From d42c3ae02f4c54fe3bdac7e0cc49c3c51e8fb517 Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Sun, 5 Jan 2025 01:17:07 +0000
Subject: [PATCH 1/2] Merge the intrinsic and user tests for
 `select_unpredictable`

[1] mentions that having a single test with `-Zmerge-functions=disabled`
is preferable to having two separate tests.  Apply that to the new
`select_unpredicatble` test here.

[1]: https://github.com/rust-lang/rust/pull/133964#issuecomment-2569693325
---
 tests/codegen/bool-select-unpredictable.rs    | 35 -------------------
 .../intrinsics/select_unpredictable.rs        | 34 +++++++++++++++++-
 2 files changed, 33 insertions(+), 36 deletions(-)
 delete mode 100644 tests/codegen/bool-select-unpredictable.rs

diff --git a/tests/codegen/bool-select-unpredictable.rs b/tests/codegen/bool-select-unpredictable.rs
deleted file mode 100644
index 1562b17754203..0000000000000
--- a/tests/codegen/bool-select-unpredictable.rs
+++ /dev/null
@@ -1,35 +0,0 @@
-//@ compile-flags: -O
-
-#![feature(select_unpredictable)]
-#![crate_type = "lib"]
-
-#[no_mangle]
-pub fn test_int(p: bool, a: u64, b: u64) -> u64 {
-    // CHECK-LABEL: define{{.*}} @test_int
-    // CHECK: select i1 %p, i64 %a, i64 %b, !unpredictable
-    p.select_unpredictable(a, b)
-}
-
-#[no_mangle]
-pub fn test_pair(p: bool, a: (u64, u64), b: (u64, u64)) -> (u64, u64) {
-    // CHECK-LABEL: define{{.*}} @test_pair
-    // CHECK: select i1 %p, {{.*}}, !unpredictable
-    p.select_unpredictable(a, b)
-}
-
-struct Large {
-    e: [u64; 100],
-}
-
-#[no_mangle]
-pub fn test_struct(p: bool, a: Large, b: Large) -> Large {
-    // CHECK-LABEL: define{{.*}} @test_struct
-    // CHECK: select i1 %p, {{.*}}, !unpredictable
-    p.select_unpredictable(a, b)
-}
-
-#[no_mangle]
-pub fn test_zst(p: bool, a: (), b: ()) -> () {
-    // CHECK-LABEL: define{{.*}} @test_zst
-    p.select_unpredictable(a, b)
-}
diff --git a/tests/codegen/intrinsics/select_unpredictable.rs b/tests/codegen/intrinsics/select_unpredictable.rs
index 2054838dd7998..b03c9708b8ecd 100644
--- a/tests/codegen/intrinsics/select_unpredictable.rs
+++ b/tests/codegen/intrinsics/select_unpredictable.rs
@@ -1,8 +1,11 @@
-//@ compile-flags: -O
+//@ compile-flags: -O -Zmerge-functions=disabled
 
 #![feature(core_intrinsics)]
+#![feature(select_unpredictable)]
 #![crate_type = "lib"]
 
+/* Test the intrinsic */
+
 #[no_mangle]
 pub fn test_int(p: bool, a: u64, b: u64) -> u64 {
     // CHECK-LABEL: define{{.*}} @test_int
@@ -33,3 +36,32 @@ pub fn test_zst(p: bool, a: (), b: ()) -> () {
     // CHECK-LABEL: define{{.*}} @test_zst
     core::intrinsics::select_unpredictable(p, a, b)
 }
+
+/* Test the user-facing version */
+
+#[no_mangle]
+pub fn test_int2(p: bool, a: u64, b: u64) -> u64 {
+    // CHECK-LABEL: define{{.*}} @test_int2
+    // CHECK: select i1 %p, i64 %a, i64 %b, !unpredictable
+    p.select_unpredictable(a, b)
+}
+
+#[no_mangle]
+pub fn test_pair2(p: bool, a: (u64, u64), b: (u64, u64)) -> (u64, u64) {
+    // CHECK-LABEL: define{{.*}} @test_pair2
+    // CHECK: select i1 %p, {{.*}}, !unpredictable
+    p.select_unpredictable(a, b)
+}
+
+#[no_mangle]
+pub fn test_struct2(p: bool, a: Large, b: Large) -> Large {
+    // CHECK-LABEL: define{{.*}} @test_struct2
+    // CHECK: select i1 %p, {{.*}}, !unpredictable
+    p.select_unpredictable(a, b)
+}
+
+#[no_mangle]
+pub fn test_zst2(p: bool, a: (), b: ()) -> () {
+    // CHECK-LABEL: define{{.*}} @test_zst2
+    p.select_unpredictable(a, b)
+}

From 74d2d4bfa475a131df0c9ee0754b022a458cd152 Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Sun, 5 Jan 2025 08:44:01 +0000
Subject: [PATCH 2/2] Expand the `select_unpredictable` test for ZSTs

For ZSTs there is no selection that needs to take place, so assert that
no `select` statement is emitted.
---
 tests/codegen/intrinsics/select_unpredictable.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tests/codegen/intrinsics/select_unpredictable.rs b/tests/codegen/intrinsics/select_unpredictable.rs
index b03c9708b8ecd..ea6127a48bf3f 100644
--- a/tests/codegen/intrinsics/select_unpredictable.rs
+++ b/tests/codegen/intrinsics/select_unpredictable.rs
@@ -31,9 +31,12 @@ pub fn test_struct(p: bool, a: Large, b: Large) -> Large {
     core::intrinsics::select_unpredictable(p, a, b)
 }
 
+// ZSTs should not need a `select` expression.
 #[no_mangle]
 pub fn test_zst(p: bool, a: (), b: ()) -> () {
     // CHECK-LABEL: define{{.*}} @test_zst
+    // CHECK-NEXT: start:
+    // CHECK-NEXT: ret void
     core::intrinsics::select_unpredictable(p, a, b)
 }
 
@@ -63,5 +66,7 @@ pub fn test_struct2(p: bool, a: Large, b: Large) -> Large {
 #[no_mangle]
 pub fn test_zst2(p: bool, a: (), b: ()) -> () {
     // CHECK-LABEL: define{{.*}} @test_zst2
+    // CHECK-NEXT: start:
+    // CHECK-NEXT: ret void
     p.select_unpredictable(a, b)
 }