Auto merge of #69333 - ecstatic-morse:revert-simd-shuffle, r=petrochenkov

Revert #69280

Resolves #69313 by reverting #69280.

After #69280, `#[rustc_args_required_const(2)]` is required on the declaration of `simd_shuffle` intrinsics. This is allowed breakage, since you can't define platform intrinsics on stable. However, the latest release of the widely used `packed_simd` crate defines these intrinsics without the requisite attribute. Since there's no urgency to merge #69280, let's revert it. We can reconsider when rust-lang/packed_simd#278 is included in a point release of `packed_simd`.

r? @petrochenkov

Author: bors

src/librustc_mir/const_eval/eval_queries.rs

@@ -72,8 +72,8 @@ fn eval_body_using_ecx<'mir, 'tcx>(
     Ok(ret)
 }
 
-/// The `InterpCx` is only meant to be used to do field and index projections into promoteds
-/// and const patterns in match arms.
+/// The `InterpCx` is only meant to be used to do field and index projections into constants for
+/// `simd_shuffle` and const patterns in match arms.
 ///
 /// The function containing the `match` that is currently being analyzed may have generic bounds
 /// that inform us about the generic bounds of the constant. E.g., using an associated constant

src/librustc_mir/transform/promote_consts.rs

@@ -24,6 +24,7 @@ use rustc_span::{Span, DUMMY_SP};
 use syntax::ast::LitKind;
 
 use rustc_index::vec::{Idx, IndexVec};
+use rustc_target::spec::abi::Abi;
 
 use std::cell::Cell;
 use std::{cmp, iter, mem, usize};
@@ -105,10 +106,11 @@ pub enum Candidate {
     /// Promotion of the `x` in `[x; 32]`.
     Repeat(Location),
 
-    /// Function calls where the callee has the unstable
-    /// `#[rustc_args_required_const]` attribute. The attribute requires that
-    /// the arguments be constant, usually because they are encoded as an
-    /// immediate operand in a platform intrinsic.
+    /// Currently applied to function calls where the callee has the unstable
+    /// `#[rustc_args_required_const]` attribute as well as the SIMD shuffle
+    /// intrinsic. The intrinsic requires the arguments are indeed constant and
+    /// the attribute currently provides the semantic requirement that arguments
+    /// must be constant.
     Argument { bb: BasicBlock, index: usize },
 }
 
@@ -216,6 +218,17 @@ impl<'tcx> Visitor<'tcx> for Collector<'_, 'tcx> {
 
         if let TerminatorKind::Call { ref func, .. } = *kind {
             if let ty::FnDef(def_id, _) = func.ty(self.body, self.tcx).kind {
+                let fn_sig = self.tcx.fn_sig(def_id);
+                if let Abi::RustIntrinsic | Abi::PlatformIntrinsic = fn_sig.abi() {
+                    let name = self.tcx.item_name(def_id);
+                    // FIXME(eddyb) use `#[rustc_args_required_const(2)]` for shuffles.
+                    if name.as_str().starts_with("simd_shuffle") {
+                        self.candidates.push(Candidate::Argument { bb: location.block, index: 2 });
+
+                        return; // Don't double count `simd_shuffle` candidates
+                    }
+                }
+
                 if let Some(constant_args) = args_required_const(self.tcx, def_id) {
                     for index in constant_args {
                         self.candidates.push(Candidate::Argument { bb: location.block, index });
@@ -717,7 +730,8 @@ pub fn validate_candidates(
         .filter(|&candidate| {
             validator.explicit = candidate.forces_explicit_promotion();
 
-            // FIXME(eddyb) also emit the errors for `#[rustc_args_required_const]` arguments here.
+            // FIXME(eddyb) also emit the errors for shuffle indices
+            // and `#[rustc_args_required_const]` arguments here.
 
             let is_promotable = validator.validate_candidate(candidate).is_ok();
             match candidate {

src/test/incremental/issue-61530.rs

@@ -1,12 +1,11 @@
-#![feature(repr_simd, platform_intrinsics, rustc_attrs)]
+#![feature(repr_simd, platform_intrinsics)]
 
 // revisions:rpass1 rpass2
 
 #[repr(simd)]
 struct I32x2(i32, i32);
 
 extern "platform-intrinsic" {
-    #[rustc_args_required_const(2)]
     fn simd_shuffle2<T, U>(x: T, y: T, idx: [u32; 2]) -> U;
 }
 

src/test/ui/issues/issue-38074.rs

@@ -1,10 +1,9 @@
 // run-pass
 // ignore-emscripten FIXME(#45351)
 
-#![feature(platform_intrinsics, repr_simd, rustc_attrs)]
+#![feature(platform_intrinsics, repr_simd)]
 
 extern "platform-intrinsic" {
-    #[rustc_args_required_const(2)]
     fn simd_shuffle2<T, U>(x: T, y: T, idx: [u32; 2]) -> U;
 }
 

src/test/ui/simd-intrinsic/simd-intrinsic-generic-elements.rs

@@ -42,13 +42,9 @@ extern "platform-intrinsic" {
     fn simd_insert<T, E>(x: T, idx: u32, y: E) -> T;
     fn simd_extract<T, E>(x: T, idx: u32) -> E;
 
-    #[rustc_args_required_const(2)]
     fn simd_shuffle2<T, U>(x: T, y: T, idx: [u32; 2]) -> U;
-    #[rustc_args_required_const(2)]
     fn simd_shuffle3<T, U>(x: T, y: T, idx: [u32; 3]) -> U;
-    #[rustc_args_required_const(2)]
     fn simd_shuffle4<T, U>(x: T, y: T, idx: [u32; 4]) -> U;
-    #[rustc_args_required_const(2)]
     fn simd_shuffle8<T, U>(x: T, y: T, idx: [u32; 8]) -> U;
 }
 

src/test/ui/simd-intrinsic/simd-intrinsic-generic-elements.stderr

@@ -1,89 +1,89 @@
 error[E0511]: invalid monomorphization of `simd_insert` intrinsic: expected SIMD input type, found non-SIMD `i32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:59:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:55:9
    |
 LL |         simd_insert(0, 0, 0);
    |         ^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_insert` intrinsic: expected inserted type `i32` (element of input `i32x4`), found `f64`
-  --> $DIR/simd-intrinsic-generic-elements.rs:61:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:57:9
    |
 LL |         simd_insert(x, 0, 1.0);
    |         ^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_extract` intrinsic: expected return type `i32` (element of input `i32x4`), found `f32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:63:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:59:9
    |
 LL |         simd_extract::<_, f32>(x, 0);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle2` intrinsic: expected SIMD input type, found non-SIMD `i32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:66:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:62:9
    |
 LL |         simd_shuffle2::<i32, i32>(0, 0, [0; 2]);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle3` intrinsic: expected SIMD input type, found non-SIMD `i32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:68:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:64:9
    |
 LL |         simd_shuffle3::<i32, i32>(0, 0, [0; 3]);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle4` intrinsic: expected SIMD input type, found non-SIMD `i32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:70:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:66:9
    |
 LL |         simd_shuffle4::<i32, i32>(0, 0, [0; 4]);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle8` intrinsic: expected SIMD input type, found non-SIMD `i32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:72:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:68:9
    |
 LL |         simd_shuffle8::<i32, i32>(0, 0, [0; 8]);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle2` intrinsic: expected return element type `i32` (element of input `i32x4`), found `f32x2` with element type `f32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:75:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:71:9
    |
 LL |         simd_shuffle2::<_, f32x2>(x, x, [0; 2]);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle3` intrinsic: expected return element type `i32` (element of input `i32x4`), found `f32x3` with element type `f32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:77:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:73:9
    |
 LL |         simd_shuffle3::<_, f32x3>(x, x, [0; 3]);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle4` intrinsic: expected return element type `i32` (element of input `i32x4`), found `f32x4` with element type `f32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:79:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:75:9
    |
 LL |         simd_shuffle4::<_, f32x4>(x, x, [0; 4]);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle8` intrinsic: expected return element type `i32` (element of input `i32x4`), found `f32x8` with element type `f32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:81:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:77:9
    |
 LL |         simd_shuffle8::<_, f32x8>(x, x, [0; 8]);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle2` intrinsic: expected return type of length 2, found `i32x8` with length 8
-  --> $DIR/simd-intrinsic-generic-elements.rs:84:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:80:9
    |
 LL |         simd_shuffle2::<_, i32x8>(x, x, [0; 2]);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle3` intrinsic: expected return type of length 3, found `i32x4` with length 4
-  --> $DIR/simd-intrinsic-generic-elements.rs:86:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:82:9
    |
 LL |         simd_shuffle3::<_, i32x4>(x, x, [0; 3]);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle4` intrinsic: expected return type of length 4, found `i32x3` with length 3
-  --> $DIR/simd-intrinsic-generic-elements.rs:88:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:84:9
    |
 LL |         simd_shuffle4::<_, i32x3>(x, x, [0; 4]);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle8` intrinsic: expected return type of length 8, found `i32x2` with length 2
-  --> $DIR/simd-intrinsic-generic-elements.rs:90:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:86:9
    |
 LL |         simd_shuffle8::<_, i32x2>(x, x, [0; 8]);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

src/test/ui/simd-intrinsic/simd-intrinsic-inlining-issue67557-ice.rs

@@ -3,10 +3,9 @@
 //
 // run-pass
 // compile-flags: -Zmir-opt-level=3
-#![feature(platform_intrinsics, repr_simd, rustc_attrs)]
+#![feature(platform_intrinsics, repr_simd)]
 
 extern "platform-intrinsic" {
-    #[rustc_args_required_const(2)]
     fn simd_shuffle2<T, U>(x: T, y: T, idx: [u32; 2]) -> U;
 }
 

src/test/ui/simd-intrinsic/simd-intrinsic-inlining-issue67557.rs

@@ -3,10 +3,9 @@
 //
 // run-pass
 // compile-flags: -Zmir-opt-level=3
-#![feature(platform_intrinsics, repr_simd, rustc_attrs)]
+#![feature(platform_intrinsics, repr_simd)]
 
 extern "platform-intrinsic" {
-    #[rustc_args_required_const(2)]
     fn simd_shuffle2<T, U>(x: T, y: T, idx: [u32; 2]) -> U;
 }
 

src/test/ui/simd/simd-intrinsic-generic-elements.rs

@@ -1,7 +1,7 @@
 // run-pass
 // ignore-emscripten FIXME(#45351) hits an LLVM assert
 
-#![feature(repr_simd, platform_intrinsics, rustc_attrs)]
+#![feature(repr_simd, platform_intrinsics)]
 
 #[repr(simd)]
 #[derive(Copy, Clone, Debug, PartialEq)]
@@ -25,13 +25,9 @@ extern "platform-intrinsic" {
     fn simd_insert<T, E>(x: T, idx: u32, y: E) -> T;
     fn simd_extract<T, E>(x: T, idx: u32) -> E;
 
-    #[rustc_args_required_const(2)]
     fn simd_shuffle2<T, U>(x: T, y: T, idx: [u32; 2]) -> U;
-    #[rustc_args_required_const(2)]
     fn simd_shuffle3<T, U>(x: T, y: T, idx: [u32; 3]) -> U;
-    #[rustc_args_required_const(2)]
     fn simd_shuffle4<T, U>(x: T, y: T, idx: [u32; 4]) -> U;
-    #[rustc_args_required_const(2)]
     fn simd_shuffle8<T, U>(x: T, y: T, idx: [u32; 8]) -> U;
 }