X-Git-Url: http://git.sourceforge.jp/view?a=blobdiff_plain;f=gcc%2Ftree-chrec.c;h=a74a49c3972af58b56aaaeeae3f7c66c6078810a;hb=4e8e57b0ce67551ca61b7883e73586ba805f0a61;hp=2d48093c0e29c79b8e44593e155212ac465d5496;hpb=9ce81338320f5a7e7df4a3c0179f2d4d8b12fd1f;p=pf3gnuchains%2Fgcc-fork.git diff --git a/gcc/tree-chrec.c b/gcc/tree-chrec.c index 2d48093c0e2..a74a49c3972 100644 --- a/gcc/tree-chrec.c +++ b/gcc/tree-chrec.c @@ -1,6 +1,6 @@ /* Chains of recurrences. - Copyright (C) 2003, 2004 Free Software Foundation, Inc. - Contributed by Sebastian Pop + Copyright (C) 2003, 2004, 2005, 2006 Free Software Foundation, Inc. + Contributed by Sebastian Pop This file is part of GCC. @@ -16,8 +16,8 @@ for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING. If not, write to the Free -Software Foundation, 59 Temple Place - Suite 330, Boston, MA -02111-1307, USA. */ +Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301, USA. */ /* This file implements operations on chains of recurrences. Chains of recurrences are used for modeling evolution functions of scalar @@ -28,13 +28,16 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA #include "system.h" #include "coretypes.h" #include "tm.h" -#include "errors.h" #include "ggc.h" #include "tree.h" +#include "real.h" #include "diagnostic.h" -#include "varray.h" +#include "cfgloop.h" +#include "tree-flow.h" #include "tree-chrec.h" #include "tree-pass.h" +#include "params.h" +#include "tree-scalar-evolution.h" @@ -60,7 +63,8 @@ chrec_fold_poly_cst (enum tree_code code, gcc_assert (cst); gcc_assert (TREE_CODE (poly) == POLYNOMIAL_CHREC); gcc_assert (!is_not_constant_evolution (cst)); - + gcc_assert (type == chrec_type (poly)); + switch (code) { case PLUS_EXPR: @@ -100,6 +104,8 @@ chrec_fold_plus_poly_poly (enum tree_code code, gcc_assert (poly1); gcc_assert (TREE_CODE (poly0) == POLYNOMIAL_CHREC); gcc_assert (TREE_CODE (poly1) == POLYNOMIAL_CHREC); + gcc_assert (chrec_type (poly0) == chrec_type (poly1)); + gcc_assert (type == chrec_type (poly0)); /* {a, +, b}_1 + {c, +, d}_2 -> {{a, +, b}_1 + c, +, d}_2, @@ -117,7 +123,9 @@ chrec_fold_plus_poly_poly (enum tree_code code, (CHREC_VARIABLE (poly1), chrec_fold_minus (type, poly0, CHREC_LEFT (poly1)), chrec_fold_multiply (type, CHREC_RIGHT (poly1), - convert (type, integer_minus_one_node))); + SCALAR_FLOAT_TYPE_P (type) + ? build_real (type, dconstm1) + : build_int_cst_type (type, -1))); } if (CHREC_VARIABLE (poly0) > CHREC_VARIABLE (poly1)) @@ -165,10 +173,15 @@ chrec_fold_multiply_poly_poly (tree type, tree poly0, tree poly1) { + tree t0, t1, t2; + int var; + gcc_assert (poly0); gcc_assert (poly1); gcc_assert (TREE_CODE (poly0) == POLYNOMIAL_CHREC); gcc_assert (TREE_CODE (poly1) == POLYNOMIAL_CHREC); + gcc_assert (chrec_type (poly0) == chrec_type (poly1)); + gcc_assert (type == chrec_type (poly0)); /* {a, +, b}_1 * {c, +, d}_2 -> {c*{a, +, b}_1, +, d}_2, {a, +, b}_2 * {c, +, d}_1 -> {a*{c, +, d}_1, +, b}_2, @@ -189,28 +202,27 @@ chrec_fold_multiply_poly_poly (tree type, /* poly0 and poly1 are two polynomials in the same variable, {a, +, b}_x * {c, +, d}_x -> {a*c, +, a*d + b*c + b*d, +, 2*b*d}_x. */ - return - build_polynomial_chrec - (CHREC_VARIABLE (poly0), - build_polynomial_chrec - (CHREC_VARIABLE (poly0), - - /* "a*c". */ - chrec_fold_multiply (type, CHREC_LEFT (poly0), CHREC_LEFT (poly1)), - /* "a*d + b*c + b*d". */ - chrec_fold_plus - (type, chrec_fold_multiply (type, CHREC_LEFT (poly0), CHREC_RIGHT (poly1)), - - chrec_fold_plus - (type, - chrec_fold_multiply (type, CHREC_RIGHT (poly0), CHREC_LEFT (poly1)), - chrec_fold_multiply (type, CHREC_RIGHT (poly0), CHREC_RIGHT (poly1))))), - - /* "2*b*d". */ - chrec_fold_multiply - (type, build_int_cst (NULL_TREE, 2), - chrec_fold_multiply (type, CHREC_RIGHT (poly0), CHREC_RIGHT (poly1)))); + /* "a*c". */ + t0 = chrec_fold_multiply (type, CHREC_LEFT (poly0), CHREC_LEFT (poly1)); + + /* "a*d + b*c + b*d". */ + t1 = chrec_fold_multiply (type, CHREC_LEFT (poly0), CHREC_RIGHT (poly1)); + t1 = chrec_fold_plus (type, t1, chrec_fold_multiply (type, + CHREC_RIGHT (poly0), + CHREC_LEFT (poly1))); + t1 = chrec_fold_plus (type, t1, chrec_fold_multiply (type, + CHREC_RIGHT (poly0), + CHREC_RIGHT (poly1))); + /* "2*b*d". */ + t2 = chrec_fold_multiply (type, CHREC_RIGHT (poly0), CHREC_RIGHT (poly1)); + t2 = chrec_fold_multiply (type, SCALAR_FLOAT_TYPE_P (type) + ? build_real (type, dconst2) + : build_int_cst (type, 2), t2); + + var = CHREC_VARIABLE (poly0); + return build_polynomial_chrec (var, t0, + build_polynomial_chrec (var, t1, t2)); } /* When the operands are automatically_generated_chrec_p, the fold has @@ -239,10 +251,8 @@ chrec_fold_automatically_generated_operands (tree op0, /* Fold the addition of two chrecs. */ static tree -chrec_fold_plus_1 (enum tree_code code, - tree type, - tree op0, - tree op1) +chrec_fold_plus_1 (enum tree_code code, tree type, + tree op0, tree op1) { if (automatically_generated_chrec_p (op0) || automatically_generated_chrec_p (op1)) @@ -283,15 +293,24 @@ chrec_fold_plus_1 (enum tree_code code, (CHREC_VARIABLE (op1), chrec_fold_minus (type, op0, CHREC_LEFT (op1)), chrec_fold_multiply (type, CHREC_RIGHT (op1), - convert (type, - integer_minus_one_node))); + SCALAR_FLOAT_TYPE_P (type) + ? build_real (type, dconstm1) + : build_int_cst_type (type, -1))); default: - if (tree_contains_chrecs (op0) - || tree_contains_chrecs (op1)) - return build (code, type, op0, op1); - else - return fold (build (code, type, op0, op1)); + { + int size = 0; + if ((tree_contains_chrecs (op0, &size) + || tree_contains_chrecs (op1, &size)) + && size < PARAM_VALUE (PARAM_SCEV_MAX_EXPR_SIZE)) + return build2 (code, type, op0, op1); + else if (size < PARAM_VALUE (PARAM_SCEV_MAX_EXPR_SIZE)) + return fold_build2 (code, type, + fold_convert (type, op0), + fold_convert (type, op1)); + else + return chrec_dont_know; + } } } } @@ -303,6 +322,10 @@ chrec_fold_plus (tree type, tree op0, tree op1) { + if (automatically_generated_chrec_p (op0) + || automatically_generated_chrec_p (op1)) + return chrec_fold_automatically_generated_operands (op0, op1); + if (integer_zerop (op0)) return op1; if (integer_zerop (op1)) @@ -318,6 +341,10 @@ chrec_fold_minus (tree type, tree op0, tree op1) { + if (automatically_generated_chrec_p (op0) + || automatically_generated_chrec_p (op1)) + return chrec_fold_automatically_generated_operands (op0, op1); + if (integer_zerop (op1)) return op0; @@ -347,7 +374,7 @@ chrec_fold_multiply (tree type, if (integer_onep (op1)) return op0; if (integer_zerop (op1)) - return convert (type, integer_zero_node); + return build_int_cst (type, 0); return build_polynomial_chrec (CHREC_VARIABLE (op0), @@ -360,7 +387,7 @@ chrec_fold_multiply (tree type, return op1; if (integer_zerop (op0)) - return convert (type, integer_zero_node); + return build_int_cst (type, 0); switch (TREE_CODE (op1)) { @@ -374,8 +401,8 @@ chrec_fold_multiply (tree type, if (integer_onep (op1)) return op0; if (integer_zerop (op1)) - return convert (type, integer_zero_node); - return fold (build (MULT_EXPR, type, op0, op1)); + return build_int_cst (type, 0); + return fold_build2 (MULT_EXPR, type, op0, op1); } } } @@ -384,63 +411,111 @@ chrec_fold_multiply (tree type, /* Operations. */ -/* The factorial. */ - +/* Evaluate the binomial coefficient. Return NULL_TREE if the intermediate + calculation overflows, otherwise return C(n,k) with type TYPE. */ + static tree -tree_fold_factorial (tree f) +tree_fold_binomial (tree type, tree n, unsigned int k) { - if (tree_int_cst_sgn (f) <= 0) - return integer_one_node; + unsigned HOST_WIDE_INT lidx, lnum, ldenom, lres, ldum; + HOST_WIDE_INT hidx, hnum, hdenom, hres, hdum; + unsigned int i; + tree res; + + /* Handle the most frequent cases. */ + if (k == 0) + return build_int_cst (type, 1); + if (k == 1) + return fold_convert (type, n); + + /* Check that k <= n. */ + if (TREE_INT_CST_HIGH (n) == 0 + && TREE_INT_CST_LOW (n) < k) + return NULL_TREE; + + /* Numerator = n. */ + lnum = TREE_INT_CST_LOW (n); + hnum = TREE_INT_CST_HIGH (n); + + /* Denominator = 2. */ + ldenom = 2; + hdenom = 0; + + /* Index = Numerator-1. */ + if (lnum == 0) + { + hidx = hnum - 1; + lidx = ~ (unsigned HOST_WIDE_INT) 0; + } else - return fold - (build (MULT_EXPR, integer_type_node, f, - tree_fold_factorial (fold (build (MINUS_EXPR, integer_type_node, - f, integer_one_node))))); -} + { + hidx = hnum; + lidx = lnum - 1; + } -/* The binomial coefficient. */ + /* Numerator = Numerator*Index = n*(n-1). */ + if (mul_double (lnum, hnum, lidx, hidx, &lnum, &hnum)) + return NULL_TREE; -static tree -tree_fold_binomial (tree n, - tree k) -{ - return fold - (build (EXACT_DIV_EXPR, integer_type_node, tree_fold_factorial (n), - fold (build (MULT_EXPR, integer_type_node, - tree_fold_factorial (k), - tree_fold_factorial - (fold (build (MINUS_EXPR, integer_type_node, - n, k))))))); + for (i = 3; i <= k; i++) + { + /* Index--. */ + if (lidx == 0) + { + hidx--; + lidx = ~ (unsigned HOST_WIDE_INT) 0; + } + else + lidx--; + + /* Numerator *= Index. */ + if (mul_double (lnum, hnum, lidx, hidx, &lnum, &hnum)) + return NULL_TREE; + + /* Denominator *= i. */ + mul_double (ldenom, hdenom, i, 0, &ldenom, &hdenom); + } + + /* Result = Numerator / Denominator. */ + div_and_round_double (EXACT_DIV_EXPR, 1, lnum, hnum, ldenom, hdenom, + &lres, &hres, &ldum, &hdum); + + res = build_int_cst_wide (type, lres, hres); + return int_fits_type_p (res, type) ? res : NULL_TREE; } /* Helper function. Use the Newton's interpolating formula for evaluating the value of the evolution function. */ static tree -chrec_evaluate (unsigned var, - tree chrec, - tree n, - tree k) +chrec_evaluate (unsigned var, tree chrec, tree n, unsigned int k) { - tree type = chrec_type (chrec); - tree binomial_n_k = tree_fold_binomial (n, k); - - if (TREE_CODE (chrec) == POLYNOMIAL_CHREC) + tree arg0, arg1, binomial_n_k; + tree type = TREE_TYPE (chrec); + + while (TREE_CODE (chrec) == POLYNOMIAL_CHREC + && CHREC_VARIABLE (chrec) > var) + chrec = CHREC_LEFT (chrec); + + if (TREE_CODE (chrec) == POLYNOMIAL_CHREC + && CHREC_VARIABLE (chrec) == var) { - if (CHREC_VARIABLE (chrec) > var) - return chrec_evaluate (var, CHREC_LEFT (chrec), n, k); - - if (CHREC_VARIABLE (chrec) == var) - return chrec_fold_plus - (type, - fold (build (MULT_EXPR, type, binomial_n_k, CHREC_LEFT (chrec))), - chrec_evaluate (var, CHREC_RIGHT (chrec), n, - fold (build (PLUS_EXPR, type, k, integer_one_node)))); - - return fold (build (MULT_EXPR, type, binomial_n_k, chrec)); + arg0 = chrec_evaluate (var, CHREC_RIGHT (chrec), n, k + 1); + if (arg0 == chrec_dont_know) + return chrec_dont_know; + binomial_n_k = tree_fold_binomial (type, n, k); + if (!binomial_n_k) + return chrec_dont_know; + arg1 = fold_build2 (MULT_EXPR, type, + CHREC_LEFT (chrec), binomial_n_k); + return chrec_fold_plus (type, arg0, arg1); } - else - return fold (build (MULT_EXPR, type, binomial_n_k, chrec)); + + binomial_n_k = tree_fold_binomial (type, n, k); + if (!binomial_n_k) + return chrec_dont_know; + + return fold_build2 (MULT_EXPR, type, chrec, binomial_n_k); } /* Evaluates "CHREC (X)" when the varying variable is VAR. @@ -468,24 +543,22 @@ chrec_apply (unsigned var, /* When the symbols are defined in an outer loop, it is possible to symbolically compute the apply, since the symbols are constants with respect to the varying loop. */ - || chrec_contains_symbols_defined_in_loop (chrec, var) - || chrec_contains_symbols (x)) + || chrec_contains_symbols_defined_in_loop (chrec, var)) return chrec_dont_know; - + if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, "(chrec_apply \n"); + if (TREE_CODE (x) == INTEGER_CST && SCALAR_FLOAT_TYPE_P (type)) + x = build_real_from_int_cst (type, x); + if (evolution_function_is_affine_p (chrec)) { /* "{a, +, b} (x)" -> "a + b*x". */ - if (TREE_CODE (CHREC_LEFT (chrec)) == INTEGER_CST - && integer_zerop (CHREC_LEFT (chrec))) - res = chrec_fold_multiply (type, CHREC_RIGHT (chrec), x); - - else - res = chrec_fold_plus (type, CHREC_LEFT (chrec), - chrec_fold_multiply (type, - CHREC_RIGHT (chrec), x)); + x = chrec_convert (type, x, NULL_TREE); + res = chrec_fold_multiply (type, CHREC_RIGHT (chrec), x); + if (!integer_zerop (CHREC_LEFT (chrec))) + res = chrec_fold_plus (type, CHREC_LEFT (chrec), res); } else if (TREE_CODE (chrec) != POLYNOMIAL_CHREC) @@ -494,8 +567,7 @@ chrec_apply (unsigned var, else if (TREE_CODE (x) == INTEGER_CST && tree_int_cst_sgn (x) == 1) /* testsuite/.../ssa-chrec-38.c. */ - res = chrec_evaluate (var, chrec, x, integer_zero_node); - + res = chrec_evaluate (var, chrec, x, 0); else res = chrec_dont_know; @@ -522,7 +594,9 @@ chrec_replace_initial_condition (tree chrec, { if (automatically_generated_chrec_p (chrec)) return chrec; - + + gcc_assert (chrec_type (chrec) == chrec_type (init_cond)); + switch (TREE_CODE (chrec)) { case POLYNOMIAL_CHREC: @@ -637,7 +711,7 @@ chrec_component_in_loop_num (tree chrec, } /* Returns the evolution part in LOOP_NUM. Example: the call - evolution_part_in_loop_num (1, {{0, +, 1}_1, +, 2}_1) returns + evolution_part_in_loop_num ({{0, +, 1}_1, +, 2}_1, 1) returns {1, +, 2}_1 */ tree @@ -648,7 +722,7 @@ evolution_part_in_loop_num (tree chrec, } /* Returns the initial condition in LOOP_NUM. Example: the call - initial_condition_in_loop_num ({{0, +, 1}_1, +, 2}_2, 1) returns + initial_condition_in_loop_num ({{0, +, 1}_1, +, 2}_2, 2) returns {0, +, 1}_1 */ tree @@ -668,14 +742,20 @@ reset_evolution_in_loop (unsigned loop_num, tree chrec, tree new_evol) { + gcc_assert (chrec_type (chrec) == chrec_type (new_evol)); + if (TREE_CODE (chrec) == POLYNOMIAL_CHREC && CHREC_VARIABLE (chrec) > loop_num) - return build - (TREE_CODE (chrec), - build_int_cst (NULL_TREE, CHREC_VARIABLE (chrec)), - reset_evolution_in_loop (loop_num, CHREC_LEFT (chrec), new_evol), - reset_evolution_in_loop (loop_num, CHREC_RIGHT (chrec), new_evol)); - + { + tree left = reset_evolution_in_loop (loop_num, CHREC_LEFT (chrec), + new_evol); + tree right = reset_evolution_in_loop (loop_num, CHREC_RIGHT (chrec), + new_evol); + return build3 (POLYNOMIAL_CHREC, TREE_TYPE (left), + build_int_cst (NULL_TREE, CHREC_VARIABLE (chrec)), + left, right); + } + while (TREE_CODE (chrec) == POLYNOMIAL_CHREC && CHREC_VARIABLE (chrec) == loop_num) chrec = CHREC_LEFT (chrec); @@ -703,7 +783,7 @@ chrec_merge (tree chrec1, if (chrec2 == chrec_not_analyzed_yet) return chrec1; - if (operand_equal_p (chrec1, chrec2, 0)) + if (eq_evolutions_p (chrec1, chrec2)) return chrec1; return chrec_dont_know; @@ -815,29 +895,34 @@ chrec_contains_undetermined (tree chrec) } } -/* Determines whether the tree EXPR contains chrecs. */ +/* Determines whether the tree EXPR contains chrecs, and increment + SIZE if it is not a NULL pointer by an estimation of the depth of + the tree. */ bool -tree_contains_chrecs (tree expr) +tree_contains_chrecs (tree expr, int *size) { if (expr == NULL_TREE) return false; + + if (size) + (*size)++; if (tree_is_chrec (expr)) return true; - + switch (TREE_CODE_LENGTH (TREE_CODE (expr))) { case 3: - if (tree_contains_chrecs (TREE_OPERAND (expr, 2))) + if (tree_contains_chrecs (TREE_OPERAND (expr, 2), size)) return true; case 2: - if (tree_contains_chrecs (TREE_OPERAND (expr, 1))) + if (tree_contains_chrecs (TREE_OPERAND (expr, 1), size)) return true; case 1: - if (tree_contains_chrecs (TREE_OPERAND (expr, 0))) + if (tree_contains_chrecs (TREE_OPERAND (expr, 0), size)) return true; default: @@ -845,6 +930,64 @@ tree_contains_chrecs (tree expr) } } +/* Recursive helper function. */ + +static bool +evolution_function_is_invariant_rec_p (tree chrec, int loopnum) +{ + if (evolution_function_is_constant_p (chrec)) + return true; + + if (TREE_CODE (chrec) == SSA_NAME + && expr_invariant_in_loop_p (current_loops->parray[loopnum], + chrec)) + return true; + + if (TREE_CODE (chrec) == POLYNOMIAL_CHREC) + { + if (CHREC_VARIABLE (chrec) == (unsigned) loopnum + || !evolution_function_is_invariant_rec_p (CHREC_RIGHT (chrec), + loopnum) + || !evolution_function_is_invariant_rec_p (CHREC_LEFT (chrec), + loopnum)) + return false; + return true; + } + + switch (TREE_CODE_LENGTH (TREE_CODE (chrec))) + { + case 2: + if (!evolution_function_is_invariant_rec_p (TREE_OPERAND (chrec, 1), + loopnum)) + return false; + + case 1: + if (!evolution_function_is_invariant_rec_p (TREE_OPERAND (chrec, 0), + loopnum)) + return false; + return true; + + default: + return false; + } + + return false; +} + +/* Return true if CHREC is invariant in loop LOOPNUM, false otherwise. */ + +bool +evolution_function_is_invariant_p (tree chrec, int loopnum) +{ + if (evolution_function_is_constant_p (chrec)) + return true; + + if (current_loops != NULL) + return evolution_function_is_invariant_rec_p (chrec, loopnum); + + return false; +} + /* Determine whether the given tree is an affine multivariate evolution. */ @@ -933,16 +1076,200 @@ evolution_function_is_univariate_p (tree chrec) } } +/* Returns the number of variables of CHREC. Example: the call + nb_vars_in_chrec ({{0, +, 1}_5, +, 2}_6) returns 2. */ + +unsigned +nb_vars_in_chrec (tree chrec) +{ + if (chrec == NULL_TREE) + return 0; + + switch (TREE_CODE (chrec)) + { + case POLYNOMIAL_CHREC: + return 1 + nb_vars_in_chrec + (initial_condition_in_loop_num (chrec, CHREC_VARIABLE (chrec))); + + default: + return 0; + } +} + +/* Returns true if TYPE is a type in that we cannot directly perform + arithmetics, even though it is a scalar type. */ + +static bool +avoid_arithmetics_in_type_p (tree type) +{ + /* Ada frontend uses subtypes -- an arithmetic cannot be directly performed + in the subtype, but a base type must be used, and the result then can + be casted to the subtype. */ + if (TREE_CODE (type) == INTEGER_TYPE && TREE_TYPE (type) != NULL_TREE) + return true; + + return false; +} + +static tree chrec_convert_1 (tree, tree, tree, bool); + +/* Converts BASE and STEP of affine scev to TYPE. LOOP is the loop whose iv + the scev corresponds to. AT_STMT is the statement at that the scev is + evaluated. USE_OVERFLOW_SEMANTICS is true if this function should assume that + the rules for overflow of the given language apply (e.g., that signed + arithmetics in C does not overflow) -- i.e., to use them to avoid unnecessary + tests, but also to enforce that the result follows them. Returns true if the + conversion succeeded, false otherwise. */ + +bool +convert_affine_scev (struct loop *loop, tree type, + tree *base, tree *step, tree at_stmt, + bool use_overflow_semantics) +{ + tree ct = TREE_TYPE (*step); + bool enforce_overflow_semantics; + bool must_check_src_overflow, must_check_rslt_overflow; + tree new_base, new_step; + + /* If we cannot perform arithmetic in TYPE, avoid creating an scev. */ + if (avoid_arithmetics_in_type_p (type)) + return false; + + /* In general, + (TYPE) (BASE + STEP * i) = (TYPE) BASE + (TYPE -- sign extend) STEP * i, + but we must check some assumptions. + + 1) If [BASE, +, STEP] wraps, the equation is not valid when precision + of CT is smaller than the precision of TYPE. For example, when we + cast unsigned char [254, +, 1] to unsigned, the values on left side + are 254, 255, 0, 1, ..., but those on the right side are + 254, 255, 256, 257, ... + 2) In case that we must also preserve the fact that signed ivs do not + overflow, we must additionally check that the new iv does not wrap. + For example, unsigned char [125, +, 1] casted to signed char could + become a wrapping variable with values 125, 126, 127, -128, -127, ..., + which would confuse optimizers that assume that this does not + happen. */ + must_check_src_overflow = TYPE_PRECISION (ct) < TYPE_PRECISION (type); + + enforce_overflow_semantics = (use_overflow_semantics + && nowrap_type_p (type)); + if (enforce_overflow_semantics) + { + /* We can avoid checking whether the result overflows in the following + cases: + + -- must_check_src_overflow is true, and the range of TYPE is superset + of the range of CT -- i.e., in all cases except if CT signed and + TYPE unsigned. + -- both CT and TYPE have the same precision and signedness, and we + verify instead that the source does not overflow (this may be + easier than verifying it for the result, as we may use the + information about the semantics of overflow in CT). */ + if (must_check_src_overflow) + { + if (TYPE_UNSIGNED (type) && !TYPE_UNSIGNED (ct)) + must_check_rslt_overflow = true; + else + must_check_rslt_overflow = false; + } + else if (TYPE_UNSIGNED (ct) == TYPE_UNSIGNED (type) + && TYPE_PRECISION (ct) == TYPE_PRECISION (type)) + { + must_check_rslt_overflow = false; + must_check_src_overflow = true; + } + else + must_check_rslt_overflow = true; + } + else + must_check_rslt_overflow = false; + + if (must_check_src_overflow + && scev_probably_wraps_p (*base, *step, at_stmt, loop, + use_overflow_semantics)) + return false; + + new_base = chrec_convert_1 (type, *base, at_stmt, + use_overflow_semantics); + /* The step must be sign extended, regardless of the signedness + of CT and TYPE. This only needs to be handled specially when + CT is unsigned -- to avoid e.g. unsigned char [100, +, 255] + (with values 100, 99, 98, ...) from becoming signed or unsigned + [100, +, 255] with values 100, 355, ...; the sign-extension is + performed by default when CT is signed. */ + new_step = *step; + if (TYPE_PRECISION (type) > TYPE_PRECISION (ct) && TYPE_UNSIGNED (ct)) + new_step = chrec_convert_1 (signed_type_for (ct), new_step, at_stmt, + use_overflow_semantics); + new_step = chrec_convert_1 (type, new_step, at_stmt, use_overflow_semantics); + + if (automatically_generated_chrec_p (new_base) + || automatically_generated_chrec_p (new_step)) + return false; + + if (must_check_rslt_overflow + /* Note that in this case we cannot use the fact that signed variables + do not overflow, as this is what we are verifying for the new iv. */ + && scev_probably_wraps_p (new_base, new_step, at_stmt, loop, false)) + return false; + + *base = new_base; + *step = new_step; + return true; +} -/* Convert the initial condition of chrec to type. */ +/* Convert CHREC to TYPE. When the analyzer knows the context in + which the CHREC is built, it sets AT_STMT to the statement that + contains the definition of the analyzed variable, otherwise the + conversion is less accurate: the information is used for + determining a more accurate estimation of the number of iterations. + By default AT_STMT could be safely set to NULL_TREE. + + The following rule is always true: TREE_TYPE (chrec) == + TREE_TYPE (CHREC_LEFT (chrec)) == TREE_TYPE (CHREC_RIGHT (chrec)). + An example of what could happen when adding two chrecs and the type + of the CHREC_RIGHT is different than CHREC_LEFT is: + + {(uint) 0, +, (uchar) 10} + + {(uint) 0, +, (uchar) 250} + + that would produce a wrong result if CHREC_RIGHT is not (uint): + + {(uint) 0, +, (uchar) 4} + + instead of + + {(uint) 0, +, (uint) 260} +*/ tree -chrec_convert (tree type, - tree chrec) +chrec_convert (tree type, tree chrec, tree at_stmt) { - tree ct; - + return chrec_convert_1 (type, chrec, at_stmt, true); +} + +/* Convert CHREC to TYPE. When the analyzer knows the context in + which the CHREC is built, it sets AT_STMT to the statement that + contains the definition of the analyzed variable, otherwise the + conversion is less accurate: the information is used for + determining a more accurate estimation of the number of iterations. + By default AT_STMT could be safely set to NULL_TREE. + + USE_OVERFLOW_SEMANTICS is true if this function should assume that + the rules for overflow of the given language apply (e.g., that signed + arithmetics in C does not overflow) -- i.e., to use them to avoid unnecessary + tests, but also to enforce that the result follows them. */ + +static tree +chrec_convert_1 (tree type, tree chrec, tree at_stmt, + bool use_overflow_semantics) +{ + tree ct, res; + tree base, step; + struct loop *loop; + if (automatically_generated_chrec_p (chrec)) return chrec; @@ -950,38 +1277,121 @@ chrec_convert (tree type, if (ct == type) return chrec; - if (TYPE_PRECISION (ct) < TYPE_PRECISION (type)) - return count_ev_in_wider_type (type, chrec); + if (!evolution_function_is_affine_p (chrec)) + goto keep_cast; - switch (TREE_CODE (chrec)) - { - case POLYNOMIAL_CHREC: - return build_polynomial_chrec (CHREC_VARIABLE (chrec), - chrec_convert (type, - CHREC_LEFT (chrec)), - chrec_convert (type, - CHREC_RIGHT (chrec))); + loop = current_loops->parray[CHREC_VARIABLE (chrec)]; + base = CHREC_LEFT (chrec); + step = CHREC_RIGHT (chrec); - default: - { - tree res = convert (type, chrec); - - /* Don't propagate overflows. */ - TREE_OVERFLOW (res) = 0; - if (CONSTANT_CLASS_P (res)) - TREE_CONSTANT_OVERFLOW (res) = 0; - return res; - } + if (convert_affine_scev (loop, type, &base, &step, at_stmt, + use_overflow_semantics)) + return build_polynomial_chrec (loop->num, base, step); + + /* If we cannot propagate the cast inside the chrec, just keep the cast. */ +keep_cast: + res = fold_convert (type, chrec); + + /* Don't propagate overflows. */ + if (CONSTANT_CLASS_P (res)) + { + TREE_CONSTANT_OVERFLOW (res) = 0; + TREE_OVERFLOW (res) = 0; } + + /* But reject constants that don't fit in their type after conversion. + This can happen if TYPE_MIN_VALUE or TYPE_MAX_VALUE are not the + natural values associated with TYPE_PRECISION and TYPE_UNSIGNED, + and can cause problems later when computing niters of loops. Note + that we don't do the check before converting because we don't want + to reject conversions of negative chrecs to unsigned types. */ + if (TREE_CODE (res) == INTEGER_CST + && TREE_CODE (type) == INTEGER_TYPE + && !int_fits_type_p (res, type)) + res = chrec_dont_know; + + return res; } -/* Returns the type of the chrec. */ +/* Convert CHREC to TYPE, without regard to signed overflows. Returns the new + chrec if something else than what chrec_convert would do happens, NULL_TREE + otherwise. */ -tree -chrec_type (tree chrec) +tree +chrec_convert_aggressive (tree type, tree chrec) { - if (automatically_generated_chrec_p (chrec)) + tree inner_type, left, right, lc, rc; + + if (automatically_generated_chrec_p (chrec) + || TREE_CODE (chrec) != POLYNOMIAL_CHREC) return NULL_TREE; - - return TREE_TYPE (chrec); + + inner_type = TREE_TYPE (chrec); + if (TYPE_PRECISION (type) > TYPE_PRECISION (inner_type)) + return NULL_TREE; + + /* If we cannot perform arithmetic in TYPE, avoid creating an scev. */ + if (avoid_arithmetics_in_type_p (type)) + return NULL_TREE; + + left = CHREC_LEFT (chrec); + right = CHREC_RIGHT (chrec); + lc = chrec_convert_aggressive (type, left); + if (!lc) + lc = chrec_convert (type, left, NULL_TREE); + rc = chrec_convert_aggressive (type, right); + if (!rc) + rc = chrec_convert (type, right, NULL_TREE); + + return build_polynomial_chrec (CHREC_VARIABLE (chrec), lc, rc); +} + +/* Returns true when CHREC0 == CHREC1. */ + +bool +eq_evolutions_p (tree chrec0, + tree chrec1) +{ + if (chrec0 == NULL_TREE + || chrec1 == NULL_TREE + || TREE_CODE (chrec0) != TREE_CODE (chrec1)) + return false; + + if (chrec0 == chrec1) + return true; + + switch (TREE_CODE (chrec0)) + { + case INTEGER_CST: + return operand_equal_p (chrec0, chrec1, 0); + + case POLYNOMIAL_CHREC: + return (CHREC_VARIABLE (chrec0) == CHREC_VARIABLE (chrec1) + && eq_evolutions_p (CHREC_LEFT (chrec0), CHREC_LEFT (chrec1)) + && eq_evolutions_p (CHREC_RIGHT (chrec0), CHREC_RIGHT (chrec1))); + default: + return false; + } +} + +/* Returns EV_GROWS if CHREC grows (assuming that it does not overflow), + EV_DECREASES if it decreases, and EV_UNKNOWN if we cannot determine + which of these cases happens. */ + +enum ev_direction +scev_direction (tree chrec) +{ + tree step; + + if (!evolution_function_is_affine_p (chrec)) + return EV_DIR_UNKNOWN; + + step = CHREC_RIGHT (chrec); + if (TREE_CODE (step) != INTEGER_CST) + return EV_DIR_UNKNOWN; + + if (tree_int_cst_sign_bit (step)) + return EV_DIR_DECREASES; + else + return EV_DIR_GROWS; }