Re: [PATCH 2/2] gcov: Fix incorrect gimple line LOCATION [PR97923]

[Richard Biener <richard.guenther@gmail.com>]

On Thu, Mar 2, 2023 at 3:31 AM Xionghu Luo via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> For case like belowi test.c:
>
> 1:int foo(char c)
> 2:{
> 3:  return ((c >= 'A' && c <= 'Z')
> 4:       || (c >= 'a' && c <= 'z')
> 5:       || (c >= '0' && c <='0'));}
>
> the generated line number is incorrect for condition c>='A' of block 2:
> Thus correct the condition op0 location.
>
> gcno diff before and with this patch:
>
> test.gcno:  575:                  block 11: 1:0001(tree)
> test.gcno:  583:    01450000:  35:LINES
> -test.gcno:  595:                  block 2:`test.c':1, 5
> +test.gcno:  595:                  block 2:`test.c':1, 3
> test.gcno:  626:    01450000:  31:LINES
> test.gcno:  638:                  block 3:`test.c':3
> test.gcno:  665:    01450000:  31:LINES
> test.gcno:  677:                  block 4:`test.c':4
> test.gcno:  704:    01450000:  31:LINES
> test.gcno:  716:                  block 5:`test.c':4
> test.gcno:  743:    01450000:  31:LINES
> test.gcno:  755:                  block 6:`test.c':5
>
> Also save line id in line vector for gcov debug use.
>
> Regression tested pass on x86_64-linux-gnu and aarch64-linux-gnu, OK for
> master?
>
> gcc/ChangeLog:
>
>         PR gcov/97923
>         * gcov.cc (line_info::line_info): Init id.
>         (solve_flow_graph): Fix typo.
>         (add_line_counts): Set line->id.
>         * gimplify.cc (shortcut_cond_r): Correct cond expr op0 location.
>
> gcc/testsuite/ChangeLog:
>
>         PR gcov/97923
>         * gcc.misc-tests/gcov-pr97923.c: New test.
>
> Signed-off-by: Xionghu Luo <xionghuluo@tencent.com>
> ---
>  gcc/gcov.cc                                 |  9 ++++++---
>  gcc/gimplify.cc                             |  6 ++++--
>  gcc/testsuite/gcc.misc-tests/gcov-pr97923.c | 13 +++++++++++++
>  3 files changed, 23 insertions(+), 5 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.misc-tests/gcov-pr97923.c
>
> diff --git a/gcc/gcov.cc b/gcc/gcov.cc
> index 2ec7248cc0e..77ca94c71c4 100644
> --- a/gcc/gcov.cc
> +++ b/gcc/gcov.cc
> @@ -205,6 +205,8 @@ public:
>    /* Execution count.  */
>    gcov_type count;
>
> +  unsigned id;
> +
>    /* Branches from blocks that end on this line.  */
>    vector<arc_info *> branches;
>
> @@ -216,8 +218,8 @@ public:
>    unsigned has_unexecuted_block : 1;
>  };
>
> -line_info::line_info (): count (0), branches (), blocks (), exists (false),
> -  unexceptional (0), has_unexecuted_block (0)
> +line_info::line_info (): count (0), id (0), branches (), blocks (),
> +  exists (false), unexceptional (0), has_unexecuted_block (0)
>  {
>  }
>
> @@ -2370,7 +2372,7 @@ solve_flow_graph (function_info *fn)
>
>    /* If the graph has been correctly solved, every block will have a
>       valid count.  */
> -  for (unsigned i = 0; ix < fn->blocks.size (); i++)
> +  for (unsigned i = 0; i < fn->blocks.size (); i++)
>      if (!fn->blocks[i].count_valid)
>        {
>         fnotice (stderr, "%s:graph is unsolvable for '%s'\n",
> @@ -2730,6 +2732,7 @@ add_line_counts (coverage_info *coverage, function_info *fn)
>                     }
>                   line->count += block->count;
>                 }
> +             line->id = ln;
>             }
>
>           has_any_line = true;
> diff --git a/gcc/gimplify.cc b/gcc/gimplify.cc
> index ade6e335da7..341a27b033e 100644
> --- a/gcc/gimplify.cc
> +++ b/gcc/gimplify.cc
> @@ -3915,7 +3915,8 @@ shortcut_cond_r (tree pred, tree *true_label_p, tree *false_label_p,
>         false_label_p = &local_label;
>
>        /* Keep the original source location on the first 'if'.  */
> -      t = shortcut_cond_r (TREE_OPERAND (pred, 0), NULL, false_label_p, locus);
> +      tree op0 = TREE_OPERAND (pred, 0);
> +      t = shortcut_cond_r (op0, NULL, false_label_p, EXPR_LOCATION (op0));
>        append_to_statement_list (t, &expr);

The comment now no longer is true?  For the else arm we use
rexpr_location, why not
here as well?  To quote the following lines:

      /* Set the source location of the && on the second 'if'.  */
      new_locus = rexpr_location (pred, locus);
      t = shortcut_cond_r (TREE_OPERAND (pred, 1), true_label_p, false_label_p,
                           new_locus);
      append_to_statement_list (t, &expr);

with your change the location of the outer COND_EXPR is lost?  Can we guarantee
that it's used for the first operand of a if (a && b && c)?  It would
be nice to expand
the leading comment for such a three operand case and explain how it's supposed
to work.

I didn't look at the gcov changes, leaving those to the gcov maintainer(s).

Richard.

>
>        /* Set the source location of the && on the second 'if'.  */
> @@ -3938,7 +3939,8 @@ shortcut_cond_r (tree pred, tree *true_label_p, tree *false_label_p,
>         true_label_p = &local_label;
>
>        /* Keep the original source location on the first 'if'.  */
> -      t = shortcut_cond_r (TREE_OPERAND (pred, 0), true_label_p, NULL, locus);
> +      tree op0 = TREE_OPERAND (pred, 0);
> +      t = shortcut_cond_r (op0, true_label_p, NULL, EXPR_LOCATION (op0));
>        append_to_statement_list (t, &expr);
>
>        /* Set the source location of the || on the second 'if'.  */
> diff --git a/gcc/testsuite/gcc.misc-tests/gcov-pr97923.c b/gcc/testsuite/gcc.misc-tests/gcov-pr97923.c
> new file mode 100644
> index 00000000000..ad4f7d40817
> --- /dev/null
> +++ b/gcc/testsuite/gcc.misc-tests/gcov-pr97923.c
> @@ -0,0 +1,13 @@
> +/* { dg-options "-fprofile-arcs -ftest-coverage" } */
> +/* { dg-do run { target native } } */
> +
> +int foo(int c)
> +{
> +  return ((c >= 'A' && c <= 'Z') /* count(1*) */
> +      || (c >= 'a' && c <= 'z') /* count(1*) */
> +      || (c >= '0' && c <= '0')); /* count(1*) */
> +}
> +
> +int main() { foo(0); }
> +
> +/* { dg-final { run-gcov gcov-pr97923-1.c } } */
> --
> 2.27.0
>