Auto merge of #90382 - alexcrichton:wasm64-libstd, r=joshtriplett

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.

Author: bors

Cargo.lock

@@ -678,9 +678,9 @@ dependencies = [
 
 [[package]]
 name = "compiler_builtins"
-version = "0.1.49"
+version = "0.1.52"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "20b1438ef42c655665a8ab2c1c6d605a305f031d38d9be689ddfef41a20f3aa2"
+checksum = "b6591c2442ee984e2b264638a8b5e7ae44fd47b32d28e3a08e2e9c3cdb0c2fb0"
 dependencies = [
  "cc",
  "rustc-std-workspace-core",
@@ -1028,9 +1028,9 @@ dependencies = [
 
 [[package]]
 name = "dlmalloc"
-version = "0.2.1"
+version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "332570860c2edf2d57914987bf9e24835425f75825086b6ba7d1e6a3e4f1f254"
+checksum = "a6fe28e0bf9357092740362502f5cc7955d8dc125ebda71dec72336c2e15c62e"
 dependencies = [
  "compiler_builtins",
  "libc",

compiler/rustc_codegen_llvm/src/asm.rs

@@ -320,7 +320,7 @@ impl AsmBuilderMethods<'tcx> for Builder<'a, 'll, 'tcx> {
                 InlineAsmArch::Mips | InlineAsmArch::Mips64 => {}
                 InlineAsmArch::S390x => {}
                 InlineAsmArch::SpirV => {}
-                InlineAsmArch::Wasm32 => {}
+                InlineAsmArch::Wasm32 | InlineAsmArch::Wasm64 => {}
                 InlineAsmArch::Bpf => {}
             }
         }

compiler/rustc_codegen_llvm/src/builder.rs

@@ -769,7 +769,7 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         // we like. To ensure that LLVM picks the right instruction we choose
         // the raw wasm intrinsic functions which avoid LLVM inserting all the
         // other control flow automatically.
-        if self.sess().target.arch == "wasm32" {
+        if self.sess().target.is_like_wasm {
             let src_ty = self.cx.val_ty(val);
             if self.cx.type_kind(src_ty) != TypeKind::Vector {
                 let float_width = self.cx.float_width(src_ty);
@@ -791,7 +791,7 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
     fn fptosi(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
         // see `fptoui` above for why wasm is different here
-        if self.sess().target.arch == "wasm32" {
+        if self.sess().target.is_like_wasm {
             let src_ty = self.cx.val_ty(val);
             if self.cx.type_kind(src_ty) != TypeKind::Vector {
                 let float_width = self.cx.float_width(src_ty);

compiler/rustc_codegen_llvm/src/consts.rs

@@ -490,7 +490,7 @@ impl StaticMethods for CodegenCx<'ll, 'tcx> {
 
             // Wasm statics with custom link sections get special treatment as they
             // go into custom sections of the wasm executable.
-            if self.tcx.sess.opts.target_triple.triple().starts_with("wasm32") {
+            if self.tcx.sess.target.is_like_wasm {
                 if let Some(section) = attrs.link_section {
                     let section = llvm::LLVMMDStringInContext(
                         self.llcx,

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -75,7 +75,9 @@ unsafe fn configure_llvm(sess: &Session) {
         if sess.print_llvm_passes() {
             add("-debug-pass=Structure", false);
         }
-        if !sess.opts.debugging_opts.no_generate_arange_section {
+        if sess.target.generate_arange_section
+            && !sess.opts.debugging_opts.no_generate_arange_section
+        {
             add("-generate-arange-section", false);
         }
 

compiler/rustc_target/src/asm/mod.rs

@@ -189,6 +189,7 @@ pub enum InlineAsmArch {
     S390x,
     SpirV,
     Wasm32,
+    Wasm64,
     Bpf,
 }
 
@@ -212,6 +213,7 @@ impl FromStr for InlineAsmArch {
             "s390x" => Ok(Self::S390x),
             "spirv" => Ok(Self::SpirV),
             "wasm32" => Ok(Self::Wasm32),
+            "wasm64" => Ok(Self::Wasm64),
             "bpf" => Ok(Self::Bpf),
             _ => Err(()),
         }
@@ -318,7 +320,7 @@ impl InlineAsmReg {
             InlineAsmArch::SpirV => {
                 Self::SpirV(SpirVInlineAsmReg::parse(arch, has_feature, target, &name)?)
             }
-            InlineAsmArch::Wasm32 => {
+            InlineAsmArch::Wasm32 | InlineAsmArch::Wasm64 => {
                 Self::Wasm(WasmInlineAsmReg::parse(arch, has_feature, target, &name)?)
             }
             InlineAsmArch::Bpf => {
@@ -529,7 +531,9 @@ impl InlineAsmRegClass {
             }
             InlineAsmArch::S390x => Self::S390x(S390xInlineAsmRegClass::parse(arch, name)?),
             InlineAsmArch::SpirV => Self::SpirV(SpirVInlineAsmRegClass::parse(arch, name)?),
-            InlineAsmArch::Wasm32 => Self::Wasm(WasmInlineAsmRegClass::parse(arch, name)?),
+            InlineAsmArch::Wasm32 | InlineAsmArch::Wasm64 => {
+                Self::Wasm(WasmInlineAsmRegClass::parse(arch, name)?)
+            }
             InlineAsmArch::Bpf => Self::Bpf(BpfInlineAsmRegClass::parse(arch, name)?),
         })
     }
@@ -725,7 +729,7 @@ pub fn allocatable_registers(
             spirv::fill_reg_map(arch, has_feature, target, &mut map);
             map
         }
-        InlineAsmArch::Wasm32 => {
+        InlineAsmArch::Wasm32 | InlineAsmArch::Wasm64 => {
             let mut map = wasm::regclass_map();
             wasm::fill_reg_map(arch, has_feature, target, &mut map);
             map

compiler/rustc_target/src/spec/mod.rs

@@ -1357,6 +1357,9 @@ pub struct TargetOptions {
 
     /// Minimum number of bits in #[repr(C)] enum. Defaults to 32.
     pub c_enum_min_bits: u64,
+
+    /// Whether or not the DWARF `.debug_aranges` section should be generated.
+    pub generate_arange_section: bool,
 }
 
 impl Default for TargetOptions {
@@ -1462,6 +1465,7 @@ impl Default for TargetOptions {
             supported_sanitizers: SanitizerSet::empty(),
             default_adjusted_cabi: None,
             c_enum_min_bits: 32,
+            generate_arange_section: true,
         }
     }
 }
@@ -2047,6 +2051,7 @@ impl Target {
         key!(supported_sanitizers, SanitizerSet)?;
         key!(default_adjusted_cabi, Option<Abi>)?;
         key!(c_enum_min_bits, u64);
+        key!(generate_arange_section, bool);
 
         if base.is_builtin {
             // This can cause unfortunate ICEs later down the line.
@@ -2286,6 +2291,7 @@ impl ToJson for Target {
         target_option_val!(split_debuginfo);
         target_option_val!(supported_sanitizers);
         target_option_val!(c_enum_min_bits);
+        target_option_val!(generate_arange_section);
 
         if let Some(abi) = self.default_adjusted_cabi {
             d.insert("default-adjusted-cabi".to_string(), Abi::name(abi).to_json());

compiler/rustc_target/src/spec/wasm32_unknown_emscripten.rs

@@ -37,7 +37,7 @@ pub fn target() -> Target {
         is_like_emscripten: true,
         panic_strategy: PanicStrategy::Unwind,
         post_link_args,
-        families: vec!["unix".to_string()],
+        families: vec!["unix".to_string(), "wasm".to_string()],
         ..options
     };
     Target {

compiler/rustc_target/src/spec/wasm64_unknown_unknown.rs

@@ -23,11 +23,15 @@ 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());
+
+    // Any engine that implements wasm64 will surely implement the rest of these
+    // features since they were all merged into the official spec by the time
+    // wasm64 was designed.
+    options.features = "+bulk-memory,+mutable-globals,+sign-ext,+nontrapping-fptoint".to_string();
 
     Target {
         llvm_target: "wasm64-unknown-unknown".to_string(),

compiler/rustc_target/src/spec/wasm_base.rs

@@ -128,6 +128,12 @@ pub fn options() -> TargetOptions {
         // gdb scripts don't work on wasm blobs
         emit_debug_gdb_scripts: false,
 
+        // There's more discussion of this at
+        // https://bugs.llvm.org/show_bug.cgi?id=52442 but the general result is
+        // that this isn't useful for wasm and has tricky issues with
+        // representation, so this is disabled.
+        generate_arange_section: false,
+
         ..Default::default()
     }
 }