From a64c73a2f00ab4ab6a7485b34626d07ea2b2d519 Mon Sep 17 00:00:00 2001 From: Wilco Dijkstra Date: Sun, 20 Sep 2015 16:34:44 +0000 Subject: [PATCH] [AArch64][1/5] Reimplement aarch64_bitmask_imm 2015-09-20 Wilco Dijkstra * config/aarch64/aarch64.c (aarch64_bitmask_imm): Reimplement using faster algorithm. From-SVN: r227946 --- gcc/ChangeLog | 5 +++ gcc/config/aarch64/aarch64.c | 62 ++++++++++++++++++++++++++++++------ 2 files changed, 58 insertions(+), 9 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 8bb16d04bd3..9810ec6e345 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2015-09-20 Wilco Dijkstra + + * config/aarch64/aarch64.c (aarch64_bitmask_imm): Reimplement using + faster algorithm. + 2015-09-20 Jeff Law PR tree-optimization/47679 diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c index bbac271488f..2e7b9ec0567 100644 --- a/gcc/config/aarch64/aarch64.c +++ b/gcc/config/aarch64/aarch64.c @@ -3405,19 +3405,63 @@ aarch64_movw_imm (HOST_WIDE_INT val, machine_mode mode) || (val & (((HOST_WIDE_INT) 0xffff) << 16)) == val); } +/* Multipliers for repeating bitmasks of width 32, 16, 8, 4, and 2. */ + +static const unsigned HOST_WIDE_INT bitmask_imm_mul[] = + { + 0x0000000100000001ull, + 0x0001000100010001ull, + 0x0101010101010101ull, + 0x1111111111111111ull, + 0x5555555555555555ull, + }; + /* Return true if val is a valid bitmask immediate. */ + bool -aarch64_bitmask_imm (HOST_WIDE_INT val, machine_mode mode) +aarch64_bitmask_imm (HOST_WIDE_INT val_in, machine_mode mode) { - if (GET_MODE_SIZE (mode) < 8) - { - /* Replicate bit pattern. */ - val &= (HOST_WIDE_INT) 0xffffffff; - val |= val << 32; - } - return bsearch (&val, aarch64_bitmasks, AARCH64_NUM_BITMASKS, - sizeof (aarch64_bitmasks[0]), aarch64_bitmasks_cmp) != NULL; + unsigned HOST_WIDE_INT val, tmp, mask, first_one, next_one; + int bits; + + /* Check for a single sequence of one bits and return quickly if so. + The special cases of all ones and all zeroes returns false. */ + val = (unsigned HOST_WIDE_INT) val_in; + tmp = val + (val & -val); + + if (tmp == (tmp & -tmp)) + return (val + 1) > 1; + + /* Replicate 32-bit immediates so we can treat them as 64-bit. */ + if (mode == SImode) + val = (val << 32) | (val & 0xffffffff); + + /* Invert if the immediate doesn't start with a zero bit - this means we + only need to search for sequences of one bits. */ + if (val & 1) + val = ~val; + + /* Find the first set bit and set tmp to val with the first sequence of one + bits removed. Return success if there is a single sequence of ones. */ + first_one = val & -val; + tmp = val & (val + first_one); + + if (tmp == 0) + return true; + + /* Find the next set bit and compute the difference in bit position. */ + next_one = tmp & -tmp; + bits = clz_hwi (first_one) - clz_hwi (next_one); + mask = val ^ tmp; + + /* Check the bit position difference is a power of 2, and that the first + sequence of one bits fits within 'bits' bits. */ + if ((mask >> bits) != 0 || bits != (bits & -bits)) + return false; + + /* Check the sequence of one bits is repeated 64/bits times. */ + return val == mask * bitmask_imm_mul[__builtin_clz (bits) - 26]; } -- 2.30.2