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author | Kugan Vivekanandarajah <kuganv@linaro.org> | 2013-11-27 12:17:05 +0000 |
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committer | Christophe Lyon <clyon@gcc.gnu.org> | 2013-11-27 13:17:05 +0100 |
commit | 30b8f78b72ce08c5fdc00eead80282ca12e433ac (patch) | |
tree | 2bce9a61019a73e1ac15aec945ce47ae5c2c3b72 /libgcc/libgcc2.c | |
parent | 536da97c4eaa6ac7b8a65205dafd23c904395a39 (diff) | |
download | gcc-30b8f78b72ce08c5fdc00eead80282ca12e433ac.zip gcc-30b8f78b72ce08c5fdc00eead80282ca12e433ac.tar.gz gcc-30b8f78b72ce08c5fdc00eead80282ca12e433ac.tar.bz2 |
tm.texi.in (TARGET_HAS_NO_HW_DIVIDE): Define.
2013-11-27 Kugan Vivekanandarajah <kuganv@linaro.org>
gcc/
* doc/tm.texi.in (TARGET_HAS_NO_HW_DIVIDE): Define.
* doc/tm.texi (TARGET_HAS_NO_HW_DIVIDE): Regenerate.
libgcc/
* libgcc2.c (__udivmoddi4): Define new implementation when
TARGET_HAS_NO_HW_DIVIDE is defined, for processors without any
divide instructions.
From-SVN: r205444
Diffstat (limited to 'libgcc/libgcc2.c')
-rw-r--r-- | libgcc/libgcc2.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/libgcc/libgcc2.c b/libgcc/libgcc2.c index bec411b..8c4cc6a 100644 --- a/libgcc/libgcc2.c +++ b/libgcc/libgcc2.c @@ -934,6 +934,74 @@ __parityDI2 (UDWtype x) #endif #ifdef L_udivmoddi4 +#ifdef TARGET_HAS_NO_HW_DIVIDE + +#if (defined (L_udivdi3) || defined (L_divdi3) || \ + defined (L_umoddi3) || defined (L_moddi3)) +static inline __attribute__ ((__always_inline__)) +#endif +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; +} +#else #if (defined (L_udivdi3) || defined (L_divdi3) || \ defined (L_umoddi3) || defined (L_moddi3)) @@ -1152,6 +1220,7 @@ __udivmoddi4 (UDWtype n, UDWtype d, UDWtype *rp) return ww.ll; } #endif +#endif #ifdef L_divdi3 DWtype |