From df8ab6ee0bb76d872ef6b666ce871b0d8829b24b Mon Sep 17 00:00:00 2001
From: Joe Groff <jgroff@apple.com>
Date: Fri, 12 Sep 2025 11:20:57 -0700
Subject: [PATCH] SILGen: Don't copy_addr [take] trivial address-only values.

This is a new case that comes up with `InlineArray`, since an `InlineArray`
with unknown count but known trivial element type is trivial but still
address-only due to its unknown size. We are inconsistent about whether
we emit formal copies or not of these values; they should generally
be unnecessary as long as the memory location of a value is sufficiently
long-lived, but the SIL verifier still reasonably considers a `[take]` as
an invalidation of the memory, even though at runtime a take is a no-op.
Since the take is unnecessary, we can just not take when we copy out of
a trivial address location. Fixes #84141 | rdar://160007939.
---
 lib/SILGen/SILGenLValue.cpp                   |  4 +++-
 test/SILGen/trivial_address_only_switch.swift | 15 +++++++++++++++
 test/SILGen/variadic-generic-tuples.swift     |  2 +-
 3 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 test/SILGen/trivial_address_only_switch.swift

diff --git a/lib/SILGen/SILGenLValue.cpp b/lib/SILGen/SILGenLValue.cpp
index 2c906ddb64c..23df4448b9f 100644
--- a/lib/SILGen/SILGenLValue.cpp
+++ b/lib/SILGen/SILGenLValue.cpp
@@ -5234,7 +5234,9 @@ void SILGenFunction::emitSemanticStore(SILLocation loc,
     assert(!silConv.useLoweredAddresses() ||
            (dest->getType().isAddressOnly(F) == rvalue->getType().isAddress()));
     if (rvalue->getType().isAddress()) {
-      B.createCopyAddr(loc, rvalue, dest, IsTake, isInit);
+      B.createCopyAddr(loc, rvalue, dest,
+                       rvalue->getType().isTrivial(F) ? IsNotTake : IsTake,
+                       isInit);
     } else {
       emitUnloweredStoreOfCopy(B, loc, rvalue, dest, isInit);
     }
diff --git a/test/SILGen/trivial_address_only_switch.swift b/test/SILGen/trivial_address_only_switch.swift
new file mode 100644
index 00000000000..8a272250b80
--- /dev/null
+++ b/test/SILGen/trivial_address_only_switch.swift
@@ -0,0 +1,15 @@
+// RUN: %target-swift-emit-silgen -verify -disable-availability-checking %s
+
+public enum StreamYieldResult<let count: Int>: Sendable {
+    case literal(buffer: InlineArray<count, UInt8>)
+    case end(buffer: InlineArray<count, UInt8>, endIndex: Int)
+    
+    public func buffer() -> InlineArray<count, UInt8> {
+        switch self {
+        case .literal(let b):
+            return b
+        case .end(let b, _):
+            return b
+        }
+    }
+}
diff --git a/test/SILGen/variadic-generic-tuples.swift b/test/SILGen/variadic-generic-tuples.swift
index 6c63a488110..007253c2be7 100644
--- a/test/SILGen/variadic-generic-tuples.swift
+++ b/test/SILGen/variadic-generic-tuples.swift
@@ -102,7 +102,7 @@ public struct Container<each T> {
 //   Finally, the actual assignment.
 // CHECK-NEXT:    [[ACCESS:%.*]] = begin_access [modify] [unknown] %1 :
 // CHECK-NEXT:    [[FIELD:%.*]] = struct_element_addr [[ACCESS]] : $*Container<repeat each T>, #Container.storage
-// CHECK-NEXT:    copy_addr [take] [[COPY2]] to [[FIELD]] : $*(repeat Stored<each T>)
+// CHECK-NEXT:    copy_addr [[COPY2]] to [[FIELD]] : $*(repeat Stored<each T>)
 // CHECK-NEXT:    end_access [[ACCESS]]
 //   Clean up.
 // CHECK-NEXT:    dealloc_stack [[COPY2]]