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Fix bugs.

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L_fallback_32bits: section did not compute remainder correctly.
L_sub_loop1: section did not track r6 correctly.

Also correctly annotate which instructions need to set the flags.

BRANCH=none
BUG=none
TEST=now passes the tests in
http://www.hackersdelight.org/hdcodetxt/divmnu64.c.txt
Change-Id: Ib55a3bbbcee35c7f21dc67f51038783ea1d26f6c
Reviewed-on: https://chromium-review.googlesource.com/396397
Commit-Ready: Marius Schilder <mschilder@chromium.org>
Tested-by: Marius Schilder <mschilder@chromium.org>
Reviewed-by: Marius Schilder <mschilder@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
This commit is contained in:
Marius Schilder
2016-10-10 19:28:49 -07:00
committed by chrome-bot
parent 180ac77e16
commit d4bff62d36
1 changed files with 30 additions and 30 deletions
Download Patch File Download Diff File Expand all files Collapse all files

60
core/cortex-m/uldivmod.S
View File

@@ -68,7 +68,7 @@ __aeabi_uldivmod:
blo L_upper_result
L_denom_shift_loop1:
lsls r5, #1
lsl r5, #1
lsls r7, #1
bmi L_upper_result @ dont shift if overflow
cmp r1, r7
@@ -77,23 +77,26 @@ L_denom_shift_loop1:
L_upper_result:
mov r3, r1
mov r2, r0
movs r1, #0 @ upper result = 0
mov r1, #0 @ upper result = 0
mov r6, #0
L_sub_loop1:
cmp r3, r7
bcc L_dont_sub1 @ if (num>denom)
orr r1, r5 @ result(r7:r6) |= bitmask(r5)
subs r2, r6 @ num -= denom
sbcs r3, r7
bhs L_done_sub1
subs r3, r7 @ num -= denom
orrs r1, r5 @ result(r7:r6) |= bitmask(r5)
L_dont_sub1:
eor r1, r5 @ undo add mask
adds r2, r6 @ undo subtract
adc r3, r7
L_done_sub1:
lsrs r7, #1 @ denom(r7:r6) >>= 1
rrx r6, r6
lsrs r5, #1 @ bitmask(r5) >>= 1
bne L_sub_loop1
movs r5, #1
lsls r5, #31
movs r6, #0
rrx r5, r5
b L_lower_result
@@ -113,9 +116,9 @@ L_fallback_32bits:
mov r1, r0
udiv r0, r2 @ r0 = quotient
mul r3, r0, r2 @ r3 = quotient * divisor
subs r2, r3, r2 @ r2 = remainder
movs r1, #0
movs r3, #0
sub r2, r1, r3 @ r2 = remainder
mov r1, #0
mov r3, #0
bx lr
@@ -133,18 +136,17 @@ L_large_denom:
@ Shift left the denominator until it is greater than the numerator
movs r1, #0 @ high word of result is 0
movs r5, #1 @ bitmask
mov r1, #0 @ high word of result is 0
mov r5, #1 @ bitmask
adds r7, #0 @ dont shift if denominator would overflow
bmi L_lower_result
cmp r3, r7
blo L_lower_result
L_denom_shift_loop4:
lsls r5, #1
lsls r7, #1
lsls r6, #1
adcs r7, r1 @ r1=0
lsl r5, #1
lsls r6, #1 @ denom(r7:r6) <<= 1
adcs r7, r7
bmi L_lower_result @ dont shift if overflow
cmp r3, r7
bhs L_denom_shift_loop4
@@ -155,20 +157,18 @@ L_lower_result:
movs r0, #0
L_sub_loop4:
mov r4, r3
cmp r2, r6
sbcs r4, r7
bcc L_dont_sub4 @ if (num>denom)
orr r0, r5 @ result(r1:r0) |= bitmask(r5)
subs r2, r6 @ numerator -= denom
sbcs r3, r7
orrs r0, r5 @ result(r1:r0) |= bitmask(r5)
L_dont_sub4:
bhs L_done_sub4
lsls r4, r7, #31 @ denom(r7:r6) >>= 1
lsrs r6, #1
lsrs r7, #1
orrs r6, r4
eor r0, r5 @ undo add mask
adds r2, r6 @ undo subtract
adc r3, r7
L_done_sub4:
lsrs r7, #1 @ denom(r7:r6) >>= 1
rrx r6, r6
lsrs r5, #1 @ bitmask(r5) >>= 1
bne L_sub_loop4