rep
at byte offset. */
gcc_assert (maxbitsize % BITS_PER_UNIT == 0);
- /* Round up bitsize to multiples of BITS_PER_UNIT. */
- bitsize = (bitsize + BITS_PER_UNIT - 1) & ~(BITS_PER_UNIT - 1);
-
/* Find the smallest nice mode to use. */
for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
mode = GET_MODE_WIDER_MODE (mode))
Index: gcc/testsuite/gnat.dg/specs/pack7.ads
===================================================================
--- gcc/testsuite/gnat.dg/specs/pack7.ads (revision 0)
+++ gcc/testsuite/gnat.dg/specs/pack7.ads (revision 0)
@@ -0,0 +1,13 @@
+-- { dg-do compile }
+
+package Pack7 is
+
+ type R (D : Natural) is record
+ S : String (1 .. D);
+ N : Natural;
+ B : Boolean;
+ end record;
+ for R'Alignment use 4;
+ pragma Pack (R);
+
+end Pack7;