Merge pull request rust-lang#4608 from rust-lang/rustup-2025-09-29

Automatic Rustup

Author: RalfJung

CONTRIBUTING.md

@@ -31,8 +31,8 @@ bootstrapping, the compiler architecture, source code representation, and more.
 
 ## [Getting help](https://rustc-dev-guide.rust-lang.org/getting-started.html#asking-questions)
 
-There are many ways you can get help when you're stuck. Rust has many platforms for this:
-[internals], [rust-zulip], and [rust-discord]. It is recommended to ask for help on
+There are many ways you can get help when you're stuck. Rust has two platforms for this:
+[internals] and [rust-zulip]. It is recommended to ask for help on
 the [rust-zulip], but any of these platforms are great ways to seek help and even
 find a mentor! You can learn more about asking questions and getting help in the
 [Asking Questions](https://rustc-dev-guide.rust-lang.org/getting-started.html#asking-questions) chapter of the [rustc-dev-guide].
@@ -47,5 +47,4 @@ refer to [this section][contributing-bug-reports] and [open an issue][issue temp
 [contributing-bug-reports]: https://rustc-dev-guide.rust-lang.org/contributing.html#bug-reports
 [issue template]: https://github.com/rust-lang/rust/issues/new/choose
 [internals]: https://internals.rust-lang.org
-[rust-discord]: http://discord.gg/rust-lang
 [rust-zulip]: https://rust-lang.zulipchat.com

Cargo.lock

@@ -334,8 +334,10 @@ dependencies = [
  "anyhow",
  "build_helper",
  "curl",
+ "hex",
  "indexmap",
  "serde",
+ "sha2",
  "toml 0.8.23",
 ]
 
@@ -5239,9 +5241,9 @@ dependencies = [
 
 [[package]]
 name = "stringdex"
-version = "0.0.1-alpha9"
+version = "0.0.1-alpha10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7081029913fd7d591c0112182aba8c98ae886b4f12edb208130496cd17dc3c15"
+checksum = "0fa846a7d509d1828a4f90962dc09810e161abcada7fc6a921e92c168d0811d7"
 dependencies = [
  "stacker",
 ]

bootstrap.example.toml

@@ -768,16 +768,15 @@
 # make this default to false.
 #rust.lld = false in all cases, except on `x86_64-unknown-linux-gnu` as described above, where it is true
 
-# Indicates whether LLD will be used to link Rust crates during bootstrap on
-# supported platforms.
+# Indicates if we should override the linker used to link Rust crates during bootstrap to be LLD.
 # If set to `true` or `"external"`, a global `lld` binary that has to be in $PATH
 # will be used.
 # If set to `"self-contained"`, rust-lld from the snapshot compiler will be used.
 #
 # On MSVC, LLD will not be used if we're cross linking.
 #
 # Explicitly setting the linker for a target will override this option when targeting MSVC.
-#rust.use-lld = false
+#rust.bootstrap-override-lld = false
 
 # Indicates whether some LLVM tools, like llvm-objdump, will be made available in the
 # sysroot.
@@ -950,7 +949,7 @@
 # Linker to be used to bootstrap Rust code. Note that the
 # default value is platform specific, and if not specified it may also depend on
 # what platform is crossing to what platform.
-# Setting this will override the `use-lld` option for Rust code when targeting MSVC.
+# Setting this will override the `bootstrap-override-lld` option for Rust code when targeting MSVC.
 #linker = "cc" (path)
 
 # Should rustc and the standard library be built with split debuginfo? Default

compiler/rustc_ast/src/expand/autodiff_attrs.rs

@@ -6,6 +6,7 @@
 use std::fmt::{self, Display, Formatter};
 use std::str::FromStr;
 
+use crate::expand::typetree::TypeTree;
 use crate::expand::{Decodable, Encodable, HashStable_Generic};
 use crate::{Ty, TyKind};
 
@@ -84,6 +85,8 @@ pub struct AutoDiffItem {
     /// The name of the function being generated
     pub target: String,
     pub attrs: AutoDiffAttrs,
+    pub inputs: Vec<TypeTree>,
+    pub output: TypeTree,
 }
 
 #[derive(Clone, Eq, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
@@ -275,14 +278,22 @@ impl AutoDiffAttrs {
         !matches!(self.mode, DiffMode::Error | DiffMode::Source)
     }
 
-    pub fn into_item(self, source: String, target: String) -> AutoDiffItem {
-        AutoDiffItem { source, target, attrs: self }
+    pub fn into_item(
+        self,
+        source: String,
+        target: String,
+        inputs: Vec<TypeTree>,
+        output: TypeTree,
+    ) -> AutoDiffItem {
+        AutoDiffItem { source, target, inputs, output, attrs: self }
     }
 }
 
 impl fmt::Display for AutoDiffItem {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "Differentiating {} -> {}", self.source, self.target)?;
-        write!(f, " with attributes: {:?}", self.attrs)
+        write!(f, " with attributes: {:?}", self.attrs)?;
+        write!(f, " with inputs: {:?}", self.inputs)?;
+        write!(f, " with output: {:?}", self.output)
     }
 }

compiler/rustc_ast/src/expand/typetree.rs

@@ -31,6 +31,7 @@ pub enum Kind {
     Half,
     Float,
     Double,
+    F128,
     Unknown,
 }
 

compiler/rustc_codegen_gcc/src/builder.rs

@@ -1383,6 +1383,7 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         _src_align: Align,
         size: RValue<'gcc>,
         flags: MemFlags,
+        _tt: Option<rustc_ast::expand::typetree::FncTree>, // Autodiff TypeTrees are LLVM-only, ignored in GCC backend
     ) {
         assert!(!flags.contains(MemFlags::NONTEMPORAL), "non-temporal memcpy not supported");
         let size = self.intcast(size, self.type_size_t(), false);

compiler/rustc_codegen_gcc/src/intrinsic/mod.rs

@@ -770,6 +770,7 @@ impl<'gcc, 'tcx> ArgAbiExt<'gcc, 'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
                     scratch_align,
                     bx.const_usize(self.layout.size.bytes()),
                     MemFlags::empty(),
+                    None,
                 );
 
                 bx.lifetime_end(scratch, scratch_size);

compiler/rustc_codegen_llvm/src/abi.rs

@@ -246,6 +246,7 @@ impl<'ll, 'tcx> ArgAbiExt<'ll, 'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
                     scratch_align,
                     bx.const_usize(copy_bytes),
                     MemFlags::empty(),
+                    None,
                 );
                 bx.lifetime_end(llscratch, scratch_size);
             }

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -563,6 +563,8 @@ fn enable_autodiff_settings(ad: &[config::AutoDiff]) {
             config::AutoDiff::Enable => {}
             // We handle this below
             config::AutoDiff::NoPostopt => {}
+            // Disables TypeTree generation
+            config::AutoDiff::NoTT => {}
         }
     }
     // This helps with handling enums for now.

compiler/rustc_codegen_llvm/src/builder.rs

@@ -2,6 +2,7 @@ use std::borrow::{Borrow, Cow};
 use std::ops::Deref;
 use std::{iter, ptr};
 
+use rustc_ast::expand::typetree::FncTree;
 pub(crate) mod autodiff;
 pub(crate) mod gpu_offload;
 
@@ -1107,11 +1108,12 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         src_align: Align,
         size: &'ll Value,
         flags: MemFlags,
+        tt: Option<FncTree>,
     ) {
         assert!(!flags.contains(MemFlags::NONTEMPORAL), "non-temporal memcpy not supported");
         let size = self.intcast(size, self.type_isize(), false);
         let is_volatile = flags.contains(MemFlags::VOLATILE);
-        unsafe {
+        let memcpy = unsafe {
             llvm::LLVMRustBuildMemCpy(
                 self.llbuilder,
                 dst,
@@ -1120,7 +1122,16 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
                 src_align.bytes() as c_uint,
                 size,
                 is_volatile,
-            );
+            )
+        };
+
+        // TypeTree metadata for memcpy is especially important: when Enzyme encounters
+        // a memcpy during autodiff, it needs to know the structure of the data being
+        // copied to properly track derivatives. For example, copying an array of floats
+        // vs. copying a struct with mixed types requires different derivative handling.
+        // The TypeTree tells Enzyme exactly what memory layout to expect.
+        if let Some(tt) = tt {
+            crate::typetree::add_tt(self.cx().llmod, self.cx().llcx, memcpy, tt);
         }
     }