diff options
Diffstat (limited to 'gcc/tree.c')
| -rw-r--r-- | gcc/tree.c | 113 |
1 files changed, 113 insertions, 0 deletions
@@ -2214,6 +2214,119 @@ tree_floor_log2 (const_tree expr) : floor_log2 (low)); } +/* Return number of known trailing zero bits in EXPR, or, if the value of + EXPR is known to be zero, the precision of it's type. */ + +unsigned int +tree_ctz (const_tree expr) +{ + if (!INTEGRAL_TYPE_P (TREE_TYPE (expr)) + && !POINTER_TYPE_P (TREE_TYPE (expr))) + return 0; + + unsigned int ret1, ret2, prec = TYPE_PRECISION (TREE_TYPE (expr)); + switch (TREE_CODE (expr)) + { + case INTEGER_CST: + ret1 = tree_to_double_int (expr).trailing_zeros (); + return MIN (ret1, prec); + case SSA_NAME: + ret1 = get_nonzero_bits (expr).trailing_zeros (); + return MIN (ret1, prec); + case PLUS_EXPR: + case MINUS_EXPR: + case BIT_IOR_EXPR: + case BIT_XOR_EXPR: + case MIN_EXPR: + case MAX_EXPR: + ret1 = tree_ctz (TREE_OPERAND (expr, 0)); + if (ret1 == 0) + return ret1; + ret2 = tree_ctz (TREE_OPERAND (expr, 1)); + return MIN (ret1, ret2); + case POINTER_PLUS_EXPR: + ret1 = tree_ctz (TREE_OPERAND (expr, 0)); + ret2 = tree_ctz (TREE_OPERAND (expr, 1)); + /* Second operand is sizetype, which could be in theory + wider than pointer's precision. Make sure we never + return more than prec. */ + ret2 = MIN (ret2, prec); + return MIN (ret1, ret2); + case BIT_AND_EXPR: + ret1 = tree_ctz (TREE_OPERAND (expr, 0)); + ret2 = tree_ctz (TREE_OPERAND (expr, 1)); + return MAX (ret1, ret2); + case MULT_EXPR: + ret1 = tree_ctz (TREE_OPERAND (expr, 0)); + ret2 = tree_ctz (TREE_OPERAND (expr, 1)); + return MIN (ret1 + ret2, prec); + case LSHIFT_EXPR: + ret1 = tree_ctz (TREE_OPERAND (expr, 0)); + if (host_integerp (TREE_OPERAND (expr, 1), 1) + && ((unsigned HOST_WIDE_INT) tree_low_cst (TREE_OPERAND (expr, 1), 1) + < (unsigned HOST_WIDE_INT) prec)) + { + ret2 = tree_low_cst (TREE_OPERAND (expr, 1), 1); + return MIN (ret1 + ret2, prec); + } + return ret1; + case RSHIFT_EXPR: + if (host_integerp (TREE_OPERAND (expr, 1), 1) + && ((unsigned HOST_WIDE_INT) tree_low_cst (TREE_OPERAND (expr, 1), 1) + < (unsigned HOST_WIDE_INT) prec)) + { + ret1 = tree_ctz (TREE_OPERAND (expr, 0)); + ret2 = tree_low_cst (TREE_OPERAND (expr, 1), 1); + if (ret1 > ret2) + return ret1 - ret2; + } + return 0; + case TRUNC_DIV_EXPR: + case CEIL_DIV_EXPR: + case FLOOR_DIV_EXPR: + case ROUND_DIV_EXPR: + case EXACT_DIV_EXPR: + if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST + && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) == 1) + { + int l = tree_log2 (TREE_OPERAND (expr, 1)); + if (l >= 0) + { + ret1 = tree_ctz (TREE_OPERAND (expr, 0)); + ret2 = l; + if (ret1 > ret2) + return ret1 - ret2; + } + } + return 0; + CASE_CONVERT: + ret1 = tree_ctz (TREE_OPERAND (expr, 0)); + if (ret1 && ret1 == TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (expr, 0)))) + ret1 = prec; + return MIN (ret1, prec); + case SAVE_EXPR: + return tree_ctz (TREE_OPERAND (expr, 0)); + case COND_EXPR: + ret1 = tree_ctz (TREE_OPERAND (expr, 1)); + if (ret1 == 0) + return 0; + ret2 = tree_ctz (TREE_OPERAND (expr, 2)); + return MIN (ret1, ret2); + case COMPOUND_EXPR: + return tree_ctz (TREE_OPERAND (expr, 1)); + case ADDR_EXPR: + ret1 = get_pointer_alignment (CONST_CAST_TREE (expr)); + if (ret1 > BITS_PER_UNIT) + { + ret1 = ctz_hwi (ret1 / BITS_PER_UNIT); + return MIN (ret1, prec); + } + return 0; + default: + return 0; + } +} + /* Return 1 if EXPR is the real constant zero. Trailing zeroes matter for decimal float constants, so don't return 1 for them. */ |