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Fix passing of struct with bitfields on x86-64

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Commit 4aa866af ("Fix AMD64 return value ABI in expression
evaluation") introduced a regression when calling a function with a
structure that contains bitfields.

Because the caller of amd64_has_unaligned_fields handles bitfields
already, it seemed to me that the simplest fix was to ignore bitfields
here.

gdb/ChangeLog
2019-04-24  Tom Tromey  <tromey@adacore.com>

	* amd64-tdep.c (amd64_has_unaligned_fields): Ignore bitfields.

gdb/testsuite/ChangeLog
2019-04-24  Tom Tromey  <tromey@adacore.com>

	* gdb.arch/amd64-eval.exp: Test bitfield return.
	* gdb.arch/amd64-eval.cc (struct Bitfields): New.
	(class Foo) <return_bitfields>: New method.
	(main): Call it.
This commit is contained in:
Tom Tromey 2019-04-16 11:11:10 -06:00
parent 1b8dd64326
commit a59240a41a
5 changed files with 37 additions and 4 deletions
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4
gdb/ChangeLog
View file

@ -1,3 +1,7 @@
2019-04-24 Tom Tromey <tromey@adacore.com>
* amd64-tdep.c (amd64_has_unaligned_fields): Ignore bitfields.
2019-04-23 Andrew Burgess <andrew.burgess@embecosm.com>
* s12z-tdep.c (s12z_unwind_pc): Delete.

10
gdb/amd64-tdep.c
View file

@ -555,11 +555,13 @@ amd64_has_unaligned_fields (struct type *type)
int bitpos = TYPE_FIELD_BITPOS (type, i);
int align = type_align(subtype);
/* Ignore static fields, or empty fields, for example nested
empty structures. */
/* Ignore static fields, empty fields (for example nested
empty structures), and bitfields (these are handled by
the caller). */
if (field_is_static (&TYPE_FIELD (type, i))
|| (TYPE_FIELD_BITSIZE (type, i) == 0
&& TYPE_LENGTH (subtype) == 0))
&& TYPE_LENGTH (subtype) == 0)
|| TYPE_FIELD_PACKED (type, i))
continue;
if (bitpos % 8 != 0)
@ -569,7 +571,7 @@ amd64_has_unaligned_fields (struct type *type)
if (bytepos % align != 0)
return true;
if (amd64_has_unaligned_fields(subtype))
if (amd64_has_unaligned_fields (subtype))
return true;
}
}

7
gdb/testsuite/ChangeLog
View file

@ -1,3 +1,10 @@
2019-04-24 Tom Tromey <tromey@adacore.com>
* gdb.arch/amd64-eval.exp: Test bitfield return.
* gdb.arch/amd64-eval.cc (struct Bitfields): New.
(class Foo) <return_bitfields>: New method.
(main): Call it.
2019-04-23 Andrew Burgess <andrew.burgess@embecosm.com>
* gdb.cp/many-args.cc: New file.

18
gdb/testsuite/gdb.arch/amd64-eval.cc
View file

@ -63,6 +63,16 @@ struct UnalignedFieldsInBase : public UnalignedFields
int32_t x2;
};
struct Bitfields
{
Bitfields(unsigned int x, unsigned int y)
: fld(x), fld2(y)
{}
unsigned fld : 7;
unsigned fld2 : 7;
};
class Foo
{
public:
@ -101,6 +111,13 @@ public:
return UnalignedFieldsInBase (x, y, x2);
}
Bitfields
return_bitfields (unsigned int x, unsigned int y)
{
assert (this->tag == EXPECTED_TAG);
return Bitfields(x, y);
}
private:
/* Use a tag to detect if the "this" value is correct. */
static const int EXPECTED_TAG = 0xF00F00F0;
@ -116,5 +133,6 @@ main (int argc, char *argv[])
foo.return_non_trivial_destructor(3);
foo.return_unaligned(4, 5);
foo.return_unaligned_in_base(6, 7, 8);
foo.return_bitfields(23, 74);
return 0; // break-here
}

2
gdb/testsuite/gdb.arch/amd64-eval.exp
View file

@ -41,3 +41,5 @@ gdb_test "call foo.return_unaligned(78, 9.25)" \
" = {x = 78, y = 9.25}"
gdb_test "call foo.return_unaligned_in_base(23, 4.5, 67)" \
" = {<UnalignedFields> = {x = 23, y = 4.5}, x2 = 67}"
gdb_test "call foo.return_bitfields(23, 74)" \
" = {fld = 23, fld2 = 74}"