[PATCH 7/7] gdb: define builtin long type to be 64 bits on amd64 Cygwin

Simon Marchi
2020-03-16T17:08:54Z

From: Simon Marchi <simon.marchi@efficios.com>

On Windows x86-64 (when building with MinGW), the size of the "long"
type is 32 bits. amd64_windows_init_abi therefore does:

set_gdbarch_long_bit (gdbarch, 32);

This is also used when the chosen OS ABI is Cygwin, where the "long"
type is 64 bits. GDB therefore gets sizeof(long) wrong when using the
builtin long type:

$ ./gdb -nx --data-directory=data-directory -batch -ex "set architecture i386:x86-64" -ex "set osabi Cygwin" -ex "print sizeof(long)"
The target architecture is assumed to be i386:x86-64
$1 = 4

This patch makes GDB avoid setting the size of the long type to 32 bits
when using the Cygwin OS ABI. it will inherit the value set in
amd64_init_abi.

With this patch, I get:

$ ./gdb -nx --data-directory=data-directory -batch -ex "set architecture i386:x86-64" -ex "set osabi Cygwin" -ex "print sizeof(long)"
The target architecture is assumed to be i386:x86-64
$1 = 8

gdb/ChangeLog:

PR gdb/21500
* amd64-windows-tdep.c (amd64_windows_init_abi): Rename
to...
(amd64_windows_init_abi_common): ... this. Don't set size of
long type.
(amd64_windows_init_abi): New function.
(amd64_cygwin_init_abi): New function.
(_initialize_amd64_windows_tdep): Use amd64_cygwin_init_abi for
the Cygwin OS ABI.
* i386-windows-tdep.c (_initialize_i386_windows_tdep): Clarify
comment.
---
gdb/amd64-windows-tdep.c | 23 +++++++++++++++++------
gdb/i386-windows-tdep.c | 2 +-
2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/gdb/amd64-windows-tdep.c b/gdb/amd64-windows-tdep.c
index e0346f8628fe..6d5076d1c437 100644
--- a/gdb/amd64-windows-tdep.c
+++ b/gdb/amd64-windows-tdep.c
@@ -1209,7 +1209,7 @@ amd64_windows_auto_wide_charset (void)
}

static void
-amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+amd64_windows_init_abi_common (gdbarch_info info, struct gdbarch *gdbarch)
{
/* The dwarf2 unwinder (appended very early by i386_gdbarch_init) is
preferred over the SEH one. The reasons are:
@@ -1229,9 +1229,6 @@ amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)

windows_init_abi (info, gdbarch);

- /* On Windows, "long"s are only 32bit. */
- set_gdbarch_long_bit (gdbarch, 32);
-
/* Function calls. */
set_gdbarch_push_dummy_call (gdbarch, amd64_windows_push_dummy_call);
set_gdbarch_return_value (gdbarch, amd64_windows_return_value);
@@ -1244,6 +1241,21 @@ amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
set_gdbarch_auto_wide_charset (gdbarch, amd64_windows_auto_wide_charset);
}

+static void
+amd64_windows_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+ amd64_windows_init_abi_common (info, gdbarch);
+
+ /* On Windows, "long"s are only 32bit. */
+ set_gdbarch_long_bit (gdbarch, 32);
+}
+
+static void
+amd64_cygwin_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+ amd64_windows_init_abi_common (info, gdbarch);
+}
+
static gdb_osabi
amd64_windows_osabi_sniffer (bfd *abfd)
{
@@ -1262,11 +1274,10 @@ void _initialize_amd64_windows_tdep ();
void
_initialize_amd64_windows_tdep ()
{
- /* The Cygwin and Windows OS ABIs are currently equivalent. */
gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64, GDB_OSABI_WINDOWS,
amd64_windows_init_abi);
gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64, GDB_OSABI_CYGWIN,
- amd64_windows_init_abi);
+ amd64_cygwin_init_abi);

gdbarch_register_osabi_sniffer (bfd_arch_i386, bfd_target_coff_flavour,
amd64_windows_osabi_sniffer);
diff --git a/gdb/i386-windows-tdep.c b/gdb/i386-windows-tdep.c
index bd6107b02f1f..b26731c6bf28 100644
--- a/gdb/i386-windows-tdep.c
+++ b/gdb/i386-windows-tdep.c
@@ -270,7 +270,7 @@ _initialize_i386_windows_tdep ()
gdbarch_register_osabi_sniffer (bfd_arch_i386, bfd_target_elf_flavour,
i386_cygwin_core_osabi_sniffer);

- /* The Windows and Cygwin OS ABIs are currently equivalent. */
+ /* The Windows and Cygwin OS ABIs are currently equivalent on i386. */
gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_WINDOWS,
i386_windows_init_abi);
gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_CYGWIN,
--
2.25.1