std: Get the standard library compiling for wasm64

This commit goes through and updates various `#[cfg]` as appropriate to
get the wasm64-unknown-unknown target behaving similarly to the
wasm32-unknown-unknown target. Most of this is just updating various
conditions for `target_arch = "wasm32"` to also account for `target_arch
= "wasm64"` where appropriate. This commit also lists `wasm64` as an
allow-listed architecture to not have the `restricted_std` feature
enabled, enabling experimentation with `-Z build-std` externally.

The main goal of this commit is to enable playing around with
`wasm64-unknown-unknown` externally via `-Z build-std` in a way that's
similar to the `wasm32-unknown-unknown` target. These targets are
effectively the same and only differ in their pointer size, but wasm64
is much newer and has much less ecosystem/library support so it'll still
take time to get wasm64 fully-fledged.

13 files changed, 41 insertions, 22 deletions

diff --git a/compiler/rustc_target/src/spec/wasm64_unknown_unknown.rs b/compiler/rustc_target/src/spec/wasm64_unknown_unknown.rs
index fb6526c0e72..7eacbb43640 100644
--- a/compiler/rustc_target/src/spec/wasm64_unknown_unknown.rs
+++ b/compiler/rustc_target/src/spec/wasm64_unknown_unknown.rs
@@ -23,11 +23,10 @@ pub fn target() -> Target {
     // 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());
+
+    let lld_args = options.pre_link_args.get_mut(&LinkerFlavor::Lld(LldFlavor::Wasm)).unwrap();
+    lld_args.push("--no-entry".to_string());
+    lld_args.push("-mwasm64".to_string());
 
     Target {
         llvm_target: "wasm64-unknown-unknown".to_string(),
diff --git a/library/core/src/ffi.rs b/library/core/src/ffi.rs
index b208ddd4b27..ea3de680afe 100644
--- a/library/core/src/ffi.rs
+++ b/library/core/src/ffi.rs
@@ -63,6 +63,7 @@ impl fmt::Debug for c_void {
     all(not(target_arch = "aarch64"), not(target_arch = "powerpc"), not(target_arch = "x86_64")),
     all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")),
     target_arch = "wasm32",
+    target_arch = "wasm64",
     target_arch = "asmjs",
     windows
 ))]
@@ -86,6 +87,7 @@ pub struct VaListImpl<'f> {
     all(not(target_arch = "aarch64"), not(target_arch = "powerpc"), not(target_arch = "x86_64")),
     all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")),
     target_arch = "wasm32",
+    target_arch = "wasm64",
     target_arch = "asmjs",
     windows
 ))]
@@ -186,6 +188,7 @@ pub struct VaList<'a, 'f: 'a> {
         ),
         all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")),
         target_arch = "wasm32",
+        target_arch = "wasm64",
         target_arch = "asmjs",
         windows
     ))]
@@ -195,6 +198,7 @@ pub struct VaList<'a, 'f: 'a> {
         any(target_arch = "aarch64", target_arch = "powerpc", target_arch = "x86_64"),
         any(not(target_arch = "aarch64"), not(any(target_os = "macos", target_os = "ios"))),
         not(target_arch = "wasm32"),
+        not(target_arch = "wasm64"),
         not(target_arch = "asmjs"),
         not(windows)
     ))]
@@ -207,6 +211,7 @@ pub struct VaList<'a, 'f: 'a> {
     all(not(target_arch = "aarch64"), not(target_arch = "powerpc"), not(target_arch = "x86_64")),
     all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")),
     target_arch = "wasm32",
+    target_arch = "wasm64",
     target_arch = "asmjs",
     windows
 ))]
@@ -228,6 +233,7 @@ impl<'f> VaListImpl<'f> {
     any(target_arch = "aarch64", target_arch = "powerpc", target_arch = "x86_64"),
     any(not(target_arch = "aarch64"), not(any(target_os = "macos", target_os = "ios"))),
     not(target_arch = "wasm32"),
+    not(target_arch = "wasm64"),
     not(target_arch = "asmjs"),
     not(windows)
 ))]
diff --git a/library/panic_abort/src/lib.rs b/library/panic_abort/src/lib.rs
index ac75ce7f221..d31df0da364 100644
--- a/library/panic_abort/src/lib.rs
+++ b/library/panic_abort/src/lib.rs
@@ -117,7 +117,8 @@ pub unsafe extern "C-unwind" fn __rust_start_panic(_payload: *mut &mut dyn BoxMe
 pub mod personalities {
     #[rustc_std_internal_symbol]
     #[cfg(not(any(
-        all(target_arch = "wasm32", not(target_os = "emscripten"),),
+        all(target_arch = "wasm32", not(target_os = "emscripten")),
+        all(target_arch = "wasm64", not(target_os = "emscripten")),
         all(target_os = "windows", target_env = "gnu", target_arch = "x86_64",),
     )))]
     pub extern "C" fn rust_eh_personality() {}
diff --git a/library/panic_unwind/src/dummy.rs b/library/panic_unwind/src/dummy.rs
index 4667ede2baa..a4bcd216c60 100644
--- a/library/panic_unwind/src/dummy.rs
+++ b/library/panic_unwind/src/dummy.rs
@@ -1,6 +1,6 @@
-//! Unwinding for *wasm32* target.
+//! Unwinding for unsupported target.
 //!
-//! Right now we don't support this, so this is just stubs.
+//! Stubs that simply abort for targets that don't support unwinding otherwise.
 
 use alloc::boxed::Box;
 use core::any::Any;
diff --git a/library/panic_unwind/src/lib.rs b/library/panic_unwind/src/lib.rs
index b5d0ca2572c..4815249f7d5 100644
--- a/library/panic_unwind/src/lib.rs
+++ b/library/panic_unwind/src/lib.rs
@@ -57,6 +57,7 @@ cfg_if::cfg_if! {
     } else {
         // Targets that don't support unwinding.
         // - arch=wasm32
+        // - arch=wasm64
         // - os=none ("bare metal" targets)
         // - os=uefi
         // - os=espidf
diff --git a/library/std/Cargo.toml b/library/std/Cargo.toml
index 248ecdf4bef..85658bf9e3c 100644
--- a/library/std/Cargo.toml
+++ b/library/std/Cargo.toml
@@ -35,7 +35,7 @@ features = ['read_core', 'elf', 'macho', 'pe', 'unaligned', 'archive']
 [dev-dependencies]
 rand = "0.7"
 
-[target.'cfg(any(all(target_arch = "wasm32", not(target_os = "emscripten")), all(target_vendor = "fortanix", target_env = "sgx")))'.dependencies]
+[target.'cfg(any(all(any(target_arch = "wasm32", target_arch = "wasm64"), not(target_os = "emscripten")), all(target_vendor = "fortanix", target_env = "sgx")))'.dependencies]
 dlmalloc = { version = "0.2.1", features = ['rustc-dep-of-std'] }
 
 [target.x86_64-fortanix-unknown-sgx.dependencies]
diff --git a/library/std/build.rs b/library/std/build.rs
index cc7184d57f1..43168e77296 100644
--- a/library/std/build.rs
+++ b/library/std/build.rs
@@ -25,6 +25,7 @@ fn main() {
         || target.contains("haiku")
         || target.contains("vxworks")
         || target.contains("wasm32")
+        || target.contains("wasm64")
         || target.contains("asmjs")
         || target.contains("espidf")
         || target.contains("solid")
diff --git a/library/std/src/sys/common/alloc.rs b/library/std/src/sys/common/alloc.rs
index 576667c0173..9665d1fa892 100644
--- a/library/std/src/sys/common/alloc.rs
+++ b/library/std/src/sys/common/alloc.rs
@@ -24,7 +24,8 @@ pub const MIN_ALIGN: usize = 8;
     target_arch = "mips64",
     target_arch = "s390x",
     target_arch = "sparc64",
-    target_arch = "riscv64"
+    target_arch = "riscv64",
+    target_arch = "wasm64",
 )))]
 pub const MIN_ALIGN: usize = 16;
 
diff --git a/library/std/src/sys/mod.rs b/library/std/src/sys/mod.rs
index 8b8be6ebc2f..38f45fef918 100644
--- a/library/std/src/sys/mod.rs
+++ b/library/std/src/sys/mod.rs
@@ -40,7 +40,7 @@ cfg_if::cfg_if! {
     } else if #[cfg(target_os = "wasi")] {
         mod wasi;
         pub use self::wasi::*;
-    } else if #[cfg(target_arch = "wasm32")] {
+    } else if #[cfg(any(target_arch = "wasm32", target_arch = "wasm64"))] {
         mod wasm;
         pub use self::wasm::*;
     } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
diff --git a/library/std/src/sys/wasm/alloc.rs b/library/std/src/sys/wasm/alloc.rs
index ef0ca3dd478..bf5dc0273c0 100644
--- a/library/std/src/sys/wasm/alloc.rs
+++ b/library/std/src/sys/wasm/alloc.rs
@@ -1,8 +1,8 @@
-//! This is an implementation of a global allocator on the wasm32 platform when
+//! This is an implementation of a global allocator on the wasm platform when
 //! emscripten is not in use. In that situation there's no actual runtime for us
 //! to lean on for allocation, so instead we provide our own!
 //!
-//! The wasm32 instruction set has two instructions for getting the current
+//! The wasm instruction set has two instructions for getting the current
 //! amount of memory and growing the amount of memory. These instructions are the
 //! foundation on which we're able to build an allocator, so we do so! Note that
 //! the instructions are also pretty "global" and this is the "global" allocator
diff --git a/library/std/src/sys_common/mod.rs b/library/std/src/sys_common/mod.rs
index 5a5913ebd79..0f2a8cd0012 100644
--- a/library/std/src/sys_common/mod.rs
+++ b/library/std/src/sys_common/mod.rs
@@ -41,6 +41,7 @@ cfg_if::cfg_if! {
                  target_os = "hermit",
                  feature = "restricted-std",
                  all(target_arch = "wasm32", not(target_os = "emscripten")),
+                 all(target_arch = "wasm64", not(target_os = "emscripten")),
                  all(target_vendor = "fortanix", target_env = "sgx")))] {
         pub use crate::sys::net;
     } else {
diff --git a/library/std/src/thread/local.rs b/library/std/src/thread/local.rs
index c53290ec0c7..37f9cc40be6 100644
--- a/library/std/src/thread/local.rs
+++ b/library/std/src/thread/local.rs
@@ -172,7 +172,7 @@ macro_rules! __thread_local_inner {
             //
             // FIXME(#84224) this should come after the `target_thread_local`
             // block.
-            #[cfg(all(target_arch = "wasm32", not(target_feature = "atomics")))]
+            #[cfg(all(any(target_arch = "wasm32", target_arch = "wasm64"), not(target_feature = "atomics")))]
             {
                 static mut VAL: $t = $init;
                 Some(&VAL)
@@ -181,7 +181,10 @@ macro_rules! __thread_local_inner {
             // If the platform has support for `#[thread_local]`, use it.
             #[cfg(all(
                 target_thread_local,
-                not(all(target_arch = "wasm32", not(target_feature = "atomics"))),
+                not(all(
+                    any(target_arch = "wasm32", target_arch = "wasm64"),
+                    not(target_feature = "atomics"),
+                )),
             ))]
             {
                 // If a dtor isn't needed we can do something "very raw" and
@@ -238,7 +241,10 @@ macro_rules! __thread_local_inner {
             // same implementation as below for os thread locals.
             #[cfg(all(
                 not(target_thread_local),
-                not(all(target_arch = "wasm32", not(target_feature = "atomics"))),
+                not(all(
+                    any(target_arch = "wasm32", target_arch = "wasm64"),
+                    not(target_feature = "atomics"),
+                )),
             ))]
             {
                 #[inline]
@@ -285,21 +291,21 @@ macro_rules! __thread_local_inner {
             // The issue of "should enable on Windows sometimes" is #84933
             #[cfg_attr(not(windows), inline)]
             unsafe fn __getit() -> $crate::option::Option<&'static $t> {
-                #[cfg(all(target_arch = "wasm32", not(target_feature = "atomics")))]
+                #[cfg(all(any(target_arch = "wasm32", target_arch = "wasm64"), not(target_feature = "atomics")))]
                 static __KEY: $crate::thread::__StaticLocalKeyInner<$t> =
                     $crate::thread::__StaticLocalKeyInner::new();
 
                 #[thread_local]
                 #[cfg(all(
                     target_thread_local,
-                    not(all(target_arch = "wasm32", not(target_feature = "atomics"))),
+                    not(all(any(target_arch = "wasm32", target_arch = "wasm64"), not(target_feature = "atomics"))),
                 ))]
                 static __KEY: $crate::thread::__FastLocalKeyInner<$t> =
                     $crate::thread::__FastLocalKeyInner::new();
 
                 #[cfg(all(
                     not(target_thread_local),
-                    not(all(target_arch = "wasm32", not(target_feature = "atomics"))),
+                    not(all(any(target_arch = "wasm32", target_arch = "wasm64"), not(target_feature = "atomics"))),
                 ))]
                 static __KEY: $crate::thread::__OsLocalKeyInner<$t> =
                     $crate::thread::__OsLocalKeyInner::new();
@@ -479,10 +485,10 @@ mod lazy {
     }
 }
 
-/// On some platforms like wasm32 there's no threads, so no need to generate
+/// On some platforms like wasm there's no threads, so no need to generate
 /// thread locals and we can instead just use plain statics!
 #[doc(hidden)]
-#[cfg(all(target_arch = "wasm32", not(target_feature = "atomics")))]
+#[cfg(all(any(target_arch = "wasm32", target_arch = "wasm64"), not(target_feature = "atomics")))]
 pub mod statik {
     use super::lazy::LazyKeyInner;
     use crate::fmt;
diff --git a/library/std/src/thread/mod.rs b/library/std/src/thread/mod.rs
index 2a155ce3117..41f7bf55f22 100644
--- a/library/std/src/thread/mod.rs
+++ b/library/std/src/thread/mod.rs
@@ -200,7 +200,10 @@ pub use self::local::fast::Key as __FastLocalKeyInner;
 #[doc(hidden)]
 pub use self::local::os::Key as __OsLocalKeyInner;
 #[unstable(feature = "libstd_thread_internals", issue = "none")]
-#[cfg(all(target_arch = "wasm32", not(target_feature = "atomics")))]
+#[cfg(all(
+    any(target_arch = "wasm32", target_arch = "wasm64"),
+    not(target_feature = "atomics")
+))]
 #[doc(hidden)]
 pub use self::local::statik::Key as __StaticLocalKeyInner;