Fixes SjLj preparation step on iOS

include/llvm/InitializePasses.h

@@ -275,6 +275,9 @@ void initializeBBVectorizePass(PassRegistry&);
 void initializeMachineFunctionPrinterPassPass(PassRegistry&);
 void initializeStackMapLivenessPass(PassRegistry&);
 void initializeLoadCombinePass(PassRegistry&);
+
+// Specific to the rust-lang llvm branch:
+void initializeNullCheckEliminationPass(PassRegistry&);
 }
 
 #endif

include/llvm/LinkAllPasses.h

@@ -160,6 +160,9 @@ namespace {
       (void) llvm::createScalarizerPass();
       (void) llvm::createSeparateConstOffsetFromGEPPass();
 
+      // Specific to the rust-lang llvm branch:
+      (void) llvm::createNullCheckEliminationPass();
+
       (void)new llvm::IntervalPartition();
       (void)new llvm::FindUsedTypes();
       (void)new llvm::ScalarEvolution();

include/llvm/Transforms/Scalar.h

@@ -388,6 +388,13 @@ FunctionPass *createSeparateConstOffsetFromGEPPass();
 //
 BasicBlockPass *createLoadCombinePass();
 
+// Specific to the rust-lang llvm branch:
+//===----------------------------------------------------------------------===//
+//
+// NullCheckElimination - Eliminate null checks.
+//
+FunctionPass *createNullCheckEliminationPass();
+
 } // End llvm namespace
 
 #endif

lib/CodeGen/SjLjEHPrepare.cpp

@@ -249,18 +249,18 @@ void SjLjEHPrepare::lowerIncomingArguments(Function &F) {
        ++AI) {
     Type *Ty = AI->getType();
 
-    // Aggregate types can't be cast, but are legal argument types, so we have
-    // to handle them differently. We use an extract/insert pair as a
-    // lightweight method to achieve the same goal.
     if (isa<StructType>(Ty) || isa<ArrayType>(Ty)) {
-      Instruction *EI = ExtractValueInst::Create(AI, 0, "", AfterAllocaInsPt);
-      Instruction *NI = InsertValueInst::Create(AI, EI, 0);
-      NI->insertAfter(EI);
-      AI->replaceAllUsesWith(NI);
-
-      // Set the operand of the instructions back to the AllocaInst.
-      EI->setOperand(0, AI);
-      NI->setOperand(0, AI);
+      // Aggregate types can't be cast, but are legal argument types,
+      // so we have to handle them differently.  We use
+      // select i8 true, %arg, undef to achieve the same goal
+      Value *TrueValue = ConstantInt::getTrue(F.getContext());
+      Value *UndefValue = UndefValue::get(Ty);
+      Instruction *SI = SelectInst::Create(TrueValue, AI, UndefValue,
+                                           AI->getName() + ".tmp",
+                                           AfterAllocaInsPt);
+      AI->replaceAllUsesWith(SI);
+
+      SI->setOperand(1, AI);
     } else {
       // This is always a no-op cast because we're casting AI to AI->getType()
       // so src and destination types are identical. BitCast is the only

lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -187,6 +187,8 @@ void PassManagerBuilder::populateModulePassManager(PassManagerBase &MPM) {
   MPM.add(createEarlyCSEPass());              // Catch trivial redundancies
   MPM.add(createJumpThreadingPass());         // Thread jumps.
   MPM.add(createCorrelatedValuePropagationPass()); // Propagate conditionals
+  // Specific to the rust-lang llvm branch:
+  MPM.add(createNullCheckEliminationPass());  // Eliminate null checks
   MPM.add(createCFGSimplificationPass());     // Merge & remove BBs
   MPM.add(createInstructionCombiningPass());  // Combine silly seq's
   addExtensionsToPM(EP_Peephole, MPM);
@@ -218,6 +220,8 @@ void PassManagerBuilder::populateModulePassManager(PassManagerBase &MPM) {
   addExtensionsToPM(EP_Peephole, MPM);
   MPM.add(createJumpThreadingPass());         // Thread jumps
   MPM.add(createCorrelatedValuePropagationPass());
+  // Specific to the rust-lang llvm branch:
+  MPM.add(createNullCheckEliminationPass());  // Eliminate null checks
   MPM.add(createDeadStoreEliminationPass());  // Delete dead stores
 
   addExtensionsToPM(EP_ScalarOptimizerLate, MPM);

lib/Transforms/Scalar/CMakeLists.txt

@@ -22,6 +22,7 @@ add_llvm_library(LLVMScalarOpts
   LoopUnswitch.cpp
   LowerAtomic.cpp
   MemCpyOptimizer.cpp
+  NullCheckElimination.cpp
   PartiallyInlineLibCalls.cpp
   Reassociate.cpp
   Reg2Mem.cpp