3 files changed, 17 insertions, 3 deletions
diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index c41a41980eb..8c1e865762c 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -1064,11 +1064,25 @@ 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,
+        mut order: rustc_codegen_ssa::common::AtomicOrdering,
         failure_order: rustc_codegen_ssa::common::AtomicOrdering,
         weak: bool,
     ) -> &'ll Value {
         let weak = if weak { llvm::True } else { llvm::False };
+        if llvm_util::get_version() < (13, 0, 0) {
+            use rustc_codegen_ssa::common::AtomicOrdering::*;
+            // Older llvm has the pre-C++17 restriction on
+            // success and failure memory ordering,
+            // requiring the former to be at least as strong as the latter.
+            // So, for llvm 12, we upgrade the success ordering to a stronger
+            // one if necessary.
+            match (order, failure_order) {
+                (Relaxed, Acquire) => order = Acquire,
+                (Release, Acquire) => order = AcquireRelease,
+                (_, SequentiallyConsistent) => order = SequentiallyConsistent,
+                _ => {}
+            }
+        }
         unsafe {
             llvm::LLVMRustBuildAtomicCmpXchg(
                 self.llbuilder,
diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index b5c31fcebe0..c007728095f 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -906,7 +906,7 @@ impl<'ll> CodegenCx<'ll, '_> {
             return eh_catch_typeinfo;
         }
         let tcx = self.tcx;
-        assert!(self.sess().target.is_like_emscripten);
+        assert!(self.sess().target.os == "emscripten");
         let eh_catch_typeinfo = match tcx.lang_items().eh_catch_typeinfo() {
             Some(def_id) => self.get_static(def_id),
             _ => {
diff --git a/compiler/rustc_codegen_llvm/src/intrinsic.rs b/compiler/rustc_codegen_llvm/src/intrinsic.rs
index a18f5b9dd7f..9f364749287 100644
--- a/compiler/rustc_codegen_llvm/src/intrinsic.rs
+++ b/compiler/rustc_codegen_llvm/src/intrinsic.rs
@@ -441,7 +441,7 @@ fn try_intrinsic<'ll>(
         bx.store(bx.const_i32(0), dest, ret_align);
     } else if wants_msvc_seh(bx.sess()) {
         codegen_msvc_try(bx, try_func, data, catch_func, dest);
-    } else if bx.sess().target.is_like_emscripten {
+    } else if bx.sess().target.os == "emscripten" {
         codegen_emcc_try(bx, try_func, data, catch_func, dest);
     } else {
         codegen_gnu_try(bx, try_func, data, catch_func, dest);