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8314468: Improve Compiler loops

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Reviewed-by: jwilhelm, epeter
Backport-of: 86e71472aefc26175cfc00d44f255f64893e477b
This commit is contained in:
Tobias Hartmann
2023-10-20 10:54:34 +00:00
parent a4e78f30fc
commit c20cfeabf1
1 changed files with 12 additions and 9 deletions
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21
src/hotspot/share/c1/c1_RangeCheckElimination.cpp
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@@ -404,8 +404,11 @@ 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);
@@ -448,9 +451,9 @@ void RangeCheckEliminator::in_block_motion(BlockBegin *block, AccessIndexedList
}
}
} else {
int last_integer = 0;
jint last_integer = 0;
Instruction *last_instruction = index;
int base = 0;
jint base = 0;
ArithmeticOp *ao = index->as_ArithmeticOp();
while (ao != nullptr && (ao->x()->as_Constant() || ao->y()->as_Constant()) && (ao->op() == Bytecodes::_iadd || ao->op() == Bytecodes::_isub)) {
@@ -462,12 +465,12 @@ void RangeCheckEliminator::in_block_motion(BlockBegin *block, AccessIndexedList
}
if (c) {
int value = c->type()->as_IntConstant()->value();
jint value = c->type()->as_IntConstant()->value();
if (value != min_jint) {
if (ao->op() == Bytecodes::_isub) {
value = -value;
}
base += value;
base = java_add(base, value);
last_integer = base;
last_instruction = other;
}
@@ -489,12 +492,12 @@ 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
@@ -843,7 +846,7 @@ 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!");