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

[Simon Marchi <simon.marchi@polymtl.ca>]

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