Re: [PATCH] MATCH: [PR110937/PR100798] (a ? ~b : b) should be optimized to b ^ -(a)

[Christophe Lyon <christophe.lyon@linaro.org>]

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Hi Andrew,


On Wed, 9 Aug 2023 at 21:20, Andrew Pinski via Gcc-patches <
gcc-patches@gcc.gnu.org> wrote:

> This adds a simple match pattern for this case.
> I noticed it a couple of different places.
> One while I was looking at code generation of a parser and
> also while I was looking at locations where bitwise_inverted_equal_p
> should be used more.
>
> Committed as approved after bootstrapped and tested on x86_64-linux-gnu
> with no regressions.
>
>         PR tree-optimization/110937
>         PR tree-optimization/100798
>
> gcc/ChangeLog:
>
>         * match.pd (`a ? ~b : b`): Handle this
>         case.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.dg/tree-ssa/bool-14.c: New test.
>         * gcc.dg/tree-ssa/bool-15.c: New test.
>         * gcc.dg/tree-ssa/phi-opt-33.c: New test.
>         * gcc.dg/tree-ssa/20030709-2.c: Update testcase
>         so `a ? -1 : 0` is not used to hit the match
>         pattern.
>

Our CI noticed that your patch introduced regressions as follows on aarch64:

 Running gcc:gcc.target/aarch64/aarch64.exp ...
FAIL: gcc.target/aarch64/cond_op_imm_1.c scan-assembler csinv\tw[0-9]*.*
FAIL: gcc.target/aarch64/cond_op_imm_1.c scan-assembler csinv\tx[0-9]*.*

Running gcc:gcc.target/aarch64/sve/aarch64-sve.exp ...
FAIL: gcc.target/aarch64/sve/cond_unary_5.c scan-assembler-not \\tmov\\tz
FAIL: gcc.target/aarch64/sve/cond_unary_5.c scan-assembler-times
\\tneg\\tz[0-9]+\\.b, p[0-7]/m, 3
FAIL: gcc.target/aarch64/sve/cond_unary_5.c scan-assembler-times
\\tneg\\tz[0-9]+\\.h, p[0-7]/m, 2
FAIL: gcc.target/aarch64/sve/cond_unary_5.c scan-assembler-times
\\tneg\\tz[0-9]+\\.s, p[0-7]/m, 1
FAIL: gcc.target/aarch64/sve/cond_unary_5.c scan-assembler-times
\\tnot\\tz[0-9]+\\.b, p[0-7]/m, 3
FAIL: gcc.target/aarch64/sve/cond_unary_5.c scan-assembler-times
\\tnot\\tz[0-9]+\\.h, p[0-7]/m, 2
FAIL: gcc.target/aarch64/sve/cond_unary_5.c scan-assembler-times
\\tnot\\tz[0-9]+\\.s, p[0-7]/m, 1

Hopefully you'll just need to update the testcases (I didn't check
manually, I think you can easily reproduce this on aarch64?)

Thanks,

Christophe




> ---
>  gcc/match.pd                               | 14 ++++++++++++++
>  gcc/testsuite/gcc.dg/tree-ssa/20030709-2.c |  5 +++--
>  gcc/testsuite/gcc.dg/tree-ssa/bool-14.c    | 15 +++++++++++++++
>  gcc/testsuite/gcc.dg/tree-ssa/bool-15.c    | 18 ++++++++++++++++++
>  gcc/testsuite/gcc.dg/tree-ssa/phi-opt-33.c | 13 +++++++++++++
>  5 files changed, 63 insertions(+), 2 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/bool-14.c
>  create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/bool-15.c
>  create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/phi-opt-33.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 9b4819e5be7..fc630b63563 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -6460,6 +6460,20 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>        (if (cmp == NE_EXPR)
>         { constant_boolean_node (true, type); })))))))
>
> +#if GIMPLE
> +/* a?~t:t -> (-(a))^t */
> +(simplify
> + (cond @0 @1 @2)
> + (if (INTEGRAL_TYPE_P (type)
> +      && bitwise_inverted_equal_p (@1, @2))
> +  (with {
> +    auto prec = TYPE_PRECISION (type);
> +    auto unsign = TYPE_UNSIGNED (type);
> +    tree inttype = build_nonstandard_integer_type (prec, unsign);
> +   }
> +   (convert (bit_xor (negate (convert:inttype @0)) (convert:inttype
> @2))))))
> +#endif
> +
>  /* Simplify pointer equality compares using PTA.  */
>  (for neeq (ne eq)
>   (simplify
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/20030709-2.c
> b/gcc/testsuite/gcc.dg/tree-ssa/20030709-2.c
> index 5009cd69cfe..78938f919d4 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/20030709-2.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/20030709-2.c
> @@ -29,15 +29,16 @@ union tree_node
>  };
>  int make_decl_rtl (tree, int);
>  void *
> -get_alias_set (t)
> +get_alias_set (t, t1)
>       tree t;
> +     void *t1;
>  {
>    long set;
>    if (t->decl.rtl)
>      return (t->decl.rtl->fld[1].rtmem
>             ? 0
>             : (((t->decl.rtl ? t->decl.rtl: (make_decl_rtl (t, 0),
> t->decl.rtl)))->fld[1]).rtmem);
> -  return (void*)-1;
> +  return t1;
>  }
>
>  /* There should be precisely one load of ->decl.rtl.  If there is
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bool-14.c
> b/gcc/testsuite/gcc.dg/tree-ssa/bool-14.c
> new file mode 100644
> index 00000000000..0149380a63b
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/bool-14.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized-raw" } */
> +/* PR tree-optimization/110937 */
> +
> +_Bool f2(_Bool a, _Bool b)
> +{
> +        if (a)
> +          return !b;
> +        return b;
> +}
> +
> +/* We should be able to remove the conditional and convert it to an xor.
> */
> +/* { dg-final { scan-tree-dump-not "gimple_cond " "optimized" } } */
> +/* { dg-final { scan-tree-dump-not "gimple_phi " "optimized" } } */
> +/* { dg-final { scan-tree-dump-times "bit_xor_expr, " 1 "optimized" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bool-15.c
> b/gcc/testsuite/gcc.dg/tree-ssa/bool-15.c
> new file mode 100644
> index 00000000000..1f496663863
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/bool-15.c
> @@ -0,0 +1,18 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized-raw" } */
> +/* PR tree-optimization/110937 */
> +
> +_Bool f2(int x, int y, int w, int z)
> +{
> +  _Bool a = x == y;
> +  _Bool b = w == z;
> +  if (a)
> +    return !b;
> +  return b;
> +}
> +
> +/* We should be able to remove the conditional and convert it to an xor.
> */
> +/* { dg-final { scan-tree-dump-not "gimple_cond " "optimized" } } */
> +/* { dg-final { scan-tree-dump-not "gimple_phi " "optimized" } } */
> +/* { dg-final { scan-tree-dump-not "ne_expr, " "optimized" } } */
> +/* { dg-final { scan-tree-dump-times "bit_xor_expr, " 1 "optimized" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-33.c
> b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-33.c
> new file mode 100644
> index 00000000000..b79fe44187a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-33.c
> @@ -0,0 +1,13 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized-raw" } */
> +/* PR tree-optimization/100798 */
> +
> +int f(int a, int t)
> +{
> +  return (a=='s' ? ~t : t);
> +}
> +
> +/* This should be convert into t^-(a=='s').  */
> +/* { dg-final { scan-tree-dump-times "bit_xor_expr, " 1 "optimized" } } */
> +/* { dg-final { scan-tree-dump-times "negate_expr, " 1 "optimized" } } */
> +/* { dg-final { scan-tree-dump-not "bit_not_expr, " "optimized" } } */
> --
> 2.31.1
>
>