[AArch64][1/5] Reimplement aarch64_bitmask_imm
2015-09-20 Wilco Dijkstra <wdijkstr@arm.com> * config/aarch64/aarch64.c (aarch64_bitmask_imm): Reimplement using faster algorithm. From-SVN: r227946
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2015-09-20 Wilco Dijkstra <wdijkstr@arm.com>
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* config/aarch64/aarch64.c (aarch64_bitmask_imm): Reimplement using
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faster algorithm.
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2015-09-20 Jeff Law <law@redhat.com>
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PR tree-optimization/47679
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@ -3405,19 +3405,63 @@ aarch64_movw_imm (HOST_WIDE_INT val, machine_mode mode)
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|| (val & (((HOST_WIDE_INT) 0xffff) << 16)) == val);
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}
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/* Multipliers for repeating bitmasks of width 32, 16, 8, 4, and 2. */
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static const unsigned HOST_WIDE_INT bitmask_imm_mul[] =
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{
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0x0000000100000001ull,
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0x0001000100010001ull,
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0x0101010101010101ull,
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0x1111111111111111ull,
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0x5555555555555555ull,
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};
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/* Return true if val is a valid bitmask immediate. */
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bool
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aarch64_bitmask_imm (HOST_WIDE_INT val, machine_mode mode)
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aarch64_bitmask_imm (HOST_WIDE_INT val_in, machine_mode mode)
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{
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if (GET_MODE_SIZE (mode) < 8)
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{
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/* Replicate bit pattern. */
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val &= (HOST_WIDE_INT) 0xffffffff;
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val |= val << 32;
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}
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return bsearch (&val, aarch64_bitmasks, AARCH64_NUM_BITMASKS,
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sizeof (aarch64_bitmasks[0]), aarch64_bitmasks_cmp) != NULL;
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unsigned HOST_WIDE_INT val, tmp, mask, first_one, next_one;
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int bits;
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/* Check for a single sequence of one bits and return quickly if so.
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The special cases of all ones and all zeroes returns false. */
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val = (unsigned HOST_WIDE_INT) val_in;
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tmp = val + (val & -val);
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if (tmp == (tmp & -tmp))
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return (val + 1) > 1;
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/* Replicate 32-bit immediates so we can treat them as 64-bit. */
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if (mode == SImode)
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val = (val << 32) | (val & 0xffffffff);
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/* Invert if the immediate doesn't start with a zero bit - this means we
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only need to search for sequences of one bits. */
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if (val & 1)
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val = ~val;
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/* Find the first set bit and set tmp to val with the first sequence of one
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bits removed. Return success if there is a single sequence of ones. */
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first_one = val & -val;
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tmp = val & (val + first_one);
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if (tmp == 0)
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return true;
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/* Find the next set bit and compute the difference in bit position. */
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next_one = tmp & -tmp;
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bits = clz_hwi (first_one) - clz_hwi (next_one);
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mask = val ^ tmp;
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/* Check the bit position difference is a power of 2, and that the first
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sequence of one bits fits within 'bits' bits. */
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if ((mask >> bits) != 0 || bits != (bits & -bits))
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return false;
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/* Check the sequence of one bits is repeated 64/bits times. */
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return val == mask * bitmask_imm_mul[__builtin_clz (bits) - 26];
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}
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