On Mon, Apr 24, 2023 at 11:33 PM Andrew Pinski via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> This adds a few patterns from phiopt's minmax_replacement
> for (A CMP B) ? MIN/MAX<A, C> : MIN/MAX <B, C> .
> It is progress to remove minmax_replacement from phiopt.
> There are still some more cases dealing with constants on the
> edges (0/INT_MAX) to handle in match.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
OK.
> gcc/ChangeLog:
>
> * match.pd: Add patterns for
> "(A CMP B) ? MIN/MAX<A, C> : MIN/MAX <B, C>".
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/minmax-16.c: Update testcase slightly.
> * gcc.dg/tree-ssa/split-path-1.c: Also disable tree-loop-if-convert
> as that now does the combining.
> ---
> gcc/match.pd | 16 ++++++++++++++++
> gcc/testsuite/gcc.dg/tree-ssa/minmax-16.c | 10 ++++++++--
> gcc/testsuite/gcc.dg/tree-ssa/split-path-1.c | 3 ++-
> 3 files changed, 26 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 6d3aaf45a93..5d5aae24509 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -4843,6 +4843,22 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (convert @c0))))))))
> #endif
>
> +/* These was part of minmax phiopt. */
> +/* Optimize (a CMP b) ? minmax<a, c> : minmax<b, c>
> + to minmax<min/max<a, b>, c> */
> +(for minmax (min max)
> + (for cmp (lt le gt ge)
> + (simplify
> + (cond (cmp @1 @3) (minmax:c @1 @4) (minmax:c @2 @4))
> + (with
> + {
> + tree_code code = minmax_from_comparison (cmp, @1, @2, @1, @3);
> + }
> + (if (code == MIN_EXPR)
> + (minmax (min @1 @2) @4)
> + (if (code == MAX_EXPR)
> + (minmax (max @1 @2) @4)))))))
> +
> /* X != C1 ? -X : C2 simplifies to -X when -C1 == C2. */
> (simplify
> (cond (ne @0 INTEGER_CST@1) (negate@3 @0) INTEGER_CST@2)
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/minmax-16.c
> b/gcc/testsuite/gcc.dg/tree-ssa/minmax-16.c
> index 4febd092d83..623b12b3f74 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/minmax-16.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/minmax-16.c
> @@ -1,5 +1,5 @@
> /* { dg-do run } */
> -/* { dg-options "-O -fdump-tree-phiopt -g" } */
> +/* { dg-options "-O -fdump-tree-phiopt -fdump-tree-optimized -g" } */
>
> #include <stdint.h>
>
> @@ -25,5 +25,11 @@ main (void)
> return 0;
> }
>
> -/* { dg-final { scan-tree-dump-times "MIN_EXPR" 3 "phiopt1" } } */
> +/* After phiopt1, there really should be only 3 MIN_EXPR in the IR
> (including debug statements).
> + But the way phiopt does not cleanup the CFG all the time, the PHI might
> still reference the
> + alternative bb's moved statement.
> + Note in the end, we do dce the statement and other debug statements to
> end up with only 2 MIN_EXPR.
> + So check that too. */
> +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 4 "phiopt1" } } */
> +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 2 "optimized" } } */
> /* { dg-final { scan-tree-dump-times "MAX_EXPR" 0 "phiopt1" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/split-path-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/split-path-1.c
> index 902dde44a50..b670dee8d10 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/split-path-1.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/split-path-1.c
> @@ -1,5 +1,6 @@
> /* { dg-do run } */
> -/* { dg-options "-O2 -fsplit-paths -fdump-tree-split-paths-details --param
> max-jump-thread-duplication-stmts=20 -fno-ssa-phiopt" } */
> +/* Note both PHI-OPT and the loop if conversion pass converts the inner if
> to be branchless using min/max. */
> +/* { dg-options "-O2 -fsplit-paths -fdump-tree-split-paths-details --param
> max-jump-thread-duplication-stmts=20 -fno-ssa-phiopt
> -fno-tree-loop-if-convert" } */
>
> #include <stdio.h>
> #include <stdlib.h>
> --
> 2.39.1
>
