[gdb.base] Convert multi-line function call into in foll-exec.c

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  • [gdb.base] Convert multi-line function call into in foll-exec.c
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Commit Message

Philippe Waroquiers via Gdb-patches June 3, 2021, 2:57 p.m.
[AMD Official Use Only - Internal Distribution Only]

Hi Simon and all,

Could you please review this GDB patch. Patch is attached with this email and also inlined here. Thanks in advance

Problem Description:
Following 8 test points started to fail after the clang backend patch(https://reviews.llvm.org/D91734).

FAIL: gdb.base/foll-exec.exp: step through execlp call
FAIL: gdb.base/foll-exec.exp: step after execlp call
FAIL: gdb.base/foll-exec.exp: print execd-program/global_i (after execlp)
FAIL: gdb.base/foll-exec.exp: print execd-program/local_j (after execlp)
FAIL: gdb.base/foll-exec.exp: print follow-exec/local_k (after execlp)
FAIL: gdb.base/foll-exec.exp: step through execl call
FAIL: gdb.base/foll-exec.exp: step after execl call
FAIL: gdb.base/foll-exec.exp: print execd-program/local_j (after execl)

Sample gdb.base/foll-exec.c test file snippet :
. . .
42   execlp (prog, /* tbreak-execlp */
43           prog,
44           "execlp arg1 from foll-exec",
45           (char *) 0);
46
47   printf ("foll-exec is about to execl(execd-prog)...\n");
. . .

Resolution:

We had discussed 2 ways of handling this issue earlier, i.e.


  1.  Adding few extra "next" command during these multi-line function call
  2.  combine these multi-line function call into single line in foll-exec.c


This PR has taken the latter approach and converted the multi-line function call into single line in foll-exec.c, thereby there is no change in .debug_line entries now and test case works as expected.

NOTE: earlier I had sent a test patch(sent on 2021-04-15) with first approach and it was suggested to follow the second approach, hence now I am sending this PR with the second approach

regards,
bhuvan

Patch content inlined:

From 77e09b9b9a19dfb35a748fd57d7a16eb52f1b6ee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9Cbhkumarn=E2=80=9D?= Bhuvanendra.KumarN@amd.com<mailto:Bhuvanendra.KumarN@amd.com>

Date: Thu, 3 Jun 2021 17:50:28 +0530
Subject: [PATCH] [gdb.base] Convert multi-line function call into
single line.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

After this clang backend patch(https://reviews.llvm.org/D91734), 8 test points
started to FAIL in this test case. As mentioned in this PR, "...this test is
trying to "next" over a function call; gcc attributes all parameter evaluation
to the function name, while clang will attribute each parameter to its own
location. And when the parameters span across multiple source lines, the
is_stmt heuristic kicks in, so we stop on each line with actual parameters...".

gdb.base/foll-exec.c test file snippet :
. . .
42   execlp (prog, /* tbreak-execlp */
43           prog,
44           "execlp arg1 from foll-exec",
45           (char *) 0);
46
47   printf ("foll-exec is about to execl(execd-prog)...\n");
. . .

Line table: (before clang backend patch for the above code snippet) :
0x000000b0: 84 address += 8,  line += 2
            0x000000000020196a     42      3      1   0             0
0x000000b1: 08 DW_LNS_const_add_pc (0x0000000000000011)
0x000000b2: 41 address += 3,  line += 5
            0x000000000020197e     47      3      1   0             0

Line table: (after clang backend patch for the above code snippet) :
0x000000b5: 84 address += 8,  line += 2
            0x0000000000201958     42     11      1   0             0
0x000000b6: 05 DW_LNS_set_column (4)
0x000000b8: 75 address += 7,  line += 1
            0x000000000020195f     43      4      1   0             0
0x000000b9: 05 DW_LNS_set_column (3)
0x000000bb: 73 address += 7,  line += -1
            0x0000000000201966     42      3      1   0             0
0x000000bc: 08 DW_LNS_const_add_pc (0x0000000000000011)
0x000000bd: 4f address += 4,  line += 5
            0x000000000020197b     47      3      1   0             0

Following 8 test points started to fail after the above clang backend patch.

FAIL: gdb.base/foll-exec.exp: step through execlp call
FAIL: gdb.base/foll-exec.exp: step after execlp call
FAIL: gdb.base/foll-exec.exp: print execd-program/global_i (after execlp)
FAIL: gdb.base/foll-exec.exp: print execd-program/local_j (after execlp)
FAIL: gdb.base/foll-exec.exp: print follow-exec/local_k (after execlp)
FAIL: gdb.base/foll-exec.exp: step through execl call
FAIL: gdb.base/foll-exec.exp: step after execl call
FAIL: gdb.base/foll-exec.exp: print execd-program/local_j (after execl)

As we can note, reason for these new test failures is due to additional
.debug_line entries getting created in case of clang compiler, hence to fix
this issue, test case required either additional "next" command during
these multi-line function call or combine these multi-line function call into
single line. This PR has taken the latter approach and converted the multi-line
function call into single line in foll-exec.c, thereby there is no change in
.debug_line entries now and test case works as expected.
---
gdb/testsuite/ChangeLog            |  5 +++++
gdb/testsuite/gdb.base/foll-exec.c | 11 ++---------
2 files changed, 7 insertions(+), 9 deletions(-)

Comments

Philippe Waroquiers via Gdb-patches June 3, 2021, 3:38 p.m. | #1
> diff --git a/gdb/testsuite/gdb.base/foll-exec.c b/gdb/testsuite/gdb.base/foll-exec.c

> 

> index fea62b06db4..f1b97aca4a4 100644

> 

> --- a/gdb/testsuite/gdb.base/foll-exec.c

> 

> +++ b/gdb/testsuite/gdb.base/foll-exec.c

> 

> @@ -39,18 +39,11 @@ int main (int argc, char ** argv)

> 

>    memcpy (prog + len - 9, "execd-prog", 10);

> 

>    prog[len + 1] = 0;

> 

> -  execlp (prog, /* tbreak-execlp */

> 

> -             prog,

> 

> -             "execlp arg1 from foll-exec",

> 

> -             (char *) 0);

> 

> +  execlp (prog, /* tbreak-execlp */ prog, "execlp arg1 from foll-exec", (char *) 0);

> 

>    printf ("foll-exec is about to execl(execd-prog)...\n");

> 

> -  execl (prog,  /* tbreak-execl */

> 

> -           prog,

> 

> -           "execl arg1 from foll-exec",

> 

> -           "execl arg2 from foll-exec",

> 

> -           (char *) 0);

> 

> +  execl (prog, /* tbreak-execl */ prog, "execl arg1 from foll-exec", "execl arg2 from foll-exec", (char *) 0);

> 

>    {

> 

>      static char * argv[] = {


Since these lines exceed the normal line length limit of 80 columns,
please add a comment above to say why the call is all on one line.
Otherwise, someone may be tempted to "fix it" and put it back on
multiple lines (such a comment may be useful in the other test too).

Thanks,

Simon
Philippe Waroquiers via Gdb-patches June 7, 2021, 6:31 a.m. | #2
[AMD Official Use Only - Internal Distribution Only]

Hi Simon,

> Since these lines exceed the normal line length limit of 80 columns, please add a comment above to say why the call is all on one line.


I have added the required comment in the source file, could you please review/approve the updated patch. 
I have attached the updated patch and also inlined here

regards,
bhuvan

Patch inlined:

From 8f77e54fad98f17f3f34d07a0275de521aeed74f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9Cbhkumarn=E2=80=9D?= <Bhuvanendra.KumarN@amd.com>

Date: Thu, 3 Jun 2021 17:50:28 +0530
Subject: [PATCH] [gdb.base] Convert multi-line function call into
 single line.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

After this clang backend patch(https://reviews.llvm.org/D91734), 8 test points
started to FAIL in this test case. As mentioned in this PR, "...this test is
trying to "next" over a function call; gcc attributes all parameter evaluation
to the function name, while clang will attribute each parameter to its own
location. And when the parameters span across multiple source lines, the
is_stmt heuristic kicks in, so we stop on each line with actual parameters...".

gdb.base/foll-exec.c test file snippet :
. . .
 42   execlp (prog, /* tbreak-execlp */
 43           prog,
 44           "execlp arg1 from foll-exec",
 45           (char *) 0);
 46
 47   printf ("foll-exec is about to execl(execd-prog)...\n");
. . .

Line table: (before clang backend patch for the above code snippet) :
0x000000b0: 84 address += 8,  line += 2
            0x000000000020196a     42      3      1   0             0
0x000000b1: 08 DW_LNS_const_add_pc (0x0000000000000011)
0x000000b2: 41 address += 3,  line += 5
            0x000000000020197e     47      3      1   0             0

Line table: (after clang backend patch for the above code snippet) :
0x000000b5: 84 address += 8,  line += 2
            0x0000000000201958     42     11      1   0             0
0x000000b6: 05 DW_LNS_set_column (4)
0x000000b8: 75 address += 7,  line += 1
            0x000000000020195f     43      4      1   0             0
0x000000b9: 05 DW_LNS_set_column (3)
0x000000bb: 73 address += 7,  line += -1
            0x0000000000201966     42      3      1   0             0
0x000000bc: 08 DW_LNS_const_add_pc (0x0000000000000011)
0x000000bd: 4f address += 4,  line += 5
            0x000000000020197b     47      3      1   0             0

Following 8 test points started to fail after the above clang backend patch.

FAIL: gdb.base/foll-exec.exp: step through execlp call
FAIL: gdb.base/foll-exec.exp: step after execlp call
FAIL: gdb.base/foll-exec.exp: print execd-program/global_i (after execlp)
FAIL: gdb.base/foll-exec.exp: print execd-program/local_j (after execlp)
FAIL: gdb.base/foll-exec.exp: print follow-exec/local_k (after execlp)
FAIL: gdb.base/foll-exec.exp: step through execl call
FAIL: gdb.base/foll-exec.exp: step after execl call
FAIL: gdb.base/foll-exec.exp: print execd-program/local_j (after execl)

As we can note, reason for these new test failures is due to additional
.debug_line entries getting created in case of clang compiler, hence to fix
this issue, test case required either additional “next” command during
these multi-line function call or combine these multi-line function call into
single line. This PR has taken the latter approach and converted the multi-line
function call into single line in foll-exec.c, thereby there is no change in
.debug_line entries now and test case works as expected.
---
 gdb/testsuite/ChangeLog            |  5 +++++
 gdb/testsuite/gdb.base/foll-exec.c | 19 ++++++++++---------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 7959f58c3c4..1873f9ddf05 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2021-06-03  Bhuvanendra Kumar N  <Bhuvanendra.KumarN@amd.com>
+
+	* gdb.base/foll-exec.c: convert the multi-line function call into
+	single line.
+
 2021-06-02  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
 	* gdb.dwarf2/per-bfd-sharing.exp: Fix temp-dir leakage.
diff --git a/gdb/testsuite/gdb.base/foll-exec.c b/gdb/testsuite/gdb.base/foll-exec.c
index fea62b06db4..77a29860ebc 100644
--- a/gdb/testsuite/gdb.base/foll-exec.c
+++ b/gdb/testsuite/gdb.base/foll-exec.c
@@ -39,18 +39,19 @@ int main (int argc, char ** argv)
   memcpy (prog + len - 9, "execd-prog", 10);
   prog[len + 1] = 0;
 
-  execlp (prog, /* tbreak-execlp */
-	  prog,
-	  "execlp arg1 from foll-exec",
-	  (char *) 0);
+  /* In the following function call, maximum line length exceed the limit 80.
+     This is intentional and required for clang compiler such that complete
+     function call should be in a single line, please do not make it
+     multi-line */
+  execlp (prog, /* tbreak-execlp */ prog, "execlp arg1 from foll-exec", (char *) 0);
 
   printf ("foll-exec is about to execl(execd-prog)...\n");
 
-  execl (prog,	/* tbreak-execl */
-	 prog,
-	 "execl arg1 from foll-exec",
-	 "execl arg2 from foll-exec",
-	 (char *) 0);
+  /* In the following function call, maximum line length exceed the limit 80.
+     This is intentional and required for clang compiler such that complete
+     function call should be in a single line, please do not make it
+     multi-line */
+  execl (prog,	/* tbreak-execl */ prog, "execl arg1 from foll-exec", "execl arg2 from foll-exec", (char *) 0);
 
   {
     static char * argv[] = {
-- 
2.17.1

-----Original Message-----
From: Simon Marchi <simon.marchi@polymtl.ca> 

Sent: Thursday, June 3, 2021 9:09 PM
To: Kumar N, Bhuvanendra <Bhuvanendra.KumarN@amd.com>; gdb-patches@sourceware.org
Cc: George, Jini Susan <JiniSusan.George@amd.com>; Achra, Nitika <Nitika.Achra@amd.com>; Sharma, Alok Kumar <AlokKumar.Sharma@amd.com>; E, Nagajyothi <Nagajyothi.E@amd.com>; Tomar, Sourabh Singh <SourabhSingh.Tomar@amd.com>
Subject: Re: [PATCH] [gdb.base] Convert multi-line function call into in foll-exec.c

[CAUTION: External Email]

> diff --git a/gdb/testsuite/gdb.base/foll-exec.c 

> b/gdb/testsuite/gdb.base/foll-exec.c

>

> index fea62b06db4..f1b97aca4a4 100644

>

> --- a/gdb/testsuite/gdb.base/foll-exec.c

>

> +++ b/gdb/testsuite/gdb.base/foll-exec.c

>

> @@ -39,18 +39,11 @@ int main (int argc, char ** argv)

>

>    memcpy (prog + len - 9, "execd-prog", 10);

>

>    prog[len + 1] = 0;

>

> -  execlp (prog, /* tbreak-execlp */

>

> -             prog,

>

> -             "execlp arg1 from foll-exec",

>

> -             (char *) 0);

>

> +  execlp (prog, /* tbreak-execlp */ prog, "execlp arg1 from 

> + foll-exec", (char *) 0);

>

>    printf ("foll-exec is about to execl(execd-prog)...\n");

>

> -  execl (prog,  /* tbreak-execl */

>

> -           prog,

>

> -           "execl arg1 from foll-exec",

>

> -           "execl arg2 from foll-exec",

>

> -           (char *) 0);

>

> +  execl (prog, /* tbreak-execl */ prog, "execl arg1 from foll-exec", 

> + "execl arg2 from foll-exec", (char *) 0);

>

>    {

>

>      static char * argv[] = {


Since these lines exceed the normal line length limit of 80 columns, please add a comment above to say why the call is all on one line.
Otherwise, someone may be tempted to "fix it" and put it back on multiple lines (such a comment may be useful in the other test too).

Thanks,

Simon
Philippe Waroquiers via Gdb-patches June 7, 2021, 3:07 p.m. | #3
On 2021-06-07 2:31 a.m., Kumar N, Bhuvanendra wrote:
> [AMD Official Use Only - Internal Distribution Only]

> 

> Hi Simon,

> 

>> Since these lines exceed the normal line length limit of 80 columns, please add a comment above to say why the call is all on one line.

> 

> I have added the required comment in the source file, could you please review/approve the updated patch. 

> I have attached the updated patch and also inlined here

> 

> regards,

> bhuvan

> 

> Patch inlined:

> 

> From 8f77e54fad98f17f3f34d07a0275de521aeed74f Mon Sep 17 00:00:00 2001

> From: =?UTF-8?q?=E2=80=9Cbhkumarn=E2=80=9D?= <Bhuvanendra.KumarN@amd.com>

> Date: Thu, 3 Jun 2021 17:50:28 +0530

> Subject: [PATCH] [gdb.base] Convert multi-line function call into

>  single line.

> MIME-Version: 1.0

> Content-Type: text/plain; charset=UTF-8

> Content-Transfer-Encoding: 8bit

> 

> After this clang backend patch(https://reviews.llvm.org/D91734), 8 test points

> started to FAIL in this test case. As mentioned in this PR, "...this test is

> trying to "next" over a function call; gcc attributes all parameter evaluation

> to the function name, while clang will attribute each parameter to its own

> location. And when the parameters span across multiple source lines, the

> is_stmt heuristic kicks in, so we stop on each line with actual parameters...".

> 

> gdb.base/foll-exec.c test file snippet :

> . . .

>  42   execlp (prog, /* tbreak-execlp */

>  43           prog,

>  44           "execlp arg1 from foll-exec",

>  45           (char *) 0);

>  46

>  47   printf ("foll-exec is about to execl(execd-prog)...\n");

> . . .

> 

> Line table: (before clang backend patch for the above code snippet) :

> 0x000000b0: 84 address += 8,  line += 2

>             0x000000000020196a     42      3      1   0             0

> 0x000000b1: 08 DW_LNS_const_add_pc (0x0000000000000011)

> 0x000000b2: 41 address += 3,  line += 5

>             0x000000000020197e     47      3      1   0             0

> 

> Line table: (after clang backend patch for the above code snippet) :

> 0x000000b5: 84 address += 8,  line += 2

>             0x0000000000201958     42     11      1   0             0

> 0x000000b6: 05 DW_LNS_set_column (4)

> 0x000000b8: 75 address += 7,  line += 1

>             0x000000000020195f     43      4      1   0             0

> 0x000000b9: 05 DW_LNS_set_column (3)

> 0x000000bb: 73 address += 7,  line += -1

>             0x0000000000201966     42      3      1   0             0

> 0x000000bc: 08 DW_LNS_const_add_pc (0x0000000000000011)

> 0x000000bd: 4f address += 4,  line += 5

>             0x000000000020197b     47      3      1   0             0

> 

> Following 8 test points started to fail after the above clang backend patch.

> 

> FAIL: gdb.base/foll-exec.exp: step through execlp call

> FAIL: gdb.base/foll-exec.exp: step after execlp call

> FAIL: gdb.base/foll-exec.exp: print execd-program/global_i (after execlp)

> FAIL: gdb.base/foll-exec.exp: print execd-program/local_j (after execlp)

> FAIL: gdb.base/foll-exec.exp: print follow-exec/local_k (after execlp)

> FAIL: gdb.base/foll-exec.exp: step through execl call

> FAIL: gdb.base/foll-exec.exp: step after execl call

> FAIL: gdb.base/foll-exec.exp: print execd-program/local_j (after execl)

> 

> As we can note, reason for these new test failures is due to additional

> .debug_line entries getting created in case of clang compiler, hence to fix

> this issue, test case required either additional “next” command during

> these multi-line function call or combine these multi-line function call into

> single line. This PR has taken the latter approach and converted the multi-line

> function call into single line in foll-exec.c, thereby there is no change in

> .debug_line entries now and test case works as expected.

> ---

>  gdb/testsuite/ChangeLog            |  5 +++++

>  gdb/testsuite/gdb.base/foll-exec.c | 19 ++++++++++---------

>  2 files changed, 15 insertions(+), 9 deletions(-)

> 

> diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog

> index 7959f58c3c4..1873f9ddf05 100644

> --- a/gdb/testsuite/ChangeLog

> +++ b/gdb/testsuite/ChangeLog

> @@ -1,3 +1,8 @@

> +2021-06-03  Bhuvanendra Kumar N  <Bhuvanendra.KumarN@amd.com>

> +

> +	* gdb.base/foll-exec.c: convert the multi-line function call into

> +	single line.

> +

>  2021-06-02  Bernd Edlinger  <bernd.edlinger@hotmail.de>

>  

>  	* gdb.dwarf2/per-bfd-sharing.exp: Fix temp-dir leakage.

> diff --git a/gdb/testsuite/gdb.base/foll-exec.c b/gdb/testsuite/gdb.base/foll-exec.c

> index fea62b06db4..77a29860ebc 100644

> --- a/gdb/testsuite/gdb.base/foll-exec.c

> +++ b/gdb/testsuite/gdb.base/foll-exec.c

> @@ -39,18 +39,19 @@ int main (int argc, char ** argv)

>    memcpy (prog + len - 9, "execd-prog", 10);

>    prog[len + 1] = 0;

>  

> -  execlp (prog, /* tbreak-execlp */

> -	  prog,

> -	  "execlp arg1 from foll-exec",

> -	  (char *) 0);

> +  /* In the following function call, maximum line length exceed the limit 80.

> +     This is intentional and required for clang compiler such that complete

> +     function call should be in a single line, please do not make it

> +     multi-line */

> +  execlp (prog, /* tbreak-execlp */ prog, "execlp arg1 from foll-exec", (char *) 0);

>  

>    printf ("foll-exec is about to execl(execd-prog)...\n");

>  

> -  execl (prog,	/* tbreak-execl */

> -	 prog,

> -	 "execl arg1 from foll-exec",

> -	 "execl arg2 from foll-exec",

> -	 (char *) 0);

> +  /* In the following function call, maximum line length exceed the limit 80.

> +     This is intentional and required for clang compiler such that complete

> +     function call should be in a single line, please do not make it

> +     multi-line */

> +  execl (prog,	/* tbreak-execl */ prog, "execl arg1 from foll-exec", "execl arg2 from foll-exec", (char *) 0);

>  

>    {

>      static char * argv[] = {

> 


This is ok, please just make sure to finish the sentence in the comment
appropriately, with a period and two spaces before the */.

Simon
Philippe Waroquiers via Gdb-patches June 7, 2021, 3:19 p.m. | #4
[AMD Official Use Only - Internal Distribution Only]

Hi,

> please just make sure to finish the sentence in the comment appropriately, with a period and two spaces before the */.


Sure, will make these changes before pushing the changes, Thanks Simon for your review comments.

regards,
bhuvan

-----Original Message-----
From: Simon Marchi <simon.marchi@polymtl.ca> 

Sent: Monday, June 7, 2021 8:37 PM
To: Kumar N, Bhuvanendra <Bhuvanendra.KumarN@amd.com>; gdb-patches@sourceware.org
Cc: George, Jini Susan <JiniSusan.George@amd.com>; Achra, Nitika <Nitika.Achra@amd.com>; Sharma, Alok Kumar <AlokKumar.Sharma@amd.com>; E, Nagajyothi <Nagajyothi.E@amd.com>; Tomar, Sourabh Singh <SourabhSingh.Tomar@amd.com>
Subject: Re: [PATCH] [gdb.base] Convert multi-line function call into in foll-exec.c

[CAUTION: External Email]

On 2021-06-07 2:31 a.m., Kumar N, Bhuvanendra wrote:
> [AMD Official Use Only - Internal Distribution Only]

>

> Hi Simon,

>

>> Since these lines exceed the normal line length limit of 80 columns, please add a comment above to say why the call is all on one line.

>

> I have added the required comment in the source file, could you please review/approve the updated patch.

> I have attached the updated patch and also inlined here

>

> regards,

> bhuvan

>

> Patch inlined:

>

> From 8f77e54fad98f17f3f34d07a0275de521aeed74f Mon Sep 17 00:00:00 2001

> From: =?UTF-8?q?=E2=80=9Cbhkumarn=E2=80=9D?= 

> <Bhuvanendra.KumarN@amd.com>

> Date: Thu, 3 Jun 2021 17:50:28 +0530

> Subject: [PATCH] [gdb.base] Convert multi-line function call into  

> single line.

> MIME-Version: 1.0

> Content-Type: text/plain; charset=UTF-8

> Content-Transfer-Encoding: 8bit

>

> After this clang backend 

> patch(https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%

> 2Freviews.llvm.org%2FD91734&amp;data=04%7C01%7CBhuvanendra.KumarN%40am

> d.com%7C448d6971a0fb40f9a9c408d929c5f931%7C3dd8961fe4884e608e11a82d994

> e183d%7C0%7C0%7C637586752539681728%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4

> wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=FfdJKw05LGNtRgJMPTTNsKXKIC86roCe6zHSwoQr%2FUA%3D&amp;reserved=0), 8 test points started to FAIL in this test case. As mentioned in this PR, "...this test is trying to "next" over a function call; gcc attributes all parameter evaluation to the function name, while clang will attribute each parameter to its own location. And when the parameters span across multiple source lines, the is_stmt heuristic kicks in, so we stop on each line with actual parameters...".

>

> gdb.base/foll-exec.c test file snippet :

> . . .

>  42   execlp (prog, /* tbreak-execlp */

>  43           prog,

>  44           "execlp arg1 from foll-exec",

>  45           (char *) 0);

>  46

>  47   printf ("foll-exec is about to execl(execd-prog)...\n");

> . . .

>

> Line table: (before clang backend patch for the above code snippet) :

> 0x000000b0: 84 address += 8,  line += 2

>             0x000000000020196a     42      3      1   0             0

> 0x000000b1: 08 DW_LNS_const_add_pc (0x0000000000000011)

> 0x000000b2: 41 address += 3,  line += 5

>             0x000000000020197e     47      3      1   0             0

>

> Line table: (after clang backend patch for the above code snippet) :

> 0x000000b5: 84 address += 8,  line += 2

>             0x0000000000201958     42     11      1   0             0

> 0x000000b6: 05 DW_LNS_set_column (4)

> 0x000000b8: 75 address += 7,  line += 1

>             0x000000000020195f     43      4      1   0             0

> 0x000000b9: 05 DW_LNS_set_column (3)

> 0x000000bb: 73 address += 7,  line += -1

>             0x0000000000201966     42      3      1   0             0

> 0x000000bc: 08 DW_LNS_const_add_pc (0x0000000000000011)

> 0x000000bd: 4f address += 4,  line += 5

>             0x000000000020197b     47      3      1   0             0

>

> Following 8 test points started to fail after the above clang backend patch.

>

> FAIL: gdb.base/foll-exec.exp: step through execlp call

> FAIL: gdb.base/foll-exec.exp: step after execlp call

> FAIL: gdb.base/foll-exec.exp: print execd-program/global_i (after 

> execlp)

> FAIL: gdb.base/foll-exec.exp: print execd-program/local_j (after 

> execlp)

> FAIL: gdb.base/foll-exec.exp: print follow-exec/local_k (after execlp)

> FAIL: gdb.base/foll-exec.exp: step through execl call

> FAIL: gdb.base/foll-exec.exp: step after execl call

> FAIL: gdb.base/foll-exec.exp: print execd-program/local_j (after 

> execl)

>

> As we can note, reason for these new test failures is due to 

> additional .debug_line entries getting created in case of clang 

> compiler, hence to fix this issue, test case required either 

> additional “next” command during these multi-line function call or 

> combine these multi-line function call into single line. This PR has 

> taken the latter approach and converted the multi-line function call 

> into single line in foll-exec.c, thereby there is no change in .debug_line entries now and test case works as expected.

> ---

>  gdb/testsuite/ChangeLog            |  5 +++++

>  gdb/testsuite/gdb.base/foll-exec.c | 19 ++++++++++---------

>  2 files changed, 15 insertions(+), 9 deletions(-)

>

> diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index 

> 7959f58c3c4..1873f9ddf05 100644

> --- a/gdb/testsuite/ChangeLog

> +++ b/gdb/testsuite/ChangeLog

> @@ -1,3 +1,8 @@

> +2021-06-03  Bhuvanendra Kumar N  <Bhuvanendra.KumarN@amd.com>

> +

> +     * gdb.base/foll-exec.c: convert the multi-line function call into

> +     single line.

> +

>  2021-06-02  Bernd Edlinger  <bernd.edlinger@hotmail.de>

>

>       * gdb.dwarf2/per-bfd-sharing.exp: Fix temp-dir leakage.

> diff --git a/gdb/testsuite/gdb.base/foll-exec.c 

> b/gdb/testsuite/gdb.base/foll-exec.c

> index fea62b06db4..77a29860ebc 100644

> --- a/gdb/testsuite/gdb.base/foll-exec.c

> +++ b/gdb/testsuite/gdb.base/foll-exec.c

> @@ -39,18 +39,19 @@ int main (int argc, char ** argv)

>    memcpy (prog + len - 9, "execd-prog", 10);

>    prog[len + 1] = 0;

>

> -  execlp (prog, /* tbreak-execlp */

> -       prog,

> -       "execlp arg1 from foll-exec",

> -       (char *) 0);

> +  /* In the following function call, maximum line length exceed the limit 80.

> +     This is intentional and required for clang compiler such that complete

> +     function call should be in a single line, please do not make it

> +     multi-line */

> +  execlp (prog, /* tbreak-execlp */ prog, "execlp arg1 from 

> + foll-exec", (char *) 0);

>

>    printf ("foll-exec is about to execl(execd-prog)...\n");

>

> -  execl (prog,       /* tbreak-execl */

> -      prog,

> -      "execl arg1 from foll-exec",

> -      "execl arg2 from foll-exec",

> -      (char *) 0);

> +  /* In the following function call, maximum line length exceed the limit 80.

> +     This is intentional and required for clang compiler such that complete

> +     function call should be in a single line, please do not make it

> +     multi-line */

> +  execl (prog,       /* tbreak-execl */ prog, "execl arg1 from foll-exec", "execl arg2 from foll-exec", (char *) 0);

>

>    {

>      static char * argv[] = {

>


This is ok, please just make sure to finish the sentence in the comment appropriately, with a period and two spaces before the */.

Simon

Patch

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 7959f58c3c4..1873f9ddf05 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@ 
+2021-06-03  Bhuvanendra Kumar N  Bhuvanendra.KumarN@amd.com<mailto:Bhuvanendra.KumarN@amd.com>
+
+          * gdb.base/foll-exec.c: convert the multi-line function call into
+          single line.
+
2021-06-02  Bernd Edlinger  bernd.edlinger@hotmail.de<mailto:bernd.edlinger@hotmail.de>
            * gdb.dwarf2/per-bfd-sharing.exp: Fix temp-dir leakage.
diff --git a/gdb/testsuite/gdb.base/foll-exec.c b/gdb/testsuite/gdb.base/foll-exec.c
index fea62b06db4..f1b97aca4a4 100644
--- a/gdb/testsuite/gdb.base/foll-exec.c
+++ b/gdb/testsuite/gdb.base/foll-exec.c
@@ -39,18 +39,11 @@  int main (int argc, char ** argv)
   memcpy (prog + len - 9, "execd-prog", 10);
   prog[len + 1] = 0;
-  execlp (prog, /* tbreak-execlp */
-             prog,
-             "execlp arg1 from foll-exec",
-             (char *) 0);
+  execlp (prog, /* tbreak-execlp */ prog, "execlp arg1 from foll-exec", (char *) 0);
   printf ("foll-exec is about to execl(execd-prog)...\n");
-  execl (prog,  /* tbreak-execl */
-           prog,
-           "execl arg1 from foll-exec",
-           "execl arg2 from foll-exec",
-           (char *) 0);
+  execl (prog, /* tbreak-execl */ prog, "execl arg1 from foll-exec", "execl arg2 from foll-exec", (char *) 0);
   {
     static char * argv[] = {
--
2.17.1