remove 'platform-intrinsic' ABI leftovers

Author: RalfJung

compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs

@@ -1,4 +1,4 @@
-//! Codegen of intrinsics. This includes `extern "rust-intrinsic"`, `extern "platform-intrinsic"`
+//! Codegen of intrinsics. This includes `extern "rust-intrinsic"`,
 //! and LLVM intrinsics that have symbol names starting with `llvm.`.
 
 macro_rules! intrinsic_args {

compiler/rustc_codegen_cranelift/src/intrinsics/simd.rs

@@ -1,4 +1,4 @@
-//! Codegen `extern "platform-intrinsic"` intrinsics.
+//! Codegen SIMD intrinsics.
 
 use cranelift_codegen::ir::immediates::Offset32;
 use rustc_target::abi::Endian;

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -1,5 +1,4 @@
-//! Type-checking for the rust-intrinsic and platform-intrinsic
-//! intrinsics that the compiler exposes.
+//! Type-checking for the rust-intrinsic intrinsics that the compiler exposes.
 
 use rustc_abi::ExternAbi;
 use rustc_errors::codes::*;

compiler/rustc_middle/src/ty/instance.rs

@@ -71,7 +71,7 @@ pub enum InstanceKind<'tcx> {
     /// - coroutines
     Item(DefId),
 
-    /// An intrinsic `fn` item (with `"rust-intrinsic"` or `"platform-intrinsic"` ABI).
+    /// An intrinsic `fn` item (with `"rust-intrinsic"` ABI).
     ///
     /// Alongside `Virtual`, this is the only `InstanceKind` that does not have its own callable MIR.
     /// Instead, codegen and const eval "magically" evaluate calls to intrinsics purely in the