diff --git a/lib/SILOptimizer/SILCombiner/SILCombinerCastVisitors.cpp b/lib/SILOptimizer/SILCombiner/SILCombinerCastVisitors.cpp
index fe92106003fa8..1ad347ac6304c 100644
--- a/lib/SILOptimizer/SILCombiner/SILCombinerCastVisitors.cpp
+++ b/lib/SILOptimizer/SILCombiner/SILCombinerCastVisitors.cpp
@@ -790,7 +790,7 @@ SILInstruction *SILCombiner::visitConvertEscapeToNoEscapeInst(
   //
   // This unblocks the `thin_to_thick_function` peephole optimization below.
   if (auto *CFI = dyn_cast<ConvertFunctionInst>(Cvt->getOperand())) {
-    if (CFI->getSingleUse()) {
+    if (hasOneNonDebugUse(CFI)) {
       if (auto *TTTFI = dyn_cast<ThinToThickFunctionInst>(CFI->getOperand())) {
         if (TTTFI->getSingleUse()) {
           auto convertedThickType = CFI->getType().castTo<SILFunctionType>();
@@ -836,7 +836,7 @@ SILInstruction *SILCombiner::visitConvertEscapeToNoEscapeInst(
   // %vjp' = convert_escape_to_noescape %vjp
   // %y = differentiable_function(%orig', %jvp', %vjp')
   if (auto *DFI = dyn_cast<DifferentiableFunctionInst>(Cvt->getOperand())) {
-    if (DFI->hasOneUse()) {
+    if (hasOneNonDebugUse(DFI)) {
       auto createConvertEscapeToNoEscape =
         [&](NormalDifferentiableFunctionTypeComponent extractee) {
           if (!DFI->hasExtractee(extractee))
@@ -1020,9 +1020,7 @@ SILCombiner::visitConvertFunctionInst(ConvertFunctionInst *cfi) {
   // %vjp' = convert_function %vjp
   // %y = differentiable_function(%orig', %jvp', %vjp')
   if (auto *DFI = dyn_cast<DifferentiableFunctionInst>(cfi->getOperand())) {
-    // Workaround for a problem with OSSA: https://github.com/swiftlang/swift/issues/78848
-    // TODO: remove this if-statement once the underlying problem is fixed.
-    if (cfi->getFunction()->hasOwnership())
+    if (!hasOneNonDebugUse(DFI))
       return nullptr;
 
     auto createConvertFunctionOfComponent =
diff --git a/test/AutoDiff/sil_combine.sil b/test/AutoDiff/sil_combine.sil
index 741d226e63aaa..e69a29a95fe88 100644
--- a/test/AutoDiff/sil_combine.sil
+++ b/test/AutoDiff/sil_combine.sil
@@ -59,3 +59,139 @@ bb0(%orig : $@callee_guaranteed (Float) -> Float):
 // CHECK:   [[EXTRACTED_VJP:%.*]] = differentiable_function_extract [vjp] [[DIFF_FN]] : $@differentiable(reverse) @callee_guaranteed (Float) -> Float
 // CHECK:   return [[EXTRACTED_VJP]] : $@callee_guaranteed (Float) -> (Float, @owned @callee_guaranteed (Float) -> Float)
 // CHECK-LABEL: } // end sil function 'differentiable_function_extract_vjp_undefined' 
+
+// MARK: `convert_function` hoisting
+
+// This should optimize down single partial_apply that escapes
+sil @differential_function_convert_single_use : $@convention(thin) (@convention(thin) (Float) -> Float, @convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float) -> @callee_guaranteed (@in_guaranteed Float) -> Float {
+bb0(%orig: $@convention(thin) (Float) -> Float, %thunk: $@convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float):
+  %thick_orig = thin_to_thick_function %orig to $@callee_guaranteed (Float) -> Float
+
+  %pa = partial_apply [callee_guaranteed] %thunk(%thick_orig) : $@convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float
+  %conv_pa = convert_function %pa to $@callee_guaranteed @substituted <τ_0_0> (@in_guaranteed τ_0_0) -> Float for <Float>
+
+  %diff_fn = differentiable_function [parameters 0] [results 0] %conv_pa with_derivative {
+   undef : $@callee_guaranteed @substituted <τ_0_0, τ_0_1> (@in_guaranteed τ_0_0) -> (Float, @owned @callee_guaranteed @substituted <τ_0_0> (@in_guaranteed τ_0_0) -> Float for <τ_0_1>) for <Float, Float>,
+   undef : $@callee_guaranteed @substituted <τ_0_0, τ_0_1> (@in_guaranteed τ_0_0) -> (Float, @owned @callee_guaranteed @substituted <τ_0_0> (Float) -> @out τ_0_0 for <τ_0_1>) for <Float, Float>
+  }
+
+  debug_value %diff_fn, let, name "f", argno 1
+
+  %conv_diff = convert_function %diff_fn to $@differentiable(reverse) @callee_guaranteed (@in_guaranteed Float) -> Float
+  %conv_orig = differentiable_function_extract [original] %conv_diff
+  return %conv_orig
+}
+
+// CHECK-LABEL: sil @differential_function_convert_single_use
+// CHECK: bb0(%[[ORIG_FN:.*]] : $@convention(thin) (Float) -> Float, %[[THUNK:.*]] : $@convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float)
+// CHECK: %[[TT_CONV:.*]] = thin_to_thick_function %[[ORIG_FN]] : $@convention(thin) (Float) -> Float to $@callee_guaranteed (Float) -> Float
+// CHECK: %[[PA:.*]] = partial_apply [callee_guaranteed] %[[THUNK]](%[[TT_CONV]]) : $@convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float
+// CHECKL return %[[PA]] : $@callee_guaranteed (@in_guaranteed Float) -> Float
+
+sil @blackhole : $(@differentiable(reverse) @callee_guaranteed @substituted<T> (@in_guaranteed T) -> Float for <Float>) -> ()
+
+// differentiable_function has multiple uses, so we cannot commute it with convert_function, check that all instructions are there
+
+sil @differential_function_convert_multiple_use : $@convention(thin) (@convention(thin) (Float) -> Float, @convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float) -> @callee_guaranteed (@in_guaranteed Float) -> Float {
+bb0(%orig: $@convention(thin) (Float) -> Float, %thunk: $@convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float):
+  %thick_orig = thin_to_thick_function %orig to $@callee_guaranteed (Float) -> Float
+
+  %pa = partial_apply [callee_guaranteed] %thunk(%thick_orig) : $@convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float
+  %conv_pa = convert_function %pa to $@callee_guaranteed @substituted <τ_0_0> (@in_guaranteed τ_0_0) -> Float for <Float>
+
+  %diff_fn = differentiable_function [parameters 0] [results 0] %conv_pa with_derivative {
+   undef : $@callee_guaranteed @substituted <τ_0_0, τ_0_1> (@in_guaranteed τ_0_0) -> (Float, @owned @callee_guaranteed @substituted <τ_0_0> (@in_guaranteed τ_0_0) -> Float for <τ_0_1>) for <Float, Float>,
+   undef : $@callee_guaranteed @substituted <τ_0_0, τ_0_1> (@in_guaranteed τ_0_0) -> (Float, @owned @callee_guaranteed @substituted <τ_0_0> (Float) -> @out τ_0_0 for <τ_0_1>) for <Float, Float>
+  }
+
+  debug_value %diff_fn, let, name "f", argno 1
+
+  %conv_diff = convert_function %diff_fn to $@differentiable(reverse) @callee_guaranteed (@in_guaranteed Float) -> Float
+  %conv_orig = differentiable_function_extract [original] %conv_diff
+
+  %blackhole = function_ref @blackhole : $@convention(thin) (@differentiable(reverse) @callee_guaranteed @substituted<T> (@in_guaranteed T) -> Float for <Float>) -> ()
+  apply %blackhole(%diff_fn) : $@convention(thin) (@differentiable(reverse) @callee_guaranteed @substituted<T> (@in_guaranteed T) -> Float for <Float>) -> ()
+
+  return %conv_orig : $@callee_guaranteed (@in_guaranteed Float) -> Float
+}
+
+// CHECK-LABEL: sil @differential_function_convert_multiple_use
+// CHECK: convert_function
+// CHECK: differentiable_function
+// CHECK: convert_function
+// CHECK: differentiable_function_extract
+
+// MARK: `convert_escape_to_noescape` hoisting
+
+sil @blackhole2 : $(@differentiable(reverse) @callee_guaranteed (@in_guaranteed Float) -> Float) -> ()
+
+// Here we should be able to unfold partial_apply down to direct function call
+
+sil @differential_function_noescape_single_use : $@convention(thin) (@convention(thin) (Float) -> Float, @convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float) -> () {
+bb0(%orig: $@convention(thin) (Float) -> Float, %thunk: $@convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float):
+  %thick_orig = thin_to_thick_function %orig to $@callee_guaranteed (Float) -> Float
+
+  %pa = partial_apply [callee_guaranteed] %thunk(%thick_orig) : $@convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float
+
+  %diff_fn = differentiable_function [parameters 0] [results 0] %pa with_derivative {
+   undef : $@callee_guaranteed (@in_guaranteed Float) -> (Float, @owned @callee_guaranteed (@in_guaranteed Float) -> Float),
+   undef : $@callee_guaranteed (@in_guaranteed Float) -> (Float, @owned @callee_guaranteed (Float) -> @out Float)
+  }
+
+  debug_value %diff_fn, let, name "f", argno 1
+
+  %conv_diff = convert_escape_to_noescape %diff_fn to $@noescape @differentiable(reverse) @callee_guaranteed (@in_guaranteed Float) -> Float
+  %conv_orig = differentiable_function_extract [original] %conv_diff
+
+  %arg = alloc_stack $Float
+  apply %conv_orig(%arg) : $@noescape @callee_guaranteed (@in_guaranteed Float) -> Float
+
+  dealloc_stack %arg : $*Float
+  strong_release %pa
+
+  %res = tuple ()
+  return %res : $()
+}
+
+// CHECK-LABEL: sil @differential_function_noescape_single_use
+// CHECK: bb0(%[[ORIG_FN:.*]] : $@convention(thin) (Float) -> Float, %[[THUNK:.*]] : $@convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float)
+// CHECK: %[[TT_CONV:.*]] = thin_to_thick_function %[[ORIG_FN]] : $@convention(thin) (Float) -> Float to $@callee_guaranteed (Float) -> Float
+// CHECK: %[[ARG:.*]] = alloc_stack $Float
+// CHECK: apply %[[THUNK]](%[[ARG]], %[[TT_CONV]]) : $@convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float
+
+
+// differentiable_function has multiple uses, so we cannot commute it with convert_escape_to_noescape, check that all instructions are there
+
+sil @differential_function_noescape_multiple_use : $@convention(thin) (@convention(thin) (Float) -> Float, @convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float) -> () {
+bb0(%orig: $@convention(thin) (Float) -> Float, %thunk: $@convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float):
+  %thick_orig = thin_to_thick_function %orig to $@callee_guaranteed (Float) -> Float
+
+  %pa = partial_apply [callee_guaranteed] %thunk(%thick_orig) : $@convention(thin) (@in_guaranteed Float, @guaranteed @callee_guaranteed (Float) -> Float) -> Float
+
+  %diff_fn = differentiable_function [parameters 0] [results 0] %pa with_derivative {
+   undef : $@callee_guaranteed (@in_guaranteed Float) -> (Float, @owned @callee_guaranteed (@in_guaranteed Float) -> Float),
+   undef : $@callee_guaranteed (@in_guaranteed Float) -> (Float, @owned @callee_guaranteed (Float) -> @out Float)
+  }
+
+  debug_value %diff_fn, let, name "f", argno 1
+
+  %conv_diff = convert_escape_to_noescape %diff_fn to $@noescape @differentiable(reverse) @callee_guaranteed (@in_guaranteed Float) -> Float
+  %conv_orig = differentiable_function_extract [original] %conv_diff
+
+  %arg = alloc_stack $Float
+  apply %conv_orig(%arg) : $@noescape @callee_guaranteed (@in_guaranteed Float) -> Float
+
+  %blackhole = function_ref @blackhole2 : $@convention(thin) (@differentiable(reverse) @callee_guaranteed (@in_guaranteed Float) -> Float) -> ()
+  apply %blackhole(%diff_fn) : $@convention(thin) (@differentiable(reverse) @callee_guaranteed (@in_guaranteed Float) -> Float) -> ()
+
+  dealloc_stack %arg : $*Float
+  strong_release %pa
+
+  %res = tuple ()
+  return %res : $()
+}
+
+// CHECK-LABEL: sil @differential_function_noescape_multiple_use
+// CHECK: differentiable_function
+// CHECK: convert_escape_to_noescape
+// CHECK: differentiable_function_extract