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8314468: Improve Compiler loops

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Co-authored-by: Dean Long <dlong@openjdk.org>
Reviewed-by: rhalade, mschoene, iveresov, kvn
This commit is contained in:
Tobias Hartmann 2023-10-20 07:32:47 +00:00 committed by Henry Jen
parent fac49b8375
commit ed238e8b88
1 changed files with 9 additions and 6 deletions
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15
src/hotspot/share/c1/c1_RangeCheckElimination.cpp
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@ -421,8 +421,11 @@ void RangeCheckEliminator::add_access_indexed_info(InstructionList &indices, int
aii->_max = idx;
aii->_list = new AccessIndexedList();
} else if (idx >= aii->_min && idx <= aii->_max) {
remove_range_check(ai);
return;
// Guard against underflow/overflow (see 'range_cond' check in RangeCheckEliminator::in_block_motion)
if (aii->_max < 0 || (aii->_max + min_jint) <= aii->_min) {
remove_range_check(ai);
return;
}
}
aii->_min = MIN2(aii->_min, idx);
aii->_max = MAX2(aii->_max, idx);
@ -484,7 +487,7 @@ void RangeCheckEliminator::in_block_motion(BlockBegin *block, AccessIndexedList
if (ao->op() == Bytecodes::_isub) {
value = -value;
}
base += value;
base = java_add(base, value);
last_integer = base;
last_instruction = other;
}
@ -506,12 +509,12 @@ void RangeCheckEliminator::in_block_motion(BlockBegin *block, AccessIndexedList
assert(info != nullptr, "Info must not be null");
// if idx < 0, max > 0, max + idx may fall between 0 and
// length-1 and if min < 0, min + idx may overflow and be >=
// length-1 and if min < 0, min + idx may underflow/overflow and be >=
// 0. The predicate wouldn't trigger but some accesses could
// be with a negative index. This test guarantees that for the
// min and max value that are kept the predicate can't let
// some incorrect accesses happen.
bool range_cond = (info->_max < 0 || info->_max + min_jint <= info->_min);
bool range_cond = (info->_max < 0 || (info->_max + min_jint) <= info->_min);
// Generate code only if more than 2 range checks can be eliminated because of that.
// 2 because at least 2 comparisons are done
@ -859,7 +862,7 @@ void RangeCheckEliminator::process_access_indexed(BlockBegin *loop_header, Block
);
remove_range_check(ai);
} else if (_optimistic && loop_header) {
} else if (false && _optimistic && loop_header) {
assert(ai->array(), "Array must not be null!");
assert(ai->index(), "Index must not be null!");