Rollup merge of #80525 - devsnek:wasm64, r=nagisa

wasm64 support

There is still some upstream llvm work needed before this can land.

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -317,7 +317,7 @@ pub fn from_fn_attrs(cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value, instance: ty::
     // Note that currently the `wasm-import-module` doesn't do anything, but
     // eventually LLVM 7 should read this and ferry the appropriate import
     // module to the output file.
-    if cx.tcx.sess.target.arch == "wasm32" {
+    if cx.tcx.sess.target.is_like_wasm {
         if let Some(module) = wasm_import_module(cx.tcx, instance.def_id()) {
             llvm::AddFunctionAttrStringValue(
                 llfn,

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -170,10 +170,7 @@ pub fn target_machine_factory(
     // On the wasm target once the `atomics` feature is enabled that means that
     // we're no longer single-threaded, or otherwise we don't want LLVM to
     // lower atomic operations to single-threaded operations.
-    if singlethread
-        && sess.target.llvm_target.contains("wasm32")
-        && sess.target_features.contains(&sym::atomics)
-    {
+    if singlethread && sess.target.is_like_wasm && sess.target_features.contains(&sym::atomics) {
         singlethread = false;
     }
 

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -1083,9 +1083,9 @@ pub fn compile_unit_metadata(
             );
         }
 
-        // Insert `llvm.ident` metadata on the wasm32 targets since that will
+        // Insert `llvm.ident` metadata on the wasm targets since that will
         // get hooked up to the "producer" sections `processed-by` information.
-        if tcx.sess.opts.target_triple.triple().starts_with("wasm32") {
+        if tcx.sess.target.is_like_wasm {
             let name_metadata = llvm::LLVMMDStringInContext(
                 debug_context.llcontext,
                 rustc_producer.as_ptr().cast(),