1 files changed, 107 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Transforms/Utils/Mem2Reg.cpp b/contrib/llvm/lib/Transforms/Utils/Mem2Reg.cpp
new file mode 100644
index 000000000000..24b3b12930ac
--- /dev/null
+++ b/contrib/llvm/lib/Transforms/Utils/Mem2Reg.cpp
@@ -0,0 +1,107 @@
+//===- Mem2Reg.cpp - The -mem2reg pass, a wrapper around the Utils lib ----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass is a simple pass wrapper around the PromoteMemToReg function call
+// exposed by the Utils library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/Mem2Reg.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/PromoteMemToReg.h"
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "mem2reg"
+
+STATISTIC(NumPromoted, "Number of alloca's promoted");
+
+static bool promoteMemoryToRegister(Function &F, DominatorTree &DT,
+                                    AssumptionCache &AC) {
+  std::vector<AllocaInst *> Allocas;
+  BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function
+  bool Changed = false;
+
+  while (1) {
+    Allocas.clear();
+
+    // Find allocas that are safe to promote, by looking at all instructions in
+    // the entry node
+    for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
+      if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca?
+        if (isAllocaPromotable(AI))
+          Allocas.push_back(AI);
+
+    if (Allocas.empty())
+      break;
+
+    PromoteMemToReg(Allocas, DT, nullptr, &AC);
+    NumPromoted += Allocas.size();
+    Changed = true;
+  }
+  return Changed;
+}
+
+PreservedAnalyses PromotePass::run(Function &F, FunctionAnalysisManager &AM) {
+  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
+  auto &AC = AM.getResult<AssumptionAnalysis>(F);
+  if (!promoteMemoryToRegister(F, DT, AC))
+    return PreservedAnalyses::all();
+
+  // FIXME: This should also 'preserve the CFG'.
+  return PreservedAnalyses::none();
+}
+
+namespace {
+struct PromoteLegacyPass : public FunctionPass {
+  static char ID; // Pass identification, replacement for typeid
+  PromoteLegacyPass() : FunctionPass(ID) {
+    initializePromoteLegacyPassPass(*PassRegistry::getPassRegistry());
+  }
+
+  // runOnFunction - To run this pass, first we calculate the alloca
+  // instructions that are safe for promotion, then we promote each one.
+  //
+  bool runOnFunction(Function &F) override {
+    if (skipFunction(F))
+      return false;
+
+    DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+    AssumptionCache &AC =
+        getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
+    return promoteMemoryToRegister(F, DT, AC);
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<AssumptionCacheTracker>();
+    AU.addRequired<DominatorTreeWrapperPass>();
+    AU.setPreservesCFG();
+  }
+  };
+}  // end of anonymous namespace
+
+char PromoteLegacyPass::ID = 0;
+INITIALIZE_PASS_BEGIN(PromoteLegacyPass, "mem2reg", "Promote Memory to "
+                                                    "Register",
+                      false, false)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_END(PromoteLegacyPass, "mem2reg", "Promote Memory to Register",
+                    false, false)
+
+// createPromoteMemoryToRegister - Provide an entry point to create this pass.
+//
+FunctionPass *llvm::createPromoteMemoryToRegisterPass() {
+  return new PromoteLegacyPass();
+}