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Use nonzero bits to refine range in split_constant_offset (PR 81635)
This patch is part 2 of the fix for PR 81635. It means that
split_constant_offset can handle loops like:
for (unsigned int i = 0; i < n; i += 4)
{
a[i] = ...;
a[i + 1] = ...;
}
CCP records that "i" must have its low 2 bits clear, but we don't
include this information in the range of "i", which remains [0, +INF].
I tried making set_nonzero_bits update the range info in the same
way that set_range_info updates the nonzero bits, but it regressed
cases like vrp117.c and made some other tests worse.
vrp117.c has a multiplication by 10, so CCP can infer that the low bit
of the result is clear. If we included that in the range, the range
would go from [-INF, +INF] to [-INF, not-quite-+INF]. However,
the multiplication is also known to overflow in all cases, so VRP
saturates the result to [INT_MAX, INT_MAX]. This obviously creates a
contradiction with the nonzero bits, and intersecting the new saturated
range with an existing not-quite-+INF range would make us drop to
VR_UNDEFINED. We're prepared to fold a comparison with an [INT_MAX,
INT_MAX] value but not with a VR_UNDEFINED value.
The other problems were created when intersecting [-INF, not-quite-+INF]
with a useful VR_ANTI_RANGE like ~[-1, 1]. The intersection would
keep the former range rather than the latter.
The patch therefore keeps the adjustment local to split_constant_offset
for now, but adds a helper routine so that it's easy to move this later.
2018-02-08 Richard Sandiford <richard.sandiford@linaro.org>
gcc/
PR tree-optimization/81635
* wide-int.h (wi::round_down_for_mask, wi::round_up_for_mask): Declare.
* wide-int.cc (wi::round_down_for_mask, wi::round_up_for_mask)
(test_round_for_mask): New functions.
(wide_int_cc_tests): Call test_round_for_mask.
* tree-vrp.h (intersect_range_with_nonzero_bits): Declare.
* tree-vrp.c (intersect_range_with_nonzero_bits): New function.
* tree-data-ref.c (split_constant_offset_1): Use it to refine the
range returned by get_range_info.
gcc/testsuite/
PR tree-optimization/81635
* gcc.dg/vect/bb-slp-pr81635-3.c: New test.
* gcc.dg/vect/bb-slp-pr81635-4.c: Likewise.
From-SVN: r257491
This commit is contained in:
Richard Sandiford
Richard Sandiford
parent
39aa9b2369
commit
fff2290073
@ -1,3 +1,15 @@
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2018-02-08 Richard Sandiford <richard.sandiford@linaro.org>
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PR tree-optimization/81635
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* wide-int.h (wi::round_down_for_mask, wi::round_up_for_mask): Declare.
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* wide-int.cc (wi::round_down_for_mask, wi::round_up_for_mask)
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(test_round_for_mask): New functions.
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(wide_int_cc_tests): Call test_round_for_mask.
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* tree-vrp.h (intersect_range_with_nonzero_bits): Declare.
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* tree-vrp.c (intersect_range_with_nonzero_bits): New function.
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* tree-data-ref.c (split_constant_offset_1): Use it to refine the
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range returned by get_range_info.
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2018-02-08 Jan Hubicka <hubicka@ucw.cz>
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PR ipa/81360
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@ -1,3 +1,9 @@
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2018-02-08 Richard Sandiford <richard.sandiford@linaro.org>
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PR tree-optimization/81635
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* gcc.dg/vect/bb-slp-pr81635-3.c: New test.
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* gcc.dg/vect/bb-slp-pr81635-4.c: Likewise.
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2018-02-08 Andreas Krebbel <krebbel@linux.vnet.ibm.com>
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* gcc.target/s390/nobp-function-pointer-attr.c: New test.
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62
gcc/testsuite/gcc.dg/vect/bb-slp-pr81635-3.c
Normal file
62
gcc/testsuite/gcc.dg/vect/bb-slp-pr81635-3.c
Normal file
@ -0,0 +1,62 @@
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/* { dg-do compile } */
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/* { dg-additional-options "-fno-tree-loop-vectorize" } */
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/* { dg-require-effective-target vect_double } */
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/* { dg-require-effective-target lp64 } */
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void
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f1 (double *p, double *q, unsigned int n)
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{
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p = (double *) __builtin_assume_aligned (p, sizeof (double) * 2);
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q = (double *) __builtin_assume_aligned (q, sizeof (double) * 2);
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for (unsigned int i = 0; i < n; i += 4)
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{
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double a = q[i] + p[i];
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double b = q[i + 1] + p[i + 1];
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q[i] = a;
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q[i + 1] = b;
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}
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}
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void
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f2 (double *p, double *q, unsigned int n)
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{
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p = (double *) __builtin_assume_aligned (p, sizeof (double) * 2);
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q = (double *) __builtin_assume_aligned (q, sizeof (double) * 2);
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for (unsigned int i = 0; i < n; i += 2)
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{
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double a = q[i] + p[i];
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double b = q[i + 1] + p[i + 1];
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q[i] = a;
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q[i + 1] = b;
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}
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}
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void
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f3 (double *p, double *q, unsigned int n)
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{
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p = (double *) __builtin_assume_aligned (p, sizeof (double) * 2);
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q = (double *) __builtin_assume_aligned (q, sizeof (double) * 2);
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for (unsigned int i = 0; i < n; i += 6)
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{
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double a = q[i] + p[i];
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double b = q[i + 1] + p[i + 1];
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q[i] = a;
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q[i + 1] = b;
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}
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}
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void
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f4 (double *p, double *q, unsigned int start, unsigned int n)
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{
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p = (double *) __builtin_assume_aligned (p, sizeof (double) * 2);
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q = (double *) __builtin_assume_aligned (q, sizeof (double) * 2);
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for (unsigned int i = start & -2; i < n; i += 2)
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{
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double a = q[i] + p[i];
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double b = q[i + 1] + p[i + 1];
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q[i] = a;
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q[i + 1] = b;
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}
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}
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/* { dg-final { scan-tree-dump-times "basic block vectorized" 4 "slp1" } } */
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47
gcc/testsuite/gcc.dg/vect/bb-slp-pr81635-4.c
Normal file
47
gcc/testsuite/gcc.dg/vect/bb-slp-pr81635-4.c
Normal file
@ -0,0 +1,47 @@
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/* { dg-do compile } */
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/* { dg-additional-options "-fno-tree-loop-vectorize" } */
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/* { dg-require-effective-target lp64 } */
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void
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f1 (double *p, double *q, unsigned int n)
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{
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p = (double *) __builtin_assume_aligned (p, sizeof (double) * 2);
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q = (double *) __builtin_assume_aligned (q, sizeof (double) * 2);
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for (unsigned int i = 0; i < n; i += 1)
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{
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double a = q[i] + p[i];
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double b = q[i + 1] + p[i + 1];
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q[i] = a;
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q[i + 1] = b;
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}
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}
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void
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f2 (double *p, double *q, unsigned int n)
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{
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p = (double *) __builtin_assume_aligned (p, sizeof (double) * 2);
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q = (double *) __builtin_assume_aligned (q, sizeof (double) * 2);
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for (unsigned int i = 0; i < n; i += 3)
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{
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double a = q[i] + p[i];
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double b = q[i + 1] + p[i + 1];
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q[i] = a;
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q[i + 1] = b;
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}
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}
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void
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f3 (double *p, double *q, unsigned int start, unsigned int n)
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{
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p = (double *) __builtin_assume_aligned (p, sizeof (double) * 2);
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q = (double *) __builtin_assume_aligned (q, sizeof (double) * 2);
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for (unsigned int i = start; i < n; i += 2)
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{
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double a = q[i] + p[i];
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double b = q[i + 1] + p[i + 1];
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q[i] = a;
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q[i + 1] = b;
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}
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}
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/* { dg-final { scan-tree-dump-not "basic block vectorized" "slp1" } } */
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@ -721,7 +721,13 @@ split_constant_offset_1 (tree type, tree op0, enum tree_code code, tree op1,
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if (TREE_CODE (tmp_var) != SSA_NAME)
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return false;
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wide_int var_min, var_max;
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if (get_range_info (tmp_var, &var_min, &var_max) != VR_RANGE)
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value_range_type vr_type = get_range_info (tmp_var, &var_min,
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&var_max);
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wide_int var_nonzero = get_nonzero_bits (tmp_var);
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signop sgn = TYPE_SIGN (itype);
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if (intersect_range_with_nonzero_bits (vr_type, &var_min,
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&var_max, var_nonzero,
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sgn) != VR_RANGE)
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return false;
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/* See whether the range of OP0 (i.e. TMP_VAR + TMP_OFF)
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@ -729,7 +735,6 @@ split_constant_offset_1 (tree type, tree op0, enum tree_code code, tree op1,
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operations done in ITYPE. The addition must overflow
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at both ends of the range or at neither. */
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bool overflow[2];
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signop sgn = TYPE_SIGN (itype);
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unsigned int prec = TYPE_PRECISION (itype);
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wide_int woff = wi::to_wide (tmp_off, prec);
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wide_int op0_min = wi::add (var_min, woff, sgn, &overflow[0]);
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@ -171,6 +171,53 @@ vrp_val_is_min (const_tree val)
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&& operand_equal_p (val, type_min, 0)));
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}
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/* VR_TYPE describes a range with mininum value *MIN and maximum
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value *MAX. Restrict the range to the set of values that have
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no bits set outside NONZERO_BITS. Update *MIN and *MAX and
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return the new range type.
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SGN gives the sign of the values described by the range. */
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enum value_range_type
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intersect_range_with_nonzero_bits (enum value_range_type vr_type,
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wide_int *min, wide_int *max,
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const wide_int &nonzero_bits,
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signop sgn)
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{
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if (vr_type == VR_RANGE)
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{
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*max = wi::round_down_for_mask (*max, nonzero_bits);
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/* Check that the range contains at least one valid value. */
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if (wi::gt_p (*min, *max, sgn))
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return VR_UNDEFINED;
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*min = wi::round_up_for_mask (*min, nonzero_bits);
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gcc_checking_assert (wi::le_p (*min, *max, sgn));
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}
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if (vr_type == VR_ANTI_RANGE)
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{
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*max = wi::round_up_for_mask (*max, nonzero_bits);
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/* If the calculation wrapped, we now have a VR_RANGE whose
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lower bound is *MAX and whose upper bound is *MIN. */
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if (wi::gt_p (*min, *max, sgn))
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{
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std::swap (*min, *max);
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*max = wi::round_down_for_mask (*max, nonzero_bits);
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gcc_checking_assert (wi::le_p (*min, *max, sgn));
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return VR_RANGE;
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}
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*min = wi::round_down_for_mask (*min, nonzero_bits);
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gcc_checking_assert (wi::le_p (*min, *max, sgn));
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/* Check whether we now have an empty set of values. */
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if (*min - 1 == *max)
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return VR_UNDEFINED;
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}
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return vr_type;
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}
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/* Set value range VR to VR_UNDEFINED. */
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@ -61,6 +61,8 @@ extern void extract_range_from_unary_expr (value_range *vr,
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tree op0_type);
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extern bool vrp_operand_equal_p (const_tree, const_tree);
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extern enum value_range_type intersect_range_with_nonzero_bits
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(enum value_range_type, wide_int *, wide_int *, const wide_int &, signop);
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struct assert_info
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{
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112
gcc/wide-int.cc
112
gcc/wide-int.cc
@ -2132,6 +2132,70 @@ wi::only_sign_bit_p (const wide_int_ref &x)
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return only_sign_bit_p (x, x.precision);
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}
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/* Return VAL if VAL has no bits set outside MASK. Otherwise round VAL
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down to the previous value that has no bits set outside MASK.
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This rounding wraps for signed values if VAL is negative and
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the top bit of MASK is clear.
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For example, round_down_for_mask (6, 0xf1) would give 1 and
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round_down_for_mask (24, 0xf1) would give 17. */
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wide_int
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wi::round_down_for_mask (const wide_int &val, const wide_int &mask)
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{
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/* Get the bits in VAL that are outside the mask. */
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wide_int extra_bits = wi::bit_and_not (val, mask);
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if (extra_bits == 0)
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return val;
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/* Get a mask that includes the top bit in EXTRA_BITS and is all 1s
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below that bit. */
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unsigned int precision = val.get_precision ();
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wide_int lower_mask = wi::mask (precision - wi::clz (extra_bits),
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false, precision);
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/* Clear the bits that aren't in MASK, but ensure that all bits
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in MASK below the top cleared bit are set. */
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return (val & mask) | (mask & lower_mask);
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}
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/* Return VAL if VAL has no bits set outside MASK. Otherwise round VAL
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up to the next value that has no bits set outside MASK. The rounding
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wraps if there are no suitable values greater than VAL.
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For example, round_up_for_mask (6, 0xf1) would give 16 and
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round_up_for_mask (24, 0xf1) would give 32. */
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wide_int
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wi::round_up_for_mask (const wide_int &val, const wide_int &mask)
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{
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/* Get the bits in VAL that are outside the mask. */
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wide_int extra_bits = wi::bit_and_not (val, mask);
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if (extra_bits == 0)
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return val;
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/* Get a mask that is all 1s above the top bit in EXTRA_BITS. */
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unsigned int precision = val.get_precision ();
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wide_int upper_mask = wi::mask (precision - wi::clz (extra_bits),
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true, precision);
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/* Get the bits of the mask that are above the top bit in EXTRA_BITS. */
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upper_mask &= mask;
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/* Conceptually we need to:
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- clear bits of VAL outside UPPER_MASK
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- add the lowest bit in UPPER_MASK to VAL (or add 0 if UPPER_MASK is 0)
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- propagate the carry through the bits of VAL in UPPER_MASK
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If (~VAL & UPPER_MASK) is nonzero, the carry eventually
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reaches that bit and the process leaves all lower bits clear.
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If (~VAL & UPPER_MASK) is zero then the result is also zero. */
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wide_int tmp = wi::bit_and_not (upper_mask, val);
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return (val | tmp) & -tmp;
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}
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/*
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* Private utilities.
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*/
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@ -2384,6 +2448,53 @@ test_overflow ()
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}
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}
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/* Test the round_{down,up}_for_mask functions. */
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static void
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test_round_for_mask ()
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{
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unsigned int prec = 18;
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ASSERT_EQ (17, wi::round_down_for_mask (wi::shwi (17, prec),
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wi::shwi (0xf1, prec)));
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ASSERT_EQ (17, wi::round_up_for_mask (wi::shwi (17, prec),
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wi::shwi (0xf1, prec)));
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ASSERT_EQ (1, wi::round_down_for_mask (wi::shwi (6, prec),
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wi::shwi (0xf1, prec)));
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ASSERT_EQ (16, wi::round_up_for_mask (wi::shwi (6, prec),
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wi::shwi (0xf1, prec)));
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ASSERT_EQ (17, wi::round_down_for_mask (wi::shwi (24, prec),
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wi::shwi (0xf1, prec)));
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ASSERT_EQ (32, wi::round_up_for_mask (wi::shwi (24, prec),
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wi::shwi (0xf1, prec)));
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ASSERT_EQ (0x011, wi::round_down_for_mask (wi::shwi (0x22, prec),
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wi::shwi (0x111, prec)));
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ASSERT_EQ (0x100, wi::round_up_for_mask (wi::shwi (0x22, prec),
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wi::shwi (0x111, prec)));
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ASSERT_EQ (100, wi::round_down_for_mask (wi::shwi (101, prec),
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wi::shwi (0xfc, prec)));
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ASSERT_EQ (104, wi::round_up_for_mask (wi::shwi (101, prec),
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wi::shwi (0xfc, prec)));
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ASSERT_EQ (0x2bc, wi::round_down_for_mask (wi::shwi (0x2c2, prec),
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wi::shwi (0xabc, prec)));
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ASSERT_EQ (0x800, wi::round_up_for_mask (wi::shwi (0x2c2, prec),
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wi::shwi (0xabc, prec)));
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ASSERT_EQ (0xabc, wi::round_down_for_mask (wi::shwi (0xabd, prec),
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wi::shwi (0xabc, prec)));
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ASSERT_EQ (0, wi::round_up_for_mask (wi::shwi (0xabd, prec),
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wi::shwi (0xabc, prec)));
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ASSERT_EQ (0xabc, wi::round_down_for_mask (wi::shwi (0x1000, prec),
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wi::shwi (0xabc, prec)));
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ASSERT_EQ (0, wi::round_up_for_mask (wi::shwi (0x1000, prec),
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wi::shwi (0xabc, prec)));
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}
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/* Run all of the selftests within this file, for all value types. */
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void
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@ -2393,6 +2504,7 @@ wide_int_cc_tests ()
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run_all_wide_int_tests <offset_int> ();
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run_all_wide_int_tests <widest_int> ();
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test_overflow ();
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test_round_for_mask ();
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}
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} // namespace selftest
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@ -3308,6 +3308,8 @@ namespace wi
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wide_int set_bit_in_zero (unsigned int, unsigned int);
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wide_int insert (const wide_int &x, const wide_int &y, unsigned int,
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unsigned int);
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wide_int round_down_for_mask (const wide_int &, const wide_int &);
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wide_int round_up_for_mask (const wide_int &, const wide_int &);
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template <typename T>
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T mask (unsigned int, bool);
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