On Wed, Jun 22, 2022 at 11:03 PM Richard Biener
<richard.guent...@gmail.com> wrote:
>
> On Wed, Jun 22, 2022 at 7:13 PM H.J. Lu <hjl.to...@gmail.com> wrote:
> >
> > On Wed, Jun 22, 2022 at 4:39 AM Richard Biener
> > <richard.guent...@gmail.com> wrote:
> > >
> > > On Tue, Jun 21, 2022 at 11:03 PM H.J. Lu via Gcc-patches
> > > <gcc-patches@gcc.gnu.org> wrote:
> > > >
> > > > When memchr is applied on a constant string of no more than the bytes of
> > > > a word, inline memchr by checking each byte in the constant string.
> > > >
> > > > int f (int a)
> > > > {
> > > > return __builtin_memchr ("eE", a, 2) != 0;
> > > > }
> > > >
> > > > is simplified to
> > > >
> > > > int f (int a)
> > > > {
> > > > return (char) a == 'e' || (char) a == 'E';
> > > > }
> > > >
> > > > gcc/
> > > >
> > > > PR tree-optimization/103798
> > > > * match.pd (__builtin_memchr (const_str, a, N)): Inline memchr
> > > > with constant strings of no more than the bytes of a word.
> > >
> > > Please do this in strlenopt or so, with match.pd you will end up moving
> > > the memchr loads across possible aliasing stores to the point of the
> > > comparison.
> >
> > strlenopt is run after many other passes. The code won't be well optimized.
>
> What followup optimizations do you expect? That is, other builtins are only
reassociation and dce turn
_5 = a_2(D) == 101;
_6 = a_2(D) == 69;
_1 = _5 | _6;
_4 = (int) _1;
into
_7 = a_2(D) & -33;
_8 = _7 == 69;
_1 = _8;
_4 = (int) _1;
> expanded inline at RTL expansion time?
Some high level optimizations will be missed and
TARGET_GIMPLE_FOLD_BUILTIN improves builtins
codegen.
> > Since we are only optimizing
> >
> > __builtin_memchr ("eE", a, 2) != 0;
> >
> > I don't see any aliasing store issues here.
>
> Ah, I failed to see the STRING_CST restriction. Note that when optimizing for
> size this doesn't look very good.
True.
> I would expect a target might produce some vector code for
> memchr ("aAbBcCdDeE...", c, 9) != 0 by splatting 'c', doing
> a v16qimode compare, masking off excess elements beyond length
> and then comparing against zero or for == 0 against all-ones.
>
> The repetitive pattern result also suggests an implementation elsewhere,
> if you think strlenopt is too late there would be forwprop as well.
forwprop seems a good place.
Thanks.
> Richard.
>
>
>
> > > Richard.
> > >
> > > > gcc/testsuite/
> > > >
> > > > PR tree-optimization/103798
> > > > * c-c++-common/pr103798-1.c: New test.
> > > > * c-c++-common/pr103798-2.c: Likewise.
> > > > * c-c++-common/pr103798-3.c: Likewise.
> > > > * c-c++-common/pr103798-4.c: Likewise.
> > > > * c-c++-common/pr103798-5.c: Likewise.
> > > > * c-c++-common/pr103798-6.c: Likewise.
> > > > * c-c++-common/pr103798-7.c: Likewise.
> > > > * c-c++-common/pr103798-8.c: Likewise.
> > > > ---
> > > > gcc/match.pd | 136 ++++++++++++++++++++++++
> > > > gcc/testsuite/c-c++-common/pr103798-1.c | 28 +++++
> > > > gcc/testsuite/c-c++-common/pr103798-2.c | 30 ++++++
> > > > gcc/testsuite/c-c++-common/pr103798-3.c | 28 +++++
> > > > gcc/testsuite/c-c++-common/pr103798-4.c | 28 +++++
> > > > gcc/testsuite/c-c++-common/pr103798-5.c | 26 +++++
> > > > gcc/testsuite/c-c++-common/pr103798-6.c | 27 +++++
> > > > gcc/testsuite/c-c++-common/pr103798-7.c | 27 +++++
> > > > gcc/testsuite/c-c++-common/pr103798-8.c | 27 +++++
> > > > 9 files changed, 357 insertions(+)
> > > > create mode 100644 gcc/testsuite/c-c++-common/pr103798-1.c
> > > > create mode 100644 gcc/testsuite/c-c++-common/pr103798-2.c
> > > > create mode 100644 gcc/testsuite/c-c++-common/pr103798-3.c
> > > > create mode 100644 gcc/testsuite/c-c++-common/pr103798-4.c
> > > > create mode 100644 gcc/testsuite/c-c++-common/pr103798-5.c
> > > > create mode 100644 gcc/testsuite/c-c++-common/pr103798-6.c
> > > > create mode 100644 gcc/testsuite/c-c++-common/pr103798-7.c
> > > > create mode 100644 gcc/testsuite/c-c++-common/pr103798-8.c
> > > >
> > > > diff --git a/gcc/match.pd b/gcc/match.pd
> > > > index a63b649841b..aa4766749af 100644
> > > > --- a/gcc/match.pd
> > > > +++ b/gcc/match.pd
> > > > @@ -7976,3 +7976,139 @@ and,
> > > > (match (bitwise_induction_p @0 @2 @3)
> > > > (bit_not
> > > > (nop_convert1? (bit_xor@0 (convert2? (lshift integer_onep@1 @2))
> > > > @3))))
> > > > +
> > > > +#if GIMPLE
> > > > +/* __builtin_memchr (const_str, a, N) != 0 ->
> > > > + a == const_str[0] .. || a == const_str[N-1]
> > > > + __builtin_memchr (const_str, a, N) == 0 ->
> > > > + a != const_str[0] .. && a != const_str[N-1]
> > > > + where N is less than the string size. */
> > > > +(for cmp (eq ne)
> > > > + icmp (ne eq)
> > > > + bit_op (bit_and bit_ior)
> > > > + (simplify (cmp:c @0 (BUILT_IN_MEMCHR ADDR_EXPR@1 @2 INTEGER_CST@3))
> > > > + (if (UNITS_PER_WORD <= 8
> > > > + && CHAR_TYPE_SIZE == 8
> > > > + && BITS_PER_UNIT == 8
> > > > + && CHAR_BIT == 8
> > > > + && integer_zerop (@0)
> > > > + && !integer_zerop (@3)
> > > > + && TREE_CODE (TREE_OPERAND (@1, 0)) == STRING_CST
> > > > + && TREE_STRING_LENGTH (TREE_OPERAND (@1, 0)) >= 2
> > > > + && wi::leu_p (wi::to_wide (@3), UNITS_PER_WORD)
> > > > + && wi::ltu_p (wi::to_wide (@3),
> > > > + TREE_STRING_LENGTH (TREE_OPERAND (@1, 0))))
> > > > + (with
> > > > + {
> > > > + const char *p = TREE_STRING_POINTER (TREE_OPERAND (@1, 0));
> > > > + unsigned HOST_WIDE_INT size = TREE_INT_CST_LOW (@3);
> > > > + }
> > > > + (switch
> > > > + (if (size == 1)
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[0]); }))
> > > > + (if (size == 2)
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[0]); })
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[1]); })))
> > > > + (if (size == 3)
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[0]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[1]); })
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[2]); }))))
> > > > + (if (size == 4)
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[0]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[1]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[2]); })
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[3]); })))))
> > > > + (if (size == 5)
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[0]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[1]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[2]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[3]); })
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[4]); }))))))
> > > > + (if (size == 6)
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[0]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[1]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[2]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[3]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[4]); })
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[5]); })))))))
> > > > + (if (size == 7)
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[0]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[1]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[2]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[3]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[4]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[5]); })
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[6]); }))))))))
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[0]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[1]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[2]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[3]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[4]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[5]); })
> > > > + (bit_op
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[6]); })
> > > > + (icmp (convert:char_type_node @2)
> > > > + { build_int_cst (char_type_node, p[7]); })))))))))))))
> > > > +#endif
> > > > diff --git a/gcc/testsuite/c-c++-common/pr103798-1.c
> > > > b/gcc/testsuite/c-c++-common/pr103798-1.c
> > > > new file mode 100644
> > > > index 00000000000..cd3edf569fc
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/c-c++-common/pr103798-1.c
> > > > @@ -0,0 +1,28 @@
> > > > +/* { dg-do run } */
> > > > +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int
> > > > +f (char a)
> > > > +{
> > > > + return __builtin_memchr ("a", a, 1) == 0;
> > > > +}
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int
> > > > +g (char a)
> > > > +{
> > > > + return a != 'a';
> > > > +}
> > > > +
> > > > +int
> > > > +main ()
> > > > +{
> > > > + for (int i = 0; i < 255; i++)
> > > > + if (f (i) != g (i))
> > > > + __builtin_abort ();
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +/* { dg-final { scan-assembler-not "memchr" } } */
> > > > diff --git a/gcc/testsuite/c-c++-common/pr103798-2.c
> > > > b/gcc/testsuite/c-c++-common/pr103798-2.c
> > > > new file mode 100644
> > > > index 00000000000..e7e99c3679e
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/c-c++-common/pr103798-2.c
> > > > @@ -0,0 +1,30 @@
> > > > +/* { dg-do run } */
> > > > +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> > > > +
> > > > +#include <string.h>
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int
> > > > +f (int a)
> > > > +{
> > > > + return memchr ("aE", a, 2) != NULL;
> > > > +}
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int
> > > > +g (char a)
> > > > +{
> > > > + return a == 'a' || a == 'E';
> > > > +}
> > > > +
> > > > +int
> > > > +main ()
> > > > +{
> > > > + for (int i = 0; i < 255; i++)
> > > > + if (f (i + 256) != g (i + 256))
> > > > + __builtin_abort ();
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +/* { dg-final { scan-assembler-not "memchr" } } */
> > > > diff --git a/gcc/testsuite/c-c++-common/pr103798-3.c
> > > > b/gcc/testsuite/c-c++-common/pr103798-3.c
> > > > new file mode 100644
> > > > index 00000000000..ddcedc7e238
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/c-c++-common/pr103798-3.c
> > > > @@ -0,0 +1,28 @@
> > > > +/* { dg-do run } */
> > > > +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int
> > > > +f (char a)
> > > > +{
> > > > + return __builtin_memchr ("aEgZ", a, 3) == 0;
> > > > +}
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int
> > > > +g (char a)
> > > > +{
> > > > + return a != 'a' && a != 'E' && a != 'g';
> > > > +}
> > > > +
> > > > +int
> > > > +main ()
> > > > +{
> > > > + for (int i = 0; i < 255; i++)
> > > > + if (f (i) != g (i))
> > > > + __builtin_abort ();
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +/* { dg-final { scan-assembler-not "memchr" } } */
> > > > diff --git a/gcc/testsuite/c-c++-common/pr103798-4.c
> > > > b/gcc/testsuite/c-c++-common/pr103798-4.c
> > > > new file mode 100644
> > > > index 00000000000..00e8302a833
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/c-c++-common/pr103798-4.c
> > > > @@ -0,0 +1,28 @@
> > > > +/* { dg-do run } */
> > > > +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int
> > > > +f (char a)
> > > > +{
> > > > + return __builtin_memchr ("aEgi", a, 4) != 0;
> > > > +}
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int
> > > > +g (char a)
> > > > +{
> > > > + return a == 'a' || a == 'E' || a == 'g' || a == 'i';
> > > > +}
> > > > +
> > > > +int
> > > > +main ()
> > > > +{
> > > > + for (int i = 0; i < 255; i++)
> > > > + if (f (i) != g (i))
> > > > + __builtin_abort ();
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +/* { dg-final { scan-assembler-not "memchr" } } */
> > > > diff --git a/gcc/testsuite/c-c++-common/pr103798-5.c
> > > > b/gcc/testsuite/c-c++-common/pr103798-5.c
> > > > new file mode 100644
> > > > index 00000000000..0d6487a13df
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/c-c++-common/pr103798-5.c
> > > > @@ -0,0 +1,26 @@
> > > > +/* { dg-do run { target int128 } } */
> > > > +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int f(char a)
> > > > +{
> > > > + return __builtin_memchr ("aEgiH", a, 5) == 0;
> > > > +}
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int g(char a)
> > > > +{
> > > > + return a != 'a' && a != 'E' && a != 'g' && a != 'i' && a != 'H';
> > > > +}
> > > > +
> > > > +int
> > > > +main ()
> > > > +{
> > > > + for (int i = 0; i < 255; i++)
> > > > + if (f (i) != g (i))
> > > > + __builtin_abort ();
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +/* { dg-final { scan-assembler-not "memchr" } } */
> > > > diff --git a/gcc/testsuite/c-c++-common/pr103798-6.c
> > > > b/gcc/testsuite/c-c++-common/pr103798-6.c
> > > > new file mode 100644
> > > > index 00000000000..5ccb5ee66e0
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/c-c++-common/pr103798-6.c
> > > > @@ -0,0 +1,27 @@
> > > > +/* { dg-do run { target int128 } } */
> > > > +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int f(char a)
> > > > +{
> > > > + return __builtin_memchr ("aEgiHx", a, 6) != 0;
> > > > +}
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int g(char a)
> > > > +{
> > > > + return (a == 'a' || a == 'E' || a == 'g' || a == 'i' || a == 'H'
> > > > + || a == 'x');
> > > > +}
> > > > +
> > > > +int
> > > > +main ()
> > > > +{
> > > > + for (int i = 0; i < 255; i++)
> > > > + if (f (i) != g (i))
> > > > + __builtin_abort ();
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +/* { dg-final { scan-assembler-not "memchr" } } */
> > > > diff --git a/gcc/testsuite/c-c++-common/pr103798-7.c
> > > > b/gcc/testsuite/c-c++-common/pr103798-7.c
> > > > new file mode 100644
> > > > index 00000000000..40fd38257d1
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/c-c++-common/pr103798-7.c
> > > > @@ -0,0 +1,27 @@
> > > > +/* { dg-do run { target int128 } } */
> > > > +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int f(char a)
> > > > +{
> > > > + return __builtin_memchr ("aEgiHjZ", a, 7) == 0;
> > > > +}
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int g(char a)
> > > > +{
> > > > + return (a != 'a' && a != 'E' && a != 'g' && a != 'i' && a != 'H'
> > > > + && a != 'j' && a != 'Z');
> > > > +}
> > > > +
> > > > +int
> > > > +main ()
> > > > +{
> > > > + for (int i = 0; i < 255; i++)
> > > > + if (f (i) != g (i))
> > > > + __builtin_abort ();
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +/* { dg-final { scan-assembler-not "memchr" } } */
> > > > diff --git a/gcc/testsuite/c-c++-common/pr103798-8.c
> > > > b/gcc/testsuite/c-c++-common/pr103798-8.c
> > > > new file mode 100644
> > > > index 00000000000..0841b18cea4
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/c-c++-common/pr103798-8.c
> > > > @@ -0,0 +1,27 @@
> > > > +/* { dg-do run { target int128 } } */
> > > > +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int f(int a)
> > > > +{
> > > > + return __builtin_memchr ("aEgiHx19ABC", a, 8) != 0;
> > > > +}
> > > > +
> > > > +__attribute__ ((weak))
> > > > +int g(char a)
> > > > +{
> > > > + return (a == 'a' || a == 'E' || a == 'g' || a == 'i' || a == 'H'
> > > > + || a == 'x' || a == '1' || a == '9');
> > > > +}
> > > > +
> > > > +int
> > > > +main ()
> > > > +{
> > > > + for (int i = 0; i < 255; i++)
> > > > + if (f (i + 256) != g (i + 256))
> > > > + __builtin_abort ();
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +/* { dg-final { scan-assembler-not "memchr" } } */
> > > > --
> > > > 2.36.1
> > > >
> >
> >
> >
> > --
> > H.J.
--
H.J.
