From ab8091964b0bee01bd3002ebbe049e12263c76aa Mon Sep 17 00:00:00 2001
From: Andrew Trick <atrick@apple.com>
Date: Tue, 29 Jul 2025 00:10:59 -0700
Subject: [PATCH 1/2] [NFC] add SinkAddressProjections::dump()

---
 .../swift/SILOptimizer/Utils/BasicBlockOptUtils.h   |  2 ++
 lib/SILOptimizer/Utils/BasicBlockOptUtils.cpp       | 13 +++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/include/swift/SILOptimizer/Utils/BasicBlockOptUtils.h b/include/swift/SILOptimizer/Utils/BasicBlockOptUtils.h
index d7402cc809e05..0568861f61f92 100644
--- a/include/swift/SILOptimizer/Utils/BasicBlockOptUtils.h
+++ b/include/swift/SILOptimizer/Utils/BasicBlockOptUtils.h
@@ -164,6 +164,8 @@ class SinkAddressProjections {
   ///
   /// getInBlockProjectionOperandValues() can be called before or after cloning.
   bool cloneProjections();
+
+  SWIFT_DEBUG_DUMP;
 };
 
 /// Clone a single basic block and any required successor edges within the same
diff --git a/lib/SILOptimizer/Utils/BasicBlockOptUtils.cpp b/lib/SILOptimizer/Utils/BasicBlockOptUtils.cpp
index 32bf17da930df..757e2329f1e29 100644
--- a/lib/SILOptimizer/Utils/BasicBlockOptUtils.cpp
+++ b/lib/SILOptimizer/Utils/BasicBlockOptUtils.cpp
@@ -285,3 +285,16 @@ bool SinkAddressProjections::cloneProjections() {
   }
   return true;
 }
+
+void SinkAddressProjections::dump() const {
+  llvm::dbgs() << "Old projections: ";
+  for (auto *proj : oldProjections) {
+    proj->dump();
+  }
+  if (auto *np = newProjections) {
+    llvm::dbgs() << "New projections: ";
+    for (auto *proj : *np) {
+      proj->dump();
+    }
+  }
+}

From c1e0a1d9990f317c35f5543b0e3dbd5930551cf8 Mon Sep 17 00:00:00 2001
From: Andrew Trick <atrick@apple.com>
Date: Tue, 29 Jul 2025 00:11:53 -0700
Subject: [PATCH 2/2] Fix assertion in InstructionDeleter::trackIfDead.

This assertion was triggering when deleting scope-ending operations whose
operand had been replaced with an undef:

   end_borrow undef

Related to rdar://156431548

This was triggered during simplify-cfg by after adding blocks to the worklist,
then later cleaning up dead instructions in the worklist blocks. I'm unable to
create a test case based on simplify-cfg because the assertion is completely
unrelated to the optimization that adds blocks to the worklist.
---
 lib/SILOptimizer/Utils/InstructionDeleter.cpp | 19 ++++++++++++++++---
 test/SILOptimizer/instruction_deleter.sil     | 15 +++++++++++++++
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/lib/SILOptimizer/Utils/InstructionDeleter.cpp b/lib/SILOptimizer/Utils/InstructionDeleter.cpp
index f7d4761b23a4d..ffefbc874ac46 100644
--- a/lib/SILOptimizer/Utils/InstructionDeleter.cpp
+++ b/lib/SILOptimizer/Utils/InstructionDeleter.cpp
@@ -187,9 +187,8 @@ bool InstructionDeleter::trackIfDead(SILInstruction *inst) {
   bool fixLifetime = inst->getFunction()->hasOwnership();
   if (isInstructionTriviallyDead(inst)
       || isScopeAffectingInstructionDead(inst, fixLifetime)) {
-    assert(!isIncidentalUse(inst) &&
-           (!isa<DestroyValueInst>(inst) ||
-            canTriviallyDeleteOSSAEndScopeInst(inst)) &&
+    assert(!isIncidentalUse(inst)
+           || canTriviallyDeleteOSSAEndScopeInst(inst) &&
            "Incidental uses cannot be removed in isolation. "
            "They would be removed iff the operand is dead");
     getCallbacks().notifyWillBeDeleted(inst);
@@ -356,6 +355,20 @@ static FunctionTest DeleterDeleteIfDeadTest(
       llvm::outs() << "deleteIfDead returned " << deleted << "\n";
       function.print(llvm::outs());
     });
+
+// Arguments:
+// - instruction: the instruction to delete
+// Dumps:
+// - the function
+static FunctionTest DeleterTrackIfDeadTest(
+    "deleter_track_if_dead", [](auto &function, auto &arguments, auto &test) {
+      auto *inst = arguments.takeInstruction();
+      InstructionDeleter deleter;
+      llvm::outs() << "Tracking " << *inst;
+      deleter.trackIfDead(inst);
+      deleter.cleanupDeadInstructions();
+      function.print(llvm::outs());
+    });
 } // namespace swift::test
 
 void InstructionDeleter::forceDeleteAndFixLifetimes(SILInstruction *inst) {
diff --git a/test/SILOptimizer/instruction_deleter.sil b/test/SILOptimizer/instruction_deleter.sil
index bb50d8c2f2627..91ea283b07967 100644
--- a/test/SILOptimizer/instruction_deleter.sil
+++ b/test/SILOptimizer/instruction_deleter.sil
@@ -57,3 +57,18 @@ sil [ossa] @doDeleteLoadTake : $() -> () {
   %retval = tuple ()
   return %retval : $()
 }
+
+// CHECK-LABEL: begin running test {{.*}} on trackEndBorrow
+// CHECK: Tracking   end_borrow undef : $C
+// CHECK: sil [ossa] @trackEndBorrow : $@convention(thin) () -> () {
+// CHECK: bb0:
+// CHECK-NOT: end_borrow
+// CHECK-LABEL: } // end sil function 'trackEndBorrow'
+// CHECK-LABEL: end running test {{.*}} on trackEndBorrow
+sil [ossa] @trackEndBorrow : $() -> () {
+bb0:
+  specify_test "deleter_track_if_dead @instruction"
+  end_borrow undef : $C
+  %retval = tuple ()
+  return %retval : $()
+}