mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-07-22 09:29:31 +00:00
29dbbd73de
Summary: MemorySSA uses this algorithm as well, and this enables us to reuse the code in both places. There are no actual algorithm or datastructure changes in here, just code movement. Reviewers: qcolombet, chandlerc Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D9118 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235406 91177308-0d34-0410-b5e6-96231b3b80d8
96 lines
3.1 KiB
C++
96 lines
3.1 KiB
C++
//===- IteratedDominanceFrontier.cpp - Compute IDF ------------------------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
/// \brief Compute iterated dominance frontiers using a linear time algorithm.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Analysis/IteratedDominanceFrontier.h"
|
|
#include "llvm/IR/CFG.h"
|
|
#include "llvm/IR/Dominators.h"
|
|
#include <queue>
|
|
|
|
using namespace llvm;
|
|
|
|
void IDFCalculator::calculate(SmallVectorImpl<BasicBlock *> &PHIBlocks) {
|
|
// If we haven't computed dominator tree levels, do so now.
|
|
if (DomLevels.empty()) {
|
|
for (auto DFI = df_begin(DT.getRootNode()), DFE = df_end(DT.getRootNode());
|
|
DFI != DFE; ++DFI) {
|
|
DomLevels[*DFI] = DFI.getPathLength() - 1;
|
|
}
|
|
}
|
|
|
|
// Use a priority queue keyed on dominator tree level so that inserted nodes
|
|
// are handled from the bottom of the dominator tree upwards.
|
|
typedef std::pair<DomTreeNode *, unsigned> DomTreeNodePair;
|
|
typedef std::priority_queue<DomTreeNodePair, SmallVector<DomTreeNodePair, 32>,
|
|
less_second> IDFPriorityQueue;
|
|
IDFPriorityQueue PQ;
|
|
|
|
for (BasicBlock *BB : *DefBlocks) {
|
|
if (DomTreeNode *Node = DT.getNode(BB))
|
|
PQ.push(std::make_pair(Node, DomLevels.lookup(Node)));
|
|
}
|
|
|
|
SmallVector<DomTreeNode *, 32> Worklist;
|
|
SmallPtrSet<DomTreeNode *, 32> VisitedPQ;
|
|
SmallPtrSet<DomTreeNode *, 32> VisitedWorklist;
|
|
|
|
while (!PQ.empty()) {
|
|
DomTreeNodePair RootPair = PQ.top();
|
|
PQ.pop();
|
|
DomTreeNode *Root = RootPair.first;
|
|
unsigned RootLevel = RootPair.second;
|
|
|
|
// Walk all dominator tree children of Root, inspecting their CFG edges with
|
|
// targets elsewhere on the dominator tree. Only targets whose level is at
|
|
// most Root's level are added to the iterated dominance frontier of the
|
|
// definition set.
|
|
|
|
Worklist.clear();
|
|
Worklist.push_back(Root);
|
|
VisitedWorklist.insert(Root);
|
|
|
|
while (!Worklist.empty()) {
|
|
DomTreeNode *Node = Worklist.pop_back_val();
|
|
BasicBlock *BB = Node->getBlock();
|
|
|
|
for (auto Succ : successors(BB)) {
|
|
DomTreeNode *SuccNode = DT.getNode(Succ);
|
|
|
|
// Quickly skip all CFG edges that are also dominator tree edges instead
|
|
// of catching them below.
|
|
if (SuccNode->getIDom() == Node)
|
|
continue;
|
|
|
|
unsigned SuccLevel = DomLevels.lookup(SuccNode);
|
|
if (SuccLevel > RootLevel)
|
|
continue;
|
|
|
|
if (!VisitedPQ.insert(SuccNode).second)
|
|
continue;
|
|
|
|
BasicBlock *SuccBB = SuccNode->getBlock();
|
|
if (useLiveIn && !LiveInBlocks->count(SuccBB))
|
|
continue;
|
|
|
|
PHIBlocks.emplace_back(SuccBB);
|
|
if (!DefBlocks->count(SuccBB))
|
|
PQ.push(std::make_pair(SuccNode, SuccLevel));
|
|
}
|
|
|
|
for (auto DomChild : *Node) {
|
|
if (VisitedWorklist.insert(DomChild).second)
|
|
Worklist.push_back(DomChild);
|
|
}
|
|
}
|
|
}
|
|
}
|