rust-lang · jhpratt · Jan 27, 2026 · Apr 12, 2026 · Apr 29, 2026 · Apr 29, 2026
diff --git a/compiler/rustc_codegen_gcc/.cspell.json b/compiler/rustc_codegen_gcc/.cspell.json
@@ -22,7 +22,7 @@
         "src/intrinsic/llvm.rs"
     ],
     "ignoreRegExpList": [
-        "/(FIXME|NOTE|TODO)\\([^)]+\\)/",
+        "/(FIXME|NOTE)\\([^)]+\\)/",
         "__builtin_\\w*"
     ]
 }
diff --git a/compiler/rustc_codegen_gcc/.github/workflows/ci.yml b/compiler/rustc_codegen_gcc/.github/workflows/ci.yml
@@ -26,7 +26,7 @@ jobs:
           - { gcc: "gcc-15.deb" }
           - { gcc: "gcc-15-without-int128.deb" }
         commands: [
-          "--std-tests",
+          "--std-tests --alloc-tests",
           # FIXME: re-enable asm tests when GCC can emit in the right syntax.
           # "--asm-tests",
           "--test-libcore",
@@ -36,6 +36,7 @@ jobs:
           "--test-successful-rustc --nb-parts 2 --current-part 0",
           "--test-successful-rustc --nb-parts 2 --current-part 1",
           "--projects",
+          "--gcc-asm-tests",
         ]
 
     steps:
@@ -52,9 +53,6 @@ jobs:
       # `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 llvm
 
-    - name: Install rustfmt & clippy
-      run: rustup component add rustfmt clippy
-
     - name: Download artifact
       run: curl -LO https://github.com/rust-lang/gcc/releases/latest/download/${{ matrix.libgccjit_version.gcc }}
 
@@ -88,16 +86,17 @@ jobs:
     - name: Check formatting
       run: ./y.sh fmt --check
 
-    - name: clippy
-      run: |
-        cargo clippy --all-targets -- -D warnings
-        cargo clippy --all-targets --no-default-features -- -D warnings
-        cargo clippy --manifest-path build_system/Cargo.toml --all-targets -- -D warnings
+    - name: Check todo
+      run: ./y.sh check-todo
+
+    - name: Check lints
+      run: ./y.sh clippy
 
     - name: Build
       run: |
         ./y.sh build --sysroot
         ./y.sh test --cargo-tests
+        CARGO_TEST_FLAGS="-Zmir-preserve-ub" ./y.sh test --cargo-tests -- mir_preserve_ub_empty_switch
 
     - name: Run y.sh cargo build
       run: |

diff --git a/compiler/rustc_codegen_gcc/.github/workflows/stdarch.yml b/compiler/rustc_codegen_gcc/.github/workflows/stdarch.yml
@@ -21,7 +21,7 @@ jobs:
       fail-fast: false
       matrix:
         cargo_runner: [
-          "sde -future -rtm_mode full --",
+          "sde -cpuid-in /home/runner/work/rustc_codegen_gcc/rustc_codegen_gcc/tests/cpuid.def -rtm_mode full --",
           "",
         ]
 
@@ -42,19 +42,24 @@ jobs:
     - name: Install more recent binutils
       run: |
         echo "deb http://archive.ubuntu.com/ubuntu plucky main universe" | sudo tee /etc/apt/sources.list.d/plucky-copies.list
-        sudo apt-get update
+        sudo apt-get update -o Acquire::Retries=3
         sudo apt-get install binutils
+        installed="$(dpkg-query --showformat='${Version}' --show binutils)"
+        echo "Installed binutils: $installed"
+        if dpkg --compare-versions "$installed" lt "2.44"; then
+            echo "::error::binutils upgrade failed (got $installed, need >= 2.44); the apt fetch probably failed"
+            exit 1
+        fi
 
     - name: Install Intel Software Development Emulator
       if: ${{ matrix.cargo_runner }}
       run: |
           mkdir intel-sde
           cd intel-sde
           version=10.8.0-2026-03-15
-          url_path=915934
           dir=sde-external-$version-lin
           file=$dir.tar.xz
-          wget https://downloadmirror.intel.com/$url_path/$file
+          wget http://ci-mirrors.rust-lang.org/$file
           tar xvf $file
           sudo mkdir /usr/share/intel-sde
           sudo cp -r $dir/* /usr/share/intel-sde
@@ -90,14 +95,15 @@ jobs:
     - name: Run stdarch tests
       if: ${{ !matrix.cargo_runner }}
       run: |
-        CHANNEL=release TARGET=x86_64-unknown-linux-gnu CG_RUSTFLAGS="-Ainternal_features" ./y.sh cargo test --manifest-path build/build_sysroot/sysroot_src/library/stdarch/Cargo.toml
+        # FIXME: remove --skip test_tile_ and --skip --skip test__tile when it's implemented.
+        ./y.sh test --release --stdarch-tests -- --skip test_tile_ --skip test__tile
 
     - name: Run stdarch tests
       if: ${{ matrix.cargo_runner }}
       run: |
         # FIXME: these tests fail when the sysroot is compiled with LTO because of a missing symbol in proc-macro.
-        # FIXME: remove --skip test_tile_ when it's implemented.
-        STDARCH_TEST_SKIP_FUNCTION="xsave,xsaveopt,xsave64,xsaveopt64" STDARCH_TEST_EVERYTHING=1 CHANNEL=release CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUNNER="${{ matrix.cargo_runner }}" TARGET=x86_64-unknown-linux-gnu CG_RUSTFLAGS="-Ainternal_features" ./y.sh cargo test --manifest-path build/build_sysroot/sysroot_src/library/stdarch/Cargo.toml -- --skip rtm --skip tbm --skip sse4a --skip test_tile_
+        # FIXME: remove --skip test_tile_ and --skip --skip test__tile when it's implemented.
+        STDARCH_TEST_SKIP_FUNCTION="xsave,xsaveopt,xsave64,xsaveopt64" STDARCH_TEST_EVERYTHING=1 CHANNEL=release CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUNNER="${{ matrix.cargo_runner }}" TARGET=x86_64-unknown-linux-gnu CG_RUSTFLAGS="-Ainternal_features" ./y.sh cargo test --manifest-path build/build_sysroot/sysroot_src/library/stdarch/Cargo.toml -- --skip rtm --skip tbm --skip sse4a --skip test_tile_ --skip test__tile
 
   # Summary job for the merge queue.
   # ALL THE PREVIOUS JOBS NEED TO BE ADDED TO THE `needs` SECTION OF THIS JOB!

diff --git a/compiler/rustc_codegen_gcc/.gitignore b/compiler/rustc_codegen_gcc/.gitignore
@@ -7,7 +7,7 @@ perf.data.old
 *.events
 *.string*
 gimple*
-*asm
+*_asm
 res
 test-backend
 projects

diff --git a/compiler/rustc_codegen_gcc/CONTRIBUTING.md b/compiler/rustc_codegen_gcc/CONTRIBUTING.md
@@ -112,7 +112,7 @@ Full list of debugging options can be found in the [README](Readme.md#env-vars).
 ### Code Style Guidelines
 
 - Follow Rust standard coding conventions
-- Ensure your code passes `rustfmt` and `clippy`
+- Ensure your code passes `rustfmt` and `clippy` (you can run them with `y.sh fmt` and `y.sh clippy`)
 - Add comments explaining complex logic, especially in GCC interface code
 
 ## Additional Resources

diff --git a/compiler/rustc_codegen_gcc/Cargo.lock b/compiler/rustc_codegen_gcc/Cargo.lock
@@ -31,9 +31,9 @@ checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
 [[package]]
 name = "errno"
-version = "0.3.10"
+version = "0.3.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "33d852cb9b869c2a9b3df2f71a3074817f01e1844f839a144f5fcef059a4eb5d"
+checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
 dependencies = [
  "libc",
  "windows-sys",
@@ -56,18 +56,18 @@ dependencies = [
 
 [[package]]
 name = "gccjit"
-version = "3.3.0"
+version = "4.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "26b73d18b642ce16378af78f89664841d7eeafa113682ff5d14573424eb0232a"
+checksum = "be5dafc4e649cb4a363e95a5960ef50b0c6f1b8e136ff8eb2e928b40353b5d8b"
 dependencies = [
  "gccjit_sys",
 ]
 
 [[package]]
 name = "gccjit_sys"
-version = "1.3.0"
+version = "2.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ee689456c013616942d5aef9a84d613cefcc3b335340d036f3650fc1a7459e15"
+checksum = "ab6a00a243aba2a45442bfd72b28d871137d4dac094f13de7f48cf9705112ffe"
 dependencies = [
  "libc",
 ]
@@ -117,15 +117,15 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.168"
+version = "0.2.186"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5aaeb2981e0606ca11d79718f8bb01164f1d6ed75080182d3abf017e6d244b6d"
+checksum = "68ab91017fe16c622486840e4c83c9a37afeff978bd239b5293d61ece587de66"
 
 [[package]]
 name = "linux-raw-sys"
-version = "0.9.4"
+version = "0.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cd945864f07fe9f5371a27ad7b52a172b4b499999f1d97574c9fa68373937e12"
+checksum = "32a66949e030da00e8c7d4434b251670a91556f4144941d37452769c25d58a53"
 
 [[package]]
 name = "memchr"
@@ -194,9 +194,9 @@ dependencies = [
 
 [[package]]
 name = "rustix"
-version = "1.0.7"
+version = "1.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c71e83d6afe7ff64890ec6b71d6a69bb8a610ab78ce364b3352876bb4c801266"
+checksum = "b6fe4565b9518b83ef4f91bb47ce29620ca828bd32cb7e408f0062e9930ba190"
 dependencies = [
  "bitflags",
  "errno",
@@ -216,9 +216,9 @@ dependencies = [
 
 [[package]]
 name = "tempfile"
-version = "3.20.0"
+version = "3.27.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e8a64e3985349f2441a1a9ef0b853f869006c3855f2cda6862a94d26ebb9d6a1"
+checksum = "32497e9a4c7b38532efcdebeef879707aa9f794296a4f0244f6f69e9bc8574bd"
 dependencies = [
  "fastrand",
  "getrandom",
@@ -311,78 +311,20 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
 
 [[package]]
-name = "windows-sys"
-version = "0.59.0"
+name = "windows-link"
+version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
-dependencies = [
- "windows-targets",
-]
+checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5"
 
 [[package]]
-name = "windows-targets"
-version = "0.52.6"
+name = "windows-sys"
+version = "0.61.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
+checksum = "ae137229bcbd6cdf0f7b80a31df61766145077ddf49416a728b02cb3921ff3fc"
 dependencies = [
- "windows_aarch64_gnullvm",
- "windows_aarch64_msvc",
- "windows_i686_gnu",
- "windows_i686_gnullvm",
- "windows_i686_msvc",
- "windows_x86_64_gnu",
- "windows_x86_64_gnullvm",
- "windows_x86_64_msvc",
+ "windows-link",
 ]
 
-[[package]]
-name = "windows_aarch64_gnullvm"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
-
-[[package]]
-name = "windows_aarch64_msvc"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
-
-[[package]]
-name = "windows_i686_gnu"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
-
-[[package]]
-name = "windows_i686_gnullvm"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
-
-[[package]]
-name = "windows_i686_msvc"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
-
-[[package]]
-name = "windows_x86_64_gnu"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
-
-[[package]]
-name = "windows_x86_64_gnullvm"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
-
-[[package]]
-name = "windows_x86_64_msvc"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
-
 [[package]]
 name = "wit-bindgen-rt"
 version = "0.39.0"

diff --git a/compiler/rustc_codegen_gcc/Cargo.toml b/compiler/rustc_codegen_gcc/Cargo.toml
@@ -20,7 +20,7 @@ default = ["master"]
 [dependencies]
 object = { version = "0.37.0", default-features = false, features = ["std", "read"] }
 tempfile = "3.20"
-gccjit = { version = "3.3.0", features = ["dlopen"] }
+gccjit = { version = "4.0.0", features = ["dlopen"] }
 #gccjit = { git = "https://github.com/rust-lang/gccjit.rs", branch = "error-dlopen", features = ["dlopen"] }
 
 # Local copy.

diff --git a/compiler/rustc_codegen_gcc/Readme.md b/compiler/rustc_codegen_gcc/Readme.md
@@ -136,19 +136,21 @@ $ ./y.sh cargo build --manifest-path tests/hello-world/Cargo.toml
 ### Cargo
 
 ```bash
-$ CHANNEL="release" $CG_GCCJIT_DIR/y.sh cargo run
+$ CHANNEL=release $CG_GCCJIT_DIR/y.sh cargo run
 ```
 
-If you compiled cg_gccjit in debug mode (aka you didn't pass `--release` to `./y.sh test`) you should use `CHANNEL="debug"` instead or omit `CHANNEL="release"` completely.
+If you compiled `cg_gcc` in debug mode (aka you didn't pass `--release` to `./y.sh build`) you should use `CHANNEL=debug` instead or omit `CHANNEL=release` completely.
 
 ### Rustc
 
 If you want to run `rustc` directly, you can do so with:
 
 ```bash
-$ ./y.sh rustc my_crate.rs
+$ CHANNEL=release ./y.sh rustc my_crate.rs
 ```
 
+If you compiled `cg_gcc` in debug mode (aka you didn't pass `--release` to `./y.sh build`) you should use `CHANNEL=debug` instead or omit `CHANNEL=release` completely.
+
 You can do the same manually (although we don't recommend it):
 
 ```bash

diff --git a/compiler/rustc_codegen_gcc/build_system/Cargo.lock b/compiler/rustc_codegen_gcc/build_system/Cargo.lock
@@ -1,6 +1,6 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
 name = "boml"