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
+    if singlethread && sess.target.is_like_wasm && sess.target_features.contains(&sym::atomics) {
-        && sess.target.llvm_target.contains("wasm32")
-        && 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(),

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -186,7 +186,7 @@ impl<'a> GccLinker<'a> {
         // * On OSX they have their own linker, not binutils'
         // * For WebAssembly the only functional linker is LLD, which doesn't
         //   support hint flags
-        !self.sess.target.is_like_osx && self.sess.target.arch != "wasm32"
+        !self.sess.target.is_like_osx && !self.sess.target.is_like_wasm
     }
 
     // Some platforms take hints about whether a library is static or dynamic.

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -161,7 +161,7 @@ pub fn supported_target_features(sess: &Session) -> &'static [(&'static str, Opt
         "mips" | "mips64" => MIPS_ALLOWED_FEATURES,
         "powerpc" | "powerpc64" => POWERPC_ALLOWED_FEATURES,
         "riscv32" | "riscv64" => RISCV_ALLOWED_FEATURES,
-        "wasm32" => WASM_ALLOWED_FEATURES,
+        "wasm32" | "wasm64" => WASM_ALLOWED_FEATURES,
         _ => &[],
     }
 }

compiler/rustc_session/src/config.rs

@@ -822,6 +822,9 @@ pub fn default_configuration(sess: &Session) -> CrateConfig {
         }
     }
     ret.insert((sym::target_arch, Some(Symbol::intern(arch))));
+    if sess.target.is_like_wasm {
+        ret.insert((sym::wasm, None));
+    }
     ret.insert((sym::target_endian, Some(Symbol::intern(end.as_str()))));
     ret.insert((sym::target_pointer_width, Some(Symbol::intern(&wordsz))));
     ret.insert((sym::target_env, Some(Symbol::intern(env))));

compiler/rustc_span/src/symbol.rs

@@ -1294,6 +1294,7 @@ symbols! {
         vreg,
         vreg_low16,
         warn,
+        wasm,
         wasm_import_module,
         wasm_target_feature,
         while_let,

compiler/rustc_symbol_mangling/src/lib.rs

@@ -198,7 +198,7 @@ fn compute_symbol_name(
     //
     // [1]: https://bugs.llvm.org/show_bug.cgi?id=44316
     if is_foreign
-        && (tcx.sess.target.arch != "wasm32"
+        && (!tcx.sess.target.is_like_wasm
             || !tcx.wasm_import_module_map(def_id.krate).contains_key(&def_id))
     {
         if let Some(name) = attrs.link_name {

compiler/rustc_target/src/abi/call/mod.rs

@@ -20,6 +20,7 @@ mod sparc;
 mod sparc64;
 mod wasm32;
 mod wasm32_bindgen_compat;
+mod wasm64;
 mod x86;
 mod x86_64;
 mod x86_win64;
@@ -652,6 +653,7 @@ impl<'a, Ty> FnAbi<'a, Ty> {
                 _ => wasm32_bindgen_compat::compute_abi_info(self),
             },
             "asmjs" => wasm32::compute_abi_info(cx, self),
+            "wasm64" => wasm64::compute_abi_info(cx, self),
             a => return Err(format!("unrecognized arch \"{}\" in target specification", a)),
         }
 

compiler/rustc_target/src/abi/call/wasm64.rs

@@ -0,0 +1,58 @@
+use crate::abi::call::{ArgAbi, FnAbi, Uniform};
+use crate::abi::{HasDataLayout, LayoutOf, TyAndLayout, TyAndLayoutMethods};
+
+fn unwrap_trivial_aggregate<'a, Ty, C>(cx: &C, val: &mut ArgAbi<'a, Ty>) -> bool
+where
+    Ty: TyAndLayoutMethods<'a, C> + Copy,
+    C: LayoutOf<Ty = Ty, TyAndLayout = TyAndLayout<'a, Ty>> + HasDataLayout,
+{
+    if val.layout.is_aggregate() {
+        if let Some(unit) = val.layout.homogeneous_aggregate(cx).ok().and_then(|ha| ha.unit()) {
+            let size = val.layout.size;
+            if unit.size == size {
+                val.cast_to(Uniform { unit, total: size });
+                return true;
+            }
+        }
+    }
+    false
+}
+
+fn classify_ret<'a, Ty, C>(cx: &C, ret: &mut ArgAbi<'a, Ty>)
+where
+    Ty: TyAndLayoutMethods<'a, C> + Copy,
+    C: LayoutOf<Ty = Ty, TyAndLayout = TyAndLayout<'a, Ty>> + HasDataLayout,
+{
+    ret.extend_integer_width_to(64);
+    if ret.layout.is_aggregate() && !unwrap_trivial_aggregate(cx, ret) {
+        ret.make_indirect();
+    }
+}
+
+fn classify_arg<'a, Ty, C>(cx: &C, arg: &mut ArgAbi<'a, Ty>)
+where
+    Ty: TyAndLayoutMethods<'a, C> + Copy,
+    C: LayoutOf<Ty = Ty, TyAndLayout = TyAndLayout<'a, Ty>> + HasDataLayout,
+{
+    arg.extend_integer_width_to(64);
+    if arg.layout.is_aggregate() && !unwrap_trivial_aggregate(cx, arg) {
+        arg.make_indirect_byval();
+    }
+}
+
+pub fn compute_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>)
+where
+    Ty: TyAndLayoutMethods<'a, C> + Copy,
+    C: LayoutOf<Ty = Ty, TyAndLayout = TyAndLayout<'a, Ty>> + HasDataLayout,
+{
+    if !fn_abi.ret.is_ignore() {
+        classify_ret(cx, &mut fn_abi.ret);
+    }
+
+    for arg in &mut fn_abi.args {
+        if arg.is_ignore() {
+            continue;
+        }
+        classify_arg(cx, arg);
+    }
+}

compiler/rustc_target/src/spec/mod.rs

@@ -79,7 +79,7 @@ mod solaris_base;
 mod thumb_base;
 mod uefi_msvc_base;
 mod vxworks_base;
-mod wasm32_base;
+mod wasm_base;
 mod windows_gnu_base;
 mod windows_msvc_base;
 mod windows_uwp_gnu_base;
@@ -842,6 +842,7 @@ supported_targets! {
     ("wasm32-unknown-emscripten", wasm32_unknown_emscripten),
     ("wasm32-unknown-unknown", wasm32_unknown_unknown),
     ("wasm32-wasi", wasm32_wasi),
+    ("wasm64-unknown-unknown", wasm64_unknown_unknown),
 
     ("thumbv6m-none-eabi", thumbv6m_none_eabi),
     ("thumbv7m-none-eabi", thumbv7m_none_eabi),
@@ -1076,6 +1077,8 @@ pub struct TargetOptions {
     pub is_like_emscripten: bool,
     /// Whether the target toolchain is like Fuchsia's.
     pub is_like_fuchsia: bool,
+    /// Whether a target toolchain is like WASM.
+    pub is_like_wasm: bool,
     /// Version of DWARF to use if not using the default.
     /// Useful because some platforms (osx, bsd) only want up to DWARF2.
     pub dwarf_version: Option<u32>,
@@ -1295,6 +1298,7 @@ impl Default for TargetOptions {
             is_like_emscripten: false,
             is_like_msvc: false,
             is_like_fuchsia: false,
+            is_like_wasm: false,
             dwarf_version: None,
             linker_is_gnu: false,
             allows_weak_linkage: true,
@@ -1789,6 +1793,7 @@ impl Target {
         key!(is_like_msvc, bool);
         key!(is_like_emscripten, bool);
         key!(is_like_fuchsia, bool);
+        key!(is_like_wasm, bool);
         key!(dwarf_version, Option<u32>);
         key!(linker_is_gnu, bool);
         key!(allows_weak_linkage, bool);
@@ -2027,6 +2032,7 @@ impl ToJson for Target {
         target_option_val!(is_like_msvc);
         target_option_val!(is_like_emscripten);
         target_option_val!(is_like_fuchsia);
+        target_option_val!(is_like_wasm);
         target_option_val!(dwarf_version);
         target_option_val!(linker_is_gnu);
         target_option_val!(allows_weak_linkage);

compiler/rustc_target/src/spec/tests/tests_impl.rs

@@ -50,6 +50,7 @@ impl Target {
     // and you certainly want "unknown" for the OS name.
     fn can_use_os_unknown(&self) -> bool {
         self.llvm_target == "wasm32-unknown-unknown"
+            || self.llvm_target == "wasm64-unknown-unknown"
             || (self.env == "sgx" && self.vendor == "fortanix")
     }
 }

compiler/rustc_target/src/spec/wasm32_unknown_emscripten.rs

@@ -1,8 +1,8 @@
-use super::wasm32_base;
+use super::wasm_base;
 use super::{LinkArgs, LinkerFlavor, PanicStrategy, Target, TargetOptions};
 
 pub fn target() -> Target {
-    let mut options = wasm32_base::options();
+    let mut options = wasm_base::options();
 
     let clang_args = options.pre_link_args.entry(LinkerFlavor::Gcc).or_default();
 

compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs

@@ -10,11 +10,11 @@
 //! This target is more or less managed by the Rust and WebAssembly Working
 //! Group nowadays at <https://github.com/rustwasm>.
 
-use super::wasm32_base;
+use super::wasm_base;
 use super::{LinkerFlavor, LldFlavor, Target};
 
 pub fn target() -> Target {
-    let mut options = wasm32_base::options();
+    let mut options = wasm_base::options();
     options.os = "unknown".to_string();
     options.linker_flavor = LinkerFlavor::Lld(LldFlavor::Wasm);
     let clang_args = options.pre_link_args.entry(LinkerFlavor::Gcc).or_default();

compiler/rustc_target/src/spec/wasm32_wasi.rs

@@ -72,11 +72,11 @@
 //! best we can with this target. Don't start relying on too much here unless
 //! you know what you're getting in to!
 
-use super::wasm32_base;
+use super::wasm_base;
 use super::{crt_objects, LinkerFlavor, LldFlavor, Target};
 
 pub fn target() -> Target {
-    let mut options = wasm32_base::options();
+    let mut options = wasm_base::options();
 
     options.os = "wasi".to_string();
     options.linker_flavor = LinkerFlavor::Lld(LldFlavor::Wasm);

compiler/rustc_target/src/spec/wasm64_unknown_unknown.rs

@@ -0,0 +1,39 @@
+//! A "bare wasm" target representing a WebAssembly output that makes zero
+//! assumptions about its environment.
+//!
+//! The `wasm64-unknown-unknown` target is intended to encapsulate use cases
+//! that do not rely on any imported functionality. The binaries generated are
+//! entirely self-contained by default when using the standard library. Although
+//! the standard library is available, most of it returns an error immediately
+//! (e.g. trying to create a TCP stream or something like that).
+
+use super::wasm_base;
+use super::{LinkerFlavor, LldFlavor, Target};
+
+pub fn target() -> Target {
+    let mut options = wasm_base::options();
+    options.os = "unknown".to_string();
+    options.linker_flavor = LinkerFlavor::Lld(LldFlavor::Wasm);
+    let clang_args = options.pre_link_args.get_mut(&LinkerFlavor::Gcc).unwrap();
+
+    // Make sure clang uses LLD as its linker and is configured appropriately
+    // otherwise
+    clang_args.push("--target=wasm64-unknown-unknown".to_string());
+
+    // For now this target just never has an entry symbol no matter the output
+    // type, so unconditionally pass this.
+    clang_args.push("-Wl,--no-entry".to_string());
+    options
+        .pre_link_args
+        .get_mut(&LinkerFlavor::Lld(LldFlavor::Wasm))
+        .unwrap()
+        .push("--no-entry".to_string());
+
+    Target {
+        llvm_target: "wasm64-unknown-unknown".to_string(),
+        pointer_width: 64,
+        data_layout: "e-m:e-p:64:64-i64:64-n32:64-S128".to_string(),
+        arch: "wasm64".to_string(),
+        options,
+    }
+}

compiler/rustc_target/src/spec/wasm_base.rs

@@ -60,6 +60,8 @@ pub fn options() -> TargetOptions {
     pre_link_args.insert(LinkerFlavor::Gcc, clang_args);
 
     TargetOptions {
+        is_like_wasm: true,
+
         // we allow dynamic linking, but only cdylibs. Basically we allow a
         // final library artifact that exports some symbols (a wasm module) but
         // we don't allow intermediate `dylib` crate types

src/doc/rustc/src/platform-support.md

@@ -216,6 +216,7 @@ target | std | host | notes
 `thumbv7a-uwp-windows-msvc` | ✓ |  |
 `thumbv7neon-unknown-linux-musleabihf` | ? |  | Thumb2-mode ARMv7a Linux with NEON, MUSL
 `thumbv4t-none-eabi` | * |  | ARMv4T T32
+`wasm64-unknown-unknown` | * |  | WebAssembly
 `x86_64-apple-ios-macabi` | ✓ |  | Apple Catalyst on x86_64
 `x86_64-apple-tvos` | * | | x86 64-bit tvOS
 `x86_64-unknown-none-linuxkernel` | * |  | Linux kernel modules

src/librustdoc/clean/cfg.rs

@@ -487,6 +487,7 @@ impl<'a> fmt::Display for Display<'a> {
                         "windows" => "Windows",
                         _ => "",
                     },
+                    (sym::wasm, None) => "WebAssembly",
                     (sym::target_arch, Some(arch)) => match &*arch.as_str() {
                         "aarch64" => "AArch64",
                         "arm" => "ARM",
@@ -498,7 +499,7 @@ impl<'a> fmt::Display for Display<'a> {
                         "powerpc64" => "PowerPC-64",
                         "s390x" => "s390x",
                         "sparc64" => "SPARC64",
-                        "wasm32" => "WebAssembly",
+                        "wasm32" | "wasm64" => "WebAssembly",
                         "x86" => "x86",
                         "x86_64" => "x86-64",
                         _ => "",