Support <, <=, > and >= for offset_int and widest_int
Richard Sandiford
richard.sandiford@arm.com
Fri Apr 29 12:26:00 GMT 2016
offset_int and widest_int are supposed to be at least one bit wider
than all the values they need to represent, with the extra bits
being signs. Thus offset_int is effectively int128_t and widest_int
is effectively intNNN_t, for target-dependent NNN.
Because the types are signed, there's not really any need to specify
a sign for operations like comparison. I think things would be clearer
if we supported <, <=, > and >= for them (but not for wide_int, which
doesn't have a sign).
Tested on x86_64-linux-gnu and aarch64-linux-gnu. OK to install?
Thanks,
Richard
gcc/
* wide-int.h: Update offset_int and widest_int documentation.
(WI_SIGNED_BINARY_PREDICATE_RESULT): New macro.
(wi::binary_traits): Allow ordered comparisons between offset_int and
offset_int, between widest_int and widest_int, and between either
of these types and basic C types.
(operator <, <=, >, >=): Define for the same combinations.
* tree.h (tree_int_cst_lt): Use comparison operators instead
of wi:: comparisons.
(tree_int_cst_le): Likewise.
* gimple-fold.c (fold_array_ctor_reference): Likewise.
(fold_nonarray_ctor_reference): Likewise.
* gimple-ssa-strength-reduction.c (record_increment): Likewise.
* tree-affine.c (aff_comb_cannot_overlap_p): Likewise.
* tree-parloops.c (try_transform_to_exit_first_loop_alt): Likewise.
* tree-sra.c (completely_scalarize): Likewise.
* tree-ssa-alias.c (stmt_kills_ref_p): Likewise.
* tree-ssa-reassoc.c (extract_bit_test_mask): Likewise.
* tree-vrp.c (extract_range_from_binary_expr_1): Likewise.
(check_for_binary_op_overflow): Likewise.
(search_for_addr_array): Likewise.
* ubsan.c (ubsan_expand_objsize_ifn): Likewise.
Index: gcc/wide-int.h
===================================================================
--- gcc/wide-int.h
+++ gcc/wide-int.h
@@ -53,22 +53,26 @@ along with GCC; see the file COPYING3. If not see
multiply, division, shifts, comparisons, and operations that need
overflow detected), the signedness must be specified separately.
- 2) offset_int. This is a fixed size representation that is
- guaranteed to be large enough to compute any bit or byte sized
- address calculation on the target. Currently the value is 64 + 4
- bits rounded up to the next number even multiple of
- HOST_BITS_PER_WIDE_INT (but this can be changed when the first
- port needs more than 64 bits for the size of a pointer).
-
- This flavor can be used for all address math on the target. In
- this representation, the values are sign or zero extended based
- on their input types to the internal precision. All math is done
- in this precision and then the values are truncated to fit in the
- result type. Unlike most gimple or rtl intermediate code, it is
- not useful to perform the address arithmetic at the same
- precision in which the operands are represented because there has
- been no effort by the front ends to convert most addressing
- arithmetic to canonical types.
+ 2) offset_int. This is a fixed-precision integer that can hold
+ any address offset, measured in either bits or bytes, with at
+ least one extra sign bit. At the moment the maximum address
+ size GCC supports is 64 bits. With 8-bit bytes and an extra
+ sign bit, offset_int therefore needs to have at least 68 bits
+ of precision. We round this up to 128 bits for efficiency.
+ Values of type T are converted to this precision by sign- or
+ zero-extending them based on the signedness of T.
+
+ The extra sign bit means that offset_int is effectively a signed
+ 128-bit integer, i.e. it behaves like int128_t.
+
+ Since the values are logically signed, there is no need to
+ distinguish between signed and unsigned operations. Sign-sensitive
+ comparison operators <, <=, > and >= are therefore supported.
+
+ [ Note that, even though offset_int is effectively int128_t,
+ it can still be useful to use unsigned comparisons like
+ wi::leu_p (a, b) as a more efficient short-hand for
+ "a >= 0 && a <= b". ]
3) widest_int. This representation is an approximation of
infinite precision math. However, it is not really infinite
@@ -76,9 +80,9 @@ along with GCC; see the file COPYING3. If not see
precision math where the precision is 4 times the size of the
largest integer that the target port can represent.
- widest_int is supposed to be wider than any number that it needs to
- store, meaning that there is always at least one leading sign bit.
- All widest_int values are therefore signed.
+ Like offset_int, widest_int is wider than all the values that
+ it needs to represent, so the integers are logically signed.
+ Sign-sensitive comparison operators <, <=, > and >= are supported.
There are several places in the GCC where this should/must be used:
@@ -255,6 +259,12 @@ along with GCC; see the file COPYING3. If not see
#define WI_BINARY_RESULT(T1, T2) \
typename wi::binary_traits <T1, T2>::result_type
+/* The type of result produced by a signed binary predicate on types T1 and T2.
+ This is bool if signed comparisons make sense for T1 and T2 and leads to
+ substitution failure otherwise. */
+#define WI_SIGNED_BINARY_PREDICATE_RESULT(T1, T2) \
+ typename wi::binary_traits <T1, T2>::signed_predicate_result
+
/* The type of result produced by a unary operation on type T. */
#define WI_UNARY_RESULT(T) \
typename wi::unary_traits <T>::result_type
@@ -316,7 +326,7 @@ namespace wi
VAR_PRECISION,
/* The integer has a constant precision (known at GCC compile time)
- but no defined signedness. */
+ and is signed. */
CONST_PRECISION
};
@@ -379,6 +389,7 @@ namespace wi
so as not to confuse gengtype. */
typedef generic_wide_int < fixed_wide_int_storage
<int_traits <T2>::precision> > result_type;
+ typedef bool signed_predicate_result;
};
template <typename T1, typename T2>
@@ -394,6 +405,7 @@ namespace wi
so as not to confuse gengtype. */
typedef generic_wide_int < fixed_wide_int_storage
<int_traits <T1>::precision> > result_type;
+ typedef bool signed_predicate_result;
};
template <typename T1, typename T2>
@@ -404,6 +416,7 @@ namespace wi
STATIC_ASSERT (int_traits <T1>::precision == int_traits <T2>::precision);
typedef generic_wide_int < fixed_wide_int_storage
<int_traits <T1>::precision> > result_type;
+ typedef bool signed_predicate_result;
};
template <typename T1, typename T2>
@@ -3050,6 +3063,21 @@ wi::min_precision (const T &x, signop sgn)
return get_precision (x) - clz (x);
}
+#define SIGNED_BINARY_PREDICATE(OP, F) \
+ template <typename T1, typename T2> \
+ inline WI_SIGNED_BINARY_PREDICATE_RESULT (T1, T2) \
+ OP (const T1 &x, const T2 &y) \
+ { \
+ return wi::F (x, y); \
+ }
+
+SIGNED_BINARY_PREDICATE (operator <, lts_p)
+SIGNED_BINARY_PREDICATE (operator <=, les_p)
+SIGNED_BINARY_PREDICATE (operator >, gts_p)
+SIGNED_BINARY_PREDICATE (operator >=, ges_p)
+
+#undef SIGNED_BINARY_PREDICATE
+
template<typename T>
void
gt_ggc_mx (generic_wide_int <T> *)
Index: gcc/tree.h
===================================================================
--- gcc/tree.h
+++ gcc/tree.h
@@ -5318,7 +5318,7 @@ wi::max_value (const_tree type)
inline bool
tree_int_cst_lt (const_tree t1, const_tree t2)
{
- return wi::lts_p (wi::to_widest (t1), wi::to_widest (t2));
+ return wi::to_widest (t1) < wi::to_widest (t2);
}
/* Return true if INTEGER_CST T1 is less than or equal to INTEGER_CST T2,
@@ -5327,7 +5327,7 @@ tree_int_cst_lt (const_tree t1, const_tree t2)
inline bool
tree_int_cst_le (const_tree t1, const_tree t2)
{
- return wi::les_p (wi::to_widest (t1), wi::to_widest (t2));
+ return wi::to_widest (t1) <= wi::to_widest (t2);
}
/* Returns -1 if T1 < T2, 0 if T1 == T2, and 1 if T1 > T2. T1 and T2
Index: gcc/gimple-fold.c
===================================================================
--- gcc/gimple-fold.c
+++ gcc/gimple-fold.c
@@ -5380,7 +5380,7 @@ fold_array_ctor_reference (tree type, tree ctor,
be larger than size of array element. */
if (!TYPE_SIZE_UNIT (type)
|| TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST
- || wi::lts_p (elt_size, wi::to_offset (TYPE_SIZE_UNIT (type)))
+ || elt_size < wi::to_offset (TYPE_SIZE_UNIT (type))
|| elt_size == 0)
return NULL_TREE;
@@ -5457,7 +5457,7 @@ fold_nonarray_ctor_reference (tree type, tree ctor,
fields. */
if (wi::cmps (access_end, bitoffset_end) > 0)
return NULL_TREE;
- if (wi::lts_p (offset, bitoffset))
+ if (offset < bitoffset)
return NULL_TREE;
return fold_ctor_reference (type, cval,
inner_offset.to_uhwi (), size,
Index: gcc/gimple-ssa-strength-reduction.c
===================================================================
--- gcc/gimple-ssa-strength-reduction.c
+++ gcc/gimple-ssa-strength-reduction.c
@@ -2506,8 +2506,7 @@ record_increment (slsr_cand_t c, widest_int increment, bool is_phi_adjust)
if (c->kind == CAND_ADD
&& !is_phi_adjust
&& c->index == increment
- && (wi::gts_p (increment, 1)
- || wi::lts_p (increment, -1))
+ && (increment > 1 || increment < -1)
&& (gimple_assign_rhs_code (c->cand_stmt) == PLUS_EXPR
|| gimple_assign_rhs_code (c->cand_stmt) == POINTER_PLUS_EXPR))
{
Index: gcc/tree-affine.c
===================================================================
--- gcc/tree-affine.c
+++ gcc/tree-affine.c
@@ -929,7 +929,7 @@ aff_comb_cannot_overlap_p (aff_tree *diff, const widest_int &size1,
else
{
/* We succeed if the second object starts after the first one ends. */
- return wi::les_p (size1, diff->offset);
+ return size1 <= diff->offset;
}
}
Index: gcc/tree-parloops.c
===================================================================
--- gcc/tree-parloops.c
+++ gcc/tree-parloops.c
@@ -1868,7 +1868,7 @@ try_transform_to_exit_first_loop_alt (struct loop *loop,
/* Check if nit + 1 overflows. */
widest_int type_max = wi::to_widest (TYPE_MAXVAL (nit_type));
- if (!wi::lts_p (nit_max, type_max))
+ if (nit_max >= type_max)
return false;
gimple *def = SSA_NAME_DEF_STMT (nit);
Index: gcc/tree-sra.c
===================================================================
--- gcc/tree-sra.c
+++ gcc/tree-sra.c
@@ -1055,7 +1055,7 @@ completely_scalarize (tree base, tree decl_type, HOST_WIDE_INT offset, tree ref)
idx = wi::sext (idx, TYPE_PRECISION (domain));
max = wi::sext (max, TYPE_PRECISION (domain));
}
- for (int el_off = offset; wi::les_p (idx, max); ++idx)
+ for (int el_off = offset; idx <= max; ++idx)
{
tree nref = build4 (ARRAY_REF, elemtype,
ref,
Index: gcc/tree-ssa-alias.c
===================================================================
--- gcc/tree-ssa-alias.c
+++ gcc/tree-ssa-alias.c
@@ -2380,10 +2380,10 @@ stmt_kills_ref_p (gimple *stmt, ao_ref *ref)
rbase = TREE_OPERAND (rbase, 0);
}
if (base == rbase
- && wi::les_p (offset, roffset)
- && wi::les_p (roffset + ref->max_size,
- offset + wi::lshift (wi::to_offset (len),
- LOG2_BITS_PER_UNIT)))
+ && offset <= roffset
+ && (roffset + ref->max_size
+ <= offset + wi::lshift (wi::to_offset (len),
+ LOG2_BITS_PER_UNIT)))
return true;
break;
}
Index: gcc/tree-ssa-reassoc.c
===================================================================
--- gcc/tree-ssa-reassoc.c
+++ gcc/tree-ssa-reassoc.c
@@ -2464,7 +2464,7 @@ extract_bit_test_mask (tree exp, int prec, tree totallow, tree low, tree high,
return NULL_TREE;
bias = wi::to_widest (tbias);
bias -= wi::to_widest (totallow);
- if (wi::ges_p (bias, 0) && wi::lts_p (bias, prec - max))
+ if (bias >= 0 && bias < prec - max)
{
*mask = wi::lshift (*mask, bias);
return ret;
Index: gcc/tree-vrp.c
===================================================================
--- gcc/tree-vrp.c
+++ gcc/tree-vrp.c
@@ -2749,17 +2749,17 @@ extract_range_from_binary_expr_1 (value_range *vr,
/* Sort the 4 products so that min is in prod0 and max is in
prod3. */
/* min0min1 > max0max1 */
- if (wi::gts_p (prod0, prod3))
+ if (prod0 > prod3)
std::swap (prod0, prod3);
/* min0max1 > max0min1 */
- if (wi::gts_p (prod1, prod2))
+ if (prod1 > prod2)
std::swap (prod1, prod2);
- if (wi::gts_p (prod0, prod1))
+ if (prod0 > prod1)
std::swap (prod0, prod1);
- if (wi::gts_p (prod2, prod3))
+ if (prod2 > prod3)
std::swap (prod2, prod3);
/* diff = max - min. */
@@ -3775,7 +3775,7 @@ check_for_binary_op_overflow (enum tree_code subcode, tree type,
/* If all values in [wmin, wmax] are smaller than
[wtmin, wtmax] or all are larger than [wtmin, wtmax],
the arithmetic operation will always overflow. */
- if (wi::lts_p (wmax, wtmin) || wi::gts_p (wmin, wtmax))
+ if (wmax < wtmin || wmin > wtmax)
return true;
return false;
}
@@ -6587,7 +6587,7 @@ search_for_addr_array (tree t, location_t location)
idx = mem_ref_offset (t);
idx = wi::sdiv_trunc (idx, wi::to_offset (el_sz));
- if (wi::lts_p (idx, 0))
+ if (idx < 0)
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
@@ -6599,8 +6599,8 @@ search_for_addr_array (tree t, location_t location)
"array subscript is below array bounds");
TREE_NO_WARNING (t) = 1;
}
- else if (wi::gts_p (idx, (wi::to_offset (up_bound)
- - wi::to_offset (low_bound) + 1)))
+ else if (idx > (wi::to_offset (up_bound)
+ - wi::to_offset (low_bound) + 1))
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
Index: gcc/ubsan.c
===================================================================
--- gcc/ubsan.c
+++ gcc/ubsan.c
@@ -911,8 +911,8 @@ ubsan_expand_objsize_ifn (gimple_stmt_iterator *gsi)
/* Yes, __builtin_object_size couldn't determine the
object size. */;
else if (TREE_CODE (offset) == INTEGER_CST
- && wi::ges_p (wi::to_widest (offset), -OBJSZ_MAX_OFFSET)
- && wi::les_p (wi::to_widest (offset), -1))
+ && wi::to_widest (offset) >= -OBJSZ_MAX_OFFSET
+ && wi::to_widest (offset) <= -1)
/* The offset is in range [-16K, -1]. */;
else
{
@@ -928,8 +928,8 @@ ubsan_expand_objsize_ifn (gimple_stmt_iterator *gsi)
/* If the offset is small enough, we don't need the second
run-time check. */
if (TREE_CODE (offset) == INTEGER_CST
- && wi::ges_p (wi::to_widest (offset), 0)
- && wi::les_p (wi::to_widest (offset), OBJSZ_MAX_OFFSET))
+ && wi::to_widest (offset) >= 0
+ && wi::to_widest (offset) <= OBJSZ_MAX_OFFSET)
*gsi = gsi_after_labels (then_bb);
else
{
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