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Avoid redundant work in scheduler loop header/depth calculation.

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R=jarin@chromium.org

TEST=cctest/test-scheduler/LoopedFloatingDiamond2

Review URL: https://codereview.chromium.org/702683002

Cr-Commit-Position: refs/heads/master@{#25181}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25181 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
mstarzinger@chromium.org 2014-11-06 09:15:10 +00:00
parent 8798c410e1
commit 361d7b0f0e
2 changed files with 80 additions and 28 deletions
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66
src/compiler/scheduler.cc
View File

@ -582,7 +582,7 @@ class SpecialRPONumberer : public ZoneObject {
// TODO(mstarzinger): Only for Scheduler::GenerateImmediateDominatorTree.
friend class Scheduler;
// Numbering for BasicBlockData.rpo_number_ for this block traversal:
// Numbering for BasicBlock::rpo_number for this block traversal:
static const int kBlockOnStack = -2;
static const int kBlockVisited1 = -3;
static const int kBlockVisited2 = -4;
@ -672,6 +672,7 @@ class SpecialRPONumberer : public ZoneObject {
// Find correct insertion point within existing order.
BlockList* insert_before = order_->FindForBlock(entry);
BlockList* insert_after = insert_before ? insert_before->next : NULL;
BlockList* order = insert_after;
// Perform an iterative RPO traversal using an explicit stack,
// recording backedges that form cycles. O(|B|).
@ -706,22 +707,12 @@ class SpecialRPONumberer : public ZoneObject {
}
} else {
// Finished with all successors; pop the stack and add the block.
insert_after = insert_after->Add(zone_, frame->block);
order = order->Add(zone_, frame->block);
frame->block->set_rpo_number(kBlockVisited1);
stack_depth--;
}
}
// Insert the result into any existing order.
if (insert_before == NULL) {
order_ = insert_after;
} else {
// There already is a list element for the entry block in the list, hence
// we skip the first element of the sub-list to compensate duplication.
DCHECK_EQ(insert_before->block, insert_after->block);
insert_before->next = insert_after->next;
}
// If no loops were encountered, then the order we computed was correct.
if (num_loops != 0) {
// Otherwise, compute the loop information from the backedges in order
@ -731,7 +722,7 @@ class SpecialRPONumberer : public ZoneObject {
// Initialize the "loop stack". Note the entry could be a loop header.
LoopInfo* loop =
HasLoopNumber(entry) ? &loops_[GetLoopNumber(entry)] : NULL;
order_ = NULL;
order = NULL;
// Perform an iterative post-order traversal, visiting loop bodies before
// edges that lead out of loops. Visits each block once, but linking loop
@ -752,8 +743,8 @@ class SpecialRPONumberer : public ZoneObject {
// Finish the loop body the first time the header is left on the
// stack.
DCHECK(loop != NULL && loop->header == block);
loop->start = order_->Add(zone_, block);
order_ = loop->end;
loop->start = order->Add(zone_, block);
order = loop->end;
block->set_rpo_number(kBlockVisited2);
// Pop the loop stack and continue visiting outgoing edges within
// the context of the outer loop, if any.
@ -790,7 +781,7 @@ class SpecialRPONumberer : public ZoneObject {
// Push the inner loop onto the loop stack.
DCHECK(GetLoopNumber(succ) < num_loops);
LoopInfo* next = &loops_[GetLoopNumber(succ)];
next->end = order_;
next->end = order;
next->prev = loop;
loop = next;
}
@ -802,15 +793,15 @@ class SpecialRPONumberer : public ZoneObject {
LoopInfo* info = &loops_[GetLoopNumber(block)];
for (BlockList* l = info->start; true; l = l->next) {
if (l->next == info->end) {
l->next = order_;
info->end = order_;
l->next = order;
info->end = order;
break;
}
}
order_ = info->start;
order = info->start;
} else {
// Pop a single node off the stack and add it to the order.
order_ = order_->Add(zone_, block);
order = order->Add(zone_, block);
block->set_rpo_number(kBlockVisited2);
}
stack_depth--;
@ -818,13 +809,27 @@ class SpecialRPONumberer : public ZoneObject {
}
}
// Insert result into existing order.
if (insert_before == NULL) {
order_ = order;
} else {
// There already is a list element for the entry block in the list, hence
// we skip the first element of the sub-list to compensate duplication.
DCHECK_EQ(insert_before->block, order->block);
insert_before->next = order->next;
}
// Compute the correct loop headers and set the correct loop ends.
LoopInfo* current_loop = NULL;
BasicBlock* current_header = NULL;
int loop_depth = 0;
for (BlockList* l = order_; l != NULL; l = l->next) {
BasicBlock* current_header = entry->loop_header();
int32_t loop_depth = entry->loop_depth();
if (entry->IsLoopHeader()) --loop_depth; // Entry might be a loop header.
for (BlockList* l = order; l != insert_after; l = l->next) {
BasicBlock* current = l->block;
// Reset BasicBlock::rpo_number again.
current->set_rpo_number(kBlockUnvisited1);
// Finish the previous loop(s) if we just exited them.
while (current_header != NULL && current == current_header->loop_end()) {
DCHECK(current_header->IsLoopHeader());
@ -837,7 +842,7 @@ class SpecialRPONumberer : public ZoneObject {
// Push a new loop onto the stack if this loop is a loop header.
if (HasLoopNumber(current)) {
loop_depth++;
++loop_depth;
current_loop = &loops_[GetLoopNumber(current)];
BlockList* end = current_loop->end;
current->set_loop_end(end == NULL ? BeyondEndSentinel() : end->block);
@ -972,7 +977,7 @@ class SpecialRPONumberer : public ZoneObject {
break;
}
// The list should be in same order as the final result.
DCHECK(l->block->rpo_number() == links + loop->header->rpo_number());
DCHECK(l->block->rpo_number() == links + header->rpo_number());
links++;
l = l->next;
DCHECK(links < static_cast<int>(2 * order->size())); // cycle?
@ -981,6 +986,13 @@ class SpecialRPONumberer : public ZoneObject {
DCHECK(links == end->rpo_number() - header->rpo_number());
DCHECK(end_found);
// Check loop depth of the header.
int loop_depth = 0;
for (LoopInfo* outer = loop; outer != NULL; outer = outer->prev) {
loop_depth++;
}
DCHECK_EQ(loop_depth, header->loop_depth());
// Check the contiguousness of loops.
int count = 0;
for (int j = 0; j < static_cast<int>(order->size()); j++) {
@ -990,6 +1002,7 @@ class SpecialRPONumberer : public ZoneObject {
DCHECK(!header->LoopContains(block));
} else {
DCHECK(header->LoopContains(block));
DCHECK_GE(block->loop_depth(), loop_depth);
count++;
}
}
@ -1428,13 +1441,12 @@ void Scheduler::FuseFloatingControl(BasicBlock* block, Node* node) {
cfg_builder.Run(block, node);
// Iterate on phase 2: Compute special RPO and dominator tree.
special_rpo_->UpdateSpecialRPO(block, schedule_->block(node));
// TODO(mstarzinger): Currently "iterate on" means "re-run". Fix that.
for (BasicBlock* block : schedule_->all_blocks_) {
block->set_rpo_number(-1);
block->set_dominator_depth(-1);
block->set_dominator(NULL);
}
special_rpo_->UpdateSpecialRPO(block, schedule_->block(node));
GenerateImmediateDominatorTree();
// Move previously planned nodes.

42
test/cctest/compiler/test-scheduler.cc
View File

@ -1816,7 +1816,7 @@ TEST(NestedFloatingDiamonds) {
}
TEST(LoopedFloatingDiamond) {
TEST(LoopedFloatingDiamond1) {
HandleAndZoneScope scope;
Graph graph(scope.main_zone());
CommonOperatorBuilder common(scope.main_zone());
@ -1855,6 +1855,46 @@ TEST(LoopedFloatingDiamond) {
}
TEST(LoopedFloatingDiamond2) {
HandleAndZoneScope scope;
Graph graph(scope.main_zone());
CommonOperatorBuilder common(scope.main_zone());
SimplifiedOperatorBuilder simplified(scope.main_zone());
MachineOperatorBuilder machine;
Node* start = graph.NewNode(common.Start(2));
graph.SetStart(start);
Node* p0 = graph.NewNode(common.Parameter(0), start);
Node* c = graph.NewNode(common.Int32Constant(7));
Node* loop = graph.NewNode(common.Loop(2), start, start);
Node* ind = graph.NewNode(common.Phi(kMachAnyTagged, 2), p0, p0, loop);
Node* br1 = graph.NewNode(common.Branch(), p0, graph.start());
Node* t1 = graph.NewNode(common.IfTrue(), br1);
Node* f1 = graph.NewNode(common.IfFalse(), br1);
Node* m1 = graph.NewNode(common.Merge(2), t1, f1);
Node* phi1 = graph.NewNode(common.Phi(kMachAnyTagged, 2), c, ind, m1);
Node* add = graph.NewNode(machine.IntAdd(), ind, phi1);
Node* br = graph.NewNode(common.Branch(), add, loop);
Node* t = graph.NewNode(common.IfTrue(), br);
Node* f = graph.NewNode(common.IfFalse(), br);
loop->ReplaceInput(1, t); // close loop.
ind->ReplaceInput(1, add); // close induction variable.
Node* ret = graph.NewNode(common.Return(), ind, start, f);
Node* end = graph.NewNode(common.End(), ret, f);
graph.SetEnd(end);
ComputeAndVerifySchedule(20, &graph);
}
TEST(PhisPushedDownToDifferentBranches) {
HandleAndZoneScope scope;
Graph graph(scope.main_zone());