On Fri, Sep 15, 2023 at 3:09 AM Andrew Pinski via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> I noticed we sometimes lose range information in forwprop due to a few
> match and simplify patterns optimizing away casts. So the easier way
> to these cases is to add a match for zero_one_valued_p wich mathes
> a cast from another zero_one_valued_p.
> This also adds the case of `x & zero_one_valued_p` as being zero_one_valued_p
> which allows catching more cases too.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
OK.
I wonder if it would make a difference if we'd enable ranger unconditionally
in forwprop (maybe with -O2+), currently it gets enabled sometimes only.
Richard.
> gcc/ChangeLog:
>
> * match.pd (zero_one_valued_p): Match a cast from a zero_one_valued_p.
> Also match `a & zero_one_valued_p` too.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/bool-13.c: Update testcase as we now do
> the MIN/MAX during forwprop1.
> ---
> gcc/match.pd | 10 ++++++++++
> gcc/testsuite/gcc.dg/tree-ssa/bool-13.c | 15 +++++----------
> 2 files changed, 15 insertions(+), 10 deletions(-)
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 97db0eb5f25..39c9c81966a 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -2181,6 +2181,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> && (TYPE_UNSIGNED (type)
> || TYPE_PRECISION (type) > 1))))
>
> +/* (a&1) is always [0,1] too. This is useful again when
> + the range is not known. */
> +(match zero_one_valued_p
> + (bit_and:c@0 @1 zero_one_valued_p))
> +
> +/* A conversion from an zero_one_valued_p is still a [0,1].
> + This is useful when the range of a variable is not known */
> +(match zero_one_valued_p
> + (convert@0 zero_one_valued_p))
> +
> /* Transform { 0 or 1 } * { 0 or 1 } into { 0 or 1 } & { 0 or 1 }. */
> (simplify
> (mult zero_one_valued_p@0 zero_one_valued_p@1)
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bool-13.c
> b/gcc/testsuite/gcc.dg/tree-ssa/bool-13.c
> index 438f15a484a..de8c99a7727 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/bool-13.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/bool-13.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O1 -fdump-tree-optimized -fdump-tree-original
> -fdump-tree-phiopt1 -fdump-tree-forwprop2" } */
> +/* { dg-options "-O1 -fdump-tree-optimized -fdump-tree-original
> -fdump-tree-forwprop1 -fdump-tree-forwprop2" } */
> #define bool _Bool
> int maxbool(bool ab, bool bb)
> {
> @@ -22,15 +22,10 @@ int minbool(bool ab, bool bb)
> /* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "original" } } */
> /* { dg-final { scan-tree-dump-times "if " 0 "original" } } */
>
> -/* PHI-OPT1 should have kept it as min/max. */
> -/* { dg-final { scan-tree-dump-times "MAX_EXPR" 1 "phiopt1" } } */
> -/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "phiopt1" } } */
> -/* { dg-final { scan-tree-dump-times "if " 0 "phiopt1" } } */
> -
> -/* Forwprop2 (after ccp) will convert it into &\| */
> -/* { dg-final { scan-tree-dump-times "MAX_EXPR" 0 "forwprop2" } } */
> -/* { dg-final { scan-tree-dump-times "MIN_EXPR" 0 "forwprop2" } } */
> -/* { dg-final { scan-tree-dump-times "if " 0 "forwprop2" } } */
> +/* Forwprop1 will convert it into &\| as we can detect that the arguments
> are one_zero. */
> +/* { dg-final { scan-tree-dump-times "MAX_EXPR" 0 "forwprop1" } } */
> +/* { dg-final { scan-tree-dump-times "MIN_EXPR" 0 "forwprop1" } } */
> +/* { dg-final { scan-tree-dump-times "if " 0 "forwprop1" } } */
>
> /* By optimize there should be no min/max nor if */
> /* { dg-final { scan-tree-dump-times "MAX_EXPR" 0 "optimized" } } */
> --
> 2.31.1
>
