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| author | Jakub Jelinek <jakub@redhat.com> | 2024-06-04 16:16:49 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2024-06-04 16:16:49 +0200 |
| commit | 591d30c5c97e757f63ce0d99ae9a3dbe8c75a50a (patch) | |
| tree | aa773d49def70b17ba64071998e7d3867fbad4da /gcc | |
| parent | 181861b072ff1ef650c1a9d0290a4a672b9e747c (diff) | |
| download | gcc-591d30c5c97e757f63ce0d99ae9a3dbe8c75a50a.zip gcc-591d30c5c97e757f63ce0d99ae9a3dbe8c75a50a.tar.gz gcc-591d30c5c97e757f63ce0d99ae9a3dbe8c75a50a.tar.bz2 | |
ranger: Improve CLZ fold_range [PR115337]
cfn_ctz::fold_range includes special cases for the case where .CTZ has
two arguments and so is well defined at zero, and the second argument is
equal to prec or -1, but cfn_clz::fold_range does that only for the prec
case. -1 is fairly common as well though, because the <stdbit.h> builtins
do use it now, so I think it is worth special casing that.
If we don't know anything about the argument, the difference for
.CLZ (arg, -1) is that previously the result was varying, now it will be
[-1, prec-1]. If we knew arg can't be zero, it used to be optimized before
as well into e.g. [0, prec-1] or similar.
2024-06-04 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/115337
* gimple-range-op.cc (cfn_clz::fold_range): For
m_gimple_call_internal_p handle as a special case also second argument
of -1 next to prec.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/gimple-range-op.cc | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/gcc/gimple-range-op.cc b/gcc/gimple-range-op.cc index aec3f39..1b9a847 100644 --- a/gcc/gimple-range-op.cc +++ b/gcc/gimple-range-op.cc @@ -941,8 +941,10 @@ cfn_clz::fold_range (irange &r, tree type, const irange &lh, int maxi = prec - 1; if (m_gimple_call_internal_p) { - // Only handle the single common value. - if (rh.lower_bound () == prec) + // Handle only the two common values. + if (rh.lower_bound () == -1) + mini = -1; + else if (rh.lower_bound () == prec) maxi = prec; else // Magic value to give up, unless we can prove arg is non-zero. @@ -953,7 +955,7 @@ cfn_clz::fold_range (irange &r, tree type, const irange &lh, if (wi::gt_p (lh.lower_bound (), 0, TYPE_SIGN (lh.type ()))) { maxi = prec - 1 - wi::floor_log2 (lh.lower_bound ()); - if (mini == -2) + if (mini < 0) mini = 0; } else if (!range_includes_zero_p (lh)) @@ -969,11 +971,11 @@ cfn_clz::fold_range (irange &r, tree type, const irange &lh, if (max == 0) { // If CLZ_DEFINED_VALUE_AT_ZERO is 2 with VALUE of prec, - // return [prec, prec], otherwise ignore the range. - if (maxi == prec) - mini = prec; + // return [prec, prec] or [-1, -1], otherwise ignore the range. + if (maxi == prec || mini == -1) + mini = maxi; } - else + else if (mini >= 0) mini = newmini; if (mini == -2) |