Reviewers: Jakob,
Description:
Extend bounds check elimination to constant keys.
[email protected]
BUG=v8:3367
Please review this at https://codereview.chromium.org/310333004/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+52, -34 lines):
M src/hydrogen-bce.cc
Index: src/hydrogen-bce.cc
diff --git a/src/hydrogen-bce.cc b/src/hydrogen-bce.cc
index
65c2b142c5f3c803a5a3533b57e9c9cb28ba43fa..c72a8c55d865f7bfdf4c7e21c675a710fd3b9ddd
100644
--- a/src/hydrogen-bce.cc
+++ b/src/hydrogen-bce.cc
@@ -54,6 +54,9 @@ class BoundsCheckKey : public ZoneObject {
constant = HConstant::cast(index->right());
index_base = index->left();
}
+ } else if (check->index()->IsConstant()) {
+ index_base = check->block()->graph()->GetConstant0();
+ constant = HConstant::cast(check->index());
}
if (constant != NULL && constant->HasInteger32Value()) {
@@ -222,41 +225,56 @@ class BoundsCheckBbData: public ZoneObject {
void MoveIndexIfNecessary(HValue* index_raw,
HBoundsCheck* insert_before,
HInstruction* end_of_scan_range) {
- if (!index_raw->IsAdd() && !index_raw->IsSub()) {
- // index_raw can be HAdd(index_base, offset), HSub(index_base,
offset),
- // or index_base directly. In the latter case, no need to move
anything.
- return;
- }
- HArithmeticBinaryOperation* index =
- HArithmeticBinaryOperation::cast(index_raw);
- HValue* left_input = index->left();
- HValue* right_input = index->right();
- bool must_move_index = false;
- bool must_move_left_input = false;
- bool must_move_right_input = false;
- for (HInstruction* cursor = end_of_scan_range; cursor !=
insert_before;) {
- if (cursor == left_input) must_move_left_input = true;
- if (cursor == right_input) must_move_right_input = true;
- if (cursor == index) must_move_index = true;
- if (cursor->previous() == NULL) {
- cursor = cursor->block()->dominator()->end();
- } else {
- cursor = cursor->previous();
+ // index_raw can be HAdd(index_base, offset), HSub(index_base, offset),
+ // HConstant(offset) or index_base directly.
+ // In the latter case, no need to move anything.
+ if (index_raw->IsAdd() || index_raw->IsSub()) {
+ HArithmeticBinaryOperation* index =
+ HArithmeticBinaryOperation::cast(index_raw);
+ HValue* left_input = index->left();
+ HValue* right_input = index->right();
+ bool must_move_index = false;
+ bool must_move_left_input = false;
+ bool must_move_right_input = false;
+ for (HInstruction* cursor = end_of_scan_range; cursor !=
insert_before;) {
+ if (cursor == left_input) must_move_left_input = true;
+ if (cursor == right_input) must_move_right_input = true;
+ if (cursor == index) must_move_index = true;
+ if (cursor->previous() == NULL) {
+ cursor = cursor->block()->dominator()->end();
+ } else {
+ cursor = cursor->previous();
+ }
+ }
+ if (must_move_index) {
+ index->Unlink();
+ index->InsertBefore(insert_before);
+ }
+ // The BCE algorithm only selects mergeable bounds checks that share
+ // the same "index_base", so we'll only ever have to move constants.
+ if (must_move_left_input) {
+ HConstant::cast(left_input)->Unlink();
+ HConstant::cast(left_input)->InsertBefore(index);
+ }
+ if (must_move_right_input) {
+ HConstant::cast(right_input)->Unlink();
+ HConstant::cast(right_input)->InsertBefore(index);
+ }
+ } else if (index_raw->IsConstant()) {
+ HConstant* index = HConstant::cast(index_raw);
+ bool must_move = false;
+ for (HInstruction* cursor = end_of_scan_range; cursor !=
insert_before;) {
+ if (cursor == index) must_move = true;
+ if (cursor->previous() == NULL) {
+ cursor = cursor->block()->dominator()->end();
+ } else {
+ cursor = cursor->previous();
+ }
+ }
+ if (must_move) {
+ index->Unlink();
+ index->InsertBefore(insert_before);
}
- }
- if (must_move_index) {
- index->Unlink();
- index->InsertBefore(insert_before);
- }
- // The BCE algorithm only selects mergeable bounds checks that share
- // the same "index_base", so we'll only ever have to move constants.
- if (must_move_left_input) {
- HConstant::cast(left_input)->Unlink();
- HConstant::cast(left_input)->InsertBefore(index);
- }
- if (must_move_right_input) {
- HConstant::cast(right_input)->Unlink();
- HConstant::cast(right_input)->InsertBefore(index);
}
}
--
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