Handle nil BorrowedValue during canonicalization

Author: meg-gupta

include/swift/SILOptimizer/Utils/CanonicalizeBorrowScope.h

@@ -136,7 +136,7 @@ class CanonicalizeBorrowScope {
 
 protected:
   void initBorrow(BorrowedValue borrow) {
-    assert(liveness.empty() && persistentCopies.empty());
+    assert(borrow && liveness.empty() && persistentCopies.empty());
 
     updatedCopies.clear();
     borrowedValue = borrow;

lib/SILOptimizer/Utils/CanonicalizeBorrowScope.cpp

@@ -778,9 +778,13 @@ bool CanonicalizeBorrowScope::consolidateBorrowScope() {
 
 bool CanonicalizeBorrowScope::canonicalizeFunctionArgument(
     SILFunctionArgument *arg) {
-  LLVM_DEBUG(llvm::dbgs() << "*** Canonicalize Borrow: " << borrowedValue);
+  BorrowedValue borrow(arg);
+  if (!borrow)
+    return false;
 
-  initBorrow(BorrowedValue(arg));
+  initBorrow(borrow);
+
+  LLVM_DEBUG(llvm::dbgs() << "*** Canonicalize Borrow: " << borrowedValue);
 
   SWIFT_DEFER { liveness.clear(); };
 

test/SILOptimizer/sil_combine_ossa.sil

@@ -5091,10 +5091,10 @@ bb0(%0 : @guaranteed $Function):
 
 sil [reabstraction_thunk] @thunk : $@convention(thin) (@guaranteed Klass, @guaranteed Klass) -> ()
 
-// CHECK-LABEL: sil [ossa] @test_partial_apply_apply_opt :
+// CHECK-LABEL: sil [ossa] @test_partial_apply_apply_opt1 :
 // CHECK-NOT: partial_apply
-// CHECK: } // end sil function 'test_partial_apply_apply_opt'
-sil [ossa] @test_partial_apply_apply_opt : $@convention(thin) (@guaranteed Klass, @guaranteed Klass) -> () {
+// CHECK: } // end sil function 'test_partial_apply_apply_opt1'
+sil [ossa] @test_partial_apply_apply_opt1 : $@convention(thin) (@guaranteed Klass, @guaranteed Klass) -> () {
 bb0(%0 : @guaranteed $Klass, %1 : @guaranteed $Klass):
   %c1 = copy_value %0 : $Klass
   %c2 = copy_value %1 : $Klass
@@ -5106,3 +5106,20 @@ bb0(%0 : @guaranteed $Klass, %1 : @guaranteed $Klass):
   return %7 : $()
 }
 
+// CHECK-LABEL: sil [ossa] @test_partial_apply_apply_opt2 :
+// CHECK-NOT: partial_apply
+// CHECK: } // end sil function 'test_partial_apply_apply_opt2'
+sil [ossa] @test_partial_apply_apply_opt2 : $@convention(thin) (@owned Klass, @owned Klass) -> () {
+bb0(%0 : @owned $Klass, %1 : @owned $Klass):
+  %c1 = copy_value %0 : $Klass
+  %c2 = copy_value %1 : $Klass
+  %f1 = function_ref @thunk : $@convention(thin) (@guaranteed Klass, @guaranteed Klass) -> ()
+  %p1 = partial_apply [callee_guaranteed] %f1(%c1, %c2) : $@convention(thin) (@guaranteed Klass, @guaranteed Klass) -> ()
+  %r = apply %p1() : $@callee_guaranteed () -> ()
+  destroy_value %p1 : $@callee_guaranteed () -> ()
+  destroy_value %0 : $Klass
+  destroy_value %1 : $Klass
+  %7 = tuple ()
+  return %7 : $()
+}
+