From 2d5c4a16dd833aa083f13dd3e78e3ef38afe6ebb Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Sat, 12 Nov 2022 09:35:16 +0100 Subject: [PATCH] range-op: Implement floating point division fold_range [PR107569] Here is the floating point division fold_range implementation, as I wrote in the last mail, we could outline some of the common parts into static methods with descriptive names and share them between foperator_div and foperator_mult. Regressions are +FAIL: gcc.dg/pr95115.c execution test +FAIL: libphobos.phobos/std/math/hardware.d execution test +FAIL: libphobos.phobos_shared/std/math/hardware.d execution test The first test is we have: # RANGE [frange] double [] +-NAN _3 = Inf / Inf; if (_3 ord _3) goto ; [INV] else goto ; [INV] : abort (); : before evrp, the range is correct, Inf / Inf is known NAN of unknown sign. evrp correctly folds _3 ord _3 into false and the _3 = Inf / Inf; remains in the IL, but then comes dse1 and removes it as dead statement. So, I think yet another example of the PR107608 problems where DCE? removes dead statements which raise floating point exceptions. And -fno-delete-dead-exceptions doesn't help. 2022-11-12 Jakub Jelinek PR tree-optimization/107569 * range-op-float.cc (foperator_div): New class. (floating_op_table::floating_op_table): Use foperator_div for RDIV_EXPR. --- gcc/range-op-float.cc | 178 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 178 insertions(+) diff --git a/gcc/range-op-float.cc b/gcc/range-op-float.cc index 8f411b8..047f360 100644 --- a/gcc/range-op-float.cc +++ b/gcc/range-op-float.cc @@ -2086,6 +2086,183 @@ class foperator_mult : public range_operator_float } } fop_mult; +class foperator_div : public range_operator_float +{ + void rv_fold (REAL_VALUE_TYPE &lb, REAL_VALUE_TYPE &ub, bool &maybe_nan, + tree type, + const REAL_VALUE_TYPE &lh_lb, + const REAL_VALUE_TYPE &lh_ub, + const REAL_VALUE_TYPE &rh_lb, + const REAL_VALUE_TYPE &rh_ub, + relation_kind) const final override + { + // +-0.0 / +-0.0 or +-INF / +-INF is a known NAN. + if ((real_iszero (&lh_lb) + && real_iszero (&lh_ub) + && real_iszero (&rh_lb) + && real_iszero (&rh_ub)) + || (real_isinf (&lh_lb) + && real_isinf (&lh_ub, real_isneg (&lh_lb)) + && real_isinf (&rh_lb) + && real_isinf (&rh_ub, real_isneg (&rh_lb)))) + { + real_nan (&lb, "", 0, TYPE_MODE (type)); + ub = lb; + maybe_nan = true; + return; + } + + bool both_maybe_zero = false; + bool both_maybe_inf = false; + bool must_have_signbit_zero = false; + bool must_have_signbit_nonzero = false; + + // If +-0.0 is in both ranges, it is a maybe NAN. + if (real_compare (LE_EXPR, &lh_lb, &dconst0) + && real_compare (GE_EXPR, &lh_ub, &dconst0) + && real_compare (LE_EXPR, &rh_lb, &dconst0) + && real_compare (GE_EXPR, &rh_ub, &dconst0)) + { + both_maybe_zero = true; + maybe_nan = true; + } + // If +-INF is in both ranges, it is a maybe NAN. + else if ((real_isinf (&lh_lb) || real_isinf (&lh_ub)) + && (real_isinf (&rh_lb) || real_isinf (&rh_ub))) + { + both_maybe_inf = true; + maybe_nan = true; + } + else + maybe_nan = false; + + if (real_isneg (&lh_lb) == real_isneg (&lh_ub) + && real_isneg (&rh_lb) == real_isneg (&rh_ub)) + { + if (real_isneg (&lh_lb) == real_isneg (&rh_ub)) + must_have_signbit_zero = true; + else + must_have_signbit_nonzero = true; + } + + // If dividend must be zero, the range is just +-0 + // (including if the divisor is +-INF). + // If divisor must be +-INF, the range is just +-0 + // (including if the dividend is zero). + if ((real_iszero (&lh_lb) && real_iszero (&lh_ub)) + || real_isinf (&rh_lb, false) + || real_isinf (&rh_ub, true)) + { + ub = lb = dconst0; + // If all the boundary signs are the same, [+0.0, +0.0]. + if (must_have_signbit_zero) + ; + // If divisor and dividend must have different signs, + // [-0.0, -0.0]. + else if (must_have_signbit_nonzero) + ub = lb = real_value_negate (&dconst0); + // Otherwise -> [-0.0, +0.0]. + else + lb = real_value_negate (&dconst0); + return; + } + + // If divisor must be zero, the range is just +-INF + // (including if the dividend is +-INF). + // If dividend must be +-INF, the range is just +-INF + // (including if the dividend is zero). + if ((real_iszero (&rh_lb) && real_iszero (&rh_ub)) + || real_isinf (&lh_lb, false) + || real_isinf (&lh_ub, true)) + { + // If all the boundary signs are the same, [+INF, +INF]. + if (must_have_signbit_zero) + ub = lb = dconstinf; + // If divisor and dividend must have different signs, + // [-INF, -INF]. + else if (must_have_signbit_nonzero) + ub = lb = dconstninf; + // Otherwise -> [-INF, +INF] (-INF or +INF). + else + { + lb = dconstninf; + ub = dconstinf; + } + return; + } + + // Otherwise if both operands may be zero, divisor could be + // nextafter(0.0, +-1.0) and dividend +-0.0 + // in which case result is going to INF or vice versa and + // result +0.0. So, all we can say for that case is if the + // signs of divisor and dividend are always the same we have + // [+0.0, +INF], if they are always different we have + // [-INF, -0.0]. If they vary, VARING. + // If both may be +-INF, divisor could be INF and dividend FLT_MAX, + // in which case result is going to INF or vice versa and + // result +0.0. So, all we can say for that case is if the + // signs of divisor and dividend are always the same we have + // [+0.0, +INF], if they are always different we have + // [-INF, -0.0]. If they vary, VARYING. + if (both_maybe_zero || both_maybe_inf) + { + if (must_have_signbit_zero) + { + lb = dconst0; + ub = dconstinf; + } + else if (must_have_signbit_nonzero) + { + lb = dconstninf; + ub = real_value_negate (&dconst0); + } + else + { + lb = dconstninf; + ub = dconstinf; + } + return; + } + + REAL_VALUE_TYPE cp[8]; + // Do a cross-division. At this point none of the divisions should + // produce a NAN. + gcc_assert (!maybe_nan); + frange_arithmetic (RDIV_EXPR, type, cp[0], lh_lb, rh_lb, dconstninf); + frange_arithmetic (RDIV_EXPR, type, cp[1], lh_lb, rh_ub, dconstninf); + frange_arithmetic (RDIV_EXPR, type, cp[2], lh_ub, rh_lb, dconstninf); + frange_arithmetic (RDIV_EXPR, type, cp[3], lh_ub, rh_ub, dconstninf); + frange_arithmetic (RDIV_EXPR, type, cp[4], lh_lb, rh_lb, dconstinf); + frange_arithmetic (RDIV_EXPR, type, cp[5], lh_lb, rh_ub, dconstinf); + frange_arithmetic (RDIV_EXPR, type, cp[6], lh_ub, rh_lb, dconstinf); + frange_arithmetic (RDIV_EXPR, type, cp[7], lh_ub, rh_ub, dconstinf); + + for (int i = 1; i < 4; ++i) + { + if (real_less (&cp[i], &cp[0]) + || (real_iszero (&cp[0]) && real_isnegzero (&cp[i]))) + std::swap (cp[i], cp[0]); + if (real_less (&cp[4], &cp[i + 4]) + || (real_isnegzero (&cp[4]) && real_iszero (&cp[i + 4]))) + std::swap (cp[i + 4], cp[4]); + } + lb = cp[0]; + ub = cp[4]; + + // If divisor may be zero (but is not known to be only zero), + // and dividend can't be zero, the range can go up to -INF or +INF + // depending on the signs. + if (real_compare (LE_EXPR, &rh_lb, &dconst0) + && real_compare (GE_EXPR, &rh_ub, &dconst0)) + { + if (!must_have_signbit_zero) + real_inf (&lb, true); + if (!must_have_signbit_nonzero) + real_inf (&ub, false); + } + } +} fop_div; + // Instantiate a range_op_table for floating point operations. static floating_op_table global_floating_table; @@ -2121,6 +2298,7 @@ floating_op_table::floating_op_table () set (PLUS_EXPR, fop_plus); set (MINUS_EXPR, fop_minus); set (MULT_EXPR, fop_mult); + set (RDIV_EXPR, fop_div); } // Return a pointer to the range_operator_float instance, if there is -- 2.7.4