Add test case for ub in generated LLVM IR

Author: wesleywiser

src/test/codegen/issue-105386-ub-in-debuginfo.rs

@@ -0,0 +1,22 @@
+// compile-flags: --crate-type=lib -O -Cdebuginfo=2 -Cno-prepopulate-passes
+// min-llvm-version: 15.0 # this test uses opaque pointer notation
+#![feature(stmt_expr_attributes)]
+
+pub struct S([usize; 8]);
+
+#[no_mangle]
+pub fn outer_function(x: S, y: S) -> usize {
+    (#[inline(always)]|| {
+        let _z = x;
+        y.0[0]
+    })()
+}
+
+// Check that we do not attempt to load from the spilled arg before it is assigned to
+// when generating debuginfo.
+// CHECK-LABEL: @outer_function
+// CHECK: [[spill:%.*]] = alloca %"[closure@{{.*.rs}}:9:23: 9:25]"
+// CHECK: [[ptr_tmp:%.*]] = getelementptr inbounds %"[closure@{{.*.rs}}:9:23: 9:25]", ptr [[spill]]
+// CHECK: [[load:%.*]] = load ptr, ptr [[ptr_tmp]]
+// CHECK: call void @llvm.lifetime.start{{.*}}({{.*}}, ptr [[spill]])
+// CHECK: call void @llvm.memcpy{{.*}}(ptr {{align .*}} [[spill]], ptr {{align .*}} %x