gdb: mips: Fix the handling of complex type of function return value
$ objdump -d outputs/gdb.base/varargs/varargs
00000001200012e8 <find_max_float_real>:
...
1200013b8: c7c10000 lwc1 $f1,0(s8)
1200013bc: c7c00004 lwc1 $f0,4(s8)
1200013c0: 46000886 mov.s $f2,$f1
1200013c4: 46000046 mov.s $f1,$f0
1200013c8: 46001006 mov.s $f0,$f2
1200013cc: 46000886 mov.s $f2,$f1
1200013d0: 03c0e825 move sp,s8
1200013d4: dfbe0038 ld s8,56(sp)
1200013d8: 67bd0080 daddiu sp,sp,128
1200013dc: 03e00008 jr ra
1200013e0: 00000000 nop
From the above disassembly, we can see that when the return value of the
function is a complex type and len <= 2 * MIPS64_REGSIZE, the return value
will be passed through $f0 and $f2, so fix the corresponding processing
in mips_n32n64_return_value().
$ make check RUNTESTFLAGS='GDB=../gdb gdb.base/varargs.exp --outdir=test'
Before applying the patch:
FAIL: gdb.base/varargs.exp: print find_max_float_real(4, fc1, fc2, fc3, fc4)
FAIL: gdb.base/varargs.exp: print find_max_double_real(4, dc1, dc2, dc3, dc4)
# of expected passes 9
# of unexpected failures 2
After applying the patch:
# of expected passes 11
This also fixes:
FAIL: gdb.base/callfuncs.exp: call inferior func with struct - returns float _Complex
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Co-Authored-By: Maciej W. Rozycki <macro@orcam.me.uk>
diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index 9394589..4bdbf0f 100644
--- a/gdb/mips-tdep.c
+++ b/gdb/mips-tdep.c
@@ -5217,30 +5217,44 @@ mips_n32n64_return_value (struct gdbarch *gdbarch, struct value *function,
that all composite results be handled by conversion to implicit first
parameters. The MIPS/SGI Fortran implementation has always made a
specific exception to return COMPLEX results in the floating point
- registers.] */
+ registers.]
+
+ From MIPSpro Assembly Language Programmer's Guide, Document Number:
+ 007-2418-004
+
+ Software
+ Register Name(from
+ Name fgregdef.h) Use and Linkage
+ -----------------------------------------------------------------
+ $f0, $f2 fv0, fv1 Hold results of floating-point type function
+ ($f0) and complex type function ($f0 has the
+ real part, $f2 has the imaginary part.) */
if (TYPE_LENGTH (type) > 2 * MIPS64_REGSIZE)
return RETURN_VALUE_STRUCT_CONVENTION;
- else if (type->code () == TYPE_CODE_FLT
- && TYPE_LENGTH (type) == 16
+ else if ((type->code () == TYPE_CODE_COMPLEX
+ || (type->code () == TYPE_CODE_FLT && TYPE_LENGTH (type) == 16))
&& tdep->mips_fpu_type != MIPS_FPU_NONE)
{
- /* A 128-bit floating-point value fills both $f0 and $f2. The
- two registers are used in the same as memory order, so the
- eight bytes with the lower memory address are in $f0. */
+ /* A complex value of up to 128 bits in width as well as a 128-bit
+ floating-point value goes in both $f0 and $f2. A single complex
+ value is held in the lower halves only of the respective registers.
+ The two registers are used in the same as memory order, so the
+ bytes with the lower memory address are in $f0. */
if (mips_debug)
gdb_printf (gdb_stderr, "Return float in $f0 and $f2\n");
mips_xfer_register (gdbarch, regcache,
(gdbarch_num_regs (gdbarch)
+ mips_regnum (gdbarch)->fp0),
- 8, gdbarch_byte_order (gdbarch),
+ TYPE_LENGTH (type) / 2, gdbarch_byte_order (gdbarch),
readbuf, writebuf, 0);
mips_xfer_register (gdbarch, regcache,
(gdbarch_num_regs (gdbarch)
+ mips_regnum (gdbarch)->fp0 + 2),
- 8, gdbarch_byte_order (gdbarch),
- readbuf ? readbuf + 8 : readbuf,
- writebuf ? writebuf + 8 : writebuf, 0);
+ TYPE_LENGTH (type) / 2, gdbarch_byte_order (gdbarch),
+ readbuf ? readbuf + TYPE_LENGTH (type) / 2 : readbuf,
+ (writebuf
+ ? writebuf + TYPE_LENGTH (type) / 2 : writebuf), 0);
return RETURN_VALUE_REGISTER_CONVENTION;
}
else if (type->code () == TYPE_CODE_FLT
