Re: [PATCH] tree-ssa-sink: Improve code sinking pass

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

On Wed, Mar 13, 2024 at 2:56 PM Ajit Agarwal <aagarwa1@linux.ibm.com> wrote:
>
> Hello Richard:
>
> Currently, code sinking will sink code at the use points with loop having same
> nesting depth. The following patch improves code sinking by placing the sunk
> code in begining of the block after the labels.
>
> For example :
>
> void bar();
> int j;
> void foo(int a, int b, int c, int d, int e, int f)
> {
>   int l;
>   l = a + b + c + d +e + f;
>   if (a != 5)
>     {
>       bar();
>       j = l;
>     }
> }
>
> Code Sinking does the following:
>
> void bar();
> int j;
> void foo(int a, int b, int c, int d, int e, int f)
> {
>   int l;
>
>   if (a != 5)
>     {
>       l = a + b + c + d +e + f;
>       bar();
>       j = l;
>     }
> }
>
> Bootstrapped regtested on powerpc64-linux-gnu.
>
> Thanks & Regards
>
> tree-ssa-sink: Improve code sinking pass
>
> Currently, code sinking will sink code at the use points with loop having same
> nesting depth. The following patch improves code sinking by placing the sunk
> code in begining of the block after the labels.
>
> 2024-03-13  Ajit Kumar Agarwal  <aagarwa1@linux.ibm.com>
>
> gcc/ChangeLog:
>
>         PR tree-optimization/81953
>         * tree-ssa-sink.cc (statement_sink_location):Sink statements at
>         the begining of the basic block after labels.
>
> gcc/testsuite/ChangeLog:
>
>         PR tree-optimization/81953
>         * gcc.dg/tree-ssa/ssa-sink-21.c: New test.
> ---
>  gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-21.c | 15 +++++++++++++++
>  gcc/tree-ssa-sink.cc                        |  7 ++-----
>  2 files changed, 17 insertions(+), 5 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-21.c
>
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-21.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-21.c
> new file mode 100644
> index 00000000000..d3b79ca5803
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-21.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-sink-stats" } */
> +void bar();
> +int j;
> +void foo(int a, int b, int c, int d, int e, int f)
> +{
> +  int l;
> +  l = a + b + c + d +e + f;
> +  if (a != 5)
> +    {
> +      bar();
> +      j = l;
> +    }
> +}
> +/* { dg-final { scan-tree-dump {l_12\s+=\s+_4\s+\+\s+f_11\(D\);\n\s+bar\s+\(\)} sink1 } } */
> diff --git a/gcc/tree-ssa-sink.cc b/gcc/tree-ssa-sink.cc
> index 880d6f70a80..1ec5c048fe7 100644
> --- a/gcc/tree-ssa-sink.cc
> +++ b/gcc/tree-ssa-sink.cc
> @@ -208,7 +208,6 @@ select_best_block (basic_block early_bb,
>          loop nest.  */
>        temp_bb = get_immediate_dominator (CDI_DOMINATORS, temp_bb);
>      }
> -
>    /* Placing a statement before a setjmp-like function would be invalid
>       (it cannot be reevaluated when execution follows an abnormal edge).
>       If we selected a block with abnormal predecessors, just punt.  */
> @@ -430,6 +429,7 @@ statement_sink_location (gimple *stmt, basic_block frombb,
>             continue;
>           break;
>         }
> +
>        use = USE_STMT (one_use);
>
>        if (gimple_code (use) != GIMPLE_PHI)

OK if you avoid the stray whitespace changes above.

Richard.

> @@ -439,10 +439,7 @@ statement_sink_location (gimple *stmt, basic_block frombb,
>           if (sinkbb == frombb)
>             return false;
>
> -         if (sinkbb == gimple_bb (use))
> -           *togsi = gsi_for_stmt (use);
> -         else
> -           *togsi = gsi_after_labels (sinkbb);
> +         *togsi = gsi_after_labels (sinkbb);
>
>           return true;
>         }
> --
> 2.39.3
>