6 files changed, 77 insertions, 9 deletions
diff --git a/tests/codegen/alloc-optimisation.rs b/tests/codegen/alloc-optimisation.rs
index 19f14647c1d..3735860d510 100644
--- a/tests/codegen/alloc-optimisation.rs
+++ b/tests/codegen/alloc-optimisation.rs
@@ -5,7 +5,8 @@
 pub fn alloc_test(data: u32) {
     // CHECK-LABEL: @alloc_test
     // CHECK-NEXT: start:
-    // CHECK-NEXT: {{.*}} load volatile i8, ptr @{{.*}}__rust_no_alloc_shim_is_unstable, align 1
+    // CHECK-NEXT: ; call __rustc::__rust_no_alloc_shim_is_unstable_v2
+    // CHECK-NEXT: tail call void @_R{{.+}}__rust_no_alloc_shim_is_unstable_v2()
     // CHECK-NEXT: ret void
     let x = Box::new(data);
     drop(x);
diff --git a/tests/codegen/frame-pointer-cli-control.rs b/tests/codegen/frame-pointer-cli-control.rs
new file mode 100644
index 00000000000..a65dd132763
--- /dev/null
+++ b/tests/codegen/frame-pointer-cli-control.rs
@@ -0,0 +1,61 @@
+//@ add-core-stubs
+//@ compile-flags: --crate-type=rlib -Copt-level=0
+//@ revisions: force-on aarch64-apple aarch64-apple-on aarch64-apple-off
+//@ [force-on] compile-flags: -Cforce-frame-pointers=on
+//@ [aarch64-apple] needs-llvm-components: aarch64
+//@ [aarch64-apple] compile-flags: --target=aarch64-apple-darwin
+//@ [aarch64-apple-on] needs-llvm-components: aarch64
+//@ [aarch64-apple-on] compile-flags: --target=aarch64-apple-darwin -Cforce-frame-pointers=on
+//@ [aarch64-apple-off] needs-llvm-components: aarch64
+//@ [aarch64-apple-off] compile-flags: --target=aarch64-apple-darwin -Cforce-frame-pointers=off
+/*!
+
+Tests the extent to which frame pointers can be controlled by the CLI.
+The behavior of our frame pointer options, at present, is an irreversible ratchet, where
+a "weaker" option that allows omitting frame pointers may be overridden by the target demanding
+that all code (or all non-leaf code, more often) must be compiled with frame pointers.
+This was discussed on 2025-05-22 in the T-compiler meeting and accepted as an intentional change,
+ratifying the prior decisions by compiler contributors and reviewers as correct,
+though it was also acknowledged that the flag allows somewhat confusing inputs.
+
+We find aarch64-apple-darwin useful because of its icy-clear policy regarding frame pointers,
+e.g. <https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms> says:
+
+* The frame pointer register (x29) must always address a valid frame record. Some functions —
+  such as leaf functions or tail calls — may opt not to create an entry in this list.
+  As a result, stack traces are always meaningful, even without debug information.
+
+Many Rust fn, if externally visible, may be expected to follow target ABI by tools or asm code!
+This can make it a problem to generate ABI-incorrect code, which may mean "with frame pointers".
+For this and other reasons, `-Cforce-frame-pointers=off` cannot override the target definition.
+This can cause some confusion because it is "reverse polarity" relative to C compilers, which have
+commands like `-fomit-frame-pointer`, `-fomit-leaf-frame-pointer`, or `-fno-omit-frame-pointer`!
+
+Specific cases where platforms or tools rely on frame pointers for sound or correct unwinding:
+- illumos: <https://smartos.org/bugview/OS-7515>
+- aarch64-windows: <https://github.com/rust-lang/rust/issues/123686>
+- aarch64-linux: <https://github.com/rust-lang/rust/issues/123733>
+- dtrace (freebsd and openbsd): <https://github.com/rust-lang/rust/issues/97723>
+- openbsd: <https://github.com/rust-lang/rust/issues/43575>
+- i686-msvc <https://github.com/rust-lang/backtrace-rs/pull/584#issuecomment-1966177530>
+- i686-mingw: <https://github.com/rust-lang/rust/commit/3f1d3948d6d434b34dd47f132c126a6cb6b8a4ab>
+*/
+#![feature(no_core, lang_items)]
+#![no_core]
+
+extern crate minicore;
+
+// CHECK: i32 @peach{{.*}}[[PEACH_ATTRS:\#[0-9]+]] {
+#[no_mangle]
+pub fn peach(x: u32) -> u32 {
+    x
+}
+
+// CHECK: attributes [[PEACH_ATTRS]] = {
+// force-on-SAME: {{.*}}"frame-pointer"="all"
+// aarch64-apple-SAME: {{.*}}"frame-pointer"="non-leaf"
+// aarch64-apple-on-SAME: {{.*}}"frame-pointer"="all"
+//
+// yes, we are testing this doesn't do anything:
+// aarch64-apple-off-SAME: {{.*}}"frame-pointer"="non-leaf"
+// CHECK-SAME: }
diff --git a/tests/codegen/iter-repeat-n-trivial-drop.rs b/tests/codegen/iter-repeat-n-trivial-drop.rs
index 3bb942d11d5..28173530324 100644
--- a/tests/codegen/iter-repeat-n-trivial-drop.rs
+++ b/tests/codegen/iter-repeat-n-trivial-drop.rs
@@ -1,5 +1,6 @@
 //@ compile-flags: -C opt-level=3
 //@ only-x86_64
+//@ needs-deterministic-layouts
 
 #![crate_type = "lib"]
 #![feature(iter_repeat_n)]
@@ -25,10 +26,10 @@ pub fn iter_repeat_n_next(it: &mut std::iter::RepeatN<NotCopy>) -> Option<NotCop
     // CHECK-NEXT: br i1 %[[COUNT_ZERO]], label %[[EMPTY:.+]], label %[[NOT_EMPTY:.+]]
 
     // CHECK: [[NOT_EMPTY]]:
-    // CHECK-NEXT: %[[DEC:.+]] = add i64 %[[COUNT]], -1
-    // CHECK-NEXT: store i64 %[[DEC]]
     // CHECK-NOT: br
-    // CHECK: %[[VAL:.+]] = load i16
+    // CHECK: %[[DEC:.+]] = add i64 %[[COUNT]], -1
+    // CHECK-NEXT: %[[VAL:.+]] = load i16
+    // CHECK-NEXT: store i64 %[[DEC]]
     // CHECK-NEXT: br label %[[EMPTY]]
 
     // CHECK: [[EMPTY]]:
diff --git a/tests/codegen/unwind-landingpad-inline.rs b/tests/codegen/unwind-landingpad-inline.rs
index 920774b3402..1cf606279e6 100644
--- a/tests/codegen/unwind-landingpad-inline.rs
+++ b/tests/codegen/unwind-landingpad-inline.rs
@@ -10,8 +10,10 @@
 // See https://github.com/rust-lang/rust/issues/46515
 // CHECK-LABEL: @check_no_escape_in_landingpad
 // CHECK: start:
-// CHECK-NEXT: __rust_no_alloc_shim_is_unstable
-// CHECK-NEXT: __rust_no_alloc_shim_is_unstable
+// CHECK-NEXT: ; call __rustc::__rust_no_alloc_shim_is_unstable_v2
+// CHECK-NEXT: tail call void @[[NO_ALLOC_SHIM:_R.+__rust_no_alloc_shim_is_unstable_v2]]()
+// CHECK-NEXT: ; call __rustc::__rust_no_alloc_shim_is_unstable_v2
+// CHECK-NEXT: tail call void @[[NO_ALLOC_SHIM]]()
 // CHECK-NEXT: ret void
 #[no_mangle]
 pub fn check_no_escape_in_landingpad(f: fn()) {
diff --git a/tests/codegen/vec-iter-collect-len.rs b/tests/codegen/vec-iter-collect-len.rs
index a88573522d4..807548ef883 100644
--- a/tests/codegen/vec-iter-collect-len.rs
+++ b/tests/codegen/vec-iter-collect-len.rs
@@ -4,7 +4,9 @@
 #[no_mangle]
 pub fn get_len() -> usize {
     // CHECK-LABEL: @get_len
-    // CHECK-NOT: call
-    // CHECK-NOT: invoke
+    // CHECK-NEXT: start:
+    // CHECK-NEXT: ; call __rustc::__rust_no_alloc_shim_is_unstable_v2
+    // CHECK-NEXT: tail call void @_R{{.+}}__rust_no_alloc_shim_is_unstable_v2()
+    // CHECK-NEXT: ret i{{[0-9]+}} 3
     [1, 2, 3].iter().collect::<Vec<_>>().len()
 }
diff --git a/tests/codegen/vec-optimizes-away.rs b/tests/codegen/vec-optimizes-away.rs
index f6ed2898bda..93b55454b10 100644
--- a/tests/codegen/vec-optimizes-away.rs
+++ b/tests/codegen/vec-optimizes-away.rs
@@ -5,7 +5,8 @@
 pub fn sum_me() -> i32 {
     // CHECK-LABEL: @sum_me
     // CHECK-NEXT: {{^.*:$}}
-    // CHECK-NEXT: {{.*}} load volatile i8, ptr @{{.*}}__rust_no_alloc_shim_is_unstable, align 1
+    // CHECK-NEXT: ; call __rustc::__rust_no_alloc_shim_is_unstable_v2
+    // CHECK-NEXT: tail call void @_R{{.+}}__rust_no_alloc_shim_is_unstable_v2()
     // CHECK-NEXT: ret i32 6
     vec![1, 2, 3].iter().sum::<i32>()
 }