[PATCH] Dump BB number when dumping a BB with label.

[Richard Biener]

On Thu, Jul 27, 2017 at 4:24 PM, Martin Liška <mliska@suse.cz> wrote:
> Hi.
>
> Following simple patch adds support for dumping of BBs when it's a BB
> that contains a label. That makes it easier for debugging as one can
> find destination for an edge in dump file.
>
> Sample, before:
>
> foo (int a)
> {
>   int D.1821;
>   int _1;
>   int _4;
>   int _5;
>
>   <bb 2> [0.00%] [count: INV]:
>   switch (a_2(D)) <default: <L2> [INV] [count: INV], case 0: <L0> [INV] [count: INV], case 1: <L1> [INV] [count: INV]>
>
> <L0> [0.00%] [count: INV]:
>   a_3 = a_2(D) + 2;
>
> <L1> [0.00%] [count: INV]:
>   _4 = 2;
>   goto <bb 6> (<L3>); [INV] [count: INV]
>
> <L2> [0.00%] [count: INV]:
>   _5 = 123;
>
>   # _1 = PHI <_4(4), _5(5)>
> <L3> [0.00%] [count: INV]:
>   return _1;
>
> }
>
> After:
>
> foo (int a)
> {
>   int D.1821;
>   int _1;
>   int _4;
>   int _5;
>
>   <bb 2> [0.00%] [count: INV]:
>   switch (a_2(D)) <default: <L2> [INV] [count: INV], case 0: <L0> [INV] [count: INV], case 1: <L1> [INV] [count: INV]>
>
> <L0> (<bb 3>) [0.00%] [count: INV]:
>   a_3 = a_2(D) + 2;
>
> <L1> (<bb 4>) [0.00%] [count: INV]:
>   _4 = 2;
>   goto <bb 6> (<L3>); [INV] [count: INV]
>
> <L2> (<bb 5>) [0.00%] [count: INV]:
>   _5 = 123;
>
>   # _1 = PHI <_4(4), _5(5)>
> <L3> (<bb 6>) [0.00%] [count: INV]:
>   return _1;
>
> }
>
> Patch can bootstrap on ppc64le-redhat-linux and survives regression tests.
>
> Thoughts?

I think I prefer to always see

  <bb 3> ....:

and if there's a label just dump that as well, thus

  <bb 3> ....:
  L0:

I think that's how we dump the case with multiple labels.  And always use the
implicit bb N when dumping destinations (in gotos, switches, etc).

That is, what we have now is IMHO premature prettifying losing BB
indices in the dumps
unnecessarily.

Richard.

> Martin
>
> gcc/testsuite/ChangeLog:
>
> 2017-07-27  Martin Liska  <mliska@suse.cz>
>
>         * gcc.dg/builtin-unreachable-6.c: Update scanned pattern.
>         * gcc.dg/tree-ssa/attr-hotcold-2.c: Likewise.
>         * gcc.dg/tree-ssa/ssa-ccp-18.c: Likewise.
>
> gcc/ChangeLog:
>
> 2017-07-27  Martin Liska  <mliska@suse.cz>
>
>         * gimple-pretty-print.c (dump_gimple_label): Dump BB number.
> ---
>  gcc/gimple-pretty-print.c                      | 6 +++++-
>  gcc/testsuite/gcc.dg/builtin-unreachable-6.c   | 2 +-
>  gcc/testsuite/gcc.dg/tree-ssa/attr-hotcold-2.c | 4 ++--
>  gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-18.c     | 3 +--
>  4 files changed, 9 insertions(+), 6 deletions(-)
>
>