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7153771: array bound check elimination for c1

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When possible optimize out array bound checks, inserting predicates when needed.

Reviewed-by: never, kvn, twisti
This commit is contained in:
Thomas Wuerthinger 2013-03-21 09:27:54 +01:00 • committed by Roland Westrelin
parent 2f4ecb86a2
commit 06ef4cddf7
40 changed files with 2861 additions and 153 deletions
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35
hotspot/src/share/vm/c1/c1_LinearScan.cpp
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@ -6231,26 +6231,29 @@ void ControlFlowOptimizer::delete_unnecessary_jumps(BlockList* code) {
assert(prev_op->as_OpBranch() != NULL, "branch must be of type LIR_OpBranch");
LIR_OpBranch* prev_branch = (LIR_OpBranch*)prev_op;
LIR_Op2* prev_cmp = NULL;
if (prev_branch->stub() == NULL) {
for(int j = instructions->length() - 3; j >= 0 && prev_cmp == NULL; j--) {
prev_op = instructions->at(j);
if(prev_op->code() == lir_cmp) {
assert(prev_op->as_Op2() != NULL, "branch must be of type LIR_Op2");
prev_cmp = (LIR_Op2*)prev_op;
assert(prev_branch->cond() == prev_cmp->condition(), "should be the same");
LIR_Op2* prev_cmp = NULL;
for(int j = instructions->length() - 3; j >= 0 && prev_cmp == NULL; j--) {
prev_op = instructions->at(j);
if (prev_op->code() == lir_cmp) {
assert(prev_op->as_Op2() != NULL, "branch must be of type LIR_Op2");
prev_cmp = (LIR_Op2*)prev_op;
assert(prev_branch->cond() == prev_cmp->condition(), "should be the same");
}
}
}
assert(prev_cmp != NULL, "should have found comp instruction for branch");
if (prev_branch->block() == code->at(i + 1) && prev_branch->info() == NULL) {
assert(prev_cmp != NULL, "should have found comp instruction for branch");
if (prev_branch->block() == code->at(i + 1) && prev_branch->info() == NULL) {
TRACE_LINEAR_SCAN(3, tty->print_cr("Negating conditional branch and deleting unconditional branch at end of block B%d", block->block_id()));
TRACE_LINEAR_SCAN(3, tty->print_cr("Negating conditional branch and deleting unconditional branch at end of block B%d", block->block_id()));
// eliminate a conditional branch to the immediate successor
prev_branch->change_block(last_branch->block());
prev_branch->negate_cond();
prev_cmp->set_condition(prev_branch->cond());
instructions->truncate(instructions->length() - 1);
// eliminate a conditional branch to the immediate successor
prev_branch->change_block(last_branch->block());
prev_branch->negate_cond();
prev_cmp->set_condition(prev_branch->cond());
instructions->truncate(instructions->length() - 1);
}
}
}
}