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# commit 33ee81de05e83ce12f32a491270bb4c1611399c7
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# Author: Alan Modra <amodra@gmail.com>
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# Date: Sat Aug 17 18:40:48 2013 +0930
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#
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# PowerPC LE strnlen
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# http://sourceware.org/ml/libc-alpha/2013-08/msg00098.html
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#
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# The existing strnlen code has a number of defects, so this patch is more
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# than just adding little-endian support. The changes here are similar to
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# those for memchr.
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#
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# * sysdeps/powerpc/powerpc64/power7/strnlen.S (strnlen): Add
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# little-endian support. Remove unnecessary "are we done" tests.
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# Handle "s" wrapping around zero and extremely large "size".
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# Correct main loop count. Handle single left-over word from main
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# loop inline rather than by using small_loop. Correct comments.
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# Delete "zero" tail, use "end_max" instead.
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# * sysdeps/powerpc/powerpc32/power7/strnlen.S: Likewise.
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#
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diff -urN glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/power7/strnlen.S glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/power7/strnlen.S
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--- glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/power7/strnlen.S 2014-05-28 12:40:17.000000000 -0500
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+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/power7/strnlen.S 2014-05-28 12:44:52.000000000 -0500
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@@ -30,51 +30,47 @@
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add r7,r3,r4 /* Calculate the last acceptable address. */
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cmplwi r4,16
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li r0,0 /* Word with null chars. */
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+ addi r7,r7,-1
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ble L(small_range)
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- cmplw cr7,r3,r7 /* Is the address equal or less than r3? If
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- it's equal or less, it means size is either 0
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- or a negative number. */
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- ble cr7,L(proceed)
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-
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- li r7,-1 /* Make r11 the biggest if r4 <= 0. */
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-L(proceed):
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rlwinm r6,r3,3,27,28 /* Calculate padding. */
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lwz r12,0(r8) /* Load word from memory. */
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cmpb r10,r12,r0 /* Check for null bytes in DWORD1. */
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+#ifdef __LITTLE_ENDIAN__
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+ srw r10,r10,r6
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+ slw r10,r10,r6
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+#else
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slw r10,r10,r6
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srw r10,r10,r6
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+#endif
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cmplwi cr7,r10,0 /* If r10 == 0, no null's have been found. */
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bne cr7,L(done)
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- /* Are we done already? */
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- addi r9,r8,4
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- cmplw cr6,r9,r7
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- bge cr6,L(end_max)
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-
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+ clrrwi r7,r7,2 /* Address of last word. */
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mtcrf 0x01,r8
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/* Are we now aligned to a doubleword boundary? If so, skip to
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the main loop. Otherwise, go through the alignment code. */
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bt 29,L(loop_setup)
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- /* Handle DWORD2 of pair. */
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+ /* Handle WORD2 of pair. */
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lwzu r12,4(r8)
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cmpb r10,r12,r0
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cmplwi cr7,r10,0
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bne cr7,L(done)
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- /* Are we done already? */
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- addi r9,r8,4
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- cmplw cr6,r9,r7
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- bge cr6,L(end_max)
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-
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L(loop_setup):
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- sub r5,r7,r9
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+ /* The last word we want to read in the loop below is the one
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+ containing the last byte of the string, ie. the word at
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+ (s + size - 1) & ~3, or r7. The first word read is at
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+ r8 + 4, we read 2 * cnt words, so the last word read will
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+ be at r8 + 4 + 8 * cnt - 4. Solving for cnt gives
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+ cnt = (r7 - r8) / 8 */
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+ sub r5,r7,r8
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srwi r6,r5,3 /* Number of loop iterations. */
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mtctr r6 /* Setup the counter. */
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- b L(loop)
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- /* Main loop to look for the null byte backwards in the string. Since
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+
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+ /* Main loop to look for the null byte in the string. Since
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it's a small loop (< 8 instructions), align it to 32-bytes. */
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.p2align 5
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L(loop):
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@@ -90,15 +86,18 @@
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cmplwi cr7,r5,0
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bne cr7,L(found)
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bdnz L(loop)
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- /* We're here because the counter reached 0, and that means we
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- didn't have any matches for null in the whole range. Just return
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- the original size. */
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- addi r9,r8,4
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- cmplw cr6,r9,r7
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- blt cr6,L(loop_small)
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+
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+ /* We may have one more word to read. */
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+ cmplw cr6,r8,r7
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+ beq cr6,L(end_max)
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+
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+ lwzu r12,4(r8)
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+ cmpb r10,r12,r0
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+ cmplwi cr6,r10,0
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+ bne cr6,L(done)
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L(end_max):
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- sub r3,r7,r3
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+ mr r3,r4
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blr
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/* OK, one (or both) of the words contains a null byte. Check
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@@ -123,49 +122,56 @@
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We need to make sure the null char is *before* the end of the
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range. */
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L(done):
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- cntlzw r0,r10 /* Count leading zeroes before the match. */
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- srwi r0,r0,3 /* Convert leading zeroes to bytes. */
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- add r9,r8,r0
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- sub r6,r9,r3 /* Length until the match. */
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- cmplw r9,r7
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- bgt L(end_max)
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- mr r3,r6
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- blr
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-
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- .align 4
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-L(zero):
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- li r3,0
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+#ifdef __LITTLE_ENDIAN__
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+ addi r0,r10,-1
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+ andc r0,r0,r10
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+ popcntw r0,r0
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+#else
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+ cntlzw r0,r10 /* Count leading zeros before the match. */
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+#endif
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+ sub r3,r8,r3
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+ srwi r0,r0,3 /* Convert leading/trailing zeros to bytes. */
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+ add r3,r3,r0 /* Length until the match. */
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+ cmplw r3,r4
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+ blelr
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+ mr r3,r4
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blr
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-/* Deals with size <= 32. */
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+/* Deals with size <= 16. */
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.align 4
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L(small_range):
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cmplwi r4,0
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- beq L(zero)
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+ beq L(end_max)
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+
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+ clrrwi r7,r7,2 /* Address of last word. */
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rlwinm r6,r3,3,27,28 /* Calculate padding. */
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lwz r12,0(r8) /* Load word from memory. */
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cmpb r10,r12,r0 /* Check for null bytes in WORD1. */
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+#ifdef __LITTLE_ENDIAN__
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+ srw r10,r10,r6
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+ slw r10,r10,r6
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+#else
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slw r10,r10,r6
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srw r10,r10,r6
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+#endif
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cmplwi cr7,r10,0
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bne cr7,L(done)
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- addi r9,r8,4
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- cmplw r9,r7
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- bge L(end_max)
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- b L(loop_small)
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+ cmplw r8,r7
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+ beq L(end_max)
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.p2align 5
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L(loop_small):
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lwzu r12,4(r8)
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cmpb r10,r12,r0
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- addi r9,r8,4
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cmplwi cr6,r10,0
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bne cr6,L(done)
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- cmplw r9,r7
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- bge L(end_max)
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- b L(loop_small)
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+ cmplw r8,r7
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+ bne L(loop_small)
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+ mr r3,r4
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+ blr
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+
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END (BP_SYM (__strnlen))
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weak_alias (BP_SYM (__strnlen), BP_SYM(strnlen))
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libc_hidden_builtin_def (strnlen)
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diff -urN glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/power7/strnlen.S glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/power7/strnlen.S
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--- glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/power7/strnlen.S 2014-05-28 12:40:17.000000000 -0500
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+++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/power7/strnlen.S 2014-05-28 13:24:41.000000000 -0500
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@@ -26,33 +26,29 @@
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ENTRY (BP_SYM (__strnlen))
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CALL_MCOUNT 2
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dcbt 0,r3
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- clrrdi r8,r3,3
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+ clrrdi r8,r3,3
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add r7,r3,r4 /* Calculate the last acceptable address. */
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cmpldi r4,32
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li r0,0 /* Doubleword with null chars. */
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+ addi r7,r7,-1
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+
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/* If we have less than 33 bytes to search, skip to a faster code. */
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ble L(small_range)
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- cmpld cr7,r3,r7 /* Is the address equal or less than r3? If
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- it's equal or less, it means size is either 0
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- or a negative number. */
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- ble cr7,L(proceed)
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-
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- li r7,-1 /* Make r11 the biggest if r4 <= 0. */
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-L(proceed):
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rlwinm r6,r3,3,26,28 /* Calculate padding. */
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ld r12,0(r8) /* Load doubleword from memory. */
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cmpb r10,r12,r0 /* Check for null bytes in DWORD1. */
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+#ifdef __LITTLE_ENDIAN__
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+ srd r10,r10,r6
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+ sld r10,r10,r6
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+#else
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sld r10,r10,r6
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srd r10,r10,r6
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+#endif
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cmpldi cr7,r10,0 /* If r10 == 0, no null's have been found. */
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bne cr7,L(done)
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- /* Are we done already? */
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- addi r9,r8,8
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- cmpld cr6,r9,r7
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- bge cr6,L(end_max)
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-
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+ clrrdi r7,r7,3 /* Address of last doubleword. */
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mtcrf 0x01,r8
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/* Are we now aligned to a quadword boundary? If so, skip to
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the main loop. Otherwise, go through the alignment code. */
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@@ -65,17 +61,18 @@
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cmpldi cr7,r10,0
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bne cr7,L(done)
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- /* Are we done already? */
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- addi r9,r8,8
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- cmpld cr6,r9,r7
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- bge cr6,L(end_max)
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-
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L(loop_setup):
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- sub r5,r7,r9
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+ /* The last dword we want to read in the loop below is the one
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+ containing the last byte of the string, ie. the dword at
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+ (s + size - 1) & ~7, or r7. The first dword read is at
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+ r8 + 8, we read 2 * cnt dwords, so the last dword read will
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+ be at r8 + 8 + 16 * cnt - 8. Solving for cnt gives
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+ cnt = (r7 - r8) / 16 */
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+ sub r5,r7,r8
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srdi r6,r5,4 /* Number of loop iterations. */
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mtctr r6 /* Setup the counter. */
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- b L(loop)
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- /* Main loop to look for the null byte backwards in the string. Since
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+
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+ /* Main loop to look for the null byte in the string. Since
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it's a small loop (< 8 instructions), align it to 32-bytes. */
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.p2align 5
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L(loop):
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@@ -91,15 +88,18 @@
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cmpldi cr7,r5,0
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bne cr7,L(found)
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bdnz L(loop)
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- /* We're here because the counter reached 0, and that means we
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- didn't have any matches for null in the whole range. Just return
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- the original size. */
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- addi r9,r8,8
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- cmpld cr6,r9,r7
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- blt cr6,L(loop_small)
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+
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+ /* We may have one more dword to read. */
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+ cmpld cr6,r8,r7
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5de29b |
+ beq cr6,L(end_max)
|
|
|
5de29b |
+
|
|
|
5de29b |
+ ldu r12,8(r8)
|
|
|
5de29b |
+ cmpb r10,r12,r0
|
|
|
5de29b |
+ cmpldi cr6,r10,0
|
|
|
5de29b |
+ bne cr6,L(done)
|
|
|
5de29b |
|
|
|
5de29b |
L(end_max):
|
|
|
5de29b |
- sub r3,r7,r3
|
|
|
5de29b |
+ mr r3,r4
|
|
|
5de29b |
blr
|
|
|
5de29b |
|
|
|
5de29b |
/* OK, one (or both) of the doublewords contains a null byte. Check
|
|
|
5de29b |
@@ -121,52 +121,59 @@
|
|
|
5de29b |
/* r10 has the output of the cmpb instruction, that is, it contains
|
|
|
5de29b |
0xff in the same position as the null byte in the original
|
|
|
5de29b |
doubleword from the string. Use that to calculate the length.
|
|
|
5de29b |
- We need to make sure the null char is *before* the start of the
|
|
|
5de29b |
- range (since we're going backwards). */
|
|
|
5de29b |
+ We need to make sure the null char is *before* the end of the
|
|
|
5de29b |
+ range. */
|
|
|
5de29b |
L(done):
|
|
|
5de29b |
- cntlzd r0,r10 /* Count leading zeroes before the match. */
|
|
|
5de29b |
- srdi r0,r0,3 /* Convert leading zeroes to bytes. */
|
|
|
5de29b |
- add r9,r8,r0
|
|
|
5de29b |
- sub r6,r9,r3 /* Length until the match. */
|
|
|
5de29b |
- cmpld r9,r7
|
|
|
5de29b |
- bgt L(end_max)
|
|
|
5de29b |
- mr r3,r6
|
|
|
5de29b |
- blr
|
|
|
5de29b |
-
|
|
|
5de29b |
- .align 4
|
|
|
5de29b |
-L(zero):
|
|
|
5de29b |
- li r3,0
|
|
|
5de29b |
+#ifdef __LITTLE_ENDIAN__
|
|
|
5de29b |
+ addi r0,r10,-1
|
|
|
5de29b |
+ andc r0,r0,r10
|
|
|
5de29b |
+ popcntd r0,r0
|
|
|
5de29b |
+#else
|
|
|
5de29b |
+ cntlzd r0,r10 /* Count leading zeros before the match. */
|
|
|
5de29b |
+#endif
|
|
|
5de29b |
+ sub r3,r8,r3
|
|
|
5de29b |
+ srdi r0,r0,3 /* Convert leading/trailing zeros to bytes. */
|
|
|
5de29b |
+ add r3,r3,r0 /* Length until the match. */
|
|
|
5de29b |
+ cmpld r3,r4
|
|
|
5de29b |
+ blelr
|
|
|
5de29b |
+ mr r3,r4
|
|
|
5de29b |
blr
|
|
|
5de29b |
|
|
|
5de29b |
/* Deals with size <= 32. */
|
|
|
5de29b |
.align 4
|
|
|
5de29b |
L(small_range):
|
|
|
5de29b |
cmpldi r4,0
|
|
|
5de29b |
- beq L(zero)
|
|
|
5de29b |
+ beq L(end_max)
|
|
|
5de29b |
+
|
|
|
5de29b |
+ clrrdi r7,r7,3 /* Address of last doubleword. */
|
|
|
5de29b |
|
|
|
5de29b |
rlwinm r6,r3,3,26,28 /* Calculate padding. */
|
|
|
5de29b |
- ld r12,0(r8) /* Load word from memory. */
|
|
|
5de29b |
+ ld r12,0(r8) /* Load doubleword from memory. */
|
|
|
5de29b |
cmpb r10,r12,r0 /* Check for null bytes in DWORD1. */
|
|
|
5de29b |
+#ifdef __LITTLE_ENDIAN__
|
|
|
5de29b |
+ srd r10,r10,r6
|
|
|
5de29b |
+ sld r10,r10,r6
|
|
|
5de29b |
+#else
|
|
|
5de29b |
sld r10,r10,r6
|
|
|
5de29b |
srd r10,r10,r6
|
|
|
5de29b |
+#endif
|
|
|
5de29b |
cmpldi cr7,r10,0
|
|
|
5de29b |
bne cr7,L(done)
|
|
|
5de29b |
|
|
|
5de29b |
- addi r9,r8,8
|
|
|
5de29b |
- cmpld r9,r7
|
|
|
5de29b |
- bge L(end_max)
|
|
|
5de29b |
- b L(loop_small)
|
|
|
5de29b |
+ cmpld r8,r7
|
|
|
5de29b |
+ beq L(end_max)
|
|
|
5de29b |
|
|
|
5de29b |
.p2align 5
|
|
|
5de29b |
L(loop_small):
|
|
|
5de29b |
ldu r12,8(r8)
|
|
|
5de29b |
cmpb r10,r12,r0
|
|
|
5de29b |
- addi r9,r8,8
|
|
|
5de29b |
cmpldi cr6,r10,0
|
|
|
5de29b |
bne cr6,L(done)
|
|
|
5de29b |
- cmpld r9,r7
|
|
|
5de29b |
- bge L(end_max)
|
|
|
5de29b |
- b L(loop_small)
|
|
|
5de29b |
+ cmpld r8,r7
|
|
|
5de29b |
+ bne L(loop_small)
|
|
|
5de29b |
+ mr r3,r4
|
|
|
5de29b |
+ blr
|
|
|
5de29b |
+
|
|
|
5de29b |
END (BP_SYM (__strnlen))
|
|
|
5de29b |
weak_alias (BP_SYM (__strnlen), BP_SYM(strnlen))
|
|
|
5de29b |
libc_hidden_builtin_def (strnlen)
|