From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org,
Richard Henderson <richard.henderson@linaro.org>,
Jeff Law <jeffreyalaw@gmail.com>, Xi Ruoyao <xry111@xry111.site>,
Noah Goldstein <goldstein.w.n@gmail.com>
Subject: [PATCH v12 09/31] string: Improve generic stpcpy
Date: Thu, 2 Feb 2023 15:11:27 -0300 [thread overview]
Message-ID: <20230202181149.2181553-10-adhemerval.zanella@linaro.org> (raw)
In-Reply-To: <20230202181149.2181553-1-adhemerval.zanella@linaro.org>
It follows the strategy:
- Align the destination on word boundary using byte operations.
- If source is also word aligned, read a word per time, check for
null (using has_zero from string-fzb.h), and write the remaining
bytes.
- If source is not word aligned, loop by aligning the source, and
merging the result of two reads. Similar to aligned case,
check for null with has_zero, and write the remaining bytes if
null is found.
Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64-linux-gnu,
and powerpc-linux-gnu by removing the arch-specific assembly
implementation and disabling multi-arch (it covers both LE and BE
for 64 and 32 bits).
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
string/stpcpy.c | 92 +++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 86 insertions(+), 6 deletions(-)
diff --git a/string/stpcpy.c b/string/stpcpy.c
index 8df5065cfe..dd0fef12ef 100644
--- a/string/stpcpy.c
+++ b/string/stpcpy.c
@@ -15,12 +15,12 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
-
#define NO_MEMPCPY_STPCPY_REDIRECT
#include <string.h>
+#include <stdint.h>
+#include <memcopy.h>
+#include <string-fzb.h>
+#include <string-misc.h>
#undef __stpcpy
#undef stpcpy
@@ -29,12 +29,92 @@
# define STPCPY __stpcpy
#endif
+static __always_inline char *
+write_byte_from_word (op_t *dest, op_t word)
+{
+ char *d = (char *) dest;
+ for (size_t i = 0; i < OPSIZ; i++, ++d)
+ {
+ char c = extractbyte (word, i);
+ *d = c;
+ if (c == '\0')
+ break;
+ }
+ return d;
+}
+
+static __always_inline char *
+stpcpy_aligned_loop (op_t *restrict dst, const op_t *restrict src)
+{
+ op_t word;
+ while (1)
+ {
+ word = *src++;
+ if (has_zero (word))
+ break;
+ *dst++ = word;
+ }
+
+ return write_byte_from_word (dst, word);
+}
+
+static __always_inline char *
+stpcpy_unaligned_loop (op_t *restrict dst, const op_t *restrict src,
+ uintptr_t ofs)
+{
+ op_t w2a = *src++;
+ uintptr_t sh_1 = ofs * CHAR_BIT;
+ uintptr_t sh_2 = OPSIZ * CHAR_BIT - sh_1;
+
+ op_t w2 = MERGE (w2a, sh_1, (op_t)-1, sh_2);
+ if (!has_zero (w2))
+ {
+ op_t w2b;
+
+ /* Unaligned loop. The invariant is that W2B, which is "ahead" of W1,
+ does not contain end-of-string. Therefore it is safe (and necessary)
+ to read another word from each while we do not have a difference. */
+ while (1)
+ {
+ w2b = *src++;
+ w2 = MERGE (w2a, sh_1, w2b, sh_2);
+ /* Check if there is zero on w2a. */
+ if (has_zero (w2))
+ goto out;
+ *dst++ = w2;
+ if (has_zero (w2b))
+ break;
+ w2a = w2b;
+ }
+
+ /* Align the final partial of P2. */
+ w2 = MERGE (w2b, sh_1, 0, sh_2);
+ }
+
+out:
+ return write_byte_from_word (dst, w2);
+}
+
+
/* Copy SRC to DEST, returning the address of the terminating '\0' in DEST. */
char *
STPCPY (char *dest, const char *src)
{
- size_t len = strlen (src);
- return memcpy (dest, src, len + 1) + len;
+ /* Copy just a few bytes to make DEST aligned. */
+ size_t len = (-(uintptr_t) dest) % OPSIZ;
+ for (; len != 0; len--, ++dest)
+ {
+ char c = *src++;
+ *dest = c;
+ if (c == '\0')
+ return dest;
+ }
+
+ /* DEST is now aligned to op_t, SRC may or may not be. */
+ uintptr_t ofs = (uintptr_t) src % OPSIZ;
+ return ofs == 0 ? stpcpy_aligned_loop ((op_t*) dest, (const op_t *) src)
+ : stpcpy_unaligned_loop ((op_t*) dest,
+ (const op_t *) (src - ofs) , ofs);
}
weak_alias (__stpcpy, stpcpy)
libc_hidden_def (__stpcpy)
--
2.34.1
next prev parent reply other threads:[~2023-02-02 18:12 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-02 18:11 [PATCH v12 00/31] Improve generic string routines Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 01/31] Parameterize op_t from memcopy.h Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 02/31] Parameterize OP_T_THRES " Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 03/31] Add string vectorized find and detection functions Adhemerval Zanella
2023-02-03 0:24 ` Richard Henderson
2023-02-03 12:39 ` Adhemerval Zanella Netto
2023-02-03 13:40 ` Adhemerval Zanella Netto
2023-02-04 2:54 ` Richard Henderson
2023-02-02 18:11 ` [PATCH v12 04/31] string: Improve generic strlen Adhemerval Zanella
2023-02-03 23:23 ` Noah Goldstein
2023-02-02 18:11 ` [PATCH v12 05/31] string: Improve generic strchrnul Adhemerval Zanella
2023-02-03 23:23 ` Noah Goldstein
2023-02-02 18:11 ` [PATCH v12 06/31] string: Improve generic strchr Adhemerval Zanella
2023-02-03 23:24 ` Noah Goldstein
2023-02-04 2:58 ` Richard Henderson
2023-02-06 13:07 ` Adhemerval Zanella Netto
2023-02-02 18:11 ` [PATCH v12 07/31] string: Improve generic strcmp Adhemerval Zanella
2023-02-03 23:25 ` Noah Goldstein
2023-02-02 18:11 ` [PATCH v12 08/31] string: Improve generic strncmp Adhemerval Zanella
2023-02-03 0:34 ` Richard Henderson
2023-02-21 9:28 ` Szabolcs Nagy
2023-02-21 12:24 ` Adhemerval Zanella Netto
2023-02-02 18:11 ` Adhemerval Zanella [this message]
2023-02-03 23:26 ` [PATCH v12 09/31] string: Improve generic stpcpy Noah Goldstein
2023-02-02 18:11 ` [PATCH v12 10/31] string: Improve generic strcpy Adhemerval Zanella
2023-02-03 23:26 ` Noah Goldstein
2023-02-02 18:11 ` [PATCH v12 11/31] string: Improve generic memchr Adhemerval Zanella
2023-02-03 23:26 ` Noah Goldstein
2023-02-02 18:11 ` [PATCH v12 12/31] string: Improve generic strnlen with memchr Adhemerval Zanella
2023-02-03 23:27 ` Noah Goldstein
2023-02-02 18:11 ` [PATCH v12 13/31] string: Improve generic memrchr Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 14/31] string: Improve generic strrchr with memrchr and strlen Adhemerval Zanella
2023-02-04 3:06 ` Richard Henderson
2023-02-06 14:01 ` Adhemerval Zanella Netto
2023-02-02 18:11 ` [PATCH v12 15/31] hppa: Add memcopy.h Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 16/31] hppa: Add string-fza.h, string-fzc.h, and string-fzi.h Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 17/31] alpha: Add string-fza, string-fzb.h, string-fzi.h, and string-shift.h Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 18/31] arm: Add string-fza.h Adhemerval Zanella
2023-02-20 13:24 ` Szabolcs Nagy
2023-02-20 13:45 ` Szabolcs Nagy
2023-02-20 14:01 ` Adhemerval Zanella Netto
2023-02-20 16:12 ` Szabolcs Nagy
2023-02-02 18:11 ` [PATCH v12 19/31] powerpc: " Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 20/31] sh: Add string-fzb.h Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 21/31] riscv: Add string-fza.h and string-fzi.h Adhemerval Zanella
2023-02-03 19:47 ` Noah Goldstein
2023-02-06 16:14 ` Adhemerval Zanella Netto
2023-02-02 18:11 ` [PATCH v12 22/31] string: Hook up the default implementation on test-strlen Adhemerval Zanella
2023-02-03 23:30 ` Noah Goldstein
2023-02-06 17:36 ` Adhemerval Zanella Netto
2023-02-02 18:11 ` [PATCH v12 23/31] string: Hook up the default implementation on test-strnlen Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 24/31] string: Hook up the default implementation on test-strchr Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 25/31] string: Hook up the default implementation on test-strcmp Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 26/31] string: Hook up the default implementation on test-strncmp Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 27/31] string: Hook up the default implementation on test-stpcpy Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 28/31] string: Hook up the default implementation on test-strcpy Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 29/31] string: Hook up the default implementation on test-memchr Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 30/31] string: Hook up the default implementation on test-memrchr Adhemerval Zanella
2023-02-02 18:11 ` [PATCH v12 31/31] string: Hook up the default implementation on test-strrchr Adhemerval Zanella
2023-02-03 1:55 ` Richard Henderson
2023-02-02 18:17 ` [PATCH v12 00/31] Improve generic string routines Adhemerval Zanella Netto
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