rustc_target: introduce ABI

Improve type safety by using an enum rather than strings.

Author: tamird

compiler/rustc_codegen_cranelift/src/lib.rs

@@ -47,7 +47,7 @@ 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;
+use rustc_target::spec::{ABI, Arch};
 
 pub use crate::config::*;
 use crate::prelude::*;
@@ -216,7 +216,7 @@ impl CodegenBackend for CraneliftCodegenBackend {
             Arch::X86_64
                 if sess.target.os == "windows"
                     && sess.target.env == "gnu"
-                    && sess.target.abi != "llvm" =>
+                    && sess.target.abi != ABI::Llvm =>
             {
                 false
             }

compiler/rustc_codegen_llvm/src/context.rs

@@ -29,7 +29,7 @@ use rustc_span::source_map::Spanned;
 use rustc_span::{DUMMY_SP, Span, Symbol};
 use rustc_symbol_mangling::mangle_internal_symbol;
 use rustc_target::spec::{
-    Arch, HasTargetSpec, RelocModel, SmallDataThresholdSupport, Target, TlsModel,
+    ABI, Arch, HasTargetSpec, RelocModel, SmallDataThresholdSupport, Target, TlsModel,
 };
 use smallvec::SmallVec;
 
@@ -337,7 +337,7 @@ pub(crate) unsafe fn create_module<'ll>(
     if sess.target.is_like_msvc
         || (sess.target.options.os == "windows"
             && sess.target.options.env == "gnu"
-            && sess.target.options.abi == "llvm")
+            && sess.target.options.abi == ABI::Llvm)
     {
         match sess.opts.cg.control_flow_guard {
             CFGuard::Disabled => {}

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -15,7 +15,7 @@ use rustc_fs_util::path_to_c_string;
 use rustc_middle::bug;
 use rustc_session::Session;
 use rustc_session::config::{PrintKind, PrintRequest};
-use rustc_target::spec::{Arch, MergeFunctions, PanicStrategy, SmallDataThresholdSupport};
+use rustc_target::spec::{ABI, Arch, MergeFunctions, PanicStrategy, SmallDataThresholdSupport};
 use smallvec::{SmallVec, smallvec};
 
 use crate::back::write::create_informational_target_machine;
@@ -353,7 +353,7 @@ fn update_target_reliable_float_cfg(sess: &Session, cfg: &mut TargetConfig) {
     let target_arch = &sess.target.arch;
     let target_os = sess.target.options.os.as_ref();
     let target_env = sess.target.options.env.as_ref();
-    let target_abi = sess.target.options.abi.as_ref();
+    let target_abi = &sess.target.options.abi;
     let target_pointer_width = sess.target.pointer_width;
     let version = get_version();
     let lt_20_1_1 = version < (20, 1, 1);
@@ -371,7 +371,7 @@ fn update_target_reliable_float_cfg(sess: &Session, cfg: &mut TargetConfig) {
         // Selection failure <https://github.com/llvm/llvm-project/issues/50374> (fixed in llvm21)
         (Arch::S390x, _) if lt_21_0_0 => false,
         // MinGW ABI bugs <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115054>
-        (Arch::X86_64, "windows") if target_env == "gnu" && target_abi != "llvm" => false,
+        (Arch::X86_64, "windows") if target_env == "gnu" && *target_abi != ABI::Llvm => false,
         // Infinite recursion <https://github.com/llvm/llvm-project/issues/97981>
         (Arch::CSky, _) => false,
         (Arch::Hexagon, _) if lt_21_0_0 => false, // (fixed in llvm21)
@@ -403,7 +403,7 @@ fn update_target_reliable_float_cfg(sess: &Session, cfg: &mut TargetConfig) {
         // not fail if our compiler-builtins is linked. (fixed in llvm21)
         (Arch::X86, _) if lt_21_0_0 => false,
         // MinGW ABI bugs <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115054>
-        (Arch::X86_64, "windows") if target_env == "gnu" && target_abi != "llvm" => false,
+        (Arch::X86_64, "windows") if target_env == "gnu" && *target_abi != ABI::Llvm => false,
         // There are no known problems on other platforms, so the only requirement is that symbols
         // are available. `compiler-builtins` provides all symbols required for core `f128`
         // support, so this should work for everything else.

compiler/rustc_codegen_llvm/src/va_arg.rs

@@ -7,7 +7,7 @@ use rustc_codegen_ssa::traits::{
 };
 use rustc_middle::ty::Ty;
 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf};
-use rustc_target::spec::Arch;
+use rustc_target::spec::{ABI, Arch};
 
 use crate::builder::Builder;
 use crate::llvm::{Type, Value};
@@ -270,7 +270,7 @@ fn emit_powerpc_va_arg<'ll, 'tcx>(
 
     // Rust does not currently support any powerpc softfloat targets.
     let target = &bx.cx.tcx.sess.target;
-    let is_soft_float_abi = target.abi == "softfloat";
+    let is_soft_float_abi = target.abi == ABI::SoftFloat;
     assert!(!is_soft_float_abi);
 
     // All instances of VaArgSafe are passed directly.

compiler/rustc_codegen_ssa/src/back/metadata.rs

@@ -20,7 +20,7 @@ use rustc_metadata::fs::METADATA_FILENAME;
 use rustc_middle::bug;
 use rustc_session::Session;
 use rustc_span::sym;
-use rustc_target::spec::{RelocModel, Target, ef_avr_arch};
+use rustc_target::spec::{ABI, RelocModel, Target, ef_avr_arch};
 use tracing::debug;
 
 use super::apple;
@@ -379,11 +379,11 @@ pub(super) fn elf_e_flags(architecture: Architecture, sess: &Session) -> u32 {
             }
         }
         Architecture::Csky => {
-            let e_flags = match sess.target.options.abi.as_ref() {
-                "abiv2" => elf::EF_CSKY_ABIV2,
-                _ => elf::EF_CSKY_ABIV1,
-            };
-            e_flags
+            if matches!(sess.target.options.abi, ABI::AbiV2) {
+                elf::EF_CSKY_ABIV2
+            } else {
+                elf::EF_CSKY_ABIV1
+            }
         }
         Architecture::PowerPc64 => {
             const EF_PPC64_ABI_UNKNOWN: u32 = 0;

compiler/rustc_codegen_ssa/src/common.rs

@@ -7,7 +7,7 @@ use rustc_middle::ty::{self, Instance, TyCtxt};
 use rustc_middle::{bug, mir, span_bug};
 use rustc_session::cstore::{DllCallingConvention, DllImport};
 use rustc_span::Span;
-use rustc_target::spec::{Target, Vendor};
+use rustc_target::spec::{ABI, Target, Vendor};
 
 use crate::traits::*;
 
@@ -174,7 +174,7 @@ pub fn is_mingw_gnu_toolchain(target: &Target) -> bool {
     target.vendor == Vendor::Pc
         && target.os == "windows"
         && target.env == "gnu"
-        && target.abi.is_empty()
+        && target.abi == ABI::Unspecified
 }
 
 pub fn i686_decorated_name(

compiler/rustc_session/src/config/cfg.rs

@@ -239,7 +239,7 @@ pub(crate) fn default_configuration(sess: &Session) -> Cfg {
         ins_none!(sym::sanitizer_cfi_normalize_integers);
     }
 
-    ins_str!(sym::target_abi, &sess.target.abi);
+    ins_sym!(sym::target_abi, sess.target.abi.desc_symbol());
     ins_sym!(sym::target_arch, sess.target.arch.desc_symbol());
     ins_str!(sym::target_endian, sess.target.endian.as_str());
     ins_str!(sym::target_env, &sess.target.env);
@@ -447,7 +447,7 @@ impl CheckCfg {
                 };
 
                 for target in Target::builtins().chain(iter::once(current_target.clone())) {
-                    values_target_abi.insert(Symbol::intern(&target.options.abi));
+                    values_target_abi.insert(target.options.abi.desc_symbol());
                     values_target_arch.insert(target.arch.desc_symbol());
                     values_target_endian.insert(Symbol::intern(target.options.endian.as_str()));
                     values_target_env.insert(Symbol::intern(&target.options.env));

compiler/rustc_target/src/asm/powerpc.rs

@@ -4,7 +4,7 @@ use rustc_data_structures::fx::FxIndexSet;
 use rustc_span::Symbol;
 
 use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
-use crate::spec::{RelocModel, Target};
+use crate::spec::{ABI, RelocModel, Target};
 
 def_reg_class! {
     PowerPC PowerPCInlineAsmRegClass {
@@ -104,10 +104,10 @@ fn reserved_v20to31(
     _is_clobber: bool,
 ) -> Result<(), &'static str> {
     if target.is_like_aix {
-        match &*target.options.abi {
-            "vec-default" => Err("v20-v31 (vs52-vs63) are reserved on vec-default ABI"),
-            "vec-extabi" => Ok(()),
-            _ => unreachable!("unrecognized AIX ABI"),
+        match &target.options.abi {
+            ABI::VecDefault => Err("v20-v31 (vs52-vs63) are reserved on vec-default ABI"),
+            ABI::VecExtAbi => Ok(()),
+            abi => unreachable!("unrecognized AIX ABI: {abi}"),
         }
     } else {
         Ok(())

compiler/rustc_target/src/callconv/aarch64.rs

@@ -3,7 +3,7 @@ use std::iter;
 use rustc_abi::{BackendRepr, HasDataLayout, Primitive, TyAbiInterface};
 
 use crate::callconv::{ArgAbi, FnAbi, Reg, RegKind, Uniform};
-use crate::spec::{HasTargetSpec, Target};
+use crate::spec::{ABI, HasTargetSpec, Target};
 
 /// Indicates the variant of the AArch64 ABI we are compiling for.
 /// Used to accommodate Apple and Microsoft's deviations from the usual AAPCS ABI.
@@ -33,7 +33,7 @@ where
             RegKind::Integer => false,
             // The softfloat ABI treats floats like integers, so they
             // do not get homogeneous aggregate treatment.
-            RegKind::Float => cx.target_spec().abi != "softfloat",
+            RegKind::Float => cx.target_spec().abi != ABI::SoftFloat,
             RegKind::Vector => size.bits() == 64 || size.bits() == 128,
         };
 
@@ -42,7 +42,7 @@ where
 }
 
 fn softfloat_float_abi<Ty>(target: &Target, arg: &mut ArgAbi<'_, Ty>) {
-    if target.abi != "softfloat" {
+    if target.abi != ABI::SoftFloat {
         return;
     }
     // Do *not* use the float registers for passing arguments, as that would make LLVM pick the ABI

compiler/rustc_target/src/spec/base/aix.rs

@@ -1,13 +1,13 @@
 use rustc_abi::Endian;
 
 use crate::spec::{
-    BinaryFormat, Cc, CodeModel, LinkOutputKind, LinkerFlavor, TargetOptions, Vendor, crt_objects,
-    cvs,
+    ABI, BinaryFormat, Cc, CodeModel, LinkOutputKind, LinkerFlavor, TargetOptions, Vendor,
+    crt_objects, cvs,
 };
 
 pub(crate) fn opts() -> TargetOptions {
     TargetOptions {
-        abi: "vec-extabi".into(),
+        abi: ABI::VecExtAbi,
         code_model: Some(CodeModel::Large),
         cpu: "pwr7".into(),
         os: "aix".into(),