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`

3 files changed, 11 insertions, 157 deletions

diff --git a/compiler/rustc_codegen_llvm/src/attributes.rs b/compiler/rustc_codegen_llvm/src/attributes.rs
index 73c34818446..a633ea5e5a9 100644
--- a/compiler/rustc_codegen_llvm/src/attributes.rs
+++ b/compiler/rustc_codegen_llvm/src/attributes.rs
@@ -349,17 +349,15 @@ pub fn from_fn_attrs(cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value, instance: ty::
 }
 
 pub fn provide(providers: &mut Providers) {
+    use rustc_codegen_ssa::target_features::{all_known_features, supported_target_features};
     providers.supported_target_features = |tcx, cnum| {
         assert_eq!(cnum, LOCAL_CRATE);
         if tcx.sess.opts.actually_rustdoc {
             // rustdoc needs to be able to document functions that use all the features, so
             // provide them all.
-            llvm_util::all_known_features().map(|(a, b)| (a.to_string(), b)).collect()
+            all_known_features().map(|(a, b)| (a.to_string(), b)).collect()
         } else {
-            llvm_util::supported_target_features(tcx.sess)
-                .iter()
-                .map(|&(a, b)| (a.to_string(), b))
-                .collect()
+            supported_target_features(tcx.sess).iter().map(|&(a, b)| (a.to_string(), b)).collect()
         }
     };
 
diff --git a/compiler/rustc_codegen_llvm/src/intrinsic.rs b/compiler/rustc_codegen_llvm/src/intrinsic.rs
index 7f5b09eac4f..e76e86f5651 100644
--- a/compiler/rustc_codegen_llvm/src/intrinsic.rs
+++ b/compiler/rustc_codegen_llvm/src/intrinsic.rs
@@ -793,14 +793,18 @@ fn generic_simd_intrinsic(
         require_simd!(arg_tys[1], "argument");
         let v_len = arg_tys[1].simd_size(tcx);
         require!(
-            m_len == v_len,
+            // Allow masks for vectors with fewer than 8 elements to be
+            // represented with a u8 or i8.
+            m_len == v_len || (m_len == 8 && v_len < 8),
             "mismatched lengths: mask length `{}` != other vector length `{}`",
             m_len,
             v_len
         );
         let i1 = bx.type_i1();
-        let i1xn = bx.type_vector(i1, m_len);
-        let m_i1s = bx.bitcast(args[0].immediate(), i1xn);
+        let im = bx.type_ix(v_len);
+        let i1xn = bx.type_vector(i1, v_len);
+        let m_im = bx.trunc(args[0].immediate(), im);
+        let m_i1s = bx.bitcast(m_im, i1xn);
         return Ok(bx.select(m_i1s, args[1].immediate(), args[2].immediate()));
     }
 
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 900f2df383a..d42020047fd 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -1,12 +1,12 @@
 use crate::back::write::create_informational_target_machine;
 use crate::llvm;
 use libc::c_int;
+use rustc_codegen_ssa::target_features::supported_target_features;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_feature::UnstableFeatures;
 use rustc_middle::bug;
 use rustc_session::config::PrintRequest;
 use rustc_session::Session;
-use rustc_span::symbol::sym;
 use rustc_span::symbol::Symbol;
 use rustc_target::spec::{MergeFunctions, PanicStrategy};
 use std::ffi::CString;
@@ -139,140 +139,6 @@ pub fn time_trace_profiler_finish(file_name: &str) {
 // WARNING: the features after applying `to_llvm_feature` must be known
 // to LLVM or the feature detection code will walk past the end of the feature
 // array, leading to crashes.
-
-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 to_llvm_feature<'a>(sess: &Session, s: &'a str) -> &'a str {
     let arch = if sess.target.target.arch == "x86_64" { "x86" } else { &*sess.target.target.arch };
     match (arch, s) {
@@ -306,20 +172,6 @@ pub fn target_features(sess: &Session) -> Vec<Symbol> {
         .collect()
 }
 
-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,
-        _ => &[],
-    }
-}
-
 pub fn print_version() {
     // Can be called without initializing LLVM
     unsafe {