From 3caaf0a3e81758535b289b95099032d60d5da46a Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Tue, 9 Sep 2025 00:07:45 +0200
Subject: [PATCH] Compiler hang with unaligned load-store pair. #2470

---
 releasenotes.md                               |  1 +
 src/compiler/llvm_codegen_builtins.c          |  5 ++--
 .../builtins/unaligned_load_store.c3t         |  1 +
 .../builtins/unaligned_load_store_chain.c3t   | 23 +++++++++++++++++++
 4 files changed, 27 insertions(+), 3 deletions(-)
 create mode 100644 test/test_suite/builtins/unaligned_load_store_chain.c3t

diff --git a/releasenotes.md b/releasenotes.md
index 2c331618d..16687dfb6 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -18,6 +18,7 @@
 - Overloading &[] should be enough for foreach. #2466
 - Any register allowed in X86_64 inline asm address. #2463
 - int val = some_int + some_distinct_inline_int errors that int cannot be cast to DistinctInt #2468
+- Compiler hang with unaligned load-store pair. #2470
 
 ### Stdlib changes
 - Added generic `InterfaceList` to store a list of values that implement a specific interface
diff --git a/src/compiler/llvm_codegen_builtins.c b/src/compiler/llvm_codegen_builtins.c
index 99184bba4..4c8d2a92f 100644
--- a/src/compiler/llvm_codegen_builtins.c
+++ b/src/compiler/llvm_codegen_builtins.c
@@ -169,10 +169,9 @@ INLINE void llvm_emit_unaligned_store(GenContext *c, BEValue *result_value, Expr
 	c->emitting_load_store_check = true;
 	BEValue value;
 	llvm_emit_expr(c, &value, expr->call_expr.arguments[0]);
+	llvm_value_rvalue(c, &value);
 	llvm_emit_expr(c, result_value, expr->call_expr.arguments[1]);
-	llvm_value_deref(c, &value);
-	value.alignment = expr->call_expr.arguments[2]->const_expr.ixx.i.low;
-	llvm_store(c, &value, result_value);
+	llvm_store_to_ptr_aligned(c, value.value, result_value, expr->call_expr.arguments[2]->const_expr.ixx.i.low);
 	c->emitting_load_store_check = emit_check;
 }
 
diff --git a/test/test_suite/builtins/unaligned_load_store.c3t b/test/test_suite/builtins/unaligned_load_store.c3t
index c4aa12992..bcd1144f5 100644
--- a/test/test_suite/builtins/unaligned_load_store.c3t
+++ b/test/test_suite/builtins/unaligned_load_store.c3t
@@ -1,3 +1,4 @@
+// #target: macos-x64
 module test;
 
 struct Foo
diff --git a/test/test_suite/builtins/unaligned_load_store_chain.c3t b/test/test_suite/builtins/unaligned_load_store_chain.c3t
new file mode 100644
index 000000000..2a03bf43e
--- /dev/null
+++ b/test/test_suite/builtins/unaligned_load_store_chain.c3t
@@ -0,0 +1,23 @@
+// #target: macos-x64
+module test;
+module test;
+import std, libc;
+
+fn void unaligned_load_store(void* dst, void* src) @nostrip
+{
+    $$unaligned_store(dst, $$unaligned_load((char*)src, 2), 2);
+}
+
+fn int main()
+{
+	return 0;
+}
+
+/* #expect: test.ll
+
+define void @test.unaligned_load_store(ptr %0, ptr %1) #0 {
+entry:
+  %2 = load i8, ptr %1, align 2
+  store i8 %2, ptr %0, align 2
+  ret void
+}