From 395db88f6f2a48aec1b8cf329282580528071115 Mon Sep 17 00:00:00 2001
From: Erik Eckstein <eeckstein@apple.com>
Date: Thu, 16 Oct 2025 07:14:46 +0200
Subject: [PATCH] SILVerifier: relax the check for debug vars with different
 types

Allow two identical debug variables have different types if the types are or contain local archetypes.
When cloning SIL (e.g. in LoopUnroll) local archetypes are uniqued and therefore distinct in cloned instructions.

Fixes a SIL verification error
https://github.com/swiftlang/swift/issues/84899
rdar://162660981
---
 lib/SIL/Verifier/SILVerifier.cpp          |  6 ++++-
 test/SIL/verifier-archetype-debugvars.sil | 27 +++++++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 test/SIL/verifier-archetype-debugvars.sil

diff --git a/lib/SIL/Verifier/SILVerifier.cpp b/lib/SIL/Verifier/SILVerifier.cpp
index 0c8bf89d17c7c..e08f02c68e998 100644
--- a/lib/SIL/Verifier/SILVerifier.cpp
+++ b/lib/SIL/Verifier/SILVerifier.cpp
@@ -1657,7 +1657,11 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
 
       require(lhs == rhs ||
               (lhs.isAddress() && lhs.getObjectType() == rhs) ||
-              (DebugVarTy.isAddress() && lhs == rhs.getObjectType()),
+              (DebugVarTy.isAddress() && lhs == rhs.getObjectType()) ||
+
+              // When cloning SIL (e.g. in LoopUnroll) local archetypes are uniqued
+              // and therefore distinct in cloned instructions.
+              (lhs.hasLocalArchetype() && rhs.hasLocalArchetype()),
               "Two variables with different type but same scope!");
     }
 
diff --git a/test/SIL/verifier-archetype-debugvars.sil b/test/SIL/verifier-archetype-debugvars.sil
new file mode 100644
index 0000000000000..c651d216b19c6
--- /dev/null
+++ b/test/SIL/verifier-archetype-debugvars.sil
@@ -0,0 +1,27 @@
+// RUN: %target-sil-opt %s
+
+sil_stage canonical
+
+import Builtin
+import Swift
+import SwiftShims
+
+protocol P {}
+
+sil_scope 2 { loc "test.swift":1:6 parent @testit : $@convention(thin) (@in_guaranteed any P) -> () }
+sil_scope 3 { loc "test.swift":2:7 parent 2 }
+
+// Check that the verifier does not complain about two alloc_stacks with the same variable but different existential archetypes.
+
+sil @testit : $@convention(thin) (@in_guaranteed any P) -> () {
+bb0(%0 : $*any P):
+  %1 = open_existential_addr immutable_access %0 to $*@opened("2A0E9166-A9AC-11F0-A5A7-0EA13E3AABAF", any P) Self 
+  %2 = alloc_stack [lexical] $@opened("2A0E9166-A9AC-11F0-A5A7-0EA13E3AABAF", any P) Self, var, name "x", loc "test.swift":2:7, scope 3
+  dealloc_stack %2
+  %4 = open_existential_addr immutable_access %0 to $*@opened("3A0E9166-A9AC-11F0-A5A7-0EA13E3AABAF", any P) Self 
+  %5 = alloc_stack [lexical] $@opened("3A0E9166-A9AC-11F0-A5A7-0EA13E3AABAF", any P) Self, var, name "x", loc "test.swift":2:7, scope 3
+  dealloc_stack %5
+  %r = tuple ()
+  return %r
+}
+