Merge pull request #8668 from atrick/fix

Author: swift-ci

include/swift/SIL/SILBasicBlock.h

@@ -94,7 +94,7 @@ public llvm::ilist_node<SILBasicBlock>, public SILAllocated<SILBasicBlock> {
   void push_back(SILInstruction *I);
   void push_front(SILInstruction *I);
   void remove(SILInstruction *I);
-  void erase(SILInstruction *I);
+  iterator erase(SILInstruction *I);
 
   SILInstruction &back() { return InstList.back(); }
   const SILInstruction &back() const {

lib/SIL/SILBasicBlock.cpp

@@ -90,12 +90,13 @@ void SILBasicBlock::remove(SILInstruction *I) {
   InstList.remove(I);
 }
 
-void SILBasicBlock::erase(SILInstruction *I) {
+SILBasicBlock::iterator SILBasicBlock::erase(SILInstruction *I) {
   // Notify the delete handlers that this instruction is going away.
   getModule().notifyDeleteHandlers(&*I);
   auto *F = getParent();
-  InstList.erase(I);
+  auto II = InstList.erase(I);
   F->getModule().deallocateInst(I);
+  return II;
 }
 
 /// This method unlinks 'self' from the containing SILFunction and deletes it.

lib/SILOptimizer/Mandatory/AccessMarkerElimination.cpp

@@ -45,17 +45,17 @@ struct AccessMarkerElimination : SILModuleTransform {
       // iterating in reverse eliminates more begin_access users before they
       // need to be replaced.
       for (auto &BB : reversed(F)) {
-        for (auto II = BB.rbegin(), IE = BB.rend(); II != IE;) {
-          SILInstruction *inst = &*II;
-          ++II;
+        // Don't cache the begin iterator since we're reverse iterating.
+        for (auto II = BB.end(); II != BB.begin();) {
+          SILInstruction *inst = &*(--II);
 
           if (auto beginAccess = dyn_cast<BeginAccessInst>(inst)) {
             beginAccess->replaceAllUsesWith(beginAccess->getSource());
-            beginAccess->eraseFromParent();
+            II = BB.erase(beginAccess);
           }
           if (auto endAccess = dyn_cast<EndAccessInst>(inst)) {
             assert(endAccess->use_empty());
-            endAccess->eraseFromParent();
+            II = BB.erase(endAccess);
           }
         }
       }