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tilegx: optimize string copy_byte() internal function 

We can use one "shufflebytes" instruction instead of 3 "bfins"
instructions to optimize the string functions.
This commit is contained in:
Chris Metcalf 2014-09-15 20:02:50 -04:00
parent 99d86ea324
commit 1c4c1a6f4d
2 changed files with 9 additions and 6 deletions
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4
ChangeLog
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@ -1,3 +1,7 @@
2014-10-02 Chris Metcalf <cmetcalf@tilera.com>
* sysdeps/tile/tilegx/string-endian.h (copy_byte): Optimize.
2014-10-06 Arjun Shankar <arjun.is@lostca.se>
* nptl/tst-setuid3.c: Write errors to stdout.

11
sysdeps/tile/tilegx/string-endian.h
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@ -36,12 +36,11 @@
#define REVCZ(x) __insn_ctz(x)
#endif
/* Create eight copies of the byte in a uint64_t. */
/* Create eight copies of the byte in a uint64_t. Byte Shuffle uses
the bytes of srcB as the index into the dest vector to select a
byte. With all indices of zero, the first byte is copied into all
the other bytes. */
static inline uint64_t copy_byte(uint8_t byte)
{
uint64_t word = byte;
word = __insn_bfins(word, word, 8, 15);
word = __insn_bfins(word, word, 16, 31);
word = __insn_bfins(word, word, 32, 63);
return word;
return __insn_shufflebytes(byte, 0, 0);
}