[Bug debug/96937] New: Duplicate DW_TAG_formal_parameter in out-of-line DW_TAG_subprogram instance

[Bug debug/96937] New: Duplicate DW_TAG_formal_parameter in out-of-line DW_TAG_subprogram instance

[simon.marchi at polymtl dot ca]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96937

            Bug ID: 96937
           Summary: Duplicate DW_TAG_formal_parameter in out-of-line
                    DW_TAG_subprogram instance
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: simon.marchi at polymtl dot ca
  Target Milestone: ---

While debugging GDB (compiled with GCC master and -O2) with GDB, I get:

972     do_examine (struct format_data fmt, struct gdbarch *gdbarch, CORE_ADDR
addr)
(top-gdb) frame
#0  do_examine (gdbarch=0x249a6b0, addr=0x400636, fmt=..., fmt=...) at
/home/smarchi/src/binutils-gdb/gdb/printcmd.c:972
972     do_examine (struct format_data fmt, struct gdbarch *gdbarch, CORE_ADDR
addr)

Note that the parameters shown by GDB aren't in the same order as in the
function declaration, and that "fmt" is duplicated.

0x0004e0bd:   DW_TAG_subprogram
                DW_AT_abstract_origin [DW_FORM_ref4]    (0x0004a912
"do_examine")
                ...

0x0004e0cd:     DW_TAG_formal_parameter
                  DW_AT_abstract_origin [DW_FORM_ref4]  (0x0004a92e "gdbarch")
                  ...

0x0004e0d6:     DW_TAG_formal_parameter
                  DW_AT_abstract_origin [DW_FORM_ref4]  (0x0004a93b "addr")
                  ...

0x0004e0df:     DW_TAG_variable
                  DW_AT_abstract_origin [DW_FORM_ref4]  (0x0004a948 "format")
                  ...

0x0004e0e8:     DW_TAG_variable
                  DW_AT_abstract_origin [DW_FORM_ref4]  (0x0004a955 "size")
                  ...

... some more variables ...


0x0004e130:     DW_TAG_formal_parameter
                  DW_AT_abstract_origin [DW_FORM_ref4]  (0x0004a921 "fmt")

0x0004e135:     DW_TAG_formal_parameter
                  DW_AT_abstract_origin [DW_FORM_ref4]  (0x0004a921 "fmt")


This matches what we see in GDB: the parameters are not in the same order as in
the function declaration and fmt is duplicated.  The abstract origin has them
correct:

0x0004a912:   DW_TAG_subprogram
                DW_AT_name [DW_FORM_strp]       ("do_examine")
                ...

0x0004a921:     DW_TAG_formal_parameter
                  DW_AT_name [DW_FORM_string]   ("fmt")
                  ...

0x0004a92e:     DW_TAG_formal_parameter
                  DW_AT_name [DW_FORM_strp]     ("gdbarch")
                  ...

0x0004a93b:     DW_TAG_formal_parameter
                  DW_AT_name [DW_FORM_strp]     ("addr")
                  ...

After reading bug #49828, I presume that the fact that the parameters are not
in the right order is not considered a bug.  GDB could cope with that by
sorting them to be in the same order as what's in the abstract origin.

However, having fmt there twice could maybe be considered a bug, hence I am
reporting it.

GDB commit (used as the debugged program):
c5cd900e4f197870812c2d3e2c194871c171ef42
GCC commit: 8ad3fc6ca46c603d9c3efe8e6d4a8f2ff1a893a4

[Bug debug/96937] Duplicate DW_TAG_formal_parameter in out-of-line DW_TAG_subprogram instance

[simon.marchi at polymtl dot ca]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96937

--- Comment #1 from Simon Marchi <simon.marchi at polymtl dot ca> ---
I passed the program in creduce, the result is not pretty but it's not too big
and still reproduces the problem, so I'll attach it anyway.

[Bug debug/96937] Duplicate DW_TAG_formal_parameter in out-of-line DW_TAG_subprogram instance

[simon.marchi at polymtl dot ca]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96937

--- Comment #2 from Simon Marchi <simon.marchi at polymtl dot ca> ---
Created attachment 49181
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49181&action=edit
Output from creduce

I compile the reproducer program with:

/opt/gcc/git/bin/g++ -x c++ -g3 -O2 -c bug.c

[Bug debug/96937] Duplicate DW_TAG_formal_parameter in out-of-line DW_TAG_subprogram instance

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96937

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu.org
   Last reconfirmed|                            |2020-09-07
             Status|UNCONFIRMED                 |WAITING
     Ever confirmed|0                           |1

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm, can you point out the issue in the reduced testcase?  I can't see it.  The
only cloning done I see is partial inlining so does -fno-partial-inlining fix
the issue for you?

[Bug debug/96937] Duplicate DW_TAG_formal_parameter in out-of-line DW_TAG_subprogram instance

[simon.marchi at polymtl dot ca]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96937

--- Comment #4 from Simon Marchi <simon.marchi at polymtl dot ca> ---
Created attachment 49198
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49198&action=edit
Output from creduce

[Bug debug/96937] Duplicate DW_TAG_formal_parameter in out-of-line DW_TAG_subprogram instance

[simon.marchi at polymtl dot ca]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96937

--- Comment #5 from Simon Marchi <simon.marchi at polymtl dot ca> ---
(In reply to Richard Biener from comment #3)
> Hmm, can you point out the issue in the reduced testcase?  I can't see it. 
> The only cloning done I see is partial inlining so does
> -fno-partial-inlining fix the issue for you?

Doh, I indeed uploaded the wrong thing.  My creduce test was trying to
reproduce the "wrong parameter order" problem, which I later found was probably
not considered a bug, instead of the "duplicate parameter problem".  I re-ran
it with the right test, I attached the result.

The relevant portion of the DWARF is:

0x000003bb:   DW_TAG_subprogram
                DW_AT_abstract_origin   (0x00000383 "do_examine")
                DW_AT_low_pc    (0x0000000000000000)
                DW_AT_high_pc   (0x0000000000000039)
                DW_AT_frame_base        (DW_OP_call_frame_cfa)
                DW_AT_GNU_all_call_sites        (true)
                DW_AT_sibling   (0x00000464)

0x000003d6:     DW_TAG_variable
                  DW_AT_abstract_origin (0x000003a4 "ai")

0x000003db:     DW_TAG_variable
                  DW_AT_abstract_origin (0x000003af "aq")
                  DW_AT_location        (DW_OP_fbreg -17)

0x000003e3:     DW_TAG_formal_parameter
                  DW_AT_abstract_origin (0x0000039f)
                  DW_AT_location        (<decoding error> 9f 03 00 00 9f)

0x000003ef:     DW_TAG_formal_parameter
                  DW_AT_abstract_origin (0x0000039a)
                  DW_AT_location        (<decoding error> 9a 03 00 00 9f)

0x000003fb:     DW_TAG_formal_parameter
                  DW_AT_abstract_origin (0x00000390 "y")

0x00000400:     DW_TAG_formal_parameter
                  DW_AT_abstract_origin (0x00000390 "y")

The last two DW_TAG_formal_parameter refer to the same parameter.

[Bug debug/96937] Duplicate DW_TAG_formal_parameter in out-of-line DW_TAG_subprogram instance

[wcohen at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96937

Will Cohen <wcohen at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |wcohen at redhat dot com

--- Comment #6 from Will Cohen <wcohen at redhat dot com> ---
I have similar duplications of formal parameters in some of the code compiled
linux kernel code.  I had a dwgrep (https://pmachata.github.io/dwgrep/) that
would print out each function and location with more formal parameters than
listed in the abstract origin:

 dwgrep vmlinux  -e '
let A := entry (?TAG_subprogram) !AT_declaration;
let FSTART := ((A ?AT_entry_pc @AT_entry_pc) || (A ?AT_ranges @AT_ranges low)
|| ( A low));
let B := [A child ?TAG_formal_parameter name] ;
let ABS_ORIGIN := A @AT_abstract_origin;
let C := [ABS_ORIGIN child ?TAG_formal_parameter name];
(C length != B length) B C A name FSTART'

Looking through the functions flagged I found match_id in
/arch/x86/kernel/probe_roms.c looked small and could be a starting point for a
reproducer (two pdev formal parameters):

0xffffffff8102eec0
match_id
["pdev", "vendor", "device"]
["vendor", "device", "pdev", "pdev"]
<Dwarf "vmlinux">

The  "llvm-dwarfdump -c --name=match_id vmlinux" show the duplicate pdev formal
parameters in its output:

0x005741ea: DW_TAG_subprogram
              DW_AT_abstract_origin     (0x00574134 "match_id")
              DW_AT_low_pc      (0xffffffff8102eec0)
              DW_AT_high_pc     (0xffffffff8102ef1a)
              DW_AT_frame_base  (DW_OP_call_frame_cfa)
              DW_AT_call_all_calls      (true)
              DW_AT_sibling     (0x00574291)

0x00574206:   DW_TAG_formal_parameter
                DW_AT_abstract_origin   (0x00574151 "vendor")
                DW_AT_location  (0x0006ebe0: 
                   [0xffffffff8102eec0, 0xffffffff8102eee0): DW_OP_reg2 RCX
                   [0xffffffff8102eee0, 0xffffffff8102ef1a): DW_OP_reg4 RSI)
                DW_AT_GNU_entry_view    (0x0006ebdc)

0x00574213:   DW_TAG_formal_parameter
                DW_AT_abstract_origin   (0x0057415d "device")
                DW_AT_location  (DW_OP_reg8 R8)

0x0057421b:   DW_TAG_variable
                DW_AT_abstract_origin   (0x00574169 "drv")
                DW_AT_location  (0x0006ebf6: 
                   [0xffffffff8102eeeb, 0xffffffff8102eeff): DW_OP_reg2 RCX)
                DW_AT_GNU_entry_view    (0x0006ebf4)

0x00574228:   DW_TAG_variable
                DW_AT_abstract_origin   (0x00574174 "id")
                DW_AT_location  (0x0006ec09: 
                   [0xffffffff8102eef8, 0xffffffff8102eeff): DW_OP_reg1 RDX
                   [0xffffffff8102eeff, 0xffffffff8102ef03): DW_OP_breg1
RDX+40, DW_OP_stack_value
                   [0xffffffff8102ef03, 0xffffffff8102ef19): DW_OP_reg1 RDX)
                DW_AT_GNU_entry_view    (0x0006ec03)

0x00574235:   DW_TAG_formal_parameter
                DW_AT_abstract_origin   (0x00574145 "pdev")
                DW_AT_location  (0x0006ec26: 
                   [0xffffffff8102eec0, 0xffffffff8102ef1a): <decoding error>
fa c7 cc 00 00 9f)
                DW_AT_GNU_entry_view    (0x0006ec24)

0x00574242:   DW_TAG_formal_parameter
                DW_AT_abstract_origin   (0x00574145 "pdev")

The probe_rom.i file was used a a starting point to create a smaller reproducer
with creduce which can be compiled with:

gcc  -Wp,-MMD,arch/x86/kernel/.probe_roms.o.d -nostdinc -D__KERNEL__
-fmacro-pre
fix-map=./= -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs
-fno-strict-a
liasing -fno-common -fshort-wchar -fno-PIE
-Werror=implicit-function-declaration
 -Werror=implicit-int -Werror=return-type -Wno-format-security -std=gnu89
-mno-s
se -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -fcf-protection=none -m64
-falign-jump
s=1 -falign-loops=1 -mno-80387 -mno-fp-ret-in-387 -mpreferred-stack-boundary=3
-
mskip-rax-setup -mtune=generic -mno-red-zone -mcmodel=kernel -Wno-sign-compare
-
fno-asynchronous-unwind-tables -mindirect-branch=thunk-extern
-mindirect-branch-
register -fno-jump-tables -fno-delete-null-pointer-checks -Wno-frame-address
-Wn
o-format-truncation -Wno-format-overflow -Wno-address-of-packed-member -O2
-fno-
allow-store-data-races -Wframe-larger-than=2048 -fstack-protector-strong
"-Wimpl
icit-fallthrough=5" -Wno-main -Wno-unused-but-set-variable
-Wno-unused-const-var
iable -fno-stack-clash-protection -pg -mrecord-mcount -mfentry
-DCC_USING_FENTRY
 -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -Wno-stringop-truncation 
-Wno-zero-length-bounds -Wno-array-bounds -Wno-stringop-overflow -Wno-restrict
-
Wno-maybe-uninitialized -Wno-alloc-size-larger-than -fno-strict-overflow
-fno-st
ack-check -fconserve-stack -Werror=date-time -Werror=incompatible-pointer-types 
-Werror=designated-init -Wno-packed-not-aligned -g   
-DKBUILD_MODFILE='"arch/x8
6/kernel/probe_roms"' -DKBUILD_BASENAME='"probe_roms"'
-DKBUILD_MODNAME='"probe_
roms"' -D__KBUILD_MODNAME=kmod_probe_roms -c -o probe_roms.o probe_roms.i

[Bug debug/96937] Duplicate DW_TAG_formal_parameter in out-of-line DW_TAG_subprogram instance

[wcohen at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96937

--- Comment #7 from Will Cohen <wcohen at redhat dot com> ---
Created attachment 51963
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51963&action=edit
Reproducer showing duplicate formal parameters from kernel probe_rom.i

Compiled with following to generate probe_rom.o with duplicate k formal
parameters in the debuginfo:

gcc  -Wp,-MMD,arch/x86/kernel/.probe_roms.o.d -nostdinc -D__KERNEL__
-fmacro-pre
fix-map=./= -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs
-fno-strict-a
liasing -fno-common -fshort-wchar -fno-PIE
-Werror=implicit-function-declaration
 -Werror=implicit-int -Werror=return-type -Wno-format-security -std=gnu89
-mno-s
se -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -fcf-protection=none -m64
-falign-jump
s=1 -falign-loops=1 -mno-80387 -mno-fp-ret-in-387 -mpreferred-stack-boundary=3
-
mskip-rax-setup -mtune=generic -mno-red-zone -mcmodel=kernel -Wno-sign-compare
-
fno-asynchronous-unwind-tables -mindirect-branch=thunk-extern
-mindirect-branch-
register -fno-jump-tables -fno-delete-null-pointer-checks -Wno-frame-address
-Wn
o-format-truncation -Wno-format-overflow -Wno-address-of-packed-member -O2
-fno-
allow-store-data-races -Wframe-larger-than=2048 -fstack-protector-strong
"-Wimpl
icit-fallthrough=5" -Wno-main -Wno-unused-but-set-variable
-Wno-unused-const-var
iable -fno-stack-clash-protection -pg -mrecord-mcount -mfentry
-DCC_USING_FENTRY
 -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -Wno-stringop-truncation 
-Wno-zero-length-bounds -Wno-array-bounds -Wno-stringop-overflow -Wno-restrict
-
Wno-maybe-uninitialized -Wno-alloc-size-larger-than -fno-strict-overflow
-fno-st
ack-check -fconserve-stack -Werror=date-time -Werror=incompatible-pointer-types 
-Werror=designated-init -Wno-packed-not-aligned -g   
-DKBUILD_MODFILE='"arch/x8
6/kernel/probe_roms"' -DKBUILD_BASENAME='"probe_roms"'
-DKBUILD_MODNAME='"probe_
roms"' -D__KBUILD_MODNAME=kmod_probe_roms -c -o probe_roms.o probe_roms.i