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bdc543e338
With the removal of divdi3 object from sparcv9-linux-gnu build, its definition came from libgcc and its functions internall calls .udiv. Since glibc also exports these symbols for compatibility reasons, it will end up creating PLT calls internally in libc.so. To avoid it, this patch uses the linker option --wrap to replace all the internal libc.so .udiv calls to the wrapper __wrap_.udiv. Along with strong alias in the udiv implementations, it makes linker do local calls. Checked on sparcv9-linux-gnu. * sysdeps/sparc/sparc32/Makefile (libc.so-gnulib): New rule. * sysdeps/sparc/sparc32/sparcv8/udiv.S (.udiv): Make a strong_alias to __wrap_.udiv. * sysdeps/sparc/sparc32/sparcv9/udiv.S (.udiv): Likewise. * sysdeps/sparc/sparc32/udiv.S (.udiv): Likewise.
348 lines
6.9 KiB
ArmAsm
348 lines
6.9 KiB
ArmAsm
/* This file is generated from divrem.m4; DO NOT EDIT! */
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/*
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* Division and remainder, from Appendix E of the Sparc Version 8
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* Architecture Manual, with fixes from Gordon Irlam.
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*/
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/*
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* Input: dividend and divisor in %o0 and %o1 respectively.
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*
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* m4 parameters:
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* .udiv name of function to generate
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* div div=div => %o0 / %o1; div=rem => %o0 % %o1
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* false false=true => signed; false=false => unsigned
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*
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* Algorithm parameters:
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* N how many bits per iteration we try to get (4)
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* WORDSIZE total number of bits (32)
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*
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* Derived constants:
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* TOPBITS number of bits in the top decade of a number
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*
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* Important variables:
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* Q the partial quotient under development (initially 0)
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* R the remainder so far, initially the dividend
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* ITER number of main division loop iterations required;
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* equal to ceil(log2(quotient) / N). Note that this
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* is the log base (2^N) of the quotient.
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* V the current comparand, initially divisor*2^(ITER*N-1)
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*
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* Cost:
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* Current estimate for non-large dividend is
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* ceil(log2(quotient) / N) * (10 + 7N/2) + C
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* A large dividend is one greater than 2^(31-TOPBITS) and takes a
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* different path, as the upper bits of the quotient must be developed
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* one bit at a time.
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*/
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#include <sysdep.h>
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#include <sys/trap.h>
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ENTRY(.udiv)
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! Ready to divide. Compute size of quotient; scale comparand.
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orcc %o1, %g0, %o5
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bne 1f
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mov %o0, %o3
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! Divide by zero trap. If it returns, return 0 (about as
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! wrong as possible, but that is what SunOS does...).
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ta ST_DIV0
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retl
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clr %o0
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1:
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cmp %o3, %o5 ! if %o1 exceeds %o0, done
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blu LOC(got_result) ! (and algorithm fails otherwise)
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clr %o2
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sethi %hi(1 << (32 - 4 - 1)), %g1
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cmp %o3, %g1
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blu LOC(not_really_big)
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clr %o4
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! Here the dividend is >= 2**(31-N) or so. We must be careful here,
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! as our usual N-at-a-shot divide step will cause overflow and havoc.
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! The number of bits in the result here is N*ITER+SC, where SC <= N.
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! Compute ITER in an unorthodox manner: know we need to shift V into
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! the top decade: so do not even bother to compare to R.
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1:
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cmp %o5, %g1
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bgeu 3f
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mov 1, %g2
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sll %o5, 4, %o5
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b 1b
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add %o4, 1, %o4
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! Now compute %g2.
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2: addcc %o5, %o5, %o5
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bcc LOC(not_too_big)
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add %g2, 1, %g2
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! We get here if the %o1 overflowed while shifting.
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! This means that %o3 has the high-order bit set.
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! Restore %o5 and subtract from %o3.
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sll %g1, 4, %g1 ! high order bit
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srl %o5, 1, %o5 ! rest of %o5
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add %o5, %g1, %o5
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b LOC(do_single_div)
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sub %g2, 1, %g2
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LOC(not_too_big):
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3: cmp %o5, %o3
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blu 2b
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nop
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be LOC(do_single_div)
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nop
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/* NB: these are commented out in the V8-Sparc manual as well */
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/* (I do not understand this) */
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! %o5 > %o3: went too far: back up 1 step
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! srl %o5, 1, %o5
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! dec %g2
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! do single-bit divide steps
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!
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! We have to be careful here. We know that %o3 >= %o5, so we can do the
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! first divide step without thinking. BUT, the others are conditional,
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! and are only done if %o3 >= 0. Because both %o3 and %o5 may have the high-
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! order bit set in the first step, just falling into the regular
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! division loop will mess up the first time around.
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! So we unroll slightly...
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LOC(do_single_div):
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subcc %g2, 1, %g2
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bl LOC(end_regular_divide)
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nop
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sub %o3, %o5, %o3
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mov 1, %o2
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b LOC(end_single_divloop)
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nop
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LOC(single_divloop):
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sll %o2, 1, %o2
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bl 1f
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srl %o5, 1, %o5
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! %o3 >= 0
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sub %o3, %o5, %o3
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b 2f
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add %o2, 1, %o2
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1: ! %o3 < 0
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add %o3, %o5, %o3
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sub %o2, 1, %o2
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2:
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LOC(end_single_divloop):
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subcc %g2, 1, %g2
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bge LOC(single_divloop)
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tst %o3
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b,a LOC(end_regular_divide)
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LOC(not_really_big):
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1:
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sll %o5, 4, %o5
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cmp %o5, %o3
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bleu 1b
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addcc %o4, 1, %o4
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be LOC(got_result)
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sub %o4, 1, %o4
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tst %o3 ! set up for initial iteration
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LOC(divloop):
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sll %o2, 4, %o2
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! depth 1, accumulated bits 0
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bl LOC(1.16)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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! depth 2, accumulated bits 1
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bl LOC(2.17)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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! depth 3, accumulated bits 3
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bl LOC(3.19)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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! depth 4, accumulated bits 7
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bl LOC(4.23)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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b 9f
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add %o2, (7*2+1), %o2
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LOC(4.23):
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! remainder is negative
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addcc %o3,%o5,%o3
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b 9f
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add %o2, (7*2-1), %o2
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LOC(3.19):
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! remainder is negative
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addcc %o3,%o5,%o3
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! depth 4, accumulated bits 5
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bl LOC(4.21)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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b 9f
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add %o2, (5*2+1), %o2
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LOC(4.21):
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! remainder is negative
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addcc %o3,%o5,%o3
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b 9f
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add %o2, (5*2-1), %o2
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LOC(2.17):
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! remainder is negative
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addcc %o3,%o5,%o3
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! depth 3, accumulated bits 1
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bl LOC(3.17)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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! depth 4, accumulated bits 3
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bl LOC(4.19)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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b 9f
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add %o2, (3*2+1), %o2
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LOC(4.19):
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! remainder is negative
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addcc %o3,%o5,%o3
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b 9f
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add %o2, (3*2-1), %o2
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LOC(3.17):
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! remainder is negative
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addcc %o3,%o5,%o3
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! depth 4, accumulated bits 1
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bl LOC(4.17)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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b 9f
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add %o2, (1*2+1), %o2
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LOC(4.17):
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! remainder is negative
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addcc %o3,%o5,%o3
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b 9f
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add %o2, (1*2-1), %o2
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LOC(1.16):
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! remainder is negative
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addcc %o3,%o5,%o3
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! depth 2, accumulated bits -1
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bl LOC(2.15)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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! depth 3, accumulated bits -1
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bl LOC(3.15)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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! depth 4, accumulated bits -1
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bl LOC(4.15)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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b 9f
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add %o2, (-1*2+1), %o2
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LOC(4.15):
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! remainder is negative
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addcc %o3,%o5,%o3
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b 9f
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add %o2, (-1*2-1), %o2
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LOC(3.15):
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! remainder is negative
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addcc %o3,%o5,%o3
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! depth 4, accumulated bits -3
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bl LOC(4.13)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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b 9f
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add %o2, (-3*2+1), %o2
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LOC(4.13):
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! remainder is negative
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addcc %o3,%o5,%o3
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b 9f
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add %o2, (-3*2-1), %o2
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LOC(2.15):
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! remainder is negative
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addcc %o3,%o5,%o3
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! depth 3, accumulated bits -3
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bl LOC(3.13)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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! depth 4, accumulated bits -5
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bl LOC(4.11)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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b 9f
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add %o2, (-5*2+1), %o2
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LOC(4.11):
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! remainder is negative
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addcc %o3,%o5,%o3
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b 9f
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add %o2, (-5*2-1), %o2
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LOC(3.13):
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! remainder is negative
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addcc %o3,%o5,%o3
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! depth 4, accumulated bits -7
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bl LOC(4.9)
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srl %o5,1,%o5
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! remainder is positive
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subcc %o3,%o5,%o3
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b 9f
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add %o2, (-7*2+1), %o2
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LOC(4.9):
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! remainder is negative
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addcc %o3,%o5,%o3
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b 9f
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add %o2, (-7*2-1), %o2
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9:
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LOC(end_regular_divide):
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subcc %o4, 1, %o4
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bge LOC(divloop)
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tst %o3
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bl,a LOC(got_result)
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! non-restoring fixup here (one instruction only!)
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sub %o2, 1, %o2
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LOC(got_result):
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retl
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mov %o2, %o0
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END(.udiv)
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strong_alias (.udiv, __wrap_.udiv)
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