powerpc: Optimize POWER7 strcmp trailing checks
This patch optimized the POWER7 trailing check by avoiding using byte read operations and instead use the doubleword already readed with bitwise operations.
This commit is contained in:
Rajalakshmi Srinivasaraghavan
Adhemerval Zanella
parent
54dc546139
commit
72607db038
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@ -1,3 +1,9 @@
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2015-01-13 Rajalakshmi Srinivasaraghavan <raji@linux.vnet.ibm.com>
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Adhemerval Zanella <azanella@linux.vnet.ibm.com>
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* sysdeps/powerpc/powerpc64/power7/strcmp.S (strcmp): Optimize
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trailing byte check.
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2015-01-13 David S. Miller <davem@davemloft.net>
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* include/signal.h (__sigreturn): Guard with __USE_MISC.
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@ -25,122 +25,96 @@
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/* int [r3] strcmp (const char *s1 [r3], const char *s2 [r4]) */
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.machine power7
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EALIGN (strcmp, 4, 0)
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CALL_MCOUNT 2
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or r9, r3, r4
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rldicl. r10, r9, 0, 61 /* are s1 and s2 8 byte aligned..? */
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bne cr0, L(process_unaligned_bytes)
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li r5, 0
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.align 4
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/* process input parameters on double word aligned boundary */
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ld r9, 0(r4) /* load s2 at offset=0 */
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li r10, 0 /* load mask=0 */
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cmpb r10, r9, r10 /* compare bytes at s2 with mask */
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cmpdi cr7, r10, 0 /* is NULL found ..? is end of string HIT */
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bne cr7, L(process_unaligned_bytes) /* process byte by byte */
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ld r10, 0(r3) /* load s1 at offset=0 */
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li r8, 0 /* load mask=0 */
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cmpb r8, r10, r8 /* compare bytes at s1 with mask */
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cmpdi cr7, r8, 0 /* is NULL found ..? is end of string HIT */
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bne cr7, L(process_unaligned_bytes) /* process byte by byte */
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/*s1 and s2 does not contain NULL now , so compare all 8 bytes in a GO */
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cmpb r9, r10, r9 /* compare s1 and s2 */
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cmpdi cr7, r9, -1 /* compare result with 0xFFFFFFFFFFFFFFFF */
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bne cr7, L(process_unaligned_bytes) /* s1,s2 mismatch found */
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addi r5, r3, 8 /* save next offset of s2 */
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addi r11, r4, 8 /* save next offset of s1 */
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ld r8, 8(r4) /* load s2 at offset=8 */
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li r9, 0 /* load mask=0 */
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cmpb r9, r8, r9 /* compare bytes at s2 with mask */
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cmpdi cr7, r9, 0 /* NULL found ..? */
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bne cr7, L(processBytes)/* update input and process bytes one by one */
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mr r9, r4 /* save s2 */
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li r10, 0 /* load mask=0 */
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ld r7, 8(r3) /* load s1 at offset=8 */
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cmpb r6, r7, r10 /* compare bytes at s1 with mask */
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cmpdi cr7, r6, 0 /* is NULL found */
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bne cr7, L(processBytes)/* mismatch, so process one by one */
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L(unrollDword):
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cmpb r8, r7, r8 /* compare s1 and s2 */
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cmpdi cr7, r8, -1 /* compare result with 0xFFFFFFFFFFFFFFFF */
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bne cr7, L(processBytes)/* mismatch with s1 and s2 */
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ld r8,0(r3)
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ld r10,0(r4)
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cmpb r7,r8,r5
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cmpdi cr7,r7,0
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mr r9,r7
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bne cr7,L(null_found)
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cmpld cr7,r8,r10
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bne cr7,L(different)
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addi r5, r3, 16 /* save offset=16 of s1 */
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addi r4, r9, 16 /* save offset=16 of s2 */
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ld r8, 16(r9) /* load s2 at offset=16 */
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cmpb r7, r8, r10 /* compare bytes at s2 with mask */
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cmpdi cr7, r7, 0 /* NULL found ..? */
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bne cr7, L(update2processBytes)
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ld r8,8(r3)
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ld r10,8(r4)
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cmpb r7,r8,r5
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cmpdi cr7,r7,0
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mr r9,r7
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bne cr7,L(null_found)
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cmpld cr7,r8,r10
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bne cr7,L(different)
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ld r7, 16(r3) /* load s1 at offset=16 */
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cmpb r6, r7, r10 /* check s1 for end of string */
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cmpdi cr7, r6, 0 /* end of s1 ?,then handle byte by byte */
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bne 7,L(update2processBytes)
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ld r8,16(r3)
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ld r10,16(r4)
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cmpb r7,r8,r5
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cmpdi cr7,r7,0
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mr r9,r7
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bne cr7,L(null_found)
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cmpld cr7,r8,r10
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bne cr7,L(different)
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cmpb r8, r7, r8 /* compare s1 and s2 double words */
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cmpdi cr7, r8, -1 /* compare results with 0xFFFFFFFFFFFFFFFF */
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bne cr7,L(update2processBytes)
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ld r8,24(r3)
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ld r10,24(r4)
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cmpb r7,r8,r5
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cmpdi cr7,r7,0
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mr r9,r7
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bne cr7,L(null_found)
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cmpld cr7,r8,r10
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bne cr7,L(different)
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addi r5, r3, 24 /* update s1 to offset=24 */
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addi r4, r9, 24 /* update s2 to offset=24 */
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addi r3, r3, 32
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addi r4, r4, 32
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beq cr7, L(unrollDword)
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ld r8, 24(r9) /* load s2 */
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cmpb r7, r8, r10 /* compare s2 for NULL */
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cmpdi cr7, r7, 0 /* verify if s2 is ending now */
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bne cr7,L(update2processBytes)
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.align 4
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L(null_found):
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#ifdef __LITTLE_ENDIAN__
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neg r7,r9
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and r9,r9,r7
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li r7,-1
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cntlzd r9,r9
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subfic r9,r9,71
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sld r9,r7,r9
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#else
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cntlzd r9,r9
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li r7,-1
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addi r9,r9,8
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srd r9,r7,r9
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#endif
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or r8,r8,r9
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or r10,r10,r9
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ld r7, 24(r3) /* load s1 at offset=24 */
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cmpb r6, r7, r10 /* verify for NULL */
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cmpdi cr7, r6, 0 /* is NULL found */
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bne cr7, L(update2processBytes)
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L(different):
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cmpb r9,r8,r10
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#ifdef __LITTLE_ENDIAN__
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addi r7,r9,1
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andc r9,r7,r9
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cntlzd r9,r9
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subfic r9,r9,63
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#else
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not r9,r9
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cntlzd r9,r9
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subfic r9,r9,56
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#endif
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srd r3,r8,r9
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srd r10,r10,r9
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rldicl r10,r10,0,56
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rldicl r3,r3,0,56
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subf r3,r10,r3
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blr
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cmpb r8, r7, r8 /* compare s1 and s2 */
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cmpdi cr7, r8, -1 /* are s1 and s2 same ..? */
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bne cr7, L(update2processBytes)
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addi r7, r9, 32 /* update s2 to next double word */
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addi r3, r3, 32 /* update s1 to next double word */
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ld r8, 32(r9) /* load s2 */
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mr r4, r7 /* save s2 */
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cmpb r6, r8, r10 /* compare s2 with NULL */
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cmpdi cr7, r6, 0 /* end of s2 ..? */
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bne cr7, L(process_unaligned_bytes)
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ld r6, 0(r3) /* load and compare s1 for NULL */
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cmpb r5, r6, r10
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cmpdi cr7, r5, 0
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bne cr7, L(process_unaligned_bytes)
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cmpb r8, r6, r8 /* compare s1 and s2 */
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cmpdi cr7, r8, -1
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bne cr7, L(process_unaligned_bytes)
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addi r5, r3, 8 /* increment s1 and d2 here */
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addi r11, r9, 40
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ld r8, 40(r9) /* process s2 now */
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cmpb r9, r8, r10
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cmpdi cr7, r9, 0
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bne cr7, L(processBytes)
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mr r9, r7
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ld r7, 8(r3) /* process s1 now */
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cmpb r6, r7, r10
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cmpdi cr7, r6, 0
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beq cr7, L(unrollDword) /* unroll to compare s1 and s2 */
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L(processBytes):
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mr r4, r11 /* update input params */
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mr r3, r5
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.p2align 4
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.align 4
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L(process_unaligned_bytes):
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lbz r9, 0(r3) /* load byte from s1 */
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lbz r10, 0(r4) /* load byte from s2 */
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@ -172,24 +146,19 @@ L(process_unaligned_bytes):
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addi r4, r4, 4 /* increment s2 by unroll factor */
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beq cr6, L(process_unaligned_bytes) /* unroll byte processing */
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.p2align 4
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.align 4
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L(ComputeDiff):
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extsw r9, r9
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subf r10, r10, r9 /* compute s1 - s2 */
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extsw r3, r10
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blr /* return */
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.p2align 4
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.align 4
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L(diffOfNULL):
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li r9, 0
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subf r10, r10, r9 /* compute s1 - s2 */
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extsw r3, r10 /* sign extend result */
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blr /* return */
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.p2align 4
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L(update2processBytes):
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mr r3, r5 /* update and proceed */
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b L(process_unaligned_bytes)
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END (strcmp)
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libc_hidden_builtin_def (strcmp)
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