Rollup of 10 pull requests

.gitignore

@@ -83,6 +83,7 @@ __pycache__/
 node_modules
 package-lock.json
 package.json
+/src/doc/rustc-dev-guide/mermaid.min.js
 
 ## Rustdoc GUI tests
 tests/rustdoc-gui/src/**.lock

Cargo.lock

@@ -3537,6 +3537,7 @@ dependencies = [
  "ar_archive_writer",
  "arrayvec",
  "bitflags",
+ "bstr",
  "cc",
  "either",
  "itertools",

compiler/rustc_codegen_ssa/Cargo.toml

@@ -8,6 +8,7 @@ edition = "2021"
 ar_archive_writer = "0.4.2"
 arrayvec = { version = "0.7", default-features = false }
 bitflags = "2.4.1"
+bstr = "1.11.3"
 # Pinned so `cargo update` bumps don't cause breakage. Please also update the
 # `cc` in `rustc_llvm` if you update the `cc` here.
 cc = "=1.2.7"

compiler/rustc_codegen_ssa/src/back/command.rs

@@ -13,6 +13,7 @@ pub(crate) struct Command {
     args: Vec<OsString>,
     env: Vec<(OsString, OsString)>,
     env_remove: Vec<OsString>,
+    env_clear: bool,
 }
 
 #[derive(Clone)]
@@ -36,7 +37,13 @@ impl Command {
     }
 
     fn _new(program: Program) -> Command {
-        Command { program, args: Vec::new(), env: Vec::new(), env_remove: Vec::new() }
+        Command {
+            program,
+            args: Vec::new(),
+            env: Vec::new(),
+            env_remove: Vec::new(),
+            env_clear: false,
+        }
     }
 
     pub(crate) fn arg<P: AsRef<OsStr>>(&mut self, arg: P) -> &mut Command {
@@ -79,6 +86,11 @@ impl Command {
         self
     }
 
+    pub(crate) fn env_clear(&mut self) -> &mut Command {
+        self.env_clear = true;
+        self
+    }
+
     fn _env_remove(&mut self, key: &OsStr) {
         self.env_remove.push(key.to_owned());
     }
@@ -106,6 +118,9 @@ impl Command {
         for k in &self.env_remove {
             ret.env_remove(k);
         }
+        if self.env_clear {
+            ret.env_clear();
+        }
         ret
     }
 

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -991,6 +991,7 @@ fn link_natively(
                     command: cmd,
                     escaped_output,
                     verbose: sess.opts.verbose,
+                    sysroot_dir: sess.sysroot.clone(),
                 };
                 sess.dcx().emit_err(err);
                 // If MSVC's `link.exe` was expected but the return code

compiler/rustc_codegen_ssa/src/errors.rs

@@ -351,6 +351,7 @@ pub(crate) struct LinkingFailed<'a> {
     pub command: Command,
     pub escaped_output: String,
     pub verbose: bool,
+    pub sysroot_dir: PathBuf,
 }
 
 impl<G: EmissionGuarantee> Diagnostic<'_, G> for LinkingFailed<'_> {
@@ -364,6 +365,8 @@ impl<G: EmissionGuarantee> Diagnostic<'_, G> for LinkingFailed<'_> {
         if self.verbose {
             diag.note(format!("{:?}", self.command));
         } else {
+            self.command.env_clear();
+
             enum ArgGroup {
                 Regular(OsString),
                 Objects(usize),
@@ -398,26 +401,55 @@ impl<G: EmissionGuarantee> Diagnostic<'_, G> for LinkingFailed<'_> {
                     args.push(ArgGroup::Regular(arg));
                 }
             }
-            self.command.args(args.into_iter().map(|arg_group| match arg_group {
-                ArgGroup::Regular(arg) => arg,
-                ArgGroup::Objects(n) => OsString::from(format!("<{n} object files omitted>")),
-                ArgGroup::Rlibs(dir, rlibs) => {
-                    let mut arg = dir.into_os_string();
-                    arg.push("/{");
-                    let mut first = true;
-                    for rlib in rlibs {
-                        if !first {
-                            arg.push(",");
+            let crate_hash = regex::bytes::Regex::new(r"-[0-9a-f]+\.rlib$").unwrap();
+            self.command.args(args.into_iter().map(|arg_group| {
+                match arg_group {
+                    // SAFETY: we are only matching on ASCII, not any surrogate pairs, so any replacements we do will still be valid.
+                    ArgGroup::Regular(arg) => unsafe {
+                        use bstr::ByteSlice;
+                        OsString::from_encoded_bytes_unchecked(
+                            arg.as_encoded_bytes().replace(
+                                self.sysroot_dir.as_os_str().as_encoded_bytes(),
+                                b"<sysroot>",
+                            ),
+                        )
+                    },
+                    ArgGroup::Objects(n) => OsString::from(format!("<{n} object files omitted>")),
+                    ArgGroup::Rlibs(mut dir, rlibs) => {
+                        let is_sysroot_dir = match dir.strip_prefix(&self.sysroot_dir) {
+                            Ok(short) => {
+                                dir = Path::new("<sysroot>").join(short);
+                                true
+                            }
+                            Err(_) => false,
+                        };
+                        let mut arg = dir.into_os_string();
+                        arg.push("/{");
+                        let mut first = true;
+                        for mut rlib in rlibs {
+                            if !first {
+                                arg.push(",");
+                            }
+                            first = false;
+                            if is_sysroot_dir {
+                                // SAFETY: Regex works one byte at a type, and our regex will not match surrogate pairs (because it only matches ascii).
+                                rlib = unsafe {
+                                    OsString::from_encoded_bytes_unchecked(
+                                        crate_hash
+                                            .replace(rlib.as_encoded_bytes(), b"-*")
+                                            .into_owned(),
+                                    )
+                                };
+                            }
+                            arg.push(rlib);
                         }
-                        first = false;
-                        arg.push(rlib);
+                        arg.push("}.rlib");
+                        arg
                     }
-                    arg.push("}");
-                    arg
                 }
             }));
 
-            diag.note(format!("{:?}", self.command));
+            diag.note(format!("{:?}", self.command).trim_start_matches("env -i").to_owned());
             diag.note("some arguments are omitted. use `--verbose` to show all linker arguments");
         }
 

compiler/rustc_codegen_ssa/src/mir/naked_asm.rs

@@ -1,10 +1,14 @@
+use rustc_abi::{BackendRepr, Float, Integer, Primitive, RegKind};
 use rustc_attr_parsing::InstructionSetAttr;
+use rustc_hir::def_id::DefId;
 use rustc_middle::mir::mono::{Linkage, MonoItem, MonoItemData, Visibility};
 use rustc_middle::mir::{Body, InlineAsmOperand};
-use rustc_middle::ty::layout::{HasTyCtxt, HasTypingEnv, LayoutOf};
-use rustc_middle::ty::{Instance, TyCtxt};
-use rustc_middle::{bug, ty};
+use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, HasTypingEnv, LayoutOf};
+use rustc_middle::ty::{Instance, Ty, TyCtxt};
+use rustc_middle::{bug, span_bug, ty};
 use rustc_span::sym;
+use rustc_target::callconv::{ArgAbi, FnAbi, PassMode};
+use rustc_target::spec::WasmCAbi;
 
 use crate::common;
 use crate::traits::{AsmCodegenMethods, BuilderMethods, GlobalAsmOperandRef, MiscCodegenMethods};
@@ -32,7 +36,8 @@ pub(crate) fn codegen_naked_asm<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 
     let item_data = cx.codegen_unit().items().get(&MonoItem::Fn(instance)).unwrap();
     let name = cx.mangled_name(instance);
-    let (begin, end) = prefix_and_suffix(cx.tcx(), instance, &name, item_data);
+    let fn_abi = cx.fn_abi_of_instance(instance, ty::List::empty());
+    let (begin, end) = prefix_and_suffix(cx.tcx(), instance, &name, item_data, fn_abi);
 
     let mut template_vec = Vec::new();
     template_vec.push(rustc_ast::ast::InlineAsmTemplatePiece::String(begin.into()));
@@ -103,6 +108,7 @@ enum AsmBinaryFormat {
     Elf,
     Macho,
     Coff,
+    Wasm,
 }
 
 impl AsmBinaryFormat {
@@ -111,6 +117,8 @@ impl AsmBinaryFormat {
             Self::Coff
         } else if target.is_like_osx {
             Self::Macho
+        } else if target.is_like_wasm {
+            Self::Wasm
         } else {
             Self::Elf
         }
@@ -122,6 +130,7 @@ fn prefix_and_suffix<'tcx>(
     instance: Instance<'tcx>,
     asm_name: &str,
     item_data: &MonoItemData,
+    fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
 ) -> (String, String) {
     use std::fmt::Write;
 
@@ -169,7 +178,7 @@ fn prefix_and_suffix<'tcx>(
             }
             Linkage::LinkOnceAny | Linkage::LinkOnceODR | Linkage::WeakAny | Linkage::WeakODR => {
                 match asm_binary_format {
-                    AsmBinaryFormat::Elf | AsmBinaryFormat::Coff => {
+                    AsmBinaryFormat::Elf | AsmBinaryFormat::Coff | AsmBinaryFormat::Wasm => {
                         writeln!(w, ".weak {asm_name}")?;
                     }
                     AsmBinaryFormat::Macho => {
@@ -264,7 +273,161 @@ fn prefix_and_suffix<'tcx>(
                 writeln!(end, "{}", arch_suffix).unwrap();
             }
         }
+        AsmBinaryFormat::Wasm => {
+            let section = link_section.unwrap_or(format!(".text.{asm_name}"));
+
+            writeln!(begin, ".section {section},\"\",@").unwrap();
+            // wasm functions cannot be aligned, so skip
+            write_linkage(&mut begin).unwrap();
+            if let Visibility::Hidden = item_data.visibility {
+                writeln!(begin, ".hidden {asm_name}").unwrap();
+            }
+            writeln!(begin, ".type {asm_name}, @function").unwrap();
+            if !arch_prefix.is_empty() {
+                writeln!(begin, "{}", arch_prefix).unwrap();
+            }
+            writeln!(begin, "{asm_name}:").unwrap();
+            writeln!(
+                begin,
+                ".functype {asm_name} {}",
+                wasm_functype(tcx, fn_abi, instance.def_id())
+            )
+            .unwrap();
+
+            writeln!(end).unwrap();
+            // .size is ignored for function symbols, so we can skip it
+            writeln!(end, "end_function").unwrap();
+        }
     }
 
     (begin, end)
 }
+
+/// The webassembly type signature for the given function.
+///
+/// Used by the `.functype` directive on wasm targets.
+fn wasm_functype<'tcx>(tcx: TyCtxt<'tcx>, fn_abi: &FnAbi<'tcx, Ty<'tcx>>, def_id: DefId) -> String {
+    let mut signature = String::with_capacity(64);
+
+    let ptr_type = match tcx.data_layout.pointer_size.bits() {
+        32 => "i32",
+        64 => "i64",
+        other => bug!("wasm pointer size cannot be {other} bits"),
+    };
+
+    // FIXME: remove this once the wasm32-unknown-unknown ABI is fixed
+    // please also add `wasm32-unknown-unknown` back in `tests/assembly/wasm32-naked-fn.rs`
+    // basically the commit introducing this comment should be reverted
+    if let PassMode::Pair { .. } = fn_abi.ret.mode {
+        let _ = WasmCAbi::Legacy;
+        span_bug!(
+            tcx.def_span(def_id),
+            "cannot return a pair (the wasm32-unknown-unknown ABI is broken, see https://github.com/rust-lang/rust/issues/115666"
+        );
+    }
+
+    let hidden_return = matches!(fn_abi.ret.mode, PassMode::Indirect { .. });
+
+    signature.push('(');
+
+    if hidden_return {
+        signature.push_str(ptr_type);
+        if !fn_abi.args.is_empty() {
+            signature.push_str(", ");
+        }
+    }
+
+    let mut it = fn_abi.args.iter().peekable();
+    while let Some(arg_abi) = it.next() {
+        wasm_type(tcx, &mut signature, arg_abi, ptr_type, def_id);
+        if it.peek().is_some() {
+            signature.push_str(", ");
+        }
+    }
+
+    signature.push_str(") -> (");
+
+    if !hidden_return {
+        wasm_type(tcx, &mut signature, &fn_abi.ret, ptr_type, def_id);
+    }
+
+    signature.push(')');
+
+    signature
+}
+
+fn wasm_type<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    signature: &mut String,
+    arg_abi: &ArgAbi<'_, Ty<'tcx>>,
+    ptr_type: &'static str,
+    def_id: DefId,
+) {
+    match arg_abi.mode {
+        PassMode::Ignore => { /* do nothing */ }
+        PassMode::Direct(_) => {
+            let direct_type = match arg_abi.layout.backend_repr {
+                BackendRepr::Scalar(scalar) => wasm_primitive(scalar.primitive(), ptr_type),
+                BackendRepr::Vector { .. } => "v128",
+                BackendRepr::Memory { .. } => {
+                    // FIXME: remove this branch once the wasm32-unknown-unknown ABI is fixed
+                    let _ = WasmCAbi::Legacy;
+                    span_bug!(
+                        tcx.def_span(def_id),
+                        "cannot use memory args (the wasm32-unknown-unknown ABI is broken, see https://github.com/rust-lang/rust/issues/115666"
+                    );
+                }
+                other => unreachable!("unexpected BackendRepr: {:?}", other),
+            };
+
+            signature.push_str(direct_type);
+        }
+        PassMode::Pair(_, _) => match arg_abi.layout.backend_repr {
+            BackendRepr::ScalarPair(a, b) => {
+                signature.push_str(wasm_primitive(a.primitive(), ptr_type));
+                signature.push_str(", ");
+                signature.push_str(wasm_primitive(b.primitive(), ptr_type));
+            }
+            other => unreachable!("{other:?}"),
+        },
+        PassMode::Cast { pad_i32, ref cast } => {
+            // For wasm, Cast is used for single-field primitive wrappers like `struct Wrapper(i64);`
+            assert!(!pad_i32, "not currently used by wasm calling convention");
+            assert!(cast.prefix[0].is_none(), "no prefix");
+            assert_eq!(cast.rest.total, arg_abi.layout.size, "single item");
+
+            let wrapped_wasm_type = match cast.rest.unit.kind {
+                RegKind::Integer => match cast.rest.unit.size.bytes() {
+                    ..=4 => "i32",
+                    ..=8 => "i64",
+                    _ => ptr_type,
+                },
+                RegKind::Float => match cast.rest.unit.size.bytes() {
+                    ..=4 => "f32",
+                    ..=8 => "f64",
+                    _ => ptr_type,
+                },
+                RegKind::Vector => "v128",
+            };
+
+            signature.push_str(wrapped_wasm_type);
+        }
+        PassMode::Indirect { .. } => signature.push_str(ptr_type),
+    }
+}
+
+fn wasm_primitive(primitive: Primitive, ptr_type: &'static str) -> &'static str {
+    match primitive {
+        Primitive::Int(integer, _) => match integer {
+            Integer::I8 | Integer::I16 | Integer::I32 => "i32",
+            Integer::I64 => "i64",
+            Integer::I128 => "i64, i64",
+        },
+        Primitive::Float(float) => match float {
+            Float::F16 | Float::F32 => "f32",
+            Float::F64 => "f64",
+            Float::F128 => "i64, i64",
+        },
+        Primitive::Pointer(_) => ptr_type,
+    }
+}