gdb: LoongArch: Handle special struct in dummy call

When execute the following command on LoongArch:

  make check-gdb TESTS="gdb.base/infcall-nested-structs-c++.exp"

there exist some failed testcases:

  === gdb Summary ===

  # of expected passes		5533
  # of unexpected failures	367

The root cause is related with a struct containing floating-point
members as function argument or return value for a dummy call.

(1) Structure consists of one floating-point member within FRLEN bits
    wide, it is passed in an FAR if available.
(2) Structure consists of two floating-point members both within FRLEN
    bits wide, it is passed in two FARs if available.
(3) Structure consists of one integer member within GRLEN bits wide and
    one floating-point member within FRLEN bits wide, it is passed in a
    GAR and an FAR if available.

Note that in the above cases, empty structure or union members are also
ignored even in C++.

Here is a simple test on LoongArch:

  loongson@bogon:~$ cat test.c

  #include<stdio.h>

  struct test {
	  long   a;
	  double b __attribute__((aligned(16)));
  };
  struct test val = { 88, 99.99 };
  int check_arg_struct (struct test arg)
    {
      printf("arg.a = %ld\n", arg.a);
      printf("arg.b = %f\n", arg.b);
      printf("sizeof(val) = %d\n", sizeof(val));
      return 1;
    }
  int main()
  {
     check_arg_struct (val);
     return 0;
  }
  loongson@bogon:~$ gcc -g test.c -o test
  loongson@bogon:~$ ./test
  arg.a = 88
  arg.b = 99.990000
  sizeof(val) = 32

Before:

loongson@bogon:~$ gdb test
...
(gdb) start
...
Temporary breakpoint 1, main () at test.c:19
19	   check_arg_struct (val);
(gdb) p check_arg_struct (val)
arg.a = 140737488286128
arg.b = -nan
sizeof(val) = 32
$1 = 1
...

After:

loongson@bogon:~$ gdb test
...
(gdb) start
...
Temporary breakpoint 1, main () at test.c:19
19	   check_arg_struct (val);
(gdb) p check_arg_struct (val)
arg.a = 88
arg.b = 99.990000
sizeof(val) = 32
$1 = 1
...

With this patch, there are no failed testcases:

  make check-gdb TESTS="gdb.base/infcall-nested-structs-c++.exp"

   === gdb Summary ===

   # of expected passes		5900

Signed-off-by: Hui Li <lihui@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>

diff --git a/gdb/loongarch-tdep.c b/gdb/loongarch-tdep.c
index 62c6f9b220e439348a002682765250ce0abc4d89..c65e2414bf8a35b120498adb338983a73abe914f 100644 (file)
--- a/gdb/loongarch-tdep.c
+++ b/gdb/loongarch-tdep.c
@@ -516,7 +516,8 @@ static void
 compute_struct_member (struct type *type,
                       unsigned int *fixed_point_members,
                       unsigned int *floating_point_members,
-                      bool *first_member_is_fixed_point)
+                      bool *first_member_is_fixed_point,
+                      bool *has_long_double)
 {
   for (int i = 0; i < type->num_fields (); i++)
     {
@@ -526,6 +527,12 @@ compute_struct_member (struct type *type,
 
       struct type *field_type = check_typedef (type->field (i).type ());
 
+      if ((field_type->code () == TYPE_CODE_FLT
+          && field_type->length () == 16)
+         || (field_type->code () == TYPE_CODE_COMPLEX
+             && field_type->length () == 32))
+       *has_long_double = true;
+
       if (field_type->code () == TYPE_CODE_INT
          || field_type->code () == TYPE_CODE_BOOL
          || field_type->code () == TYPE_CODE_CHAR
@@ -544,12 +551,79 @@ compute_struct_member (struct type *type,
        compute_struct_member (field_type,
                               fixed_point_members,
                               floating_point_members,
-                              first_member_is_fixed_point);
+                              first_member_is_fixed_point,
+                              has_long_double);
       else if (field_type->code () == TYPE_CODE_COMPLEX)
        (*floating_point_members) += 2;
     }
 }
 
+/* Compute the lengths and offsets of struct member.  */
+
+static void
+struct_member_info (struct type *type,
+                   unsigned int *member_offsets,
+                   unsigned int *member_lens,
+                   unsigned int offset,
+                   unsigned int *fields)
+{
+  unsigned int count = type->num_fields ();
+  unsigned int i;
+
+  for (i = 0; i < count; ++i)
+    {
+      if (type->field (i).loc_kind () != FIELD_LOC_KIND_BITPOS)
+       continue;
+
+      struct type *field_type = check_typedef (type->field (i).type ());
+      int field_offset
+       = offset + type->field (i).loc_bitpos () / TARGET_CHAR_BIT;
+
+      switch (field_type->code ())
+       {
+       case TYPE_CODE_STRUCT:
+         struct_member_info (field_type, member_offsets, member_lens,
+                             field_offset, fields);
+         break;
+
+       case TYPE_CODE_COMPLEX:
+         if (*fields == 0)
+           {
+             /* _Complex float */
+             if (field_type->length () == 8)
+               {
+                 member_offsets[0] = field_offset;
+                 member_offsets[1] = field_offset + 4;
+                 member_lens[0] = member_lens[1] = 4;
+                 *fields = 2;
+               }
+             /* _Complex double */
+             else if (field_type->length () == 16)
+               {
+                 member_offsets[0] = field_offset;
+                 member_offsets[1] = field_offset + 8;
+                 member_lens[0] = member_lens[1] = 8;
+                 *fields = 2;
+               }
+           }
+         break;
+
+       default:
+         if (*fields < 2)
+           {
+             member_offsets[*fields] = field_offset;
+             member_lens[*fields] = field_type->length ();
+           }
+         (*fields)++;
+         break;
+       }
+
+      /* only has special handling for structures with 1 or 2 fields. */
+      if (*fields > 2)
+       return;
+    }
+}
+
 /* Implement the push_dummy_call gdbarch method.  */
 
 static CORE_ADDR
@@ -569,6 +643,10 @@ loongarch_push_dummy_call (struct gdbarch *gdbarch,
   unsigned int fixed_point_members;
   unsigned int floating_point_members;
   bool first_member_is_fixed_point;
+  bool has_long_double;
+  unsigned int member_offsets[2];
+  unsigned int member_lens[2];
+  unsigned int fields;
   gdb_byte buf[1024] = { 0 };
   gdb_byte *addr = buf;
 
@@ -698,12 +776,55 @@ loongarch_push_dummy_call (struct gdbarch *gdbarch,
            fixed_point_members = 0;
            floating_point_members = 0;
            first_member_is_fixed_point = false;
+           has_long_double = false;
+           member_offsets[0] = member_offsets[1] = 0;
+           member_lens[0] = member_offsets[1] = 0;
+           fields = 0;
            compute_struct_member (type,
                                   &fixed_point_members,
                                   &floating_point_members,
-                                  &first_member_is_fixed_point);
-
-           if (len > 0 && len <= regsize)
+                                  &first_member_is_fixed_point,
+                                  &has_long_double);
+           struct_member_info (type, member_offsets, member_lens, 0, &fields);
+           /* If the structure consists of one floating-point member within
+              FRLEN bits wide, it is passed in an FAR if available. If the
+              structure consists of two floating-point members both within
+              FRLEN bits wide, it is passed in two FARs if available. If the
+              structure consists of one integer member within GRLEN bits wide
+              and one floating-point member within FRLEN bits wide, it is
+              passed in a GAR and an FAR if available. */
+           if (has_long_double == false
+               && ((fixed_point_members == 0 && floating_point_members == 1
+                    && far >= 1)
+                   || (fixed_point_members == 0 && floating_point_members == 2
+                       && far >= 2)
+                   || (fixed_point_members == 1 && floating_point_members == 1
+                       && far >= 1 && gar >= 1)))
+             {
+               if (fixed_point_members == 0 && floating_point_members == 1)
+                 {
+                   pass_in_far (regcache, far--, val + member_offsets[0]);
+                 }
+               else if (fixed_point_members == 0 && floating_point_members == 2)
+                 {
+                   pass_in_far (regcache, far--, val + member_offsets[0]);
+                   pass_in_far (regcache, far--, val + member_offsets[1]);
+                 }
+               else if (fixed_point_members == 1 && floating_point_members == 1)
+                 {
+                   if (first_member_is_fixed_point == false)
+                     {
+                       pass_in_far (regcache, far--, val + member_offsets[0]);
+                       pass_in_gar (regcache, gar--, val + member_offsets[1]);
+                     }
+                   else
+                     {
+                       pass_in_gar (regcache, gar--, val + member_offsets[0]);
+                       pass_in_far (regcache, far--, val + member_offsets[1]);
+                     }
+                 }
+             }
+           else if (len > 0 && len <= regsize)
              {
                /* The structure has only fixed-point members.  */
                if (fixed_point_members > 0 && floating_point_members == 0)
@@ -1160,14 +1281,15 @@ loongarch_return_value (struct gdbarch *gdbarch, struct value *function,
   unsigned int fixed_point_members;
   unsigned int floating_point_members;
   bool first_member_is_fixed_point;
+  bool has_long_double;
+  unsigned int member_offsets[2];
+  unsigned int member_lens[2];
+  unsigned int fields;
   int a0 = LOONGARCH_A0_REGNUM;
   int a1 = LOONGARCH_A0_REGNUM + 1;
   int f0 = LOONGARCH_FIRST_FP_REGNUM;
   int f1 = LOONGARCH_FIRST_FP_REGNUM + 1;
 
-  if (len > 2 * regsize)
-    return RETURN_VALUE_STRUCT_CONVENTION;
-
   switch (code)
     {
     case TYPE_CODE_INT:
@@ -1220,12 +1342,56 @@ loongarch_return_value (struct gdbarch *gdbarch, struct value *function,
        fixed_point_members = 0;
        floating_point_members = 0;
        first_member_is_fixed_point = false;
+       has_long_double = false;
+       member_offsets[0] = member_offsets[1] = 0;
+       member_lens[0] = member_offsets[1] = 0;
+       fields = 0;
        compute_struct_member (type,
                               &fixed_point_members,
                               &floating_point_members,
-                              &first_member_is_fixed_point);
-
-       if (len > 0 && len <= regsize)
+                              &first_member_is_fixed_point,
+                              &has_long_double);
+       struct_member_info (type, member_offsets, member_lens, 0, &fields);
+       /* struct consists of one floating-point member;
+          struct consists of two floating-point members;
+          struct consists of one floating-point member
+          and one integer member. */
+       if (has_long_double == false
+           && ((fixed_point_members == 0 && floating_point_members == 1)
+               || (fixed_point_members == 0 && floating_point_members == 2)
+               || (fixed_point_members == 1 && floating_point_members == 1)))
+         {
+           if (fixed_point_members == 0 && floating_point_members == 1)
+             {
+               loongarch_xfer_reg (regcache, f0, member_lens[0], readbuf,
+                                   writebuf, member_offsets[0]);
+             }
+           else if (fixed_point_members == 0 && floating_point_members == 2)
+             {
+               loongarch_xfer_reg (regcache, f0, member_lens[0], readbuf,
+                                   writebuf, member_offsets[0]);
+               loongarch_xfer_reg (regcache, f1, member_lens[1], readbuf,
+                                   writebuf, member_offsets[1]);
+             }
+           else if (fixed_point_members == 1 && floating_point_members == 1)
+             {
+               if (first_member_is_fixed_point == false)
+                 {
+                   loongarch_xfer_reg (regcache, f0, member_lens[0], readbuf,
+                                       writebuf, member_offsets[0]);
+                   loongarch_xfer_reg (regcache, a0, member_lens[1], readbuf,
+                                       writebuf, member_offsets[1]);
+                 }
+               else
+                 {
+                   loongarch_xfer_reg (regcache, a0, member_lens[0], readbuf,
+                                       writebuf, member_offsets[0]);
+                   loongarch_xfer_reg (regcache, f0, member_lens[1], readbuf,
+                                       writebuf, member_offsets[1]);
+                 }
+             }
+         }
+       else if (len > 0 && len <= regsize)
          {
            /* The structure has only fixed-point members.  */
            if (fixed_point_members > 0 && floating_point_members == 0)
@@ -1338,6 +1504,8 @@ loongarch_return_value (struct gdbarch *gdbarch, struct value *function,
                  }
              }
          }
+       else if (len > 2 * regsize)
+         return RETURN_VALUE_STRUCT_CONVENTION;
       }
       break;
     case TYPE_CODE_UNION:
@@ -1352,13 +1520,18 @@ loongarch_return_value (struct gdbarch *gdbarch, struct value *function,
          loongarch_xfer_reg (regcache, a0, regsize, readbuf, writebuf, 0);
          loongarch_xfer_reg (regcache, a1, len - regsize, readbuf, writebuf, regsize);
        }
+      else if (len > 2 * regsize)
+       return RETURN_VALUE_STRUCT_CONVENTION;
       break;
     case TYPE_CODE_COMPLEX:
-      {
-       /* The return value is passed in f0 and f1.  */
-       loongarch_xfer_reg (regcache, f0, len / 2, readbuf, writebuf, 0);
-       loongarch_xfer_reg (regcache, f1, len / 2, readbuf, writebuf, len / 2);
-      }
+      if (len > 0 && len <= 2 * regsize)
+       {
+         /* The return value is passed in f0 and f1.  */
+         loongarch_xfer_reg (regcache, f0, len / 2, readbuf, writebuf, 0);
+         loongarch_xfer_reg (regcache, f1, len / 2, readbuf, writebuf, len / 2);
+       }
+      else if (len > 2 * regsize)
+       return RETURN_VALUE_STRUCT_CONVENTION;
       break;
     default:
       break;