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* config/c4x/libgcc.S: (divqf3): Improve accuracy.

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From-SVN: r35335
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Michael Hayes 2000-07-30 08:12:12 +00:00 committed by Michael Hayes
parent 00c9e66354
commit 0ea1f6b69f
2 changed files with 19 additions and 10 deletions
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4
gcc/ChangeLog
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@ -1,3 +1,7 @@
2000-07-30 Michael Hayes <m.hayes@elec.canterbury.ac.nz>
* config/c4x/libgcc.S: (divqf3): Improve accuracy.
2000-07-27 Mark Mitchell <mark@codesourcery.com>
Put phi nodes after NOTE_INSN_BASIC_BLOCK.

25
gcc/config/c4x/libgcc.S
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@ -133,24 +133,29 @@ ___divqf3:
mpyf r1, r0 ; r0 = r[2] * (2.0 - r[2] * v) = r[3]
; End of 3rd iteration
or 080h, r0 ; add 1 lsb to result. needed when complemeting
; 1.0 / 2.0
rnd r0
rnd r0 ; Minimize error in x[3]'s LSBs
; Use modified last iteration
; r[4] = (r[3] * (1.0 - (v * r[3]))) + r[3]
mpyf3 r0, r3, r1 ; r1 = r[3] * v
subrf 1.0, r1 ; r1 = 1.0 - r[3] * v
mpyf r0, r1 ; r1 = r[3] * (1.0 - r[3] * v)
addf r1, r0 ; r0 = r[3] * (1.0 - r[3] * v) + r[3] = r[4]
rnd r0 ; Minimize error in x[4]'s LSBs
bud ar1 ; Delayed branch
addf r1, r0 ; r0 = r[3] * (1.0 - r[3] * v) + r[3] = r[4]
.if .REGPARM == 0
mpyf *-ar0(1), r0 ; Multiply by the dividend
.else
mpyf r2, r0 ; Multiply by the dividend
.endif
rnd r0
.if .REGPARM == 0
ldfu *-ar0(1), r2 ; Dividend in mem has only 24 bits significance
.else
rnd r2 ; Minimize error in reg dividend's LSBs
; since this may have 32 bit significance
.endif
mpyf r2, r0 ; Multiply by the dividend
rnd r0 ; Round result to 32 bits
; Branch occurs here
#endif