Add v8plus target feature to sparc and use it in create_object_file

Author: taiki-e

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -283,6 +283,12 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
         // llvm/llvm-project#111598
         ("wasm32" | "wasm64", "wide-arithmetic") if get_version() < (20, 0, 0) => None,
         ("sparc", "leoncasa") => Some(LLVMFeature::new("hasleoncasa")),
+        // In LLVM 19, there is no `v8plus` feature and `v9` means "SPARC-V9 instruction available and SPARC-V8+ ABI used".
+        // https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/llvm/lib/Target/Sparc/MCTargetDesc/SparcELFObjectWriter.cpp#L27-L28
+        // Before LLVM 19, there is no `v8plus` feature and `v9` means "SPARC-V9 instruction available".
+        // https://github.com/llvm/llvm-project/blob/llvmorg-18.1.0/llvm/lib/Target/Sparc/MCTargetDesc/SparcELFObjectWriter.cpp#L26
+        ("sparc", "v8plus") if get_version().0 == 19 => Some(LLVMFeature::new("v9")),
+        ("sparc", "v8plus") if get_version().0 < 19 => None,
         (_, s) => Some(LLVMFeature::new(s)),
     }
 }
@@ -622,6 +628,8 @@ pub(crate) fn global_llvm_features(
             .features
             .split(',')
             .filter(|v| !v.is_empty() && backend_feature_name(sess, v).is_some())
+            // Drop +v8plus feature introduced in LLVM 20.
+            .filter(|v| *v != "+v8plus" || get_version() >= (20, 0, 0))
             .map(String::from),
     );
 

compiler/rustc_codegen_ssa/src/back/metadata.rs

@@ -212,7 +212,7 @@ pub(crate) fn create_object_file(sess: &Session) -> Option<write::Object<'static
         "riscv32" => (Architecture::Riscv32, None),
         "riscv64" => (Architecture::Riscv64, None),
         "sparc" => {
-            if sess.target.options.cpu == "v9" {
+            if sess.unstable_target_features.contains(&sym::v8plus) {
                 // Target uses V8+, aka EM_SPARC32PLUS, aka 64-bit V9 but in 32-bit mode
                 (Architecture::Sparc32Plus, None)
             } else {

compiler/rustc_span/src/symbol.rs

@@ -2111,6 +2111,7 @@ symbols! {
         usize_legacy_fn_max_value,
         usize_legacy_fn_min_value,
         usize_legacy_mod,
+        v8plus,
         va_arg,
         va_copy,
         va_end,

compiler/rustc_target/src/spec/targets/sparc_unknown_linux_gnu.rs

@@ -14,6 +14,7 @@ pub(crate) fn target() -> Target {
         data_layout: "E-m:e-p:32:32-i64:64-i128:128-f128:64-n32-S64".into(),
         arch: "sparc".into(),
         options: TargetOptions {
+            features: "+v8plus".into(),
             cpu: "v9".into(),
             endian: Endian::Big,
             late_link_args: TargetOptions::link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &[

compiler/rustc_target/src/target_features.rs

@@ -548,6 +548,7 @@ const IBMZ_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
 const SPARC_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     // tidy-alphabetical-start
     ("leoncasa", Unstable(sym::sparc_target_feature), &[]),
+    ("v8plus", Unstable(sym::sparc_target_feature), &[]),
     ("v9", Unstable(sym::sparc_target_feature), &[]),
     // tidy-alphabetical-end
 ];

tests/ui/abi/sparcv8plus.rs

@@ -0,0 +1,43 @@
+//@ revisions: sparc sparcv8plus sparc_cpu_v9 sparc_feature_v8plus sparc_cpu_v9_feature_v8plus
+//@[sparc] compile-flags: --target sparc-unknown-none-elf
+//@[sparc] needs-llvm-components: sparc
+//@[sparcv8plus] compile-flags: --target sparc-unknown-linux-gnu
+//@[sparcv8plus] needs-llvm-components: sparc
+//@[sparc_cpu_v9] compile-flags: --target sparc-unknown-none-elf -C target-cpu=v9
+//@[sparc_cpu_v9] needs-llvm-components: sparc
+//@[sparc_feature_v8plus] compile-flags: --target sparc-unknown-none-elf -C target-feature=+v8plus
+//@[sparc_feature_v8plus] needs-llvm-components: sparc
+//@[sparc_cpu_v9_feature_v8plus] compile-flags: --target sparc-unknown-none-elf -C target-cpu=v9 -C target-feature=+v8plus
+//@[sparc_cpu_v9_feature_v8plus] needs-llvm-components: sparc
+//@ min-llvm-version: 19
+
+#![crate_type = "rlib"]
+#![feature(no_core, rustc_attrs, lang_items)]
+#![no_core]
+
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
+
+#[rustc_builtin_macro]
+macro_rules! compile_error {
+    () => {};
+}
+
+#[cfg(all(not(target_feature = "v8plus"), not(target_feature = "v9")))]
+compile_error!("-v8plus,-v9");
+//[sparc]~^ ERROR -v8plus,-v9
+
+// FIXME: sparc_cpu_v9 should be in "-v8plus,+v9" group (fixed in LLVM 20)
+#[cfg(all(target_feature = "v8plus", target_feature = "v9"))]
+compile_error!("+v8plus,+v9");
+//[sparcv8plus,sparc_cpu_v9_feature_v8plus,sparc_cpu_v9]~^ ERROR +v8plus,+v9
+
+// FIXME: should be rejected
+#[cfg(all(target_feature = "v8plus", not(target_feature = "v9")))]
+compile_error!("+v8plus,-v9 (FIXME)");
+//[sparc_feature_v8plus]~^ ERROR +v8plus,-v9 (FIXME)
+
+#[cfg(all(not(target_feature = "v8plus"), target_feature = "v9"))]
+compile_error!("-v8plus,+v9");

tests/ui/abi/sparcv8plus.sparc.stderr

@@ -0,0 +1,8 @@
+error: -v8plus,-v9
+  --> $DIR/sparcv8plus.rs:29:1
+   |
+LL | compile_error!("-v8plus,-v9");
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+

tests/ui/abi/sparcv8plus.sparc_cpu_v9.stderr

@@ -0,0 +1,8 @@
+error: +v8plus,+v9
+  --> $DIR/sparcv8plus.rs:34:1
+   |
+LL | compile_error!("+v8plus,+v9");
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+

tests/ui/abi/sparcv8plus.sparc_cpu_v9_feature_v8plus.stderr

@@ -0,0 +1,8 @@
+error: +v8plus,+v9
+  --> $DIR/sparcv8plus.rs:34:1
+   |
+LL | compile_error!("+v8plus,+v9");
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+

tests/ui/abi/sparcv8plus.sparc_feature_v8plus.stderr

@@ -0,0 +1,8 @@
+error: +v8plus,-v9 (FIXME)
+  --> $DIR/sparcv8plus.rs:39:1
+   |
+LL | compile_error!("+v8plus,-v9 (FIXME)");
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+