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379 lines
10 KiB
379 lines
10 KiB
# 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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+ beq cr6,L(end_max) |
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+ |
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+ ldu r12,8(r8) |
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+ cmpb r10,r12,r0 |
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+ cmpldi 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 doublewords contains a null byte. Check |
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@@ -121,52 +121,59 @@ |
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/* r10 has the output of the cmpb instruction, that is, it contains |
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0xff in the same position as the null byte in the original |
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doubleword from the string. Use that to calculate the length. |
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- We need to make sure the null char is *before* the start of the |
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- range (since we're going backwards). */ |
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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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- cntlzd r0,r10 /* Count leading zeroes before the match. */ |
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- srdi 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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- cmpld 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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+ popcntd r0,r0 |
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+#else |
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+ cntlzd 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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+ srdi 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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+ cmpld 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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.align 4 |
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L(small_range): |
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cmpldi 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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+ clrrdi r7,r7,3 /* Address of last doubleword. */ |
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rlwinm r6,r3,3,26,28 /* Calculate padding. */ |
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- ld r12,0(r8) /* Load word from memory. */ |
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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 |
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bne cr7,L(done) |
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- addi r9,r8,8 |
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- cmpld r9,r7 |
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- bge L(end_max) |
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- b L(loop_small) |
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+ cmpld 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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ldu r12,8(r8) |
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cmpb r10,r12,r0 |
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- addi r9,r8,8 |
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cmpldi cr6,r10,0 |
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bne cr6,L(done) |
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- cmpld r9,r7 |
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- bge L(end_max) |
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- b L(loop_small) |
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+ cmpld 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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