Auto merge of #77527 - jonas-schievink:rollup-szgq5he, r=jonas-schievink

Rollup of 8 pull requests

Successful merges:

 - #77072 (Minor `hash_map` doc adjustments + item attribute orderings)
 - #77368 (Backport LLVM apfloat commit to rustc_apfloat)
 - #77445 (BTreeMap: complete the compile-time test_variance test case)
 - #77504 (Support vectors with fewer than 8 elements for simd_select_bitmask)
 - #77513 (Change DocFragments from enum variant fields to structs with a nested enum)
 - #77518 (Only use Fira Sans for the first `td` in item lists)
 - #77521 (Move target feature whitelist from cg_llvm to cg_ssa)
 - #77525 (Enable RenameReturnPlace MIR optimization on mir-opt-level >= 2)

Failed merges:

r? `@ghost`

2 files changed, 151 insertions, 0 deletions

diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index d4f3bf37797..e34371ef59a 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -42,6 +42,7 @@ pub mod glue;
 pub mod meth;
 pub mod mir;
 pub mod mono_item;
+pub mod target_features;
 pub mod traits;
 
 pub struct ModuleCodegen<M> {
diff --git a/compiler/rustc_codegen_ssa/src/target_features.rs b/compiler/rustc_codegen_ssa/src/target_features.rs
new file mode 100644
index 00000000000..4c61e21901b
--- /dev/null
+++ b/compiler/rustc_codegen_ssa/src/target_features.rs
@@ -0,0 +1,150 @@
+use rustc_session::Session;
+use rustc_span::symbol::sym;
+use rustc_span::symbol::Symbol;
+
+const ARM_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
+    ("aclass", Some(sym::arm_target_feature)),
+    ("mclass", Some(sym::arm_target_feature)),
+    ("rclass", Some(sym::arm_target_feature)),
+    ("dsp", Some(sym::arm_target_feature)),
+    ("neon", Some(sym::arm_target_feature)),
+    ("crc", Some(sym::arm_target_feature)),
+    ("crypto", Some(sym::arm_target_feature)),
+    ("v5te", Some(sym::arm_target_feature)),
+    ("v6", Some(sym::arm_target_feature)),
+    ("v6k", Some(sym::arm_target_feature)),
+    ("v6t2", Some(sym::arm_target_feature)),
+    ("v7", Some(sym::arm_target_feature)),
+    ("v8", Some(sym::arm_target_feature)),
+    ("vfp2", Some(sym::arm_target_feature)),
+    ("vfp3", Some(sym::arm_target_feature)),
+    ("vfp4", Some(sym::arm_target_feature)),
+    // This is needed for inline assembly, but shouldn't be stabilized as-is
+    // since it should be enabled per-function using #[instruction_set], not
+    // #[target_feature].
+    ("thumb-mode", Some(sym::arm_target_feature)),
+];
+
+const AARCH64_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
+    ("fp", Some(sym::aarch64_target_feature)),
+    ("neon", Some(sym::aarch64_target_feature)),
+    ("sve", Some(sym::aarch64_target_feature)),
+    ("crc", Some(sym::aarch64_target_feature)),
+    ("crypto", Some(sym::aarch64_target_feature)),
+    ("ras", Some(sym::aarch64_target_feature)),
+    ("lse", Some(sym::aarch64_target_feature)),
+    ("rdm", Some(sym::aarch64_target_feature)),
+    ("fp16", Some(sym::aarch64_target_feature)),
+    ("rcpc", Some(sym::aarch64_target_feature)),
+    ("dotprod", Some(sym::aarch64_target_feature)),
+    ("tme", Some(sym::aarch64_target_feature)),
+    ("v8.1a", Some(sym::aarch64_target_feature)),
+    ("v8.2a", Some(sym::aarch64_target_feature)),
+    ("v8.3a", Some(sym::aarch64_target_feature)),
+];
+
+const X86_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
+    ("adx", Some(sym::adx_target_feature)),
+    ("aes", None),
+    ("avx", None),
+    ("avx2", None),
+    ("avx512bw", Some(sym::avx512_target_feature)),
+    ("avx512cd", Some(sym::avx512_target_feature)),
+    ("avx512dq", Some(sym::avx512_target_feature)),
+    ("avx512er", Some(sym::avx512_target_feature)),
+    ("avx512f", Some(sym::avx512_target_feature)),
+    ("avx512ifma", Some(sym::avx512_target_feature)),
+    ("avx512pf", Some(sym::avx512_target_feature)),
+    ("avx512vbmi", Some(sym::avx512_target_feature)),
+    ("avx512vl", Some(sym::avx512_target_feature)),
+    ("avx512vpopcntdq", Some(sym::avx512_target_feature)),
+    ("bmi1", None),
+    ("bmi2", None),
+    ("cmpxchg16b", Some(sym::cmpxchg16b_target_feature)),
+    ("f16c", Some(sym::f16c_target_feature)),
+    ("fma", None),
+    ("fxsr", None),
+    ("lzcnt", None),
+    ("movbe", Some(sym::movbe_target_feature)),
+    ("pclmulqdq", None),
+    ("popcnt", None),
+    ("rdrand", None),
+    ("rdseed", None),
+    ("rtm", Some(sym::rtm_target_feature)),
+    ("sha", None),
+    ("sse", None),
+    ("sse2", None),
+    ("sse3", None),
+    ("sse4.1", None),
+    ("sse4.2", None),
+    ("sse4a", Some(sym::sse4a_target_feature)),
+    ("ssse3", None),
+    ("tbm", Some(sym::tbm_target_feature)),
+    ("xsave", None),
+    ("xsavec", None),
+    ("xsaveopt", None),
+    ("xsaves", None),
+];
+
+const HEXAGON_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
+    ("hvx", Some(sym::hexagon_target_feature)),
+    ("hvx-length128b", Some(sym::hexagon_target_feature)),
+];
+
+const POWERPC_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
+    ("altivec", Some(sym::powerpc_target_feature)),
+    ("power8-altivec", Some(sym::powerpc_target_feature)),
+    ("power9-altivec", Some(sym::powerpc_target_feature)),
+    ("power8-vector", Some(sym::powerpc_target_feature)),
+    ("power9-vector", Some(sym::powerpc_target_feature)),
+    ("vsx", Some(sym::powerpc_target_feature)),
+];
+
+const MIPS_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] =
+    &[("fp64", Some(sym::mips_target_feature)), ("msa", Some(sym::mips_target_feature))];
+
+const RISCV_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
+    ("m", Some(sym::riscv_target_feature)),
+    ("a", Some(sym::riscv_target_feature)),
+    ("c", Some(sym::riscv_target_feature)),
+    ("f", Some(sym::riscv_target_feature)),
+    ("d", Some(sym::riscv_target_feature)),
+    ("e", Some(sym::riscv_target_feature)),
+];
+
+const WASM_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
+    ("simd128", Some(sym::wasm_target_feature)),
+    ("atomics", Some(sym::wasm_target_feature)),
+    ("nontrapping-fptoint", Some(sym::wasm_target_feature)),
+];
+
+/// When rustdoc is running, provide a list of all known features so that all their respective
+/// primitives may be documented.
+///
+/// IMPORTANT: If you're adding another feature list above, make sure to add it to this iterator!
+pub fn all_known_features() -> impl Iterator<Item = (&'static str, Option<Symbol>)> {
+    std::iter::empty()
+        .chain(ARM_ALLOWED_FEATURES.iter())
+        .chain(AARCH64_ALLOWED_FEATURES.iter())
+        .chain(X86_ALLOWED_FEATURES.iter())
+        .chain(HEXAGON_ALLOWED_FEATURES.iter())
+        .chain(POWERPC_ALLOWED_FEATURES.iter())
+        .chain(MIPS_ALLOWED_FEATURES.iter())
+        .chain(RISCV_ALLOWED_FEATURES.iter())
+        .chain(WASM_ALLOWED_FEATURES.iter())
+        .cloned()
+}
+
+pub fn supported_target_features(sess: &Session) -> &'static [(&'static str, Option<Symbol>)] {
+    match &*sess.target.target.arch {
+        "arm" => ARM_ALLOWED_FEATURES,
+        "aarch64" => AARCH64_ALLOWED_FEATURES,
+        "x86" | "x86_64" => X86_ALLOWED_FEATURES,
+        "hexagon" => HEXAGON_ALLOWED_FEATURES,
+        "mips" | "mips64" => MIPS_ALLOWED_FEATURES,
+        "powerpc" | "powerpc64" => POWERPC_ALLOWED_FEATURES,
+        "riscv32" | "riscv64" => RISCV_ALLOWED_FEATURES,
+        "wasm32" => WASM_ALLOWED_FEATURES,
+        _ => &[],
+    }
+}