#include "tree-eh.h"
#include "ssa.h"
#include "internal-fn.h"
+#include "range-op.h"
+#include "vr-values.h"
static struct datadep_stats
{
dump_ddrs (stderr, ddrs);
}
+/* If RESULT_RANGE is nonnull, set *RESULT_RANGE to the range of
+ OP0 CODE OP1, where:
+
+ - OP0 CODE OP1 has integral type TYPE
+ - the range of OP0 is given by OP0_RANGE and
+ - the range of OP1 is given by OP1_RANGE.
+
+ Independently of RESULT_RANGE, try to compute:
+
+ DELTA = ((sizetype) OP0 CODE (sizetype) OP1)
+ - (sizetype) (OP0 CODE OP1)
+
+ as a constant and subtract DELTA from the ssizetype constant in *OFF.
+ Return true on success, or false if DELTA is not known at compile time.
+
+ Truncation and sign changes are known to distribute over CODE, i.e.
+
+ (itype) (A CODE B) == (itype) A CODE (itype) B
+
+ for any integral type ITYPE whose precision is no greater than the
+ precision of A and B. */
+
+static bool
+compute_distributive_range (tree type, value_range &op0_range,
+ tree_code code, value_range &op1_range,
+ tree *off, value_range *result_range)
+{
+ gcc_assert (INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_TRAPS (type));
+ if (result_range)
+ {
+ range_operator *op = range_op_handler (code, type);
+ op->fold_range (*result_range, type, op0_range, op1_range);
+ }
+
+ /* The distributive property guarantees that if TYPE is no narrower
+ than SIZETYPE,
+
+ (sizetype) (OP0 CODE OP1) == (sizetype) OP0 CODE (sizetype) OP1
+
+ and so we can treat DELTA as zero. */
+ if (TYPE_PRECISION (type) >= TYPE_PRECISION (sizetype))
+ return true;
+
+ /* If overflow is undefined, we can assume that:
+
+ X == (ssizetype) OP0 CODE (ssizetype) OP1
+
+ is within the range of TYPE, i.e.:
+
+ X == (ssizetype) (TYPE) X
+
+ Distributing the (TYPE) truncation over X gives:
+
+ X == (ssizetype) (OP0 CODE OP1)
+
+ Casting both sides to sizetype and distributing the sizetype cast
+ over X gives:
+
+ (sizetype) OP0 CODE (sizetype) OP1 == (sizetype) (OP0 CODE OP1)
+
+ and so we can treat DELTA as zero. */
+ if (TYPE_OVERFLOW_UNDEFINED (type))
+ return true;
+
+ /* Compute the range of:
+
+ (ssizetype) OP0 CODE (ssizetype) OP1
+
+ The distributive property guarantees that this has the same bitpattern as:
+
+ (sizetype) OP0 CODE (sizetype) OP1
+
+ but its range is more conducive to analysis. */
+ range_cast (op0_range, ssizetype);
+ range_cast (op1_range, ssizetype);
+ value_range wide_range;
+ range_operator *op = range_op_handler (code, ssizetype);
+ bool saved_flag_wrapv = flag_wrapv;
+ flag_wrapv = 1;
+ op->fold_range (wide_range, ssizetype, op0_range, op1_range);
+ flag_wrapv = saved_flag_wrapv;
+ if (wide_range.num_pairs () != 1 || !range_int_cst_p (&wide_range))
+ return false;
+
+ wide_int lb = wide_range.lower_bound ();
+ wide_int ub = wide_range.upper_bound ();
+
+ /* Calculate the number of times that each end of the range overflows or
+ underflows TYPE. We can only calculate DELTA if the numbers match. */
+ unsigned int precision = TYPE_PRECISION (type);
+ if (!TYPE_UNSIGNED (type))
+ {
+ wide_int type_min = wi::mask (precision - 1, true, lb.get_precision ());
+ lb -= type_min;
+ ub -= type_min;
+ }
+ wide_int upper_bits = wi::mask (precision, true, lb.get_precision ());
+ lb &= upper_bits;
+ ub &= upper_bits;
+ if (lb != ub)
+ return false;
+
+ /* OP0 CODE OP1 overflows exactly arshift (LB, PRECISION) times, with
+ negative values indicating underflow. The low PRECISION bits of LB
+ are clear, so DELTA is therefore LB (== UB). */
+ *off = wide_int_to_tree (ssizetype, wi::to_wide (*off) - lb);
+ return true;
+}
+
+/* Return true if (sizetype) OP == (sizetype) (TO_TYPE) OP,
+ given that OP has type FROM_TYPE and range RANGE. Both TO_TYPE and
+ FROM_TYPE are integral types. */
+
+static bool
+nop_conversion_for_offset_p (tree to_type, tree from_type, value_range &range)
+{
+ gcc_assert (INTEGRAL_TYPE_P (to_type)
+ && INTEGRAL_TYPE_P (from_type)
+ && !TYPE_OVERFLOW_TRAPS (to_type)
+ && !TYPE_OVERFLOW_TRAPS (from_type));
+
+ /* Converting to something no narrower than sizetype and then to sizetype
+ is equivalent to converting directly to sizetype. */
+ if (TYPE_PRECISION (to_type) >= TYPE_PRECISION (sizetype))
+ return true;
+
+ /* Check whether TO_TYPE can represent all values that FROM_TYPE can. */
+ if (TYPE_PRECISION (from_type) < TYPE_PRECISION (to_type)
+ && (TYPE_UNSIGNED (from_type) || !TYPE_UNSIGNED (to_type)))
+ return true;
+
+ /* For narrowing conversions, we could in principle test whether
+ the bits in FROM_TYPE but not in TO_TYPE have a fixed value
+ and apply a constant adjustment.
+
+ For other conversions (which involve a sign change) we could
+ check that the signs are always equal, and apply a constant
+ adjustment if the signs are negative.
+
+ However, both cases should be rare. */
+ return range_fits_type_p (&range, TYPE_PRECISION (to_type),
+ TYPE_SIGN (to_type));
+}
+
static void
-split_constant_offset (tree exp, tree *var, tree *off,
+split_constant_offset (tree type, tree *var, tree *off,
+ value_range *result_range,
hash_map<tree, std::pair<tree, tree> > &cache,
unsigned *limit);
-/* Helper function for split_constant_offset. Expresses OP0 CODE OP1
- (the type of the result is TYPE) as VAR + OFF, where OFF is a nonzero
- constant of type ssizetype, and returns true. If we cannot do this
- with OFF nonzero, OFF and VAR are set to NULL_TREE instead and false
- is returned. */
+/* Helper function for split_constant_offset. If TYPE is a pointer type,
+ try to express OP0 CODE OP1 as:
+
+ POINTER_PLUS <*VAR, (sizetype) *OFF>
+
+ where:
+
+ - *VAR has type TYPE
+ - *OFF is a constant of type ssizetype.
+
+ If TYPE is an integral type, try to express (sizetype) (OP0 CODE OP1) as:
+
+ *VAR + (sizetype) *OFF
+
+ where:
+
+ - *VAR has type sizetype
+ - *OFF is a constant of type ssizetype.
+
+ In both cases, OP0 CODE OP1 has type TYPE.
+
+ Return true on success. A false return value indicates that we can't
+ do better than set *OFF to zero.
+
+ When returning true, set RESULT_RANGE to the range of OP0 CODE OP1,
+ if RESULT_RANGE is nonnull and if we can do better than assume VR_VARYING.
+
+ CACHE caches {*VAR, *OFF} pairs for SSA names that we've previously
+ visited. LIMIT counts down the number of SSA names that we are
+ allowed to process before giving up. */
static bool
split_constant_offset_1 (tree type, tree op0, enum tree_code code, tree op1,
- tree *var, tree *off,
+ tree *var, tree *off, value_range *result_range,
hash_map<tree, std::pair<tree, tree> > &cache,
unsigned *limit)
{
tree var0, var1;
tree off0, off1;
- enum tree_code ocode = code;
+ value_range op0_range, op1_range;
*var = NULL_TREE;
*off = NULL_TREE;
switch (code)
{
case INTEGER_CST:
- *var = build_int_cst (type, 0);
+ *var = size_int (0);
*off = fold_convert (ssizetype, op0);
+ if (result_range)
+ result_range->set (op0, op0);
return true;
case POINTER_PLUS_EXPR:
- ocode = PLUS_EXPR;
- /* FALLTHROUGH */
+ split_constant_offset (op0, &var0, &off0, nullptr, cache, limit);
+ split_constant_offset (op1, &var1, &off1, nullptr, cache, limit);
+ *var = fold_build2 (POINTER_PLUS_EXPR, type, var0, var1);
+ *off = size_binop (PLUS_EXPR, off0, off1);
+ return true;
+
case PLUS_EXPR:
case MINUS_EXPR:
- if (TREE_CODE (op1) == INTEGER_CST)
- {
- split_constant_offset (op0, &var0, &off0, cache, limit);
- *var = var0;
- *off = size_binop (ocode, off0, fold_convert (ssizetype, op1));
- return true;
- }
- split_constant_offset (op0, &var0, &off0, cache, limit);
- split_constant_offset (op1, &var1, &off1, cache, limit);
- *var = fold_build2 (code, type, var0, var1);
- *off = size_binop (ocode, off0, off1);
+ split_constant_offset (op0, &var0, &off0, &op0_range, cache, limit);
+ split_constant_offset (op1, &var1, &off1, &op1_range, cache, limit);
+ *off = size_binop (code, off0, off1);
+ if (!compute_distributive_range (type, op0_range, code, op1_range,
+ off, result_range))
+ return false;
+ *var = fold_build2 (code, sizetype, var0, var1);
return true;
case MULT_EXPR:
if (TREE_CODE (op1) != INTEGER_CST)
return false;
- split_constant_offset (op0, &var0, &off0, cache, limit);
- *var = fold_build2 (MULT_EXPR, type, var0, op1);
+ split_constant_offset (op0, &var0, &off0, &op0_range, cache, limit);
+ op1_range.set (op1, op1);
*off = size_binop (MULT_EXPR, off0, fold_convert (ssizetype, op1));
+ if (!compute_distributive_range (type, op0_range, code, op1_range,
+ off, result_range))
+ return false;
+ *var = fold_build2 (MULT_EXPR, sizetype, var0,
+ fold_convert (sizetype, op1));
return true;
case ADDR_EXPR:
if (poffset)
{
- split_constant_offset (poffset, &poffset, &off1, cache, limit);
+ split_constant_offset (poffset, &poffset, &off1, nullptr,
+ cache, limit);
off0 = size_binop (PLUS_EXPR, off0, off1);
- if (POINTER_TYPE_P (TREE_TYPE (base)))
- base = fold_build_pointer_plus (base, poffset);
- else
- base = fold_build2 (PLUS_EXPR, TREE_TYPE (base), base,
- fold_convert (TREE_TYPE (base), poffset));
+ base = fold_build_pointer_plus (base, poffset);
}
var0 = fold_convert (type, base);
return false;
*var = e.first;
*off = e.second;
+ /* The caller sets the range in this case. */
return true;
}
e = std::make_pair (op0, ssize_int (0));
var1 = gimple_assign_rhs2 (def_stmt);
bool res = split_constant_offset_1 (type, var0, subcode, var1,
- var, off, cache, limit);
+ var, off, nullptr, cache, limit);
if (res && use_cache)
*cache.get (op0) = std::make_pair (*var, *off);
+ /* The caller sets the range in this case. */
return res;
}
CASE_CONVERT:
{
- /* We must not introduce undefined overflow, and we must not change
- the value. Hence we're okay if the inner type doesn't overflow
- to start with (pointer or signed), the outer type also is an
- integer or pointer and the outer precision is at least as large
- as the inner. */
+ /* We can only handle the following conversions:
+
+ - Conversions from one pointer type to another pointer type.
+
+ - Conversions from one non-trapping integral type to another
+ non-trapping integral type. In this case, the recursive
+ call makes sure that:
+
+ (sizetype) OP0
+
+ can be expressed as a sizetype operation involving VAR and OFF,
+ and all we need to do is check whether:
+
+ (sizetype) OP0 == (sizetype) (TYPE) OP0
+
+ - Conversions from a non-trapping sizetype-size integral type to
+ a like-sized pointer type. In this case, the recursive call
+ makes sure that:
+
+ (sizetype) OP0 == *VAR + (sizetype) *OFF
+
+ and we can convert that to:
+
+ POINTER_PLUS <(TYPE) *VAR, (sizetype) *OFF>
+
+ - Conversions from a sizetype-sized pointer type to a like-sized
+ non-trapping integral type. In this case, the recursive call
+ makes sure that:
+
+ OP0 == POINTER_PLUS <*VAR, (sizetype) *OFF>
+
+ where the POINTER_PLUS and *VAR have the same precision as
+ TYPE (and the same precision as sizetype). Then:
+
+ (sizetype) (TYPE) OP0 == (sizetype) *VAR + (sizetype) *OFF. */
tree itype = TREE_TYPE (op0);
if ((POINTER_TYPE_P (itype)
|| (INTEGRAL_TYPE_P (itype) && !TYPE_OVERFLOW_TRAPS (itype)))
- && TYPE_PRECISION (type) >= TYPE_PRECISION (itype)
- && (POINTER_TYPE_P (type) || INTEGRAL_TYPE_P (type)))
+ && (POINTER_TYPE_P (type)
+ || (INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_TRAPS (type)))
+ && (POINTER_TYPE_P (type) == POINTER_TYPE_P (itype)
+ || (TYPE_PRECISION (type) == TYPE_PRECISION (sizetype)
+ && TYPE_PRECISION (itype) == TYPE_PRECISION (sizetype))))
{
- if (INTEGRAL_TYPE_P (itype) && TYPE_OVERFLOW_WRAPS (itype)
- && (TYPE_PRECISION (type) > TYPE_PRECISION (itype)
- || TYPE_UNSIGNED (itype) != TYPE_UNSIGNED (type)))
+ if (POINTER_TYPE_P (type))
+ {
+ split_constant_offset (op0, var, off, nullptr, cache, limit);
+ *var = fold_convert (type, *var);
+ }
+ else if (POINTER_TYPE_P (itype))
+ {
+ split_constant_offset (op0, var, off, nullptr, cache, limit);
+ *var = fold_convert (sizetype, *var);
+ }
+ else
{
- /* Split the unconverted operand and try to prove that
- wrapping isn't a problem. */
- tree tmp_var, tmp_off;
- split_constant_offset (op0, &tmp_var, &tmp_off, cache, limit);
-
- /* See whether we have an known range [A, B] for tmp_var. */
- wide_int var_min, var_max;
- signop sgn = TYPE_SIGN (itype);
- if (TREE_CODE (tmp_var) == SSA_NAME)
+ split_constant_offset (op0, var, off, &op0_range,
+ cache, limit);
+ if (!nop_conversion_for_offset_p (type, itype, op0_range))
+ return false;
+ if (result_range)
{
- value_range_kind vr_type
- = get_range_info (tmp_var, &var_min, &var_max);
- wide_int var_nonzero = get_nonzero_bits (tmp_var);
- if (intersect_range_with_nonzero_bits (vr_type, &var_min,
- &var_max,
- var_nonzero,
- sgn) != VR_RANGE)
- return false;
+ *result_range = op0_range;
+ range_cast (*result_range, type);
}
- else if (determine_value_range (tmp_var, &var_min, &var_max)
- != VR_RANGE)
- return false;
-
- /* See whether the range of OP0 (i.e. TMP_VAR + TMP_OFF)
- is known to be [A + TMP_OFF, B + TMP_OFF], with all
- operations done in ITYPE. The addition must overflow
- at both ends of the range or at neither. */
- wi::overflow_type overflow[2];
- unsigned int prec = TYPE_PRECISION (itype);
- wide_int woff = wi::to_wide (tmp_off, prec);
- wide_int op0_min = wi::add (var_min, woff, sgn, &overflow[0]);
- wi::add (var_max, woff, sgn, &overflow[1]);
- if ((overflow[0] != wi::OVF_NONE) != (overflow[1] != wi::OVF_NONE))
- return false;
-
- /* Calculate (ssizetype) OP0 - (ssizetype) TMP_VAR. */
- widest_int diff = (widest_int::from (op0_min, sgn)
- - widest_int::from (var_min, sgn));
- var0 = tmp_var;
- *off = wide_int_to_tree (ssizetype, diff);
}
- else
- split_constant_offset (op0, &var0, off, cache, limit);
- *var = fold_convert (type, var0);
return true;
}
return false;
}
}
-/* Expresses EXP as VAR + OFF, where off is a constant. The type of OFF
- will be ssizetype. */
+/* If EXP has pointer type, try to express it as:
+
+ POINTER_PLUS <*VAR, (sizetype) *OFF>
+
+ where:
+
+ - *VAR has the same type as EXP
+ - *OFF is a constant of type ssizetype.
+
+ If EXP has an integral type, try to express (sizetype) EXP as:
+
+ *VAR + (sizetype) *OFF
+
+ where:
+
+ - *VAR has type sizetype
+ - *OFF is a constant of type ssizetype.
+
+ If EXP_RANGE is nonnull, set it to the range of EXP.
+
+ CACHE caches {*VAR, *OFF} pairs for SSA names that we've previously
+ visited. LIMIT counts down the number of SSA names that we are
+ allowed to process before giving up. */
static void
-split_constant_offset (tree exp, tree *var, tree *off,
+split_constant_offset (tree exp, tree *var, tree *off, value_range *exp_range,
hash_map<tree, std::pair<tree, tree> > &cache,
unsigned *limit)
{
- tree type = TREE_TYPE (exp), op0, op1, e, o;
+ tree type = TREE_TYPE (exp), op0, op1;
enum tree_code code;
- *var = exp;
- *off = ssize_int (0);
+ code = TREE_CODE (exp);
+ if (exp_range)
+ {
+ *exp_range = type;
+ if (code == SSA_NAME)
+ {
+ wide_int var_min, var_max;
+ value_range_kind vr_kind = get_range_info (exp, &var_min, &var_max);
+ wide_int var_nonzero = get_nonzero_bits (exp);
+ vr_kind = intersect_range_with_nonzero_bits (vr_kind,
+ &var_min, &var_max,
+ var_nonzero,
+ TYPE_SIGN (type));
+ if (vr_kind == VR_RANGE)
+ *exp_range = value_range (type, var_min, var_max);
+ }
+ }
- if (tree_is_chrec (exp)
- || get_gimple_rhs_class (TREE_CODE (exp)) == GIMPLE_TERNARY_RHS)
- return;
+ if (!tree_is_chrec (exp)
+ && get_gimple_rhs_class (TREE_CODE (exp)) != GIMPLE_TERNARY_RHS)
+ {
+ extract_ops_from_tree (exp, &code, &op0, &op1);
+ if (split_constant_offset_1 (type, op0, code, op1, var, off,
+ exp_range, cache, limit))
+ return;
+ }
- code = TREE_CODE (exp);
- extract_ops_from_tree (exp, &code, &op0, &op1);
- if (split_constant_offset_1 (type, op0, code, op1, &e, &o, cache, limit))
+ *var = exp;
+ if (INTEGRAL_TYPE_P (type))
+ *var = fold_convert (sizetype, *var);
+ *off = ssize_int (0);
+ if (exp_range && code != SSA_NAME)
{
- *var = e;
- *off = o;
+ wide_int var_min, var_max;
+ if (determine_value_range (exp, &var_min, &var_max) == VR_RANGE)
+ *exp_range = value_range (type, var_min, var_max);
}
}
+/* Expresses EXP as VAR + OFF, where OFF is a constant. VAR has the same
+ type as EXP while OFF has type ssizetype. */
+
void
split_constant_offset (tree exp, tree *var, tree *off)
{
static hash_map<tree, std::pair<tree, tree> > *cache;
if (!cache)
cache = new hash_map<tree, std::pair<tree, tree> > (37);
- split_constant_offset (exp, var, off, *cache, &limit);
+ split_constant_offset (exp, var, off, nullptr, *cache, &limit);
+ *var = fold_convert (TREE_TYPE (exp), *var);
cache->empty ();
}
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