Rollup merge of #141507 - RalfJung:atomic-intrinsics, r=bjorn3

atomic_load intrinsic: use const generic parameter for ordering

We have a gazillion intrinsics for the atomics because we encode the ordering into the intrinsic name rather than making it a parameter. This is particularly bad for those operations that take two orderings. Let's fix that!

This PR only converts `load`, to see if there's any feedback that would fundamentally change the strategy we pursue for the const generic intrinsics.

The first two commits are preparation and could be a separate PR if you prefer.

`@BoxyUwU` -- I hope this is a use of const generics that is unlikely to explode? All we need is a const generic of enum type. We could funnel it through an integer if we had to but an enum is obviously nicer...

`@bjorn3` it seems like the cranelift backend entirely ignores the ordering?

2 files changed, 10 insertions, 10 deletions

diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index 5238755c8eb..fcb55a04635 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -612,7 +612,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         &mut self,
         ty: &'ll Type,
         ptr: &'ll Value,
-        order: rustc_codegen_ssa::common::AtomicOrdering,
+        order: rustc_middle::ty::AtomicOrdering,
         size: Size,
     ) -> &'ll Value {
         unsafe {
@@ -851,7 +851,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         &mut self,
         val: &'ll Value,
         ptr: &'ll Value,
-        order: rustc_codegen_ssa::common::AtomicOrdering,
+        order: rustc_middle::ty::AtomicOrdering,
         size: Size,
     ) {
         debug!("Store {:?} -> {:?}", val, ptr);
@@ -1307,8 +1307,8 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         dst: &'ll Value,
         cmp: &'ll Value,
         src: &'ll Value,
-        order: rustc_codegen_ssa::common::AtomicOrdering,
-        failure_order: rustc_codegen_ssa::common::AtomicOrdering,
+        order: rustc_middle::ty::AtomicOrdering,
+        failure_order: rustc_middle::ty::AtomicOrdering,
         weak: bool,
     ) -> (&'ll Value, &'ll Value) {
         let weak = if weak { llvm::True } else { llvm::False };
@@ -1334,7 +1334,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         op: rustc_codegen_ssa::common::AtomicRmwBinOp,
         dst: &'ll Value,
         mut src: &'ll Value,
-        order: rustc_codegen_ssa::common::AtomicOrdering,
+        order: rustc_middle::ty::AtomicOrdering,
     ) -> &'ll Value {
         // The only RMW operation that LLVM supports on pointers is compare-exchange.
         let requires_cast_to_int = self.val_ty(src) == self.type_ptr()
@@ -1360,7 +1360,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
     fn atomic_fence(
         &mut self,
-        order: rustc_codegen_ssa::common::AtomicOrdering,
+        order: rustc_middle::ty::AtomicOrdering,
         scope: SynchronizationScope,
     ) {
         let single_threaded = match scope {
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 67a66e6ec79..e27fbf94f34 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -426,14 +426,14 @@ pub(crate) enum AtomicOrdering {
 }
 
 impl AtomicOrdering {
-    pub(crate) fn from_generic(ao: rustc_codegen_ssa::common::AtomicOrdering) -> Self {
-        use rustc_codegen_ssa::common::AtomicOrdering as Common;
+    pub(crate) fn from_generic(ao: rustc_middle::ty::AtomicOrdering) -> Self {
+        use rustc_middle::ty::AtomicOrdering as Common;
         match ao {
             Common::Relaxed => Self::Monotonic,
             Common::Acquire => Self::Acquire,
             Common::Release => Self::Release,
-            Common::AcquireRelease => Self::AcquireRelease,
-            Common::SequentiallyConsistent => Self::SequentiallyConsistent,
+            Common::AcqRel => Self::AcquireRelease,
+            Common::SeqCst => Self::SequentiallyConsistent,
         }
     }
 }