/* Optimized strchr implementation for PowerPC64.
- Copyright (C) 1997, 1999, 2000, 2002, 2003, 2011 Free Software Foundation, Inc.
+ Copyright (C) 1997-2016 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
-#include <bp-sym.h>
-#include <bp-asm.h>
/* See strlen.s for comments on how this works. */
/* char * [r3] strchr (const char *s [r3] , int c [r4] ) */
-ENTRY (BP_SYM (strchr))
+ENTRY (strchr)
CALL_MCOUNT 2
#define rTMP1 r0
#define rRTN r3 /* outgoing result */
-/* Note: The Bounded pointer support in this code is broken. This code
- was inherited from PPC32 and that support was never completed.
- Currently PPC gcc does not support -fbounds-check or -fbounded-pointers.
- These artifacts are left in the code as a reminder in case we need
- bounded pointer support in the future. */
-#if __BOUNDED_POINTERS__
-# define rSTR r4
-# define rCHR r5 /* byte we're looking for, spread over the whole word */
-# define rWORD r8 /* the current word */
-#else
-# define rSTR r8 /* current word pointer */
-# define rCHR r4 /* byte we're looking for, spread over the whole word */
-# define rWORD r5 /* the current word */
-#endif
+#define rSTR r8 /* current word pointer */
+#define rCHR r4 /* byte we're looking for, spread over the whole word */
+#define rWORD r5 /* the current word */
#define rCLZB rCHR /* leading zero byte count */
#define rFEFE r6 /* constant 0xfefefefefefefeff (-0x0101010101010101) */
#define r7F7F r7 /* constant 0x7f7f7f7f7f7f7f7f */
#define rIGN r10 /* number of bits we should ignore in the first word */
#define rMASK r11 /* mask with the bits to ignore set to 0 */
#define rTMP3 r12
-
- CHECK_BOUNDS_LOW (rSTR, rTMP1, rTMP2)
- STORE_RETURN_BOUNDS (rTMP1, rTMP2)
+#define rTMP4 rIGN
+#define rTMP5 rMASK
dcbt 0,rRTN
- rlwimi rCHR, rCHR, 8, 16, 23
+ insrdi rCHR, rCHR, 8, 48
li rMASK, -1
- rlwimi rCHR, rCHR, 16, 0, 15
+ insrdi rCHR, rCHR, 16, 32
rlwinm rIGN, rRTN, 3, 26, 28
insrdi rCHR, rCHR, 32, 0
lis rFEFE, -0x101
add rFEFE, rFEFE, rTMP1
/* Test the first (partial?) word. */
ld rWORD, 0(rSTR)
+#ifdef __LITTLE_ENDIAN__
+ sld rMASK, rMASK, rIGN
+#else
srd rMASK, rMASK, rIGN
+#endif
orc rWORD, rWORD, rMASK
add rTMP1, rFEFE, rWORD
nor rTMP2, r7F7F, rWORD
- and. rTMP1, rTMP1, rTMP2
+ and. rTMP4, rTMP1, rTMP2
xor rTMP3, rCHR, rWORD
orc rTMP3, rTMP3, rMASK
b L(loopentry)
/* The loop. */
-L(loop):ldu rWORD, 8(rSTR)
- and. rTMP1, rTMP1, rTMP2
+L(loop):
+ ldu rWORD, 8(rSTR)
+ and. rTMP5, rTMP1, rTMP2
/* Test for 0. */
- add rTMP1, rFEFE, rWORD
- nor rTMP2, r7F7F, rWORD
+ add rTMP1, rFEFE, rWORD /* x - 0x01010101. */
+ nor rTMP2, r7F7F, rWORD /* ~(x | 0x7f7f7f7f) == ~x & 0x80808080. */
bne L(foundit)
- and. rTMP1, rTMP1, rTMP2
+ and. rTMP4, rTMP1, rTMP2 /* (x - 0x01010101) & ~x & 0x80808080. */
/* Start test for the bytes we're looking for. */
xor rTMP3, rCHR, rWORD
L(loopentry):
add rTMP1, rFEFE, rTMP3
nor rTMP2, r7F7F, rTMP3
beq L(loop)
+
/* There is a zero byte in the word, but may also be a matching byte (either
before or after the zero byte). In fact, we may be looking for a
- zero byte, in which case we return a match. We guess that this hasn't
- happened, though. */
-L(missed):
- and. rTMP1, rTMP1, rTMP2
+ zero byte, in which case we return a match. */
+ and. rTMP5, rTMP1, rTMP2
li rRTN, 0
- STORE_RETURN_VALUE (rSTR)
beqlr
-/* It did happen. Decide which one was first...
- I'm not sure if this is actually faster than a sequence of
- rotates, compares, and branches (we use it anyway because it's shorter). */
+/* At this point:
+ rTMP5 bytes are 0x80 for each match of c, 0 otherwise.
+ rTMP4 bytes are 0x80 for each match of 0, 0 otherwise.
+ But there may be false matches in the next most significant byte from
+ a true match due to carries. This means we need to recalculate the
+ matches using a longer method for big-endian. */
+#ifdef __LITTLE_ENDIAN__
+ addi rTMP1, rTMP5, -1
+ andc rTMP1, rTMP1, rTMP5
+ cntlzd rCLZB, rTMP1
+ addi rTMP2, rTMP4, -1
+ andc rTMP2, rTMP2, rTMP4
+ cmpld rTMP1, rTMP2
+ bgtlr
+ subfic rCLZB, rCLZB, 64-7
+#else
+/* I think we could reduce this by two instructions by keeping the "nor"
+ results from the loop for reuse here. See strlen.S tail. Similarly
+ one instruction could be pruned from L(foundit). */
and rFEFE, r7F7F, rWORD
- or rMASK, r7F7F, rWORD
+ or rTMP5, r7F7F, rWORD
and rTMP1, r7F7F, rTMP3
- or rIGN, r7F7F, rTMP3
+ or rTMP4, r7F7F, rTMP3
add rFEFE, rFEFE, r7F7F
add rTMP1, rTMP1, r7F7F
- nor rWORD, rMASK, rFEFE
- nor rTMP2, rIGN, rTMP1
+ nor rWORD, rTMP5, rFEFE
+ nor rTMP2, rTMP4, rTMP1
+ cntlzd rCLZB, rTMP2
cmpld rWORD, rTMP2
bgtlr
- cntlzd rCLZB, rTMP2
+#endif
srdi rCLZB, rCLZB, 3
add rRTN, rSTR, rCLZB
- CHECK_BOUNDS_HIGH_RTN (rSTR, rTMP2, tdlge)
- STORE_RETURN_VALUE (rSTR)
blr
L(foundit):
+#ifdef __LITTLE_ENDIAN__
+ addi rTMP1, rTMP5, -1
+ andc rTMP1, rTMP1, rTMP5
+ cntlzd rCLZB, rTMP1
+ subfic rCLZB, rCLZB, 64-7-64
+ sradi rCLZB, rCLZB, 3
+#else
and rTMP1, r7F7F, rTMP3
- or rIGN, r7F7F, rTMP3
+ or rTMP4, r7F7F, rTMP3
add rTMP1, rTMP1, r7F7F
- nor rTMP2, rIGN, rTMP1
+ nor rTMP2, rTMP4, rTMP1
cntlzd rCLZB, rTMP2
subi rSTR, rSTR, 8
srdi rCLZB, rCLZB, 3
+#endif
add rRTN, rSTR, rCLZB
- CHECK_BOUNDS_HIGH_RTN (rSTR, rTMP2, tdlge)
- STORE_RETURN_VALUE (rSTR)
blr
-END (BP_SYM (strchr))
+END (strchr)
-weak_alias (BP_SYM (strchr), BP_SYM (index))
+weak_alias (strchr, index)
libc_hidden_builtin_def (strchr)
projects / thirdparty / glibc.git / blobdiff