From 2fd904808c9367afa06e65eb8d76258f8c63935d Mon Sep 17 00:00:00 2001
From: Arnold Schwaighofer <aschwaighofer@apple.com>
Date: Mon, 25 Aug 2025 13:37:47 -0700
Subject: [PATCH] ConstantTracker: Look through mark_dependence instructions

An interposed mark_dependence should not block the heuristic that adds a
benefit when inlining a function that takes a closure argument.
---
 .../Utils/PerformanceInlinerUtils.cpp             |  3 +++
 test/SILOptimizer/inline_heuristics.sil           | 15 ++++++++++-----
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/lib/SILOptimizer/Utils/PerformanceInlinerUtils.cpp b/lib/SILOptimizer/Utils/PerformanceInlinerUtils.cpp
index 4f2a4b1164fe5..79e18782e0984 100644
--- a/lib/SILOptimizer/Utils/PerformanceInlinerUtils.cpp
+++ b/lib/SILOptimizer/Utils/PerformanceInlinerUtils.cpp
@@ -135,6 +135,9 @@ SILValue swift::stripFunctionConversions(SILValue val) {
       val = cvt->getOperand();
       result = val;
       continue;
+    } else if (auto md = dyn_cast<MarkDependenceInst>(val)) {
+      val = md->getValue();
+      result = val;
     } else {
       break;
     }
diff --git a/test/SILOptimizer/inline_heuristics.sil b/test/SILOptimizer/inline_heuristics.sil
index 50ebfe459fd5d..53ca63559eb24 100644
--- a/test/SILOptimizer/inline_heuristics.sil
+++ b/test/SILOptimizer/inline_heuristics.sil
@@ -30,22 +30,27 @@ enum E {
 	case B((Int32) -> Int32)
 }
 
+class C {
+  init()
+}
 
 // CHECK-LABEL: sil @testDirectClosure
 // CHECK: [[C:%[0-9]+]] = thin_to_thick_function
-// CHECK: apply [[C]](
+// CHECK: [[MD:%[0-9]+]] = mark_dependence [[C]]
+// CHECK: apply [[MD]](
 // CHECK: return
 
 // CHECK-LOG-LABEL: Inline into caller: testDirectClosure
 // CHECK-LOG-NEXT: decision {{.*}}, b=70,
 
-sil @testDirectClosure : $@convention(thin) () -> Int32 {
-bb0:
+sil @testDirectClosure : $@convention(thin) (@guaranteed C) -> Int32 {
+bb0(%c : $C):
   %0 = function_ref @takeDirectClosure : $@convention(thin) (@owned @callee_guaranteed (Int32) -> Int32) -> Int32
   %1 = function_ref @closure : $@convention(thin) (Int32) -> Int32
   %2 = thin_to_thick_function %1 : $@convention(thin) (Int32) -> Int32 to $@callee_guaranteed (Int32) -> Int32
-  %3 = apply %0(%2) : $@convention(thin) (@owned @callee_guaranteed (Int32) -> Int32) -> Int32
-  return %3 : $Int32
+  %3 = mark_dependence %2 on %c
+  %4 = apply %0(%3) : $@convention(thin) (@owned @callee_guaranteed (Int32) -> Int32) -> Int32
+  return %4 : $Int32
 }
 
 sil @takeDirectClosure : $@convention(thin) (@owned @callee_guaranteed (Int32) -> Int32) -> Int32 {