GCC backend subtree sync

compiler/rustc_codegen_gcc/.github/workflows/ci.yml

@@ -101,7 +101,7 @@ jobs:
 
     - name: Run y.sh cargo build
       run: |
-        ./y.sh cargo build --manifest-path tests/hello-world/Cargo.toml
+        CARGO_PROFILE_DEV_LTO=no ./y.sh cargo build --manifest-path tests/hello-world/Cargo.toml
 
     - name: Clean
       run: |
@@ -119,7 +119,7 @@ jobs:
 
     - name: Run tests
       run: |
-        ./y.sh test --release --clean --build-sysroot ${{ matrix.commands }}
+        ./y.sh test --release --clean --build-sysroot --no-builtins-tests ${{ matrix.commands }}
 
   duplicates:
     runs-on: ubuntu-24.04

compiler/rustc_codegen_gcc/.github/workflows/failures.yml

@@ -48,7 +48,9 @@ jobs:
 
     - name: Install libgccjit12
       if: matrix.libgccjit_version.gcc == 'libgccjit12.so'
-      run: sudo apt-get install libgccjit-12-dev
+      run: |
+        sudo apt-get update
+        sudo apt-get install libgccjit-12-dev
 
     - name: Setup path to libgccjit
       if: matrix.libgccjit_version.gcc == 'libgccjit12.so'

compiler/rustc_codegen_gcc/.github/workflows/gcc12.yml

@@ -46,7 +46,9 @@ jobs:
 
     - name: Install packages
       # `llvm-14-tools` is needed to install the `FileCheck` binary which is used for asm tests.
-      run: sudo apt-get install ninja-build ripgrep llvm-14-tools libgccjit-12-dev
+      run: |
+        sudo apt-get update
+        sudo apt-get install ninja-build ripgrep llvm-14-tools libgccjit-12-dev
 
     - name: Setup path to libgccjit
       run: echo 'gcc-path = "/usr/lib/gcc/x86_64-linux-gnu/12"' > config.toml

compiler/rustc_codegen_gcc/.github/workflows/m68k.yml

@@ -83,7 +83,7 @@ jobs:
       run: |
         ./y.sh prepare --only-libcore --cross
         ./y.sh build --sysroot --target-triple m68k-unknown-linux-gnu --target ${{ github.workspace }}/target_specs/m68k-unknown-linux-gnu.json
-        CG_RUSTFLAGS="-Clinker=m68k-unknown-linux-gnu-gcc" ./y.sh cargo build -Zjson-target-spec --manifest-path=./tests/hello-world/Cargo.toml --target ${{ github.workspace }}/target_specs/m68k-unknown-linux-gnu.json
+        CARGO_PROFILE_DEV_LTO=no CG_RUSTFLAGS="-Clinker=m68k-unknown-linux-gnu-gcc" ./y.sh cargo build -Zjson-target-spec --manifest-path=./tests/hello-world/Cargo.toml --target ${{ github.workspace }}/target_specs/m68k-unknown-linux-gnu.json
         ./y.sh clean all
 
     - name: Build
@@ -110,7 +110,7 @@ jobs:
 
         vm_dir=$(pwd)/vm
         cd tests/hello-world
-        CG_RUSTFLAGS="-Clinker=m68k-unknown-linux-gnu-gcc" ../../y.sh cargo build --target m68k-unknown-linux-gnu
+        CARGO_PROFILE_DEV_LTO=no CG_RUSTFLAGS="-Clinker=m68k-unknown-linux-gnu-gcc" ../../y.sh cargo build --target m68k-unknown-linux-gnu
         sudo cp target/m68k-unknown-linux-gnu/debug/hello_world $vm_dir/home/
         sudo chroot $vm_dir qemu-m68k-static /home/hello_world > hello_world_stdout
         expected_output="40"

compiler/rustc_codegen_gcc/.github/workflows/stdarch.yml

@@ -50,9 +50,11 @@ jobs:
       run: |
           mkdir intel-sde
           cd intel-sde
-          dir=sde-external-9.33.0-2024-01-07-lin
+          version=10.8.0-2026-03-15
+          url_path=915934
+          dir=sde-external-$version-lin
           file=$dir.tar.xz
-          wget https://downloadmirror.intel.com/813591/$file
+          wget https://downloadmirror.intel.com/$url_path/$file
           tar xvf $file
           sudo mkdir /usr/share/intel-sde
           sudo cp -r $dir/* /usr/share/intel-sde

compiler/rustc_codegen_gcc/Cargo.toml

@@ -9,12 +9,8 @@ license = "MIT OR Apache-2.0"
 crate-type = ["dylib"]
 
 [[test]]
-name = "lang_tests_debug"
-path = "tests/lang_tests_debug.rs"
-harness = false
-[[test]]
-name = "lang_tests_release"
-path = "tests/lang_tests_release.rs"
+name = "lang_tests"
+path = "tests/lang_tests.rs"
 harness = false
 
 [features]

compiler/rustc_codegen_gcc/build_system/src/test.rs

@@ -43,6 +43,7 @@ fn get_runners() -> Runners {
     runners.insert("--extended-regex-tests", ("Run extended regex tests", extended_regex_tests));
     runners.insert("--mini-tests", ("Run mini tests", mini_tests));
     runners.insert("--cargo-tests", ("Run cargo tests", cargo_tests));
+    runners.insert("--no-builtins-tests", ("Test #![no_builtins] attribute", no_builtins_tests));
     runners
 }
 
@@ -317,6 +318,65 @@ fn maybe_run_command_in_vm(
     Ok(())
 }
 
+/// Compile a source file to an object file and check if it contains a memset reference.
+fn object_has_memset(
+    env: &Env,
+    args: &TestArg,
+    src_file: &str,
+    obj_file_name: &str,
+) -> Result<bool, String> {
+    let cargo_target_dir = Path::new(&args.config_info.cargo_target_dir);
+    let obj_file = cargo_target_dir.join(obj_file_name);
+    let obj_file_str = obj_file.to_str().expect("obj_file to_str");
+
+    let mut command = args.config_info.rustc_command_vec();
+    command.extend_from_slice(&[
+        &src_file,
+        &"--emit",
+        &"obj",
+        &"-O",
+        &"--target",
+        &args.config_info.target_triple,
+        &"-o",
+    ]);
+    command.push(&obj_file_str);
+    run_command_with_env(&command, None, Some(env))?;
+
+    let nm_output = run_command_with_env(&[&"nm", &obj_file_str], None, Some(env))?;
+    let nm_stdout = String::from_utf8_lossy(&nm_output.stdout);
+
+    Ok(nm_stdout.contains("memset"))
+}
+
+fn no_builtins_tests(env: &Env, args: &TestArg) -> Result<(), String> {
+    // Test that the #![no_builtins] attribute prevents GCC from replacing
+    // code patterns (like loops) with calls to builtins (like memset).
+    // See https://github.com/rust-lang/rustc_codegen_gcc/issues/570
+
+    // Test 1: WITH #![no_builtins] - memset should NOT be present
+    println!("[TEST] no_builtins attribute (with #![no_builtins])");
+    let has_memset =
+        object_has_memset(env, args, "tests/no_builtins/no_builtins.rs", "no_builtins_test.o")?;
+    if has_memset {
+        return Err("no_builtins test FAILED: Found 'memset' in object file.\n\
+             The #![no_builtins] attribute should prevent GCC from replacing \n\
+             code patterns with builtin calls."
+            .to_string());
+    }
+
+    // Test 2: WITHOUT #![no_builtins] - memset SHOULD be present
+    println!("[TEST] no_builtins attribute (without #![no_builtins])");
+    let has_memset =
+        object_has_memset(env, args, "tests/no_builtins/with_builtins.rs", "with_builtins_test.o")?;
+    if !has_memset {
+        return Err("no_builtins test FAILED: 'memset' NOT found in object file.\n\
+             Without #![no_builtins], GCC should replace the loop with memset."
+            .to_string());
+    }
+
+    Ok(())
+}
+
 fn std_tests(env: &Env, args: &TestArg) -> Result<(), String> {
     let cargo_target_dir = Path::new(&args.config_info.cargo_target_dir);
     // FIXME: create a function "display_if_not_quiet" or something along the line.
@@ -1248,6 +1308,7 @@ fn run_all(env: &Env, args: &TestArg) -> Result<(), String> {
     test_libcore(env, args)?;
     extended_sysroot_tests(env, args)?;
     cargo_tests(env, args)?;
+    no_builtins_tests(env, args)?;
     test_rustc(env, args)?;
 
     Ok(())

compiler/rustc_codegen_gcc/example/mini_core.rs

@@ -15,6 +15,30 @@
 #![no_core]
 #![allow(dead_code, internal_features, ambiguous_wide_pointer_comparisons)]
 
+#[lang = "pointee_trait"]
+pub trait Pointee: PointeeSized {
+    #[lang = "metadata_type"]
+    // needed so that layout_of will return `TooGeneric` instead of `Unknown`
+    // when asked for the layout of `*const T`. Which is important for making
+    // transmutes between raw pointers (and especially pattern types of raw pointers)
+    // work.
+    type Metadata: Copy + Sync + Unpin + Freeze;
+}
+
+#[lang = "dyn_metadata"]
+pub struct DynMetadata<Dyn: PointeeSized> {
+    _vtable_ptr: NonNull<VTable>,
+    _phantom: PhantomData<Dyn>,
+}
+
+unsafe extern "C" {
+    /// Opaque type for accessing vtables.
+    ///
+    /// Private implementation detail of `DynMetadata::size_of` etc.
+    /// There is conceptually not actually any Abstract Machine memory behind this pointer.
+    type VTable;
+}
+
 #[no_mangle]
 unsafe extern "C" fn _Unwind_Resume() {
     intrinsics::unreachable();
@@ -113,7 +137,7 @@ unsafe impl<'a, T: PointeeSized> Sync for &'a T {}
 unsafe impl Sync for [u8; 16] {}
 
 #[lang = "freeze"]
-unsafe auto trait Freeze {}
+pub unsafe auto trait Freeze {}
 
 unsafe impl<T: PointeeSized> Freeze for PhantomData<T> {}
 unsafe impl<T: PointeeSized> Freeze for *const T {}
@@ -592,6 +616,13 @@ macro_rules! pattern_type {
     };
 }
 
+impl<T: PointeeSized, U: PointeeSized> CoerceUnsized<pattern_type!(*const U is !null)> for pattern_type!(*const T is !null) where
+    T: Unsize<U>
+{
+}
+
+impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<pattern_type!(U is !null)> for pattern_type!(T is !null) {}
+
 impl<T: PointeeSized, U: PointeeSized> CoerceUnsized<NonNull<U>> for NonNull<T> where T: Unsize<U> {}
 impl<T: PointeeSized, U: PointeeSized> DispatchFromDyn<NonNull<U>> for NonNull<T> where T: Unsize<U> {}
 
@@ -604,26 +635,37 @@ impl<T: PointeeSized, U: PointeeSized> CoerceUnsized<Unique<U>> for Unique<T> wh
 impl<T: PointeeSized, U: PointeeSized> DispatchFromDyn<Unique<U>> for Unique<T> where T: Unsize<U> {}
 
 #[lang = "owned_box"]
-pub struct Box<T: ?Sized, A: Allocator = Global>(Unique<T>, A);
+pub struct Box<T: ?Sized, A = Global>(Unique<T>, A);
 
-impl<T: ?Sized + Unsize<U>, U: ?Sized, A: Allocator> CoerceUnsized<Box<U, A>> for Box<T, A> {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Box<U>> for Box<T> {}
 
 impl<T> Box<T> {
     pub fn new(val: T) -> Box<T> {
         unsafe {
             let size = size_of::<T>();
             let ptr = libc::malloc(size);
             intrinsics::copy(&val as *const T as *const u8, ptr, size);
-            Box(Unique { pointer: NonNull(ptr as *const T), _marker: PhantomData }, Global)
+            Box(
+                Unique {
+                    pointer: NonNull(intrinsics::transmute::<
+                        *mut u8,
+                        pattern_type!(*const T is !null),
+                    >(ptr)),
+                    _marker: PhantomData,
+                },
+                Global,
+            )
         }
     }
 }
 
-impl<T: ?Sized, A: Allocator> Drop for Box<T, A> {
+impl<T: ?Sized, A> Drop for Box<T, A> {
     fn drop(&mut self) {
-        // inner value is dropped by compiler.
+        // inner value is dropped by compiler
         unsafe {
-            libc::free(self.0.pointer.0 as *mut u8);
+            libc::free(intrinsics::transmute::<pattern_type!(*const T is !null), *const T>(
+                self.0.pointer.0,
+            ) as *mut u8);
         }
     }
 }

compiler/rustc_codegen_gcc/libgccjit.version

@@ -1 +1 @@
-efdd0a7290c22f5438d7c5380105d353ee3e8518
+6f155cc3f5a2dff33afe6cc3ed6c2e0e605ae6a3

compiler/rustc_codegen_gcc/rust-toolchain

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2026-02-14"
+channel = "nightly-2026-04-29"
 components = ["rust-src", "rustc-dev", "llvm-tools-preview"]

compiler/rustc_codegen_gcc/src/abi.rs

@@ -224,15 +224,8 @@ impl<'gcc, 'tcx> FnAbiGccExt<'gcc, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
 
     fn ptr_to_gcc_type(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc> {
         // FIXME(antoyo): Should we do something with `FnAbiGcc::fn_attributes`?
-        let FnAbiGcc { return_type, arguments_type, is_c_variadic, on_stack_param_indices, .. } =
-            self.gcc_type(cx);
-        let pointer_type =
-            cx.context.new_function_pointer_type(None, return_type, &arguments_type, is_c_variadic);
-        cx.on_stack_params.borrow_mut().insert(
-            pointer_type.dyncast_function_ptr_type().expect("function ptr type"),
-            on_stack_param_indices,
-        );
-        pointer_type
+        let FnAbiGcc { return_type, arguments_type, is_c_variadic, .. } = self.gcc_type(cx);
+        cx.context.new_function_pointer_type(None, return_type, &arguments_type, is_c_variadic)
     }
 
     #[cfg(feature = "master")]

compiler/rustc_codegen_gcc/src/asm.rs

@@ -12,13 +12,13 @@ use rustc_codegen_ssa::traits::{
 };
 use rustc_middle::bug;
 use rustc_middle::ty::Instance;
-use rustc_span::Span;
+use rustc_span::{DUMMY_SP, Span};
 use rustc_target::asm::*;
 
 use crate::builder::Builder;
 use crate::callee::get_fn;
 use crate::context::CodegenCx;
-use crate::errors::UnwindingInlineAsm;
+use crate::errors::{NulBytesInAsm, UnwindingInlineAsm};
 use crate::type_of::LayoutGccExt;
 
 // Rust asm! and GCC Extended Asm semantics differ substantially.
@@ -530,8 +530,15 @@ impl<'a, 'gcc, 'tcx> AsmBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
             template_str.push_str(INTEL_SYNTAX_INS);
         }
 
-        // 4. Generate Extended Asm block
+        // NOTE: GCC's extended asm uses CString which cannot contain nul bytes.
+        // Emit an error if there are any nul bytes in the template string.
+        if template_str.contains('\0') {
+            let err_sp = span.first().copied().unwrap_or(DUMMY_SP);
+            self.sess().dcx().emit_err(NulBytesInAsm { span: err_sp });
+            return;
+        }
 
+        // 4. Generate Extended Asm block
         let block = self.llbb();
         let extended_asm = if let Some(dest) = dest {
             assert!(!labels.is_empty());
@@ -875,7 +882,7 @@ impl<'gcc, 'tcx> AsmCodegenMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
         template: &[InlineAsmTemplatePiece],
         operands: &[GlobalAsmOperandRef<'tcx>],
         options: InlineAsmOptions,
-        _line_spans: &[Span],
+        line_spans: &[Span],
     ) {
         let asm_arch = self.tcx.sess.asm_arch.unwrap();
 
@@ -942,6 +949,13 @@ impl<'gcc, 'tcx> AsmCodegenMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
         }
         // NOTE: seems like gcc will put the asm in the wrong section, so set it to .text manually.
         template_str.push_str("\n.popsection");
+        // NOTE: GCC's add_top_level_asm uses CString which cannot contain nul bytes.
+        // Emit an error if there are any nul bytes in the template string.
+        if template_str.contains('\0') {
+            let span = line_spans.first().copied().unwrap_or(DUMMY_SP);
+            self.tcx.dcx().emit_err(NulBytesInAsm { span });
+            return;
+        }
         self.context.add_top_level_asm(None, &template_str);
     }
 

compiler/rustc_codegen_gcc/src/base.rs

@@ -8,7 +8,8 @@ use rustc_codegen_ssa::ModuleCodegen;
 use rustc_codegen_ssa::base::maybe_create_entry_wrapper;
 use rustc_codegen_ssa::mono_item::MonoItemExt;
 use rustc_codegen_ssa::traits::DebugInfoCodegenMethods;
-use rustc_hir::attrs::Linkage;
+use rustc_hir::attrs::{AttributeKind, Linkage};
+use rustc_hir::find_attr;
 use rustc_middle::dep_graph;
 #[cfg(feature = "master")]
 use rustc_middle::mono::Visibility;
@@ -137,6 +138,17 @@ pub fn compile_codegen_unit(
         // NOTE: Rust relies on LLVM doing wrapping on overflow.
         context.add_command_line_option("-fwrapv");
 
+        // NOTE: We need to honor the `#![no_builtins]` attribute to prevent GCC from
+        // replacing code patterns (like loops) with calls to builtins (like memset).
+        // The `-fno-tree-loop-distribute-patterns` flag disables the loop distribution pass
+        // that transforms loops into calls to library functions (memset, memcpy, etc.).
+        // See GCC handling for more details:
+        // https://github.com/rust-lang/gcc/blob/efdd0a7290c22f5438d7c5380105d353ee3e8518/gcc/c-family/c-opts.cc#L953
+        let crate_attrs = tcx.hir_attrs(rustc_hir::CRATE_HIR_ID);
+        if find_attr!(crate_attrs, AttributeKind::NoBuiltins) {
+            context.add_command_line_option("-fno-tree-loop-distribute-patterns");
+        }
+
         if let Some(model) = tcx.sess.code_model() {
             use rustc_target::spec::CodeModel;