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powerpc: Fix performance issues of strcmp power10
Current implementation of strcmp for power10 has performance regression for multiple small sizes and alignment combination. Most of these performance issues are fixed by this patch. The compare loop is unrolled and page crosses of unrolled loop is handled. Thanks to Paul E. Murphy for helping in fixing the performance issues. Signed-off-by: Amrita H S <amritahs@linux.vnet.ibm.com> Co-Authored-By: Paul E. Murphy <murphyp@linux.ibm.com> Reviewed-by: Rajalakshmi Srinivasaraghavan <rajis@linux.ibm.com>
This commit is contained in:
Amrita H S
Rajalakshmi Srinivasaraghavan
parent
73d92c4b73
commit
90bcc8721e
@ -62,7 +62,7 @@
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lxvl 32+v5,reg2,r0; \
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add reg1,reg1,len_reg; \
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add reg2,reg2,len_reg; \
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vcmpnezb. v7,v4,v5; \
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vcmpnezb v7,v4,v5; \
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vctzlsbb r6,v7; \
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cmpld cr7,r6,len_reg; \
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blt cr7,L(different); \
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@ -72,70 +72,110 @@
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.machine power9
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ENTRY_TOCLESS (STRCMP, 4)
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li r11,16
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/* eq bit of cr1 used as swap status flag to indicate if
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source pointers were swapped. */
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crclr 4*cr1+eq
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vspltisb v19,-1
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andi. r7,r3,15
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sub r7,r11,r7 /* r7(nalign1) = 16 - (str1 & 15). */
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andi. r9,r4,15
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sub r5,r11,r9 /* r5(nalign2) = 16 - (str2 & 15). */
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cmpld cr7,r7,r5
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beq cr7,L(same_aligned)
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blt cr7,L(nalign1_min)
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/* Swap r3 and r4, and r7 and r5 such that r3 and r7 hold the
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pointer which is closer to the next 16B boundary so that only
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one CHECK_N_BYTES is needed before entering the loop below. */
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mr r8,r4
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mr r4,r3
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mr r3,r8
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mr r12,r7
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mr r7,r5
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mr r5,r12
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crset 4*cr1+eq /* Set bit on swapping source pointers. */
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andi. r7,r3,4095
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andi. r8,r4,4095
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cmpldi cr0,r7,4096-16
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cmpldi cr1,r8,4096-16
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bgt cr0,L(crosses)
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bgt cr1,L(crosses)
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COMPARE_16(v4,v5,0)
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.p2align 5
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L(crosses):
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andi. r7,r3,15
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subfic r7,r7,16 /* r7(nalign1) = 16 - (str1 & 15). */
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andi. r9,r4,15
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subfic r5,r9,16 /* r5(nalign2) = 16 - (str2 & 15). */
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cmpld cr7,r7,r5
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beq cr7,L(same_aligned)
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blt cr7,L(nalign1_min)
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/* nalign2 is minimum and s2 pointer is aligned. */
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CHECK_N_BYTES(r3,r4,r5)
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/* Are we on the 64B hunk which crosses a page? */
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andi. r10,r3,63 /* Determine offset into 64B hunk. */
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andi. r8,r3,15 /* The offset into the 16B hunk. */
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neg r7,r3
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andi. r9,r7,15 /* Number of bytes after a 16B cross. */
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rlwinm. r7,r7,26,0x3F /* ((r3-4096))>>6&63. */
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beq L(compare_64_pagecross)
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mtctr r7
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b L(compare_64B_unaligned)
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/* nalign1 is minimum and s1 pointer is aligned. */
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L(nalign1_min):
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CHECK_N_BYTES(r3,r4,r7)
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/* Are we on the 64B hunk which crosses a page? */
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andi. r10,r4,63 /* Determine offset into 64B hunk. */
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andi. r8,r4,15 /* The offset into the 16B hunk. */
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neg r7,r4
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andi. r9,r7,15 /* Number of bytes after a 16B cross. */
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rlwinm. r7,r7,26,0x3F /* ((r4-4096))>>6&63. */
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beq L(compare_64_pagecross)
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mtctr r7
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.p2align 5
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L(s1_aligned):
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/* r9 and r5 is number of bytes to be read after and before
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page boundary correspondingly. */
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sub r5,r5,r7
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subfic r9,r5,16
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/* Now let r7 hold the count of quadwords which can be
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checked without crossing a page boundary. quadword offset is
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(str2>>4)&0xFF. */
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rlwinm r7,r4,28,0xFF
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/* Below check is required only for first iteration. For second
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iteration and beyond, the new loop counter is always 255. */
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cmpldi r7,255
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beq L(L3)
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/* Get the initial loop count by 255-((str2>>4)&0xFF). */
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subfic r11,r7,255
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L(compare_64B_unaligned):
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COMPARE_16(v4,v5,0)
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COMPARE_16(v4,v5,16)
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COMPARE_16(v4,v5,32)
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COMPARE_16(v4,v5,48)
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addi r3,r3,64
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addi r4,r4,64
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bdnz L(compare_64B_unaligned)
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.p2align 5
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L(L1):
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/* Cross the page boundary of s2, carefully. Only for first
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iteration we have to get the count of 64B blocks to be checked.
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From second iteration and beyond, loop counter is always 63. */
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L(compare_64_pagecross):
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li r11, 63
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mtctr r11
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.p2align 5
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L(L2):
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COMPARE_16(v4,v5,0) /* Load 16B blocks using lxv. */
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cmpldi r10,16
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ble L(cross_4)
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cmpldi r10,32
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ble L(cross_3)
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cmpldi r10,48
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ble L(cross_2)
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L(cross_1):
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CHECK_N_BYTES(r3,r4,r9)
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CHECK_N_BYTES(r3,r4,r8)
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COMPARE_16(v4,v5,0)
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COMPARE_16(v4,v5,16)
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COMPARE_16(v4,v5,32)
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addi r3,r3,48
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addi r4,r4,48
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b L(compare_64B_unaligned)
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L(cross_2):
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COMPARE_16(v4,v5,0)
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addi r3,r3,16
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addi r4,r4,16
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bdnz L(L2)
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/* Cross the page boundary of s2, carefully. */
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.p2align 5
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L(L3):
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CHECK_N_BYTES(r3,r4,r5)
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CHECK_N_BYTES(r3,r4,r9)
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li r11,255 /* Load the new loop counter. */
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b L(L1)
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CHECK_N_BYTES(r3,r4,r8)
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COMPARE_16(v4,v5,0)
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COMPARE_16(v4,v5,16)
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addi r3,r3,32
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addi r4,r4,32
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b L(compare_64B_unaligned)
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L(cross_3):
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COMPARE_16(v4,v5,0)
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COMPARE_16(v4,v5,16)
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addi r3,r3,32
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addi r4,r4,32
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CHECK_N_BYTES(r3,r4,r9)
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CHECK_N_BYTES(r3,r4,r8)
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COMPARE_16(v4,v5,0)
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addi r3,r3,16
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addi r4,r4,16
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b L(compare_64B_unaligned)
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L(cross_4):
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COMPARE_16(v4,v5,0)
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COMPARE_16(v4,v5,16)
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COMPARE_16(v4,v5,32)
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addi r3,r3,48
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addi r4,r4,48
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CHECK_N_BYTES(r3,r4,r9)
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CHECK_N_BYTES(r3,r4,r8)
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b L(compare_64B_unaligned)
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.p2align 5
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L(same_aligned):
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CHECK_N_BYTES(r3,r4,r7)
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/* Align s1 to 32B and adjust s2 address.
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@ -168,18 +208,7 @@ L(16B_aligned_loop):
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/* Calculate and return the difference. */
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L(different):
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vctzlsbb r6,v7
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vextubrx r5,r6,v4
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vextubrx r4,r6,v5
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bt 4*cr1+eq,L(swapped)
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subf r3,r4,r5
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blr
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/* If src pointers were swapped, then swap the
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indices and calculate the return value. */
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L(swapped):
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subf r3,r5,r4
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blr
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TAIL(v4,v5)
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.p2align 5
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L(32B_aligned_loop):
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