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CFA: Pull in CalculateDominators

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This commit is contained in:
Greg Fischer 2017-05-08 18:32:12 -06:00 committed by David Neto
parent df6537cee0
commit d6f2979068
3 changed files with 94 additions and 94 deletions
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92
source/cfa.h
View File

@ -82,6 +82,29 @@ public:
std::function<void(cbb_ptr)> preorder,
std::function<void(cbb_ptr)> postorder,
std::function<void(cbb_ptr, cbb_ptr)> backedge);
/// @brief Calculates dominator edges for a set of blocks
///
/// Computes dominators using the algorithm of Cooper, Harvey, and Kennedy
/// "A Simple, Fast Dominance Algorithm", 2001.
///
/// The algorithm assumes there is a unique root node (a node without
/// predecessors), and it is therefore at the end of the postorder vector.
///
/// This function calculates the dominator edges for a set of blocks in the CFG.
/// Uses the dominator algorithm by Cooper et al.
///
/// @param[in] postorder A vector of blocks in post order traversal order
/// in a CFG
/// @param[in] predecessor_func Function used to get the predecessor nodes of a
/// block
///
/// @return the dominator tree of the graph, as a vector of pairs of nodes.
/// The first node in the pair is a node in the graph. The second node in the
/// pair is its immediate dominator in the sense of Cooper et.al., where a block
/// 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);
};
template<class BB> bool CFA<BB>::FindInWorkList(const vector<block_info>& work_list,
@ -130,6 +153,75 @@ template<class BB> void CFA<BB>::DepthFirstTraversal(const BB* entry,
}
}
template<class BB>
vector<pair<BB*, BB*>> CFA<BB>::CalculateDominators(
const vector<cbb_ptr>& postorder, get_blocks_func predecessor_func) {
struct block_detail {
size_t dominator; ///< The index of blocks's dominator in post order array
size_t postorder_index; ///< The index of the block in the post order array
};
const size_t undefined_dom = postorder.size();
unordered_map<cbb_ptr, block_detail> idoms;
for (size_t i = 0; i < postorder.size(); i++) {
idoms[postorder[i]] = { undefined_dom, i };
}
idoms[postorder.back()].dominator = idoms[postorder.back()].postorder_index;
bool changed = true;
while (changed) {
changed = false;
for (auto b = postorder.rbegin() + 1; b != postorder.rend(); ++b) {
const vector<BB*>& predecessors = *predecessor_func(*b);
// Find the first processed/reachable predecessor that is reachable
// in the forward traversal.
auto res = find_if(begin(predecessors), end(predecessors),
[&idoms, undefined_dom](BB* pred) {
return idoms.count(pred) &&
idoms[pred].dominator != undefined_dom;
});
if (res == end(predecessors)) continue;
const BB* idom = *res;
size_t idom_idx = idoms[idom].postorder_index;
// all other predecessors
for (const auto* p : predecessors) {
if (idom == p) continue;
// Only consider nodes reachable in the forward traversal.
// Otherwise the intersection doesn't make sense and will never
// terminate.
if (!idoms.count(p)) continue;
if (idoms[p].dominator != undefined_dom) {
size_t finger1 = idoms[p].postorder_index;
size_t finger2 = idom_idx;
while (finger1 != finger2) {
while (finger1 < finger2) {
finger1 = idoms[postorder[finger1]].dominator;
}
while (finger2 < finger1) {
finger2 = idoms[postorder[finger2]].dominator;
}
}
idom_idx = finger1;
}
}
if (idoms[*b].dominator != idom_idx) {
idoms[*b].dominator = idom_idx;
changed = true;
}
}
}
vector<pair<bb_ptr, bb_ptr>> out;
for (auto idom : idoms) {
// NOTE: performing a const cast for convenient usage with
// UpdateImmediateDominators
out.push_back({ const_cast<BB*>(get<0>(idom)),
const_cast<BB*>(postorder[get<1>(idom).dominator]) });
}
return out;
}
} // namespace spvtools
#endif // SPVTOOLS_CFA_H_

24
source/validate.h
View File

@ -34,30 +34,6 @@ class BasicBlock;
using get_blocks_func =
std::function<const std::vector<BasicBlock*>*(const BasicBlock*)>;
/// @brief Calculates dominator edges for a set of blocks
///
/// Computes dominators using the algorithm of Cooper, Harvey, and Kennedy
/// "A Simple, Fast Dominance Algorithm", 2001.
///
/// The algorithm assumes there is a unique root node (a node without
/// predecessors), and it is therefore at the end of the postorder vector.
///
/// This function calculates the dominator edges for a set of blocks in the CFG.
/// Uses the dominator algorithm by Cooper et al.
///
/// @param[in] postorder A vector of blocks in post order traversal order
/// in a CFG
/// @param[in] predecessor_func Function used to get the predecessor nodes of a
/// block
///
/// @return the dominator tree of the graph, as a vector of pairs of nodes.
/// The first node in the pair is a node in the graph. The second node in the
/// pair is its immediate dominator in the sense of Cooper et.al., where a block
/// without predecessors (such as the root node) is its own immediate dominator.
std::vector<std::pair<BasicBlock*, BasicBlock*>> CalculateDominators(
const std::vector<const BasicBlock*>& postorder,
get_blocks_func predecessor_func);
/// @brief Performs the Control Flow Graph checks
///
/// @param[in] _ the validation state of the module

72
source/validate_cfg.cpp
View File

@ -61,74 +61,6 @@ using bb_iter = vector<BasicBlock*>::const_iterator;
} // namespace
vector<pair<BasicBlock*, BasicBlock*>> CalculateDominators(
const vector<cbb_ptr>& postorder, get_blocks_func predecessor_func) {
struct block_detail {
size_t dominator; ///< The index of blocks's dominator in post order array
size_t postorder_index; ///< The index of the block in the post order array
};
const size_t undefined_dom = postorder.size();
unordered_map<cbb_ptr, block_detail> idoms;
for (size_t i = 0; i < postorder.size(); i++) {
idoms[postorder[i]] = {undefined_dom, i};
}
idoms[postorder.back()].dominator = idoms[postorder.back()].postorder_index;
bool changed = true;
while (changed) {
changed = false;
for (auto b = postorder.rbegin() + 1; b != postorder.rend(); ++b) {
const vector<BasicBlock*>& predecessors = *predecessor_func(*b);
// Find the first processed/reachable predecessor that is reachable
// in the forward traversal.
auto res = find_if(begin(predecessors), end(predecessors),
[&idoms, undefined_dom](BasicBlock* pred) {
return idoms.count(pred) &&
idoms[pred].dominator != undefined_dom;
});
if (res == end(predecessors)) continue;
const BasicBlock* idom = *res;
size_t idom_idx = idoms[idom].postorder_index;
// all other predecessors
for (const auto* p : predecessors) {
if (idom == p) continue;
// Only consider nodes reachable in the forward traversal.
// Otherwise the intersection doesn't make sense and will never
// terminate.
if (!idoms.count(p)) continue;
if (idoms[p].dominator != undefined_dom) {
size_t finger1 = idoms[p].postorder_index;
size_t finger2 = idom_idx;
while (finger1 != finger2) {
while (finger1 < finger2) {
finger1 = idoms[postorder[finger1]].dominator;
}
while (finger2 < finger1) {
finger2 = idoms[postorder[finger2]].dominator;
}
}
idom_idx = finger1;
}
}
if (idoms[*b].dominator != idom_idx) {
idoms[*b].dominator = idom_idx;
changed = true;
}
}
}
vector<pair<bb_ptr, bb_ptr>> out;
for (auto idom : idoms) {
// NOTE: performing a const cast for convenient usage with
// UpdateImmediateDominators
out.push_back({const_cast<BasicBlock*>(get<0>(idom)),
const_cast<BasicBlock*>(postorder[get<1>(idom).dominator])});
}
return out;
}
void printDominatorList(const BasicBlock& b) {
std::cout << b.id() << " is dominated by: ";
const BasicBlock* bb = &b;
@ -355,7 +287,7 @@ spv_result_t PerformCfgChecks(ValidationState_t& _) {
function.first_block(), function.AugmentedCFGSuccessorsFunction(),
ignore_block, [&](cbb_ptr b) { postorder.push_back(b); },
ignore_edge);
auto edges = libspirv::CalculateDominators(
auto edges = spvtools::CFA<libspirv::BasicBlock>::CalculateDominators(
postorder, function.AugmentedCFGPredecessorsFunction());
for (auto edge : edges) {
edge.first->SetImmediateDominator(edge.second);
@ -366,7 +298,7 @@ spv_result_t PerformCfgChecks(ValidationState_t& _) {
function.pseudo_exit_block(),
function.AugmentedCFGPredecessorsFunction(), ignore_block,
[&](cbb_ptr b) { postdom_postorder.push_back(b); }, ignore_edge);
auto postdom_edges = libspirv::CalculateDominators(
auto postdom_edges = spvtools::CFA<libspirv::BasicBlock>::CalculateDominators(
postdom_postorder, function.AugmentedCFGSuccessorsFunction());
for (auto edge : postdom_edges) {
edge.first->SetImmediatePostDominator(edge.second);