Rollup merge of rust-lang#60135 - Gilnaa:arm-none-eabi, r=nagisa

Added arm-none-eabi target

Hello,

This PR adds a new target for compiling bare-metal ARM Cortex-A programs.

I've managed to build and use this new target, but I am unclear with regards to a few details:

- I'm not sure what are the criteria for choosing between lld and gnu-ld
- When trying to build with `./x.py build --target arm-none-eabi`, the script tries to compile with `cc`, instead of `arm-none-eabi-gcc`. It could find different cross-compilers just fine, but I didn't understand where I had to specify it. (I ended up specifying `CC_arm_none_eabi=arm-none-eabi-gcc` in the environment).
- I couldn't find where I can exclude std from compiling for this target (as I guess occurs with other bare-metal targets).
- Should I add a separate target for `eabihf`?

Author: kennytm

src/ci/docker/dist-various-1/Dockerfile

@@ -120,13 +120,17 @@ ENV TARGETS=$TARGETS,armebv7r-none-eabi
 ENV TARGETS=$TARGETS,armebv7r-none-eabihf
 ENV TARGETS=$TARGETS,armv7r-none-eabi
 ENV TARGETS=$TARGETS,armv7r-none-eabihf
+ENV TARGETS=$TARGETS,armv7a-none-eabi
+ENV TARGETS=$TARGETS,armv7a-none-eabihf
 ENV TARGETS=$TARGETS,thumbv7neon-unknown-linux-gnueabihf
 
 ENV CC_mipsel_unknown_linux_musl=mipsel-openwrt-linux-gcc \
     CC_mips_unknown_linux_musl=mips-openwrt-linux-gcc \
     CC_sparc64_unknown_linux_gnu=sparc64-linux-gnu-gcc \
     CC_x86_64_unknown_redox=x86_64-unknown-redox-gcc \
     CC_armebv7r_none_eabi=arm-none-eabi-gcc \
+    CC_armv7a_none_eabi=arm-none-eabi-gcc \
+    CC_armv7a_none_eabihf=arm-none-eabi-gcc \
     CC_thumbv7neon_unknown_linux_gnueabihf=arm-linux-gnueabihf-gcc \
     AR_thumbv7neon_unknown_linux_gnueabihf=arm-linux-gnueabihf-ar \
     CXX_thumbv7neon_unknown_linux_gnueabihf=arm-linux-gnueabihf-g++

src/librustc_target/spec/armv7a_none_eabi.rs

@@ -0,0 +1,35 @@
+// Generic ARM-v7 Cortex-A target, with software floating-point emulation.
+//
+// Can be used in conjunction with the `target-feature` and
+// `target-cpu` compiler flags to opt-in more hardware-specific
+// features.
+//
+// For example, `-C target-cpu=cortex-a7`.
+
+use crate::spec::{LinkerFlavor, LldFlavor, PanicStrategy, Target, TargetOptions, TargetResult};
+
+pub fn target() -> TargetResult {
+    Ok(Target {
+        llvm_target: "armv7a-none-eabi".to_string(),
+        target_endian: "little".to_string(),
+        target_pointer_width: "32".to_string(),
+        target_c_int_width: "32".to_string(),
+        data_layout: "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
+        arch: "arm".to_string(),
+        target_os: "none".to_string(),
+        target_env: String::new(),
+        target_vendor: String::new(),
+        linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
+
+        options: TargetOptions {
+            features: "+strict-align,+v7,+thumb2,-neon".to_string(),
+            linker: Some("rust-lld".to_owned()),
+            executables: true,
+            relocation_model: "static".to_string(),
+            max_atomic_width: Some(64),
+            panic_strategy: PanicStrategy::Abort,
+            abi_blacklist: super::arm_base::abi_blacklist(),
+            .. Default::default()
+        },
+    })
+}

src/librustc_target/spec/armv7a_none_eabihf.rs

@@ -0,0 +1,35 @@
+// Generic ARM-v7 Cortex-A target, with hardware floating-point.
+//
+// Can be used in conjunction with the `target-feature` and
+// `target-cpu` compiler flags to opt-in more hardware-specific
+// features.
+//
+// For example, `-C target-cpu=cortex-a7`.
+
+use crate::spec::{LinkerFlavor, LldFlavor, PanicStrategy, Target, TargetOptions, TargetResult};
+
+pub fn target() -> TargetResult {
+    Ok(Target {
+        llvm_target: "armv7a-none-eabihf".to_string(),
+        target_endian: "little".to_string(),
+        target_pointer_width: "32".to_string(),
+        target_c_int_width: "32".to_string(),
+        data_layout: "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64".to_string(),
+        arch: "arm".to_string(),
+        target_os: "none".to_string(),
+        target_env: String::new(),
+        target_vendor: String::new(),
+        linker_flavor: LinkerFlavor::Lld(LldFlavor::Ld),
+
+        options: TargetOptions {
+            features: "+strict-align,+v7,+vfp3,+d16,+thumb2,-neon".to_string(),
+            linker: Some("rust-lld".to_owned()),
+            executables: true,
+            relocation_model: "static".to_string(),
+            max_atomic_width: Some(64),
+            panic_strategy: PanicStrategy::Abort,
+            abi_blacklist: super::arm_base::abi_blacklist(),
+            .. Default::default()
+        },
+    })
+}

src/librustc_target/spec/mod.rs

@@ -351,6 +351,8 @@ supported_targets! {
     ("s390x-unknown-linux-gnu", s390x_unknown_linux_gnu),
     ("sparc-unknown-linux-gnu", sparc_unknown_linux_gnu),
     ("sparc64-unknown-linux-gnu", sparc64_unknown_linux_gnu),
+    ("armv7a-none-eabi", armv7a_none_eabi),
+    ("armv7a-none-eabihf", armv7a_none_eabihf),
     ("arm-unknown-linux-gnueabi", arm_unknown_linux_gnueabi),
     ("arm-unknown-linux-gnueabihf", arm_unknown_linux_gnueabihf),
     ("arm-unknown-linux-musleabi", arm_unknown_linux_musleabi),

src/tools/build-manifest/src/main.rs

@@ -66,6 +66,8 @@ static TARGETS: &[&str] = &[
     "armv7r-none-eabi",
     "armv7r-none-eabihf",
     "armv7s-apple-ios",
+    "armv7a-none-eabi",
+    "armv7a-none-eabihf",
     "asmjs-unknown-emscripten",
     "i386-apple-ios",
     "i586-pc-windows-msvc",