Fix StringOptimization to handle load_borrow

rdar://140229560

Author: meg-gupta

lib/SILOptimizer/Transforms/StringOptimization.cpp

@@ -441,6 +441,8 @@ isStringStoreToIdentifyableObject(SILInstruction *inst) {
       case SILInstructionKind::DeallocStackInst:
       case SILInstructionKind::LoadInst:
         break;
+      case SILInstructionKind::LoadBorrowInst:
+        break;
       case SILInstructionKind::DebugValueInst:
         if (DebugValueInst::hasAddrVal(user))
           break;
@@ -579,12 +581,13 @@ StringOptimization::getStringFromStaticLet(SILValue value) {
   //   %ptr_to_global = apply %addressor()
   //   %global_addr = pointer_to_address %ptr_to_global
   //   %value = load %global_addr
-  auto *load = dyn_cast<LoadInst>(value);
-  if (!load)
-    return StringInfo::unknown();
+  if (!isa<LoadInst>(value) && !isa<LoadBorrowInst>(value)) {
+        return StringInfo::unknown();
+  }
+  auto *load = value->getDefiningInstruction();
 
   SILFunction *initializer = nullptr;
-  auto *globalAddr = dyn_cast<GlobalAddrInst>(load->getOperand());
+  auto *globalAddr = dyn_cast<GlobalAddrInst>(load->getOperand(0));
   if (globalAddr) {
     // The global accessor is inlined.
 
@@ -600,7 +603,7 @@ StringOptimization::getStringFromStaticLet(SILValue value) {
   } else {
     // The global accessor is not inlined, yet.
 
-    auto *pta = dyn_cast<PointerToAddressInst>(load->getOperand());
+    auto *pta = dyn_cast<PointerToAddressInst>(load->getOperand(0));
     if (!pta)
       return StringInfo::unknown();
 
@@ -651,7 +654,7 @@ StringOptimization::getStringFromStaticLet(SILValue value) {
   // This check is probably not needed, but let's be on the safe side:
   // it prevents an infinite recursion if the initializer of the global is
   // itself a load of another global, and so on.
-  if (isa<LoadInst>(initVal))
+  if (isa<LoadInst>(initVal) || isa<LoadBorrowInst>(initVal))
     return StringInfo::unknown();
 
   return getStringInfo(initVal);

test/SILOptimizer/string_optimization.swift

@@ -1,4 +1,5 @@
 // RUN: %target-build-swift -O %s -module-name=test -Xfrontend -sil-verify-all -emit-sil | %FileCheck %s
+// RUN: %target-build-swift -O %s -module-name=test -Xfrontend -sil-verify-all -emit-sil -Xfrontend -enable-ossa-modules | %FileCheck %s
 
 // RUN: %empty-directory(%t) 
 // RUN: %target-build-swift -O -module-name=test %s -o %t/a.out