[Bug d/30576] New: "Too few arguments in function call." when trying to print function return values bigger than 16 bytes

[Bug d/30576] New: "Too few arguments in function call." when trying to print function return values bigger than 16 bytes

[sourceware at cy dot md]

https://sourceware.org/bugzilla/show_bug.cgi?id=30576

            Bug ID: 30576
           Summary: "Too few arguments in function call." when trying to
                    print function return values bigger than 16 bytes
           Product: gdb
           Version: 13.1
            Status: UNCONFIRMED
          Severity: minor
          Priority: P2
         Component: d
          Assignee: unassigned at sourceware dot org
          Reporter: sourceware at cy dot md
                CC: ibuclaw at gdcproject dot org
  Target Milestone: ---

If an extern(C) function in a D program has a return value larger than 16
bytes, trying to call it and print its return value from gdb results in the
error message "Too few arguments in function call.".

Reproducer:

cat > bug.d <<EOF
extern(C) auto a() { return (ubyte[16]).init; }
extern(C) auto b() { return (ubyte[17]).init; }
void main(){}
EOF

dmd -g bug

gdb -ex start \
        -ex 'echo === a() ===\n' \
        -ex 'p a()' \
        -ex 'echo === b() ===\n' \
        -ex 'p b()' \
        -ex 'stop' \
        -ex 'quit' \
        ./bug

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[Bug d/30576] "Too few arguments in function call." when trying to print function return values bigger than 16 bytes

[liushuyu011 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30576

liushuyu <liushuyu011 at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |liushuyu011 at gmail dot com

--- Comment #1 from liushuyu <liushuyu011 at gmail dot com> ---
I think this has been fixed (I am using GDB 15):

gdb --batch -x bug.gdb ./bug1                                                   

Temporary breakpoint 1 at 0x251ea: file bug.d, line 3.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".

Temporary breakpoint 1, D main () at bug.d:3
3       void main(){}
=== a() ===
$1 = '\000' <repeats 15 times>
=== b() ===
$2 = '\000' <repeats 16 times>
A debugging session is active.

        Inferior 1 [process 681157] will be killed.

Quit anyway? (y or n) [answered Y; input not from terminal]

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[Bug d/30576] "Too few arguments in function call." when trying to print function return values bigger than 16 bytes

[sourceware at cy dot md]

https://sourceware.org/bugzilla/show_bug.cgi?id=30576

--- Comment #2 from Vladimir Panteleev <sourceware at cy dot md> ---
It still happens here. GDB 15.1, DMD v2.109.1.

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[Bug d/30576] "Too few arguments in function call." when trying to print function return values bigger than 16 bytes

[liushuyu011 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30576

--- Comment #3 from liushuyu <liushuyu011 at gmail dot com> ---
(In reply to Vladimir Panteleev from comment #2)
> It still happens here. GDB 15.1, DMD v2.109.1.

Oh, I see now, you were using the DMD compiler.

After some investigations, I think it's a DMD bug. Here's the DWARF dump of the
function bug.b():

0x000000a9:   DW_TAG_subprogram
                DW_AT_sibling   (0x000000e7)
                DW_AT_MIPS_linkage_name ("b")
                DW_AT_type      (0x00000095 "ubyte[17]")
                DW_AT_external  (0x01)
                DW_AT_pure      (0x01)
                DW_AT_name      ("bug.b")
                DW_AT_decl_file ("/tmp/./bug.d")
                DW_AT_decl_line (2)
                DW_AT_decl_column       (16)
                DW_AT_low_pc    (0x0000000000042728)
                DW_AT_high_pc   (0x0000000000042754)
                DW_AT_frame_base        (0x0000004c:
                   [0x0000000000042728, 0x0000000000042729): DW_OP_breg7 RSP+8
                   [0x0000000000042729, 0x000000000004272b): DW_OP_breg7 RSP+16
                   [0x000000000004272b, 0x0000000000042754): DW_OP_breg6
RBP+16)

0x000000d3:     DW_TAG_formal_parameter
                  DW_AT_name    ("__HID1")
                  DW_AT_type    (0x000000a4 "ubyte (*)[17]")
                  DW_AT_artificial      (0x00)
                  DW_AT_decl_file       ("/tmp/./bug.d")
                  DW_AT_decl_line       (0)
                  DW_AT_decl_column     (0)
                  DW_AT_location        (DW_OP_fbreg -24)

It seems like DMD accidentally included the stack return argument in the debug
data, which is incorrect (according to the DWARF v5 spec,
DW_TAG_formal_parameter is only valid for parameters passing into the function,
not return values).

If the DWARF dump looks abstract, basically, the debug information describes
the function as:

extern(C) ubyte[17] b(ubyte[17] __HID1);

So GDB thought you should pass something to the function.

In contrast, the GDC compiler wrote the debug information like this:

0x00000184:   DW_TAG_subprogram
                DW_AT_external  (true)
                DW_AT_name      ("b")
                DW_AT_decl_file ("/tmp/bug.d")
                DW_AT_decl_line (2)
                DW_AT_decl_column       (16)
                DW_AT_type      (0x00000166 "ubyte[17]")
                DW_AT_low_pc    (0x00000000000251c9)
                DW_AT_high_pc   (0x00000000000251e6)
                DW_AT_frame_base        (DW_OP_call_frame_cfa)
                DW_AT_call_all_calls    (true)

Which is the correct definition for your bug.b function.

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[Bug d/30576] "Too few arguments in function call." when trying to print function return values bigger than 16 bytes

[liushuyu011 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30576

--- Comment #4 from liushuyu <liushuyu011 at gmail dot com> ---
(In reply to liushuyu from comment #3)
> (In reply to Vladimir Panteleev from comment #2)
> > It still happens here. GDB 15.1, DMD v2.109.1.
> 
> Oh, I see now, you were using the DMD compiler.
> 
> After some investigations, I think it's a DMD bug. Here's the DWARF dump of
> the function bug.b():
> 
> 0x000000a9:   DW_TAG_subprogram
>                 DW_AT_sibling   (0x000000e7)
>                 DW_AT_MIPS_linkage_name ("b")
>                 DW_AT_type      (0x00000095 "ubyte[17]")
>                 DW_AT_external  (0x01)
>                 DW_AT_pure      (0x01)
>                 DW_AT_name      ("bug.b")
>                 DW_AT_decl_file ("/tmp/./bug.d")
>                 DW_AT_decl_line (2)
>                 DW_AT_decl_column       (16)
>                 DW_AT_low_pc    (0x0000000000042728)
>                 DW_AT_high_pc   (0x0000000000042754)
>                 DW_AT_frame_base        (0x0000004c:
>                    [0x0000000000042728, 0x0000000000042729): DW_OP_breg7
> RSP+8
>                    [0x0000000000042729, 0x000000000004272b): DW_OP_breg7
> RSP+16
>                    [0x000000000004272b, 0x0000000000042754): DW_OP_breg6
> RBP+16)
> 
> 0x000000d3:     DW_TAG_formal_parameter
>                   DW_AT_name    ("__HID1")
>                   DW_AT_type    (0x000000a4 "ubyte (*)[17]")
>                   DW_AT_artificial      (0x00)
>                   DW_AT_decl_file       ("/tmp/./bug.d")
>                   DW_AT_decl_line       (0)
>                   DW_AT_decl_column     (0)
>                   DW_AT_location        (DW_OP_fbreg -24)
> 
> It seems like DMD accidentally included the stack return argument in the
> debug data, which is incorrect (according to the DWARF v5 spec,
> DW_TAG_formal_parameter is only valid for parameters passing into the
> function, not implicit return values defined by ABI).
> 
> If the DWARF dump looks abstract the debug information describes
> the function as:
> 
> extern(C) ubyte[17] b(ubyte[17] __HID1);
> 
> So GDB thought you should pass something to the function.
> 
> In contrast, the GDC compiler wrote the debug information like this:
> 
> 0x00000184:   DW_TAG_subprogram
>                 DW_AT_external  (true)
>                 DW_AT_name      ("b")
>                 DW_AT_decl_file ("/tmp/bug.d")
>                 DW_AT_decl_line (2)
>                 DW_AT_decl_column       (16)
>                 DW_AT_type      (0x00000166 "ubyte[17]")
>                 DW_AT_low_pc    (0x00000000000251c9)
>                 DW_AT_high_pc   (0x00000000000251e6)
>                 DW_AT_frame_base        (DW_OP_call_frame_cfa)
>                 DW_AT_call_all_calls    (true)
> 
> Which is the correct definition for your bug.b function.

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[Bug d/30576] "Too few arguments in function call." when trying to print function return values bigger than 16 bytes

[sourceware at cy dot md]

https://sourceware.org/bugzilla/show_bug.cgi?id=30576

Vladimir Panteleev <sourceware at cy dot md> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |NOTABUG

--- Comment #5 from Vladimir Panteleev <sourceware at cy dot md> ---
Thank you, DMD bug filed: https://issues.dlang.org/show_bug.cgi?id=24888

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[Bug d/30576] "Too few arguments in function call." when trying to print function return values bigger than 16 bytes

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=30576

Sam James <sam at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://issues.dlang.org/sh
                   |                            |ow_bug.cgi?id=24888

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