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diff --git a/lib/Transforms/NaCl/PromoteI1Ops.cpp b/lib/Transforms/NaCl/PromoteI1Ops.cpp
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+++ b/lib/Transforms/NaCl/PromoteI1Ops.cpp
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+//===- PromoteI1Ops.cpp - Promote various operations on the i1 type--------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass expands out various operations on the i1 type so that
+// these i1 operations do not need to be supported by the PNaCl
+// translator.
+//
+// This is similar to the PromoteIntegers pass in that it removes uses
+// of an unusual-size integer type.  The difference is that i1 remains
+// a valid type in other operations.  i1 can still be used in phi
+// nodes, "select" instructions, in "sext" and "zext", and so on.  In
+// contrast, the integer types that PromoteIntegers removes are not
+// allowed in any context by PNaCl's ABI verifier.
+//
+// This pass expands out the following:
+//
+//  * i1 loads and stores.
+//  * All i1 comparisons and arithmetic operations, with the exception
+//    of "and", "or" and "xor", because these are used in practice and
+//    don't overflow.
+//
+// "switch" instructions on i1 are also disallowed by the PNaCl ABI
+// verifier, but they don't seem to be generated in practice and so
+// they are not currently expanded out by this pass.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/NaCl.h"
+
+using namespace llvm;
+
+namespace {
+  class PromoteI1Ops : public BasicBlockPass {
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    PromoteI1Ops() : BasicBlockPass(ID) {
+      initializePromoteI1OpsPass(*PassRegistry::getPassRegistry());
+    }
+
+    virtual bool runOnBasicBlock(BasicBlock &BB);
+  };
+}
+
+char PromoteI1Ops::ID = 0;
+INITIALIZE_PASS(PromoteI1Ops, "nacl-promote-i1-ops",
+                "Promote various operations on the i1 type",
+                false, false)
+
+static Value *promoteValue(Value *Val, bool SignExt, Instruction *InsertPt) {
+  Instruction::CastOps CastType =
+      SignExt ? Instruction::SExt : Instruction::ZExt;
+  return CopyDebug(CastInst::Create(CastType, Val,
+                                    Type::getInt8Ty(Val->getContext()),
+                                    Val->getName() + ".expand_i1_val",
+                                    InsertPt), InsertPt);
+}
+
+bool PromoteI1Ops::runOnBasicBlock(BasicBlock &BB) {
+  bool Changed = false;
+
+  Type *I1Ty = Type::getInt1Ty(BB.getContext());
+  Type *I8Ty = Type::getInt8Ty(BB.getContext());
+
+  for (BasicBlock::iterator Iter = BB.begin(), E = BB.end(); Iter != E; ) {
+    Instruction *Inst = Iter++;
+    if (LoadInst *Load = dyn_cast<LoadInst>(Inst)) {
+      if (Load->getType() == I1Ty) {
+        Changed = true;
+        Value *Ptr = CopyDebug(
+            new BitCastInst(
+                Load->getPointerOperand(), I8Ty->getPointerTo(),
+                Load->getPointerOperand()->getName() + ".i8ptr", Load), Load);
+        LoadInst *NewLoad = new LoadInst(
+            Ptr, Load->getName() + ".pre_trunc", Load);
+        CopyDebug(NewLoad, Load);
+        CopyLoadOrStoreAttrs(NewLoad, Load);
+        Value *Result = CopyDebug(new TruncInst(NewLoad, I1Ty, "", Load), Load);
+        Result->takeName(Load);
+        Load->replaceAllUsesWith(Result);
+        Load->eraseFromParent();
+      }
+    } else if (StoreInst *Store = dyn_cast<StoreInst>(Inst)) {
+      if (Store->getValueOperand()->getType() == I1Ty) {
+        Changed = true;
+        Value *Ptr = CopyDebug(
+            new BitCastInst(
+                Store->getPointerOperand(), I8Ty->getPointerTo(),
+                Store->getPointerOperand()->getName() + ".i8ptr", Store),
+            Store);
+        Value *Val = promoteValue(Store->getValueOperand(), false, Store);
+        StoreInst *NewStore = new StoreInst(Val, Ptr, Store);
+        CopyDebug(NewStore, Store);
+        CopyLoadOrStoreAttrs(NewStore, Store);
+        Store->eraseFromParent();
+      }
+    } else if (BinaryOperator *Op = dyn_cast<BinaryOperator>(Inst)) {
+      if (Op->getType() == I1Ty &&
+          !(Op->getOpcode() == Instruction::And ||
+            Op->getOpcode() == Instruction::Or ||
+            Op->getOpcode() == Instruction::Xor)) {
+        Value *Arg1 = promoteValue(Op->getOperand(0), false, Op);
+        Value *Arg2 = promoteValue(Op->getOperand(1), false, Op);
+        Value *NewOp = CopyDebug(
+            BinaryOperator::Create(
+                Op->getOpcode(), Arg1, Arg2,
+                Op->getName() + ".pre_trunc", Op), Op);
+        Value *Result = CopyDebug(new TruncInst(NewOp, I1Ty, "", Op), Op);
+        Result->takeName(Op);
+        Op->replaceAllUsesWith(Result);
+        Op->eraseFromParent();
+      }
+    } else if (ICmpInst *Op = dyn_cast<ICmpInst>(Inst)) {
+      if (Op->getOperand(0)->getType() == I1Ty) {
+        Value *Arg1 = promoteValue(Op->getOperand(0), Op->isSigned(), Op);
+        Value *Arg2 = promoteValue(Op->getOperand(1), Op->isSigned(), Op);
+        Value *Result = CopyDebug(
+            new ICmpInst(Op, Op->getPredicate(), Arg1, Arg2, ""), Op);
+        Result->takeName(Op);
+        Op->replaceAllUsesWith(Result);
+        Op->eraseFromParent();
+      }
+    }
+  }
+  return Changed;
+}
+
+BasicBlockPass *llvm::createPromoteI1OpsPass() {
+  return new PromoteI1Ops();
+}