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| author | Andrew MacLeod <amacleod@redhat.com> | 2022-01-12 13:28:55 -0500 |
|---|---|---|
| committer | Andrew MacLeod <amacleod@redhat.com> | 2022-01-13 13:51:30 -0500 |
| commit | 27e4260166950b784fe270ba4f0cae9a66faf1c4 (patch) | |
| tree | 837cf00a12e99bfb6ab81257c72301706f242f04 /gcc | |
| parent | 0b8464365b15ac108cd1d00d5bc56d229c1340de (diff) | |
| download | gcc-27e4260166950b784fe270ba4f0cae9a66faf1c4.zip gcc-27e4260166950b784fe270ba4f0cae9a66faf1c4.tar.gz gcc-27e4260166950b784fe270ba4f0cae9a66faf1c4.tar.bz2 | |
Add relation to unsigned right shift.
If the first operand and the shift value of a right shift operation are both
>= 0, then we know the LHS of the operation is <= the first operand.
PR tree-optimization/96707
gcc/
* range-op.cc (operator_rshift::lhs_op1_relation): New.
gcc/testsuite/
* g++.dg/pr96707.C: New.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/range-op.cc | 16 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/pr96707.C | 10 |
2 files changed, 26 insertions, 0 deletions
diff --git a/gcc/range-op.cc b/gcc/range-op.cc index a4f6e9e..19bdf30 100644 --- a/gcc/range-op.cc +++ b/gcc/range-op.cc @@ -1941,9 +1941,25 @@ public: const irange &lhs, const irange &op2, relation_kind rel = VREL_NONE) const; + virtual enum tree_code lhs_op1_relation (const irange &lhs, + const irange &op1, + const irange &op2) const; } op_rshift; +enum tree_code +operator_rshift::lhs_op1_relation (const irange &lhs ATTRIBUTE_UNUSED, + const irange &op1, + const irange &op2) const +{ + // If both operands range are >= 0, then the LHS <= op1. + if (!op1.undefined_p () && !op2.undefined_p () + && wi::ge_p (op1.lower_bound (), 0, TYPE_SIGN (op1.type ())) + && wi::ge_p (op2.lower_bound (), 0, TYPE_SIGN (op2.type ()))) + return LE_EXPR; + return VREL_NONE; +} + bool operator_lshift::fold_range (irange &r, tree type, const irange &op1, diff --git a/gcc/testsuite/g++.dg/pr96707.C b/gcc/testsuite/g++.dg/pr96707.C new file mode 100644 index 0000000..2653fe3 --- /dev/null +++ b/gcc/testsuite/g++.dg/pr96707.C @@ -0,0 +1,10 @@ +/* { dg-do compile} */ +/* { dg-options "-O2 -fdump-tree-evrp" } */ + +bool f(unsigned x, unsigned y) +{ + return (x >> y) <= x; +} + +/* { dg-final { scan-tree-dump "return 1" "evrp" } } */ + |