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CFA: Move TraversalRoots and ComputeAugmentedCFG into CFA

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This commit is contained in:
Greg Fischer 2017-05-23 11:31:56 -06:00 committed by GregF
parent d6f2979068
commit 3bea99d378
2 changed files with 117 additions and 86 deletions
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109
source/cfa.h
View File

@ -105,6 +105,25 @@ public:
/// without predecessors (such as the root node) is its own immediate dominator.
static vector<pair<BB*, BB*>> CalculateDominators(
const vector<cbb_ptr>& postorder, get_blocks_func predecessor_func);
// Computes a minimal set of root nodes required to traverse, in the forward
// direction, the CFG represented by the given vector of blocks, and successor
// and predecessor functions. When considering adding two nodes, each having
// predecessors, favour using the one that appears earlier on the input blocks
// list.
static std::vector<BB*> TraversalRoots(
const std::vector<BB*>& blocks,
get_blocks_func succ_func,
get_blocks_func pred_func);
static void ComputeAugmentedCFG(
std::vector<BB*>& ordered_blocks,
BB* pseudo_entry_block,
BB* pseudo_exit_block,
std::unordered_map<const BB*, std::vector<BB*>>* augmented_successors_map,
std::unordered_map<const BB*, std::vector<BB*>>* augmented_predecessors_map,
get_blocks_func succ_func,
get_blocks_func pred_func);
};
template<class BB> bool CFA<BB>::FindInWorkList(const vector<block_info>& work_list,
@ -222,6 +241,96 @@ vector<pair<BB*, BB*>> CFA<BB>::CalculateDominators(
return out;
}
template<class BB>
std::vector<BB*> CFA<BB>::TraversalRoots(
const std::vector<BB*>& blocks,
get_blocks_func succ_func,
get_blocks_func pred_func) {
// The set of nodes which have been visited from any of the roots so far.
std::unordered_set<const BB*> visited;
auto mark_visited = [&visited](const BB* b) { visited.insert(b); };
auto ignore_block = [](const BB*) {};
auto ignore_blocks = [](const BB*, const BB*) {};
auto traverse_from_root = [&mark_visited, &succ_func, &ignore_block,
&ignore_blocks](const BB* entry) {
DepthFirstTraversal(
entry, succ_func, mark_visited, ignore_block, ignore_blocks);
};
std::vector<BB*> result;
// First collect nodes without predecessors.
for (auto block : blocks) {
if (pred_func(block)->empty()) {
assert(visited.count(block) == 0 && "Malformed graph!");
result.push_back(block);
traverse_from_root(block);
}
}
// Now collect other stranded nodes. These must be in unreachable cycles.
for (auto block : blocks) {
if (visited.count(block) == 0) {
result.push_back(block);
traverse_from_root(block);
}
}
return result;
}
template<class BB>
void CFA<BB>::ComputeAugmentedCFG(
std::vector<BB*>& ordered_blocks,
BB* pseudo_entry_block, BB* pseudo_exit_block,
std::unordered_map<const BB*, std::vector<BB*>>* augmented_successors_map,
std::unordered_map<const BB*, std::vector<BB*>>* augmented_predecessors_map,
get_blocks_func succ_func,
get_blocks_func pred_func) {
// Compute the successors of the pseudo-entry block, and
// the predecessors of the pseudo exit block.
auto sources = TraversalRoots(ordered_blocks, succ_func, pred_func);
// For the predecessor traversals, reverse the order of blocks. This
// will affect the post-dominance calculation as follows:
// - Suppose you have blocks A and B, with A appearing before B in
// the list of blocks.
// - Also, A branches only to B, and B branches only to A.
// - We want to compute A as dominating B, and B as post-dominating B.
// By using reversed blocks for predecessor traversal roots discovery,
// we'll add an edge from B to the pseudo-exit node, rather than from A.
// All this is needed to correctly process the dominance/post-dominance
// constraint when A is a loop header that points to itself as its
// own continue target, and B is the latch block for the loop.
std::vector<BB*> reversed_blocks(ordered_blocks.rbegin(),
ordered_blocks.rend());
auto sinks = TraversalRoots(reversed_blocks, pred_func, succ_func);
// Wire up the pseudo entry block.
(*augmented_successors_map)[pseudo_entry_block] = sources;
for (auto block : sources) {
auto& augmented_preds = (*augmented_predecessors_map)[block];
const auto preds = pred_func(block);
augmented_preds.reserve(1 + preds->size());
augmented_preds.push_back(pseudo_entry_block);
augmented_preds.insert(augmented_preds.end(), preds->begin(), preds->end());
}
// Wire up the pseudo exit block.
(*augmented_predecessors_map)[pseudo_exit_block] = sinks;
for (auto block : sinks) {
auto& augmented_succ = (*augmented_successors_map)[block];
const auto succ = succ_func(block);
augmented_succ.reserve(1 + succ->size());
augmented_succ.push_back(pseudo_exit_block);
augmented_succ.insert(augmented_succ.end(), succ->begin(), succ->end());
}
};
} // namespace spvtools
#endif // SPVTOOLS_CFA_H_

94
source/val/function.cpp
View File

@ -33,56 +33,6 @@ using std::pair;
using std::tie;
using std::vector;
namespace {
using libspirv::BasicBlock;
// Computes a minimal set of root nodes required to traverse, in the forward
// direction, the CFG represented by the given vector of blocks, and successor
// and predecessor functions. When considering adding two nodes, each having
// predecessors, favour using the one that appears earlier on the input blocks
// list.
std::vector<BasicBlock*> TraversalRoots(const std::vector<BasicBlock*>& blocks,
libspirv::get_blocks_func succ_func,
libspirv::get_blocks_func pred_func) {
// The set of nodes which have been visited from any of the roots so far.
std::unordered_set<const BasicBlock*> visited;
auto mark_visited = [&visited](const BasicBlock* b) { visited.insert(b); };
auto ignore_block = [](const BasicBlock*) {};
auto ignore_blocks = [](const BasicBlock*, const BasicBlock*) {};
auto traverse_from_root = [&mark_visited, &succ_func, &ignore_block,
&ignore_blocks](const BasicBlock* entry) {
spvtools::CFA<libspirv::BasicBlock>::DepthFirstTraversal(
entry, succ_func, mark_visited, ignore_block, ignore_blocks);
};
std::vector<BasicBlock*> result;
// First collect nodes without predecessors.
for (auto block : blocks) {
if (pred_func(block)->empty()) {
assert(visited.count(block) == 0 && "Malformed graph!");
result.push_back(block);
traverse_from_root(block);
}
}
// Now collect other stranded nodes. These must be in unreachable cycles.
for (auto block : blocks) {
if (visited.count(block) == 0) {
result.push_back(block);
traverse_from_root(block);
}
}
return result;
}
} // anonymous namespace
namespace libspirv {
// Universal Limit of ResultID + 1
@ -324,42 +274,14 @@ void Function::ComputeAugmentedCFG() {
// the predecessors of the pseudo exit block.
auto succ_func = [](const BasicBlock* b) { return b->successors(); };
auto pred_func = [](const BasicBlock* b) { return b->predecessors(); };
auto sources = TraversalRoots(ordered_blocks_, succ_func, pred_func);
// For the predecessor traversals, reverse the order of blocks. This
// will affect the post-dominance calculation as follows:
// - Suppose you have blocks A and B, with A appearing before B in
// the list of blocks.
// - Also, A branches only to B, and B branches only to A.
// - We want to compute A as dominating B, and B as post-dominating B.
// By using reversed blocks for predecessor traversal roots discovery,
// we'll add an edge from B to the pseudo-exit node, rather than from A.
// All this is needed to correctly process the dominance/post-dominance
// constraint when A is a loop header that points to itself as its
// own continue target, and B is the latch block for the loop.
std::vector<BasicBlock*> reversed_blocks(ordered_blocks_.rbegin(),
ordered_blocks_.rend());
auto sinks = TraversalRoots(reversed_blocks, pred_func, succ_func);
// Wire up the pseudo entry block.
augmented_successors_map_[&pseudo_entry_block_] = sources;
for (auto block : sources) {
auto& augmented_preds = augmented_predecessors_map_[block];
const auto& preds = *block->predecessors();
augmented_preds.reserve(1 + preds.size());
augmented_preds.push_back(&pseudo_entry_block_);
augmented_preds.insert(augmented_preds.end(), preds.begin(), preds.end());
}
// Wire up the pseudo exit block.
augmented_predecessors_map_[&pseudo_exit_block_] = sinks;
for (auto block : sinks) {
auto& augmented_succ = augmented_successors_map_[block];
const auto& succ = *block->successors();
augmented_succ.reserve(1 + succ.size());
augmented_succ.push_back(&pseudo_exit_block_);
augmented_succ.insert(augmented_succ.end(), succ.begin(), succ.end());
}
spvtools::CFA<BasicBlock>::ComputeAugmentedCFG(
ordered_blocks_,
&pseudo_entry_block_,
&pseudo_exit_block_,
&augmented_successors_map_,
&augmented_predecessors_map_,
succ_func,
pred_func);
};
Construct& Function::AddConstruct(const Construct& new_construct) {