LLVM  8.0.0svn
OrderedInstructions.cpp
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1 //===-- OrderedInstructions.cpp - Instruction dominance function ---------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines utility to check dominance relation of 2 instructions.
11 //
12 //===----------------------------------------------------------------------===//
13 
15 using namespace llvm;
16 
17 bool OrderedInstructions::localDominates(const Instruction *InstA,
18  const Instruction *InstB) const {
19  assert(InstA->getParent() == InstB->getParent() &&
20  "Instructions must be in the same basic block");
21 
22  const BasicBlock *IBB = InstA->getParent();
23  auto OBB = OBBMap.find(IBB);
24  if (OBB == OBBMap.end())
25  OBB = OBBMap.insert({IBB, make_unique<OrderedBasicBlock>(IBB)}).first;
26  return OBB->second->dominates(InstA, InstB);
27 }
28 
29 /// Given 2 instructions, use OrderedBasicBlock to check for dominance relation
30 /// if the instructions are in the same basic block, Otherwise, use dominator
31 /// tree.
33  const Instruction *InstB) const {
34  // Use ordered basic block to do dominance check in case the 2 instructions
35  // are in the same basic block.
36  if (InstA->getParent() == InstB->getParent())
37  return localDominates(InstA, InstB);
38  return DT->dominates(InstA->getParent(), InstB->getParent());
39 }
40 
42  const Instruction *InstB) const {
43  // Use ordered basic block in case the 2 instructions are in the same basic
44  // block.
45  if (InstA->getParent() == InstB->getParent())
46  return localDominates(InstA, InstB);
47 
48  DomTreeNode *DA = DT->getNode(InstA->getParent());
49  DomTreeNode *DB = DT->getNode(InstB->getParent());
50  return DA->getDFSNumIn() < DB->getDFSNumIn();
51 }
This class represents lattice values for constants.
Definition: AllocatorList.h:24
bool dominates(const Instruction *, const Instruction *) const
Return true if first instruction dominates the second.
unsigned getDFSNumIn() const
getDFSNumIn/getDFSNumOut - These return the DFS visitation order for nodes in the dominator tree...
LLVM Basic Block Representation.
Definition: BasicBlock.h:58
bool dfsBefore(const Instruction *, const Instruction *) const
Return true if the first instruction comes before the second in the dominator tree DFS traversal if t...
DomTreeNodeBase< NodeT > * getNode(const NodeT *BB) const
getNode - return the (Post)DominatorTree node for the specified basic block.
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:249
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
const BasicBlock * getParent() const
Definition: Instruction.h:67