PowerPC: fix _Float128 type output string

PowerPC supports two 128-bit floating point formats, the IBM long double
and IEEE 128-bit float.  The issue is the DWARF information does not
distinguish between the two.  There have been proposals of how to extend
the DWARF information as discussed in

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104194

but has not been fully implemented.

GCC introduced the _Float128 internal type as a work around for the issue.
The workaround is not transparent to GDB.  The internal _Float128 type
name is printed rather then the user specified long double type.  This
patch adds a new gdbarch method to allow PowerPC to detect the GCC
workaround.  The workaround checks for "_Float128" name when reading the
base typedef from the die_info.  If the workaround is detected, the type
and format fields from the _Float128 typedef are copied to the long
double typedef.  The same is done for the complex long double typedef.

This patch fixes 74 regression test failures in
gdb.base/whatis-ptype-typedefs.exp on PowerPC with IEEE float 128 as the
default on GCC.  It fixes one regression test failure in
gdb.base/complex-parts.exp.

The patch has been tested on Power 10 where GCC defaults to IEEE Float
128-bit and on Power 10 where GCC defaults to the IBM 128-bit float.  The
patch as also been tested on X86-64 with no new regression failures.

1 files changed, 22 insertions, 0 deletions

diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 995f49e..9406458 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -114,6 +114,7 @@ struct gdbarch
   gdbarch_return_value_ftype *return_value = nullptr;
   gdbarch_return_value_as_value_ftype *return_value_as_value = default_gdbarch_return_value;
   gdbarch_get_return_buf_addr_ftype *get_return_buf_addr = default_get_return_buf_addr;
+  gdbarch_dwarf2_omit_typedef_p_ftype *dwarf2_omit_typedef_p = default_dwarf2_omit_typedef_p;
   gdbarch_return_in_first_hidden_param_p_ftype *return_in_first_hidden_param_p = default_return_in_first_hidden_param_p;
   gdbarch_skip_prologue_ftype *skip_prologue = nullptr;
   gdbarch_skip_main_prologue_ftype *skip_main_prologue = nullptr;
@@ -370,6 +371,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
   if ((gdbarch->return_value_as_value == default_gdbarch_return_value) == (gdbarch->return_value == nullptr))
     log.puts ("\n\treturn_value_as_value");
   /* Skip verify of get_return_buf_addr, invalid_p == 0 */
+  /* Skip verify of dwarf2_omit_typedef_p, invalid_p == 0 */
   /* Skip verify of return_in_first_hidden_param_p, invalid_p == 0 */
   if (gdbarch->skip_prologue == 0)
     log.puts ("\n\tskip_prologue");
@@ -789,6 +791,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
 	      "gdbarch_dump: get_return_buf_addr = <%s>\n",
 	      host_address_to_string (gdbarch->get_return_buf_addr));
   gdb_printf (file,
+	      "gdbarch_dump: dwarf2_omit_typedef_p = <%s>\n",
+	      host_address_to_string (gdbarch->dwarf2_omit_typedef_p));
+  gdb_printf (file,
 	      "gdbarch_dump: return_in_first_hidden_param_p = <%s>\n",
 	      host_address_to_string (gdbarch->return_in_first_hidden_param_p));
   gdb_printf (file,
@@ -2617,6 +2622,23 @@ set_gdbarch_get_return_buf_addr (struct gdbarch *gdbarch,
   gdbarch->get_return_buf_addr = get_return_buf_addr;
 }
 
+bool
+gdbarch_dwarf2_omit_typedef_p (struct gdbarch *gdbarch, struct type *target_type, const char *producer, const char *name)
+{
+  gdb_assert (gdbarch != NULL);
+  gdb_assert (gdbarch->dwarf2_omit_typedef_p != NULL);
+  if (gdbarch_debug >= 2)
+    gdb_printf (gdb_stdlog, "gdbarch_dwarf2_omit_typedef_p called\n");
+  return gdbarch->dwarf2_omit_typedef_p (target_type, producer, name);
+}
+
+void
+set_gdbarch_dwarf2_omit_typedef_p (struct gdbarch *gdbarch,
+				   gdbarch_dwarf2_omit_typedef_p_ftype dwarf2_omit_typedef_p)
+{
+  gdbarch->dwarf2_omit_typedef_p = dwarf2_omit_typedef_p;
+}
+
 int
 gdbarch_return_in_first_hidden_param_p (struct gdbarch *gdbarch, struct type *type)
 {