Auto merge of #122024 - clubby789:remove-spec-option-pe, r=jhpratt

Remove SpecOptionPartialEq

With the recent LLVM bump, the specialization for Option::partial_eq on types with niches is no longer necessary. I kept the manual implementation as it still gives us better codegen than the derive (will look at this seperately).

Also implemented PartialOrd/Ord by hand as it _somewhat_ improves codegen for #49892: https://godbolt.org/z/vx5Y6oW4Y

1 files changed, 40 insertions, 3 deletions

diff --git a/tests/codegen/option-nonzero-eq.rs b/tests/codegen/option-niche-eq.rs
index f637b1aef97..8b8044e9b75 100644
--- a/tests/codegen/option-nonzero-eq.rs
+++ b/tests/codegen/option-niche-eq.rs
@@ -1,4 +1,5 @@
 //@ compile-flags: -O -Zmerge-functions=disabled
+//@ min-llvm-version: 18
 #![crate_type = "lib"]
 #![feature(generic_nonzero)]
 
@@ -7,9 +8,6 @@ use core::cmp::Ordering;
 use core::ptr::NonNull;
 use core::num::NonZero;
 
-// See also tests/assembly/option-nonzero-eq.rs, for cases with `assume`s in the
-// LLVM and thus don't optimize down clearly here, but do in assembly.
-
 // CHECK-lABEL: @non_zero_eq
 #[no_mangle]
 pub fn non_zero_eq(l: Option<NonZero<u32>>, r: Option<NonZero<u32>>) -> bool {
@@ -36,3 +34,42 @@ pub fn non_null_eq(l: Option<NonNull<u8>>, r: Option<NonNull<u8>>) -> bool {
     // CHECK-NEXT: ret i1
     l == r
 }
+
+// CHECK-lABEL: @ordering_eq
+#[no_mangle]
+pub fn ordering_eq(l: Option<Ordering>, r: Option<Ordering>) -> bool {
+    // CHECK: start:
+    // CHECK-NEXT: icmp eq i8
+    // CHECK-NEXT: ret i1
+    l == r
+}
+
+#[derive(PartialEq)]
+pub enum EnumWithNiche {
+    A,
+    B,
+    C,
+    D,
+    E,
+    F,
+    G,
+}
+
+// CHECK-lABEL: @niche_eq
+#[no_mangle]
+pub fn niche_eq(l: Option<EnumWithNiche>, r: Option<EnumWithNiche>) -> bool {
+    // CHECK: start:
+    // CHECK-NEXT: icmp eq i8
+    // CHECK-NEXT: ret i1
+    l == r
+}
+
+// FIXME: This should work too
+// // FIXME-CHECK-lABEL: @bool_eq
+// #[no_mangle]
+// pub fn bool_eq(l: Option<bool>, r: Option<bool>) -> bool {
+//     // FIXME-CHECK: start:
+//     // FIXME-CHECK-NEXT: icmp eq i8
+//     // FIXME-CHECK-NEXT: ret i1
+//     l == r
+// }