[NFC] Move OrderedInstructions and InstructionPrecedenceTracking to Analysis

These classes don't make any changes to IR and have no reason to be in
Transform/Utils. This patch moves them to Analysis folder. This will allow
us reusing these classes in some analyzes, like MustExecute.

llvm-svn: 341015

1 files changed, 51 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/OrderedInstructions.cpp b/llvm/lib/Analysis/OrderedInstructions.cpp
new file mode 100644
index 00000000000..7b155208c02
--- /dev/null
+++ b/llvm/lib/Analysis/OrderedInstructions.cpp
@@ -0,0 +1,51 @@
+//===-- OrderedInstructions.cpp - Instruction dominance function ---------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines utility to check dominance relation of 2 instructions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/OrderedInstructions.h"
+using namespace llvm;
+
+bool OrderedInstructions::localDominates(const Instruction *InstA,
+                                         const Instruction *InstB) const {
+  assert(InstA->getParent() == InstB->getParent() &&
+         "Instructions must be in the same basic block");
+
+  const BasicBlock *IBB = InstA->getParent();
+  auto OBB = OBBMap.find(IBB);
+  if (OBB == OBBMap.end())
+    OBB = OBBMap.insert({IBB, make_unique<OrderedBasicBlock>(IBB)}).first;
+  return OBB->second->dominates(InstA, InstB);
+}
+
+/// Given 2 instructions, use OrderedBasicBlock to check for dominance relation
+/// if the instructions are in the same basic block, Otherwise, use dominator
+/// tree.
+bool OrderedInstructions::dominates(const Instruction *InstA,
+                                    const Instruction *InstB) const {
+  // Use ordered basic block to do dominance check in case the 2 instructions
+  // are in the same basic block.
+  if (InstA->getParent() == InstB->getParent())
+    return localDominates(InstA, InstB);
+  return DT->dominates(InstA->getParent(), InstB->getParent());
+}
+
+bool OrderedInstructions::dfsBefore(const Instruction *InstA,
+                                    const Instruction *InstB) const {
+  // Use ordered basic block in case the 2 instructions are in the same basic
+  // block.
+  if (InstA->getParent() == InstB->getParent())
+    return localDominates(InstA, InstB);
+
+  DomTreeNode *DA = DT->getNode(InstA->getParent());
+  DomTreeNode *DB = DT->getNode(InstB->getParent());
+  return DA->getDFSNumIn() < DB->getDFSNumIn();
+}