459a9b5949
Because lwzu or stwu moves the pointer, I can remove an addi instruction from the loop, so the loop is slightly faster. I wrote a benchmark in Modula-2 that exercises some of these loops. I measured its time on my old PowerPC Mac. Its user time decreases from 8.401s to 8.217s with the tighter loops.
27 lines
608 B
ArmAsm
27 lines
608 B
ArmAsm
.sect .text
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! Compare sets a, b.
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! Stack: ( a b size -- result )
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! Result is 0 if equal, nonzero if not equal.
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.define .cms
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.cms:
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lwz r3, 0(sp) ! r3 = size of each set
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srwi r7, r3, 2
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mtspr ctr, r7 ! ctr = size / 4
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add r4, sp, r3 ! r4 = pointer before set a
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add r7, r4, r3 ! r7 = pointer to store result
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! Loop with r4 in a set a and sp in set b.
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1: lwzu r5, 4(r4)
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lwzu r6, 4(sp)
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cmpw r5, r6 ! compare words
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bne 2f ! branch if not equal
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bdnz 1b ! loop ctr times
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li r3, 0 ! equal: return 0
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b 3f
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2: li r3, 1 ! not equal: return 1
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3: mr sp, r7
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stw r3, 0(sp) ! push result
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