Auto merge of #76295 - mati865:remove-mmx, r=Amanieu,oli-obk

Remove MMX from Rust

Follow-up to rust-lang/stdarch#890
This removes most of MMX from Rust (tests pass with small changes), keeping stable `is_x86_feature_detected!("mmx")` working.

Author: bors

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -948,7 +948,6 @@ extern "C" {
 
     // Operations on other types
     pub fn LLVMVoidTypeInContext(C: &Context) -> &Type;
-    pub fn LLVMX86MMXTypeInContext(C: &Context) -> &Type;
     pub fn LLVMRustMetadataTypeInContext(C: &Context) -> &Type;
 
     // Operations on all values

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -203,7 +203,6 @@ const X86_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
     ("fma", None),
     ("fxsr", None),
     ("lzcnt", None),
-    ("mmx", Some(sym::mmx_target_feature)),
     ("movbe", Some(sym::movbe_target_feature)),
     ("pclmulqdq", None),
     ("popcnt", None),

compiler/rustc_codegen_llvm/src/type_.rs

@@ -62,10 +62,6 @@ impl CodegenCx<'ll, 'tcx> {
         unsafe { llvm::LLVMIntTypeInContext(self.llcx, num_bits as c_uint) }
     }
 
-    crate fn type_x86_mmx(&self) -> &'ll Type {
-        unsafe { llvm::LLVMX86MMXTypeInContext(self.llcx) }
-    }
-
     crate fn type_vector(&self, ty: &'ll Type, len: u64) -> &'ll Type {
         unsafe { llvm::LLVMVectorType(ty, len as c_uint) }
     }

compiler/rustc_codegen_llvm/src/type_of.rs

@@ -21,23 +21,8 @@ fn uncached_llvm_type<'a, 'tcx>(
     match layout.abi {
         Abi::Scalar(_) => bug!("handled elsewhere"),
         Abi::Vector { ref element, count } => {
-            // LLVM has a separate type for 64-bit SIMD vectors on X86 called
-            // `x86_mmx` which is needed for some SIMD operations. As a bit of a
-            // hack (all SIMD definitions are super unstable anyway) we
-            // recognize any one-element SIMD vector as "this should be an
-            // x86_mmx" type. In general there shouldn't be a need for other
-            // one-element SIMD vectors, so it's assumed this won't clash with
-            // much else.
-            let use_x86_mmx = count == 1
-                && layout.size.bits() == 64
-                && (cx.sess().target.target.arch == "x86"
-                    || cx.sess().target.target.arch == "x86_64");
-            if use_x86_mmx {
-                return cx.type_x86_mmx();
-            } else {
-                let element = layout.scalar_llvm_type_at(cx, element, Size::ZERO);
-                return cx.type_vector(element, count);
-            }
+            let element = layout.scalar_llvm_type_at(cx, element, Size::ZERO);
+            return cx.type_vector(element, count);
         }
         Abi::ScalarPair(..) => {
             return cx.type_struct(

compiler/rustc_feature/src/active.rs

@@ -229,7 +229,6 @@ declare_features! (
     (active, powerpc_target_feature, "1.27.0", Some(44839), None),
     (active, mips_target_feature, "1.27.0", Some(44839), None),
     (active, avx512_target_feature, "1.27.0", Some(44839), None),
-    (active, mmx_target_feature, "1.27.0", Some(44839), None),
     (active, sse4a_target_feature, "1.27.0", Some(44839), None),
     (active, tbm_target_feature, "1.27.0", Some(44839), None),
     (active, wasm_target_feature, "1.30.0", Some(44839), None),

compiler/rustc_span/src/symbol.rs

@@ -679,7 +679,6 @@ symbols! {
         minnumf32,
         minnumf64,
         mips_target_feature,
-        mmx_target_feature,
         module,
         module_path,
         more_struct_aliases,

compiler/rustc_typeck/src/collect.rs

@@ -2363,7 +2363,6 @@ fn from_target_feature(
                 Some(sym::mips_target_feature) => rust_features.mips_target_feature,
                 Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
                 Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
-                Some(sym::mmx_target_feature) => rust_features.mmx_target_feature,
                 Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
                 Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
                 Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,

library/core/src/lib.rs

@@ -126,7 +126,6 @@
 #![feature(unwind_attributes)]
 #![feature(variant_count)]
 #![cfg_attr(bootstrap, feature(doc_alias))]
-#![feature(mmx_target_feature)]
 #![feature(tbm_target_feature)]
 #![feature(sse4a_target_feature)]
 #![feature(arm_target_feature)]

src/test/codegen/x86_mmx.rs

@@ -1,5 +1,5 @@
-#![feature(mmx_target_feature)]
+#![feature(avx512_target_feature)]
 
 #[inline]
-#[target_feature(enable = "mmx")]
+#[target_feature(enable = "avx512ifma")]
 pub unsafe fn foo() {}