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deps: backport 5f836c from v8 upstream

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Original commit message:

    Fix Hydrogen bounds check elimination

    When combining bounds checks, they must all be moved before the first load/store
    that they are guarding.

    BUG=chromium:344186
    LOG=y
    R=svenpanne@chromium.org

    Review URL: https://codereview.chromium.org/172093002

    git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19475 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

fix #8070
This commit is contained in:
Fedor Indutny 2014-08-14 19:29:28 +04:00
parent 6b97c2e986
commit fd80a31e06
1 changed files with 50 additions and 56 deletions
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106
deps/v8/src/hydrogen.cc vendored
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@ -3487,13 +3487,7 @@ class BoundsCheckBbData: public ZoneObject {
keep_new_check = true;
upper_check_ = new_check;
} else {
BuildOffsetAdd(upper_check_,
&added_upper_index_,
&added_upper_offset_,
Key()->IndexBase(),
new_check->index()->representation(),
new_offset);
upper_check_->SetOperandAt(0, added_upper_index_);
TightenCheck(upper_check_, new_check);
}
} else if (new_offset < lower_offset_) {
lower_offset_ = new_offset;
@ -3501,28 +3495,27 @@ class BoundsCheckBbData: public ZoneObject {
keep_new_check = true;
lower_check_ = new_check;
} else {
BuildOffsetAdd(lower_check_,
&added_lower_index_,
&added_lower_offset_,
Key()->IndexBase(),
new_check->index()->representation(),
new_offset);
lower_check_->SetOperandAt(0, added_lower_index_);
TightenCheck(lower_check_, new_check);
}
} else {
ASSERT(false);
// Should never have called CoverCheck() in this case.
UNREACHABLE();
}
if (!keep_new_check) {
new_check->DeleteAndReplaceWith(NULL);
} else {
HBoundsCheck* first_check = new_check == lower_check_ ? upper_check_
: lower_check_;
// The length is guaranteed to be live at first_check.
ASSERT(new_check->length() == first_check->length());
HInstruction* old_position = new_check->next();
new_check->Unlink();
new_check->InsertAfter(first_check);
MoveIndexIfNecessary(new_check->index(), new_check, old_position);
}
}
void RemoveZeroOperations() {
RemoveZeroAdd(&added_lower_index_, &added_lower_offset_);
RemoveZeroAdd(&added_upper_index_, &added_upper_offset_);
}
BoundsCheckBbData(BoundsCheckKey* key,
int32_t lower_offset,
int32_t upper_offset,
@ -3537,10 +3530,6 @@ class BoundsCheckBbData: public ZoneObject {
basic_block_(bb),
lower_check_(lower_check),
upper_check_(upper_check),
added_lower_index_(NULL),
added_lower_offset_(NULL),
added_upper_index_(NULL),
added_upper_offset_(NULL),
next_in_bb_(next_in_bb),
father_in_dt_(father_in_dt) { }
@ -3551,43 +3540,49 @@ class BoundsCheckBbData: public ZoneObject {
HBasicBlock* basic_block_;
HBoundsCheck* lower_check_;
HBoundsCheck* upper_check_;
HAdd* added_lower_index_;
HConstant* added_lower_offset_;
HAdd* added_upper_index_;
HConstant* added_upper_offset_;
BoundsCheckBbData* next_in_bb_;
BoundsCheckBbData* father_in_dt_;
void BuildOffsetAdd(HBoundsCheck* check,
HAdd** add,
HConstant** constant,
HValue* original_value,
Representation representation,
int32_t new_offset) {
HConstant* new_constant = new(BasicBlock()->zone())
HConstant(new_offset, Representation::Integer32());
if (*add == NULL) {
new_constant->InsertBefore(check);
// Because of the bounds checks elimination algorithm, the index is always
// an HAdd or an HSub here, so we can safely cast to an HBinaryOperation.
HValue* context = HBinaryOperation::cast(check->index())->context();
*add = new(BasicBlock()->zone()) HAdd(context,
original_value,
new_constant);
(*add)->AssumeRepresentation(representation);
(*add)->InsertBefore(check);
} else {
new_constant->InsertBefore(*add);
(*constant)->DeleteAndReplaceWith(new_constant);
void MoveIndexIfNecessary(HValue* index_raw,
HBoundsCheck* insert_before,
HInstruction* end_of_scan_range) {
ASSERT(index_raw->IsAdd() || index_raw->IsSub());
HBinaryOperation* 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();
}
}
// 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);
}
*constant = new_constant;
}
void RemoveZeroAdd(HAdd** add, HConstant** constant) {
if (*add != NULL && (*constant)->Integer32Value() == 0) {
(*add)->DeleteAndReplaceWith((*add)->left());
(*constant)->DeleteAndReplaceWith(NULL);
}
void TightenCheck(HBoundsCheck* original_check,
HBoundsCheck* tighter_check) {
ASSERT(original_check->length() == tighter_check->length());
MoveIndexIfNecessary(tighter_check->index(), original_check, tighter_check);
original_check->ReplaceAllUsesWith(original_check->index());
original_check->SetOperandAt(0, tighter_check->index());
}
};
@ -3683,7 +3678,6 @@ void HGraph::EliminateRedundantBoundsChecks(HBasicBlock* bb,
for (BoundsCheckBbData* data = bb_data_list;
data != NULL;
data = data->NextInBasicBlock()) {
data->RemoveZeroOperations();
if (data->FatherInDominatorTree()) {
table->Insert(data->Key(), data->FatherInDominatorTree(), zone());
} else {