3 files changed, 77 insertions, 7 deletions
diff --git a/tests/codegen/const_scalar_pair.rs b/tests/codegen/const_scalar_pair.rs
index 8f32c50b798..aa4cf7a64d5 100644
--- a/tests/codegen/const_scalar_pair.rs
+++ b/tests/codegen/const_scalar_pair.rs
@@ -2,6 +2,8 @@
 
 #![feature(inline_const)]
 
+// Test that we don't generate a memory allocation for the constant
+// and read the fields from that, but instead just create the value pair directly.
 pub fn foo() -> (i32, i32) {
     // CHECK: ret { i32, i32 } { i32 1, i32 2 }
     const { (1, 2) }
diff --git a/tests/codegen/intrinsics/transmute.rs b/tests/codegen/intrinsics/transmute.rs
index 664e697c2a5..fe42494000e 100644
--- a/tests/codegen/intrinsics/transmute.rs
+++ b/tests/codegen/intrinsics/transmute.rs
@@ -14,10 +14,10 @@ use std::intrinsics::{transmute, transmute_unchecked};
 // Some of these need custom MIR to not get removed by MIR optimizations.
 use std::intrinsics::mir::*;
 
-enum Never {}
+pub enum ZstNever {}
 
 #[repr(align(2))]
-pub struct BigNever(Never, u16, Never);
+pub struct BigNever(ZstNever, u16, ZstNever);
 
 #[repr(align(8))]
 pub struct Scalar64(i64);
@@ -56,11 +56,13 @@ pub unsafe fn check_bigger_array(x: [u32; 3]) -> [u32; 7] {
     transmute_unchecked(x)
 }
 
-// CHECK-LABEL: @check_to_uninhabited(
+// CHECK-LABEL: @check_to_empty_array(
 #[no_mangle]
 #[custom_mir(dialect = "runtime", phase = "optimized")]
-pub unsafe fn check_to_uninhabited(x: u16) -> BigNever {
+pub unsafe fn check_to_empty_array(x: [u32; 5]) -> [u32; 0] {
+    // CHECK-NOT: trap
     // CHECK: call void @llvm.trap
+    // CHECK-NOT: trap
     mir!{
         {
             RET = CastTransmute(x);
@@ -69,6 +71,37 @@ pub unsafe fn check_to_uninhabited(x: u16) -> BigNever {
     }
 }
 
+// CHECK-LABEL: @check_from_empty_array(
+#[no_mangle]
+#[custom_mir(dialect = "runtime", phase = "optimized")]
+pub unsafe fn check_from_empty_array(x: [u32; 0]) -> [u32; 5] {
+    // CHECK-NOT: trap
+    // CHECK: call void @llvm.trap
+    // CHECK-NOT: trap
+    mir!{
+        {
+            RET = CastTransmute(x);
+            Return()
+        }
+    }
+}
+
+// CHECK-LABEL: @check_to_uninhabited(
+#[no_mangle]
+#[custom_mir(dialect = "runtime", phase = "optimized")]
+pub unsafe fn check_to_uninhabited(x: u16) {
+    // CHECK-NOT: trap
+    // CHECK: call void @llvm.trap
+    // CHECK-NOT: trap
+    mir!{
+        let temp: BigNever;
+        {
+            temp = CastTransmute(x);
+            Return()
+        }
+    }
+}
+
 // CHECK-LABEL: @check_from_uninhabited(
 #[no_mangle]
 #[custom_mir(dialect = "runtime", phase = "optimized")]
@@ -366,6 +399,40 @@ pub unsafe fn check_issue_109992(x: ()) -> [(); 1] {
     }
 }
 
+// CHECK-LABEL: @check_unit_to_never(
+#[no_mangle]
+#[custom_mir(dialect = "runtime", phase = "optimized")]
+pub unsafe fn check_unit_to_never(x: ()) {
+    // This uses custom MIR to avoid MIR optimizations having removed ZST ops.
+
+    // CHECK-NOT: trap
+    // CHECK: call void @llvm.trap
+    // CHECK-NOT: trap
+    mir!{
+        let temp: ZstNever;
+        {
+            temp = CastTransmute(x);
+            Return()
+        }
+    }
+}
+
+// CHECK-LABEL: @check_unit_from_never(
+#[no_mangle]
+#[custom_mir(dialect = "runtime", phase = "optimized")]
+pub unsafe fn check_unit_from_never(x: ZstNever) -> () {
+    // This uses custom MIR to avoid MIR optimizations having removed ZST ops.
+
+    // CHECK: start
+    // CHECK-NEXT: ret void
+    mir!{
+        {
+            RET = CastTransmute(x);
+            Return()
+        }
+    }
+}
+
 // CHECK-LABEL: @check_maybe_uninit_pair(i16 %x.0, i64 %x.1)
 #[no_mangle]
 pub unsafe fn check_maybe_uninit_pair(
diff --git a/tests/codegen/issues/issue-105386-ub-in-debuginfo.rs b/tests/codegen/issues/issue-105386-ub-in-debuginfo.rs
index 2ee4d7cca0e..6e0eacfe400 100644
--- a/tests/codegen/issues/issue-105386-ub-in-debuginfo.rs
+++ b/tests/codegen/issues/issue-105386-ub-in-debuginfo.rs
@@ -1,4 +1,5 @@
-// compile-flags: --crate-type=lib -O -Cdebuginfo=2 -Cno-prepopulate-passes
+// compile-flags: --crate-type=lib -O -Cdebuginfo=2 -Cno-prepopulate-passes -Zmir-enable-passes=-ScalarReplacementOfAggregates
+// MIR SROA will decompose the closure
 // min-llvm-version: 15.0 # this test uses opaque pointer notation
 #![feature(stmt_expr_attributes)]
 
@@ -15,8 +16,8 @@ pub fn outer_function(x: S, y: S) -> usize {
 // 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-NOT: [[ptr_tmp:%.*]] = getelementptr inbounds %"[closure@{{.*.rs}}:9:23: 9:25]", ptr [[spill]]
+// CHECK: [[spill:%.*]] = alloca %"[closure@{{.*.rs}}:10:23: 10:25]"
+// CHECK-NOT: [[ptr_tmp:%.*]] = getelementptr inbounds %"[closure@{{.*.rs}}:10:23: 10:25]", ptr [[spill]]
 // CHECK-NOT: [[load:%.*]] = load ptr, ptr
 // CHECK: call void @llvm.lifetime.start{{.*}}({{.*}}, ptr [[spill]])
 // CHECK: [[inner:%.*]] = getelementptr inbounds %"{{.*}}", ptr [[spill]]