On Mon, Sep 9, 2024 at 3:11 PM Richard Biener
<richard.guent...@gmail.com> wrote:
>
> On Thu, Aug 29, 2024 at 9:03 AM <konstantinos.elefther...@vrull.eu> wrote:
> >
> > From: kelefth <konstantinos.elefther...@vrull.eu>
> >
> > In expressions like (a != b || ((a ^ b) & c) == d) and
> > (a != b || (a ^ b) == c), (a ^ b) is folded to false.
> > In the equivalent expressions (((a ^ b) & c) == d || a != b) and
> > ((a ^ b) == c || a != b) this is not happening.
> >
> > This patch adds the following simplifications in match.pd:
> > ((a ^ b) & c) == d || a != b --> 0 == d || a != b
> > (a ^ b) == c || a != b --> 0 == c || a != b
> >
> > PR tree-optimization/114326
> >
> > gcc/ChangeLog:
> >
> > * match.pd: Add two patterns to fold a ^ b to 0, when a == b.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * gcc.dg/tree-ssa/fold-xor-and-or.c: New test.
> > * gcc.dg/tree-ssa/fold-xor-or.c: New test.
> >
> > Reviewed-by: Christoph Müllner <christoph.muell...@vrull.eu>
> > Signed-off-by: Philipp Tomsich <philipp.toms...@vrull.eu>
> > Signed-off-by: Konstantinos Eleftheriou <konstantinos.elefther...@vrull.eu>
> > ---
> > gcc/match.pd | 30 ++++++++++++++++++
> > .../gcc.dg/tree-ssa/fold-xor-and-or.c | 31 +++++++++++++++++++
> > gcc/testsuite/gcc.dg/tree-ssa/fold-xor-or.c | 31 +++++++++++++++++++
> > 3 files changed, 92 insertions(+)
> > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/fold-xor-and-or.c
> > create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/fold-xor-or.c
> >
> > diff --git a/gcc/match.pd b/gcc/match.pd
> > index be211535a49..6bab3cfbde1 100644
> > --- a/gcc/match.pd
> > +++ b/gcc/match.pd
> > @@ -10727,3 +10727,33 @@ and,
> > }
> > (if (full_perm_p)
> > (vec_perm (op@3 @0 @1) @3 @2))))))
>
>> Can you please place those patterns next to related ones? I suggest
>> after (type)([0,1]@a != 0) -> (type)a and before
>> /* We can't reassociate at all for saturating types. */
Yes, I will fix that.
>
>
> > +/* ((a ^ b) & c) == d || a != b --> (0 == d || a != b). */
>
>> The comment indicates == d but you also test for other
>> comparison ops. As far as I can see your testcases also
>> only cover ==.
I will change "==" to "cmp" in the comments and add additional testcases.
My intention is to cover all operations included in "simple_comparison".
>
>
> > +(for cmp (simple_comparison)
> > + (simplify
> > + (bit_ior
> > + (cmp
> > + (bit_and
>
> This needs :c
>
> > + (bit_xor @0 @1)
>
> Likewise.
Right, I will fix these cases.
>
>
>> I think you also need :c on the comparison to match
>> d == (...).
In that case, I would need to handle non-commutative operations (e.g.
>) separately, right?
>
>
> > + tree_expr_nonzero_p@2)
> > + @3)
> > + (ne@4 @0 @1))
> > + (bit_ior
> > + (cmp
> > + { build_zero_cst (TREE_TYPE (@0)); }
> > + @3)
> > + @4)))
> > +
> > +/* (a ^ b) == c || a != b --> (0 == c || a != b). */
> > +(for cmp (simple_comparison)
> > + (simplify
> > + (bit_ior
> > + (cmp
> > + (bit_xor @0 @1)
>
> similar, :c here and also on the comparison. Same
> question with regard to == c.
>
> > + @2)
> > + (ne@3 @0 @1))
> > + (bit_ior
> > + (cmp
> > + { build_zero_cst (TREE_TYPE (@0)); }
> > + @2)
> > + @3)))
> > \ No newline at end of file
> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-and-or.c
> > b/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-and-or.c
> > new file mode 100644
> > index 00000000000..ec327e62f6e
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-and-or.c
> > @@ -0,0 +1,31 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O3 -fdump-tree-optimized" } */
> > +
> > +int cmp1(int d1, int d2) {
> > + if (((d1 ^ d2) & 0xabcd) == 0 || d1 != d2)
> > + return 0;
> > + return 1;
> > +}
> > +
> > +int cmp2(int d1, int d2) {
> > + if (d1 != d2 || ((d1 ^ d2) & 0xabcd) == 0)
> > + return 0;
> > + return 1;
> > +}
> > +
> > +typedef unsigned long int uint64_t;
> > +
> > +int cmp1_64(uint64_t d1, uint64_t d2) {
> > + if (((d1 ^ d2) & 0xabcd) == 0 || d1 != d2)
> > + return 0;
> > + return 1;
> > +}
> > +
> > +int cmp2_64(uint64_t d1, uint64_t d2) {
> > + if (d1 != d2 || ((d1 ^ d2) & 0xabcd) == 0)
> > + return 0;
> > + return 1;
> > +}
> > +
> > +/* The if should be removed, so the condition should not exist */
> > +/* { dg-final { scan-tree-dump-not "d1_\[0-9\]+.D. \\^ d2_\[0-9\]+.D."
> > "optimized" } } */
> > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-or.c
> > b/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-or.c
> > new file mode 100644
> > index 00000000000..f5fce847394
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/tree-ssa/fold-xor-or.c
> > @@ -0,0 +1,31 @@
> > +/* { dg-do compile } */
> > +/* { dg-options "-O3 -fdump-tree-optimized" } */
> > +
> > +int cmp1(int d1, int d2) {
> > + if ((d1 ^ d2) == 0xabcd || d1 != d2)
> > + return 0;
> > + return 1;
> > +}
> > +
> > +int cmp2(int d1, int d2) {
> > + if (d1 != d2 || (d1 ^ d2) == 0xabcd)
> > + return 0;
> > + return 1;
> > +}
> > +
> > +typedef unsigned long int uint64_t;
> > +
> > +int cmp1_64(uint64_t d1, uint64_t d2) {
> > + if ((d1 ^ d2) == 0xabcd || d1 != d2)
> > + return 0;
> > + return 1;
> > +}
> > +
> > +int cmp2_64(uint64_t d1, uint64_t d2) {
> > + if (d1 != d2 || (d1 ^ d2) == 0xabcd)
> > + return 0;
> > + return 1;
> > +}
> > +
> > +/* The if should be removed, so the condition should not exist */
> > +/* { dg-final { scan-tree-dump-not "d1_\[0-9\]+.D. \\^ d2_\[0-9\]+.D."
> > "optimized" } } */
> > --
> > 2.46.0
> >
Thanks for the feedback,
Konstantinos
