Update aosp/master LLVM for rebase to r256229
http://b/26987366
Change-Id: I1f29c4676a8abe633ab5707dded58d846c973d50
diff --git a/lib/Analysis/OrderedBasicBlock.cpp b/lib/Analysis/OrderedBasicBlock.cpp
new file mode 100644
index 0000000..0f0016f
--- /dev/null
+++ b/lib/Analysis/OrderedBasicBlock.cpp
@@ -0,0 +1,85 @@
+//===- OrderedBasicBlock.cpp --------------------------------- -*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the OrderedBasicBlock class. OrderedBasicBlock
+// maintains an interface where clients can query if one instruction comes
+// before another in a BasicBlock. Since BasicBlock currently lacks a reliable
+// way to query relative position between instructions one can use
+// OrderedBasicBlock to do such queries. OrderedBasicBlock is lazily built on a
+// source BasicBlock and maintains an internal Instruction -> Position map. A
+// OrderedBasicBlock instance should be discarded whenever the source
+// BasicBlock changes.
+//
+// It's currently used by the CaptureTracker in order to find relative
+// positions of a pair of instructions inside a BasicBlock.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/OrderedBasicBlock.h"
+#include "llvm/IR/Instruction.h"
+using namespace llvm;
+
+OrderedBasicBlock::OrderedBasicBlock(const BasicBlock *BasicB)
+ : NextInstPos(0), BB(BasicB) {
+ LastInstFound = BB->end();
+}
+
+/// \brief Given no cached results, find if \p A comes before \p B in \p BB.
+/// Cache and number out instruction while walking \p BB.
+bool OrderedBasicBlock::comesBefore(const Instruction *A,
+ const Instruction *B) {
+ const Instruction *Inst = nullptr;
+ assert(!(LastInstFound == BB->end() && NextInstPos != 0) &&
+ "Instruction supposed to be in NumberedInsts");
+
+ // Start the search with the instruction found in the last lookup round.
+ auto II = BB->begin();
+ auto IE = BB->end();
+ if (LastInstFound != IE)
+ II = std::next(LastInstFound);
+
+ // Number all instructions up to the point where we find 'A' or 'B'.
+ for (; II != IE; ++II) {
+ Inst = cast<Instruction>(II);
+ NumberedInsts[Inst] = NextInstPos++;
+ if (Inst == A || Inst == B)
+ break;
+ }
+
+ assert(II != IE && "Instruction not found?");
+ assert((Inst == A || Inst == B) && "Should find A or B");
+ LastInstFound = II;
+ return Inst == A;
+}
+
+/// \brief Find out whether \p A dominates \p B, meaning whether \p A
+/// comes before \p B in \p BB. This is a simplification that considers
+/// cached instruction positions and ignores other basic blocks, being
+/// only relevant to compare relative instructions positions inside \p BB.
+bool OrderedBasicBlock::dominates(const Instruction *A, const Instruction *B) {
+ assert(A->getParent() == B->getParent() &&
+ "Instructions must be in the same basic block!");
+
+ // First we lookup the instructions. If they don't exist, lookup will give us
+ // back ::end(). If they both exist, we compare the numbers. Otherwise, if NA
+ // exists and NB doesn't, it means NA must come before NB because we would
+ // have numbered NB as well if it didn't. The same is true for NB. If it
+ // exists, but NA does not, NA must come after it. If neither exist, we need
+ // to number the block and cache the results (by calling comesBefore).
+ auto NAI = NumberedInsts.find(A);
+ auto NBI = NumberedInsts.find(B);
+ if (NAI != NumberedInsts.end() && NBI != NumberedInsts.end())
+ return NAI->second < NBI->second;
+ if (NAI != NumberedInsts.end())
+ return true;
+ if (NBI != NumberedInsts.end())
+ return false;
+
+ return comesBefore(A, B);
+}