rustc_target: introduce Arch

Improve type safety by using an enum rather than strings.

Author: tamird

src/abi/mod.rs

@@ -20,6 +20,7 @@ use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_session::Session;
 use rustc_span::source_map::Spanned;
 use rustc_target::callconv::{FnAbi, PassMode};
+use rustc_target::spec::Arch;
 use smallvec::SmallVec;
 
 use self::pass_mode::*;
@@ -155,7 +156,7 @@ impl<'tcx> FunctionCx<'_, '_, 'tcx> {
             let ret = self.lib_call_unadjusted(name, params, returns, &args)[0];
 
             Cow::Owned(vec![codegen_bitcast(self, types::I128, ret)])
-        } else if ret_single_i128 && self.tcx.sess.target.arch == "s390x" {
+        } else if ret_single_i128 && self.tcx.sess.target.arch == Arch::S390x {
             // Return i128 using a return area pointer on s390x.
             let mut params = params;
             let mut args = args.to_vec();
@@ -641,7 +642,7 @@ pub(crate) fn codegen_terminator_call<'tcx>(
                 .flat_map(|arg_abi| arg_abi.get_abi_param(fx.tcx).into_iter()),
         );
 
-        if fx.tcx.sess.target.is_like_darwin && fx.tcx.sess.target.arch == "aarch64" {
+        if fx.tcx.sess.target.is_like_darwin && fx.tcx.sess.target.arch == Arch::AArch64 {
             // Add any padding arguments needed for Apple AArch64.
             // There's no need to pad the argument list unless variadic arguments are actually being
             // passed.
@@ -787,25 +788,25 @@ pub(crate) fn codegen_drop<'tcx>(
 pub(crate) fn lib_call_arg_param(tcx: TyCtxt<'_>, ty: Type, is_signed: bool) -> AbiParam {
     let param = AbiParam::new(ty);
     if ty.is_int() && u64::from(ty.bits()) < tcx.data_layout.pointer_size().bits() {
-        match (&*tcx.sess.target.arch, &*tcx.sess.target.vendor) {
-            ("x86_64", _) | ("aarch64", "apple") => match (ty, is_signed) {
+        match (tcx.sess.target.arch, tcx.sess.target.vendor.as_ref()) {
+            (Arch::X86_64, _) | (Arch::AArch64, "apple") => match (ty, is_signed) {
                 (types::I8 | types::I16, true) => param.sext(),
                 (types::I8 | types::I16, false) => param.uext(),
                 _ => param,
             },
-            ("aarch64", _) => param,
-            ("riscv64", _) => match (ty, is_signed) {
+            (Arch::AArch64, _) => param,
+            (Arch::RiscV64, _) => match (ty, is_signed) {
                 (types::I32, _) | (_, true) => param.sext(),
                 _ => param.uext(),
             },
-            ("s390x", _) => {
+            (Arch::S390x, _) => {
                 if is_signed {
                     param.sext()
                 } else {
                     param.uext()
                 }
             }
-            _ => unimplemented!("{:?}", tcx.sess.target.arch),
+            (arch, _) => unimplemented!("{arch:?}"),
         }
     } else {
         param

src/codegen_f16_f128.rs

@@ -1,8 +1,10 @@
+use rustc_target::spec::Arch;
+
 use crate::prelude::*;
 
 pub(crate) fn f16_to_f32(fx: &mut FunctionCx<'_, '_, '_>, value: Value) -> Value {
     let (value, arg_ty) =
-        if fx.tcx.sess.target.vendor == "apple" && fx.tcx.sess.target.arch == "x86_64" {
+        if fx.tcx.sess.target.vendor == "apple" && fx.tcx.sess.target.arch == Arch::X86_64 {
             (
                 fx.bcx.ins().bitcast(types::I16, MemFlags::new(), value),
                 lib_call_arg_param(fx.tcx, types::I16, false),
@@ -19,7 +21,8 @@ fn f16_to_f64(fx: &mut FunctionCx<'_, '_, '_>, value: Value) -> Value {
 }
 
 pub(crate) fn f32_to_f16(fx: &mut FunctionCx<'_, '_, '_>, value: Value) -> Value {
-    let ret_ty = if fx.tcx.sess.target.vendor == "apple" && fx.tcx.sess.target.arch == "x86_64" {
+    let ret_ty = if fx.tcx.sess.target.vendor == "apple" && fx.tcx.sess.target.arch == Arch::X86_64
+    {
         types::I16
     } else {
         types::F16
@@ -34,7 +37,8 @@ pub(crate) fn f32_to_f16(fx: &mut FunctionCx<'_, '_, '_>, value: Value) -> Value
 }
 
 fn f64_to_f16(fx: &mut FunctionCx<'_, '_, '_>, value: Value) -> Value {
-    let ret_ty = if fx.tcx.sess.target.vendor == "apple" && fx.tcx.sess.target.arch == "x86_64" {
+    let ret_ty = if fx.tcx.sess.target.vendor == "apple" && fx.tcx.sess.target.arch == Arch::X86_64
+    {
         types::I16
     } else {
         types::F16

src/common.rs

@@ -8,7 +8,7 @@ use rustc_middle::ty::layout::{
 };
 use rustc_span::source_map::Spanned;
 use rustc_target::callconv::FnAbi;
-use rustc_target::spec::{HasTargetSpec, Target};
+use rustc_target::spec::{Arch, HasTargetSpec, Target};
 
 use crate::constant::ConstantCx;
 use crate::debuginfo::FunctionDebugContext;
@@ -373,7 +373,7 @@ impl<'tcx> FunctionCx<'_, '_, 'tcx> {
             "size must be a multiple of alignment (size={size}, align={align})"
         );
 
-        let abi_align = if self.tcx.sess.target.arch == "s390x" { 8 } else { 16 };
+        let abi_align = if self.tcx.sess.target.arch == Arch::S390x { 8 } else { 16 };
         if align <= abi_align {
             let stack_slot = self.bcx.create_sized_stack_slot(StackSlotData {
                 kind: StackSlotKind::ExplicitSlot,

src/lib.rs

@@ -50,6 +50,7 @@ use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_session::Session;
 use rustc_session::config::OutputFilenames;
 use rustc_span::{Symbol, sym};
+use rustc_target::spec::Arch;
 
 pub use crate::config::*;
 use crate::prelude::*;
@@ -186,20 +187,20 @@ impl CodegenBackend for CraneliftCodegenBackend {
 
     fn target_config(&self, sess: &Session) -> TargetConfig {
         // FIXME return the actually used target features. this is necessary for #[cfg(target_feature)]
-        let target_features = if sess.target.arch == "x86_64" && sess.target.os != "none" {
-            // x86_64 mandates SSE2 support and rustc requires the x87 feature to be enabled
-            vec![sym::fxsr, sym::sse, sym::sse2, Symbol::intern("x87")]
-        } else if sess.target.arch == "aarch64" {
-            match &*sess.target.os {
+        let target_features = match sess.target.arch {
+            Arch::X86_64 if sess.target.os != "none" => {
+                // x86_64 mandates SSE2 support and rustc requires the x87 feature to be enabled
+                vec![sym::fxsr, sym::sse, sym::sse2, Symbol::intern("x87")]
+            }
+            Arch::AArch64 => match &*sess.target.os {
                 "none" => vec![],
                 // On macOS the aes, sha2 and sha3 features are enabled by default and ring
                 // fails to compile on macOS when they are not present.
                 "macos" => vec![sym::neon, sym::aes, sym::sha2, sym::sha3],
                 // AArch64 mandates Neon support
                 _ => vec![sym::neon],
-            }
-        } else {
-            vec![]
+            },
+            _ => vec![],
         };
         // FIXME do `unstable_target_features` properly
         let unstable_target_features = target_features.clone();
@@ -208,14 +209,14 @@ impl CodegenBackend for CraneliftCodegenBackend {
         // Windows, whereas LLVM 21+ and Cranelift pass it indirectly. This means that `f128` won't
         // work when linking against a LLVM-built sysroot.
         let has_reliable_f128 = !sess.target.is_like_windows;
-        let has_reliable_f16 = match &*sess.target.arch {
+        let has_reliable_f16 = match sess.target.arch {
             // FIXME(f16_f128): LLVM 20 does not support `f16` on s390x, meaning the required
             // builtins are not available in `compiler-builtins`.
-            "s390x" => false,
+            Arch::S390x => false,
             // FIXME(f16_f128): `rustc_codegen_llvm` currently disables support on Windows GNU
             // targets due to GCC using a different ABI than LLVM. Therefore `f16` won't be
             // available when using a LLVM-built sysroot.
-            "x86_64"
+            Arch::X86_64
                 if sess.target.os == "windows"
                     && sess.target.env == "gnu"
                     && sess.target.abi != "llvm" =>