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arc: libgcc: Import __udivdi3 & __udivmoddi4 to allow 64-bit division

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As reported by Kever here [1] we were unable to compile 64-bit division
code due to missing definition of __udivdi3().

Import its implementation and __udivmoddi4() as its direct dependency
from today's libgcc [2].

[1] https://patchwork.ozlabs.org/patch/1146845/
[2] 5d8723600b

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Kever Yang <kever.yang@rock-chips.com>
This commit is contained in:
Alexey Brodkin 2019-09-02 12:19:15 +03:00
parent 9ddaf1d516
commit fbf8c50163
1 changed files with 75 additions and 0 deletions
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75
arch/arc/lib/libgcc2.c
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@ -158,3 +158,78 @@ __umodsi3(long a, long b)
{
return udivmodsi4(a, b, 1);
}
UDWtype
__udivmoddi4(UDWtype n, UDWtype d, UDWtype *rp)
{
UDWtype q = 0, r = n, y = d;
UWtype lz1, lz2, i, k;
/*
* Implements align divisor shift dividend method. This algorithm
* aligns the divisor under the dividend and then perform number of
* test-subtract iterations which shift the dividend left. Number of
* iterations is k + 1 where k is the number of bit positions the
* divisor must be shifted left to align it under the dividend.
* quotient bits can be saved in the rightmost positions of the
* dividend as it shifts left on each test-subtract iteration.
*/
if (y <= r) {
lz1 = __builtin_clzll(d);
lz2 = __builtin_clzll(n);
k = lz1 - lz2;
y = (y << k);
/*
* Dividend can exceed 2 ^ (width - 1) - 1 but still be less
* than the aligned divisor. Normal iteration can drops the
* high order bit of the dividend. Therefore, first
* test-subtract iteration is a special case, saving its
* quotient bit in a separate location and not shifting
* the dividend.
*/
if (r >= y) {
r = r - y;
q = (1ULL << k);
}
if (k > 0) {
y = y >> 1;
/*
* k additional iterations where k regular test
* subtract shift dividend iterations are done.
*/
i = k;
do {
if (r >= y)
r = ((r - y) << 1) + 1;
else
r = (r << 1);
i = i - 1;
} while (i != 0);
/*
* First quotient bit is combined with the quotient
* bits resulting from the k regular iterations.
*/
q = q + r;
r = r >> k;
q = q - (r << k);
}
}
if (rp)
*rp = r;
return q;
}
UDWtype
__udivdi3(UDWtype n, UDWtype d)
{
return __udivmoddi4(n, d, (UDWtype *)0);
}