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RFA: PATCH: PR target/39545: structures with zero-length array passed/returned inconsistently
- From: "H.J. Lu" <hongjiu dot lu at intel dot com>
- To: gcc-patches at gcc dot gnu dot org
- Cc: ubizjak at gmail dot com, jh at suse dot cz
- Date: Tue, 24 Mar 2009 12:25:05 -0700
- Subject: RFA: PATCH: PR target/39545: structures with zero-length array passed/returned inconsistently
- Reply-to: "H.J. Lu" <hjl dot tools at gmail dot com>
Since flexible array member in struct is ignored when passing and
returning, we should never count it. This patch fixes it with an ABI
change warning. If it is OK, I will provide a few testcase.
Thanks.
H.J.
---
2009-03-24 H.J. Lu <hongjiu.lu@intel.com>
PR target/39545
* config/i386/i386.c (classify_argument): Ignore flexible array
member in struct and warn ABI change.
Index: gcc/config/i386/i386.c
===================================================================
--- gcc/config/i386/i386.c (revision 145000)
+++ gcc/config/i386/i386.c (working copy)
@@ -4865,9 +4865,9 @@ classify_argument (enum machine_mode mod
(mode == BLKmode) ? int_size_in_bytes (type) : (int) GET_MODE_SIZE (mode);
int words = (bytes + (bit_offset % 64) / 8 + UNITS_PER_WORD - 1) / UNITS_PER_WORD;
- /* Variable sized entities are always passed/returned in memory. */
+ /* Variable sized entities should never get here. */
if (bytes < 0)
- return 0;
+ gcc_unreachable ();
if (mode != VOIDmode
&& targetm.calls.must_pass_in_stack (mode, type))
@@ -4923,6 +4923,22 @@ classify_argument (enum machine_mode mod
}
else
{
+ /* Variable sized member is ignored. */
+ if (TYPE_MODE (TREE_TYPE (field)) == BLKmode
+ && int_size_in_bytes (TREE_TYPE (field)) < 0)
+ {
+ static bool warned;
+
+ if (!warned && warn_psabi)
+ {
+ warned = true;
+ inform (input_location,
+ "The ABI of passing struct with"
+ " a flexible array member has"
+ " changed in GCC 4.4");
+ }
+ continue;
+ }
num = classify_argument (TYPE_MODE (TREE_TYPE (field)),
TREE_TYPE (field), subclasses,
(int_bit_position (field)