Gate z inline asm template modifier

compiler/rustc_ast_lowering/src/asm.rs

@@ -261,24 +261,45 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         if class == asm::InlineAsmRegClass::Err {
                             continue;
                         }
-                        let valid_modifiers = class.valid_modifiers(asm_arch.unwrap());
+                        let valid_modifiers =
+                            class.valid_modifiers(asm_arch.unwrap(), allow_experimental_reg);
                         if !valid_modifiers.contains(&modifier) {
-                            let sub = if valid_modifiers.is_empty() {
-                                InvalidAsmTemplateModifierRegClassSub::DoesNotSupportModifier {
-                                    class_name: class.name(),
-                                }
+                            // First check if the requested modifier is missing from the valid
+                            // values because experimental registers are disabled.
+                            let unstable_modifiers = class.valid_modifiers(asm_arch.unwrap(), true);
+                            if !allow_experimental_reg && unstable_modifiers.contains(&modifier) {
+                                self.tcx.sess.create_feature_err(
+                                    InvalidAsmTemplateModifierRegClass {
+                                        placeholder_span,
+                                        op_span: op_sp,
+                                        modifier: modifier.to_string(),
+                                        sub: InvalidAsmTemplateModifierRegClassSub::ModifierIsGated {
+                                            class_name: class.name(),
+                                            feature: sym::asm_experimental_reg,
+                                            stable_modifiers: valid_modifiers.to_vec().into(),
+                                            all_modifiers: unstable_modifiers.to_vec().into(),
+                                        },
+                                    },
+                                    sym::asm_experimental_reg,
+                                ).emit();
                             } else {
-                                InvalidAsmTemplateModifierRegClassSub::SupportModifier {
-                                    class_name: class.name(),
-                                    modifiers: valid_modifiers.to_vec().into(),
-                                }
-                            };
-                            self.dcx().emit_err(InvalidAsmTemplateModifierRegClass {
-                                placeholder_span,
-                                op_span: op_sp,
-                                modifier: modifier.to_string(),
-                                sub,
-                            });
+                                let sub = if valid_modifiers.is_empty() {
+                                    InvalidAsmTemplateModifierRegClassSub::DoesNotSupportModifier {
+                                        class_name: class.name(),
+                                    }
+                                } else {
+                                    InvalidAsmTemplateModifierRegClassSub::SupportModifier {
+                                        class_name: class.name(),
+                                        modifiers: valid_modifiers.to_vec().into(),
+                                    }
+                                };
+                                self.dcx().emit_err(InvalidAsmTemplateModifierRegClass {
+                                    placeholder_span,
+                                    op_span: op_sp,
+                                    modifier: modifier.to_string(),
+                                    sub,
+                                });
+                            }
                         }
                     }
                     hir::InlineAsmOperand::Const { .. } => {

compiler/rustc_ast_lowering/src/diagnostics.rs

@@ -266,6 +266,18 @@ pub(crate) enum InvalidAsmTemplateModifierRegClassSub {
     SupportModifier { class_name: Symbol, modifiers: DiagSymbolList<char> },
     #[note("the `{$class_name}` register class does not support template modifiers")]
     DoesNotSupportModifier { class_name: Symbol },
+
+    /// Enabling a feature is needed to use the requested modifier.
+    #[note(
+        "the `{$class_name}` register class only supports the following template modifiers on stable: {$stable_modifiers}"
+    )]
+    #[note("enabling the `{$feature}` feature will allow using: {$all_modifiers}")]
+    ModifierIsGated {
+        class_name: Symbol,
+        feature: Symbol,
+        stable_modifiers: DiagSymbolList<char>,
+        all_modifiers: DiagSymbolList<char>,
+    },
 }
 
 #[derive(Diagnostic)]

compiler/rustc_target/src/asm/aarch64.rs

@@ -18,10 +18,21 @@ def_reg_class! {
 }
 
 impl AArch64InlineAsmRegClass {
-    pub fn valid_modifiers(self, _arch: super::InlineAsmArch) -> &'static [char] {
+    pub fn valid_modifiers(
+        self,
+        _arch: super::InlineAsmArch,
+        allow_experimental_reg: bool,
+    ) -> &'static [char] {
         match self {
             Self::reg => &['w', 'x'],
-            Self::vreg | Self::vreg_low16 => &['b', 'h', 's', 'd', 'q', 'v', 'z'],
+            Self::vreg | Self::vreg_low16 => {
+                if allow_experimental_reg {
+                    &['b', 'h', 's', 'd', 'q', 'v', 'z']
+                } else {
+                    &['b', 'h', 's', 'd', 'q', 'v']
+                }
+            }
+
             Self::preg | Self::ffr => &[],
         }
     }

compiler/rustc_target/src/asm/mod.rs

@@ -711,13 +711,19 @@ impl InlineAsmRegClass {
         })
     }
 
-    /// Returns the list of template modifiers that can be used with this
-    /// register class.
-    pub fn valid_modifiers(self, arch: InlineAsmArch) -> &'static [char] {
+    /// Returns the list of template modifiers that can be used with this register class, as well as
+    /// whether the `asm_experimental_reg` feature is enabled: there can be template modifiers that
+    /// apply to currently unstable registers, and we don't want to make these modifiers usable
+    /// without the feature gate.
+    pub fn valid_modifiers(
+        self,
+        arch: InlineAsmArch,
+        allow_experimental_reg: bool,
+    ) -> &'static [char] {
         match self {
             Self::X86(r) => r.valid_modifiers(arch),
             Self::Arm(r) => r.valid_modifiers(arch),
-            Self::AArch64(r) => r.valid_modifiers(arch),
+            Self::AArch64(r) => r.valid_modifiers(arch, allow_experimental_reg),
             Self::Amdgpu(r) => r.valid_modifiers(arch),
             Self::RiscV(r) => r.valid_modifiers(arch),
             Self::Nvptx(r) => r.valid_modifiers(arch),

tests/assembly-llvm/asm/aarch64-modifiers.rs

@@ -5,7 +5,7 @@
 //@ compile-flags: -Zmerge-functions=disabled
 //@ needs-llvm-components: aarch64
 
-#![feature(no_core)]
+#![feature(asm_experimental_reg, no_core)]
 #![crate_type = "rlib"]
 #![no_core]
 #![allow(asm_sub_register)]

tests/ui/asm/aarch64/bad-reg.stderr

@@ -30,7 +30,7 @@ LL |         asm!("{:r}", in(vreg) foo);
    |               |
    |               template modifier
    |
-   = note: the `vreg` register class supports the following template modifiers: `b`, `h`, `s`, `d`, `q`, `v`, and `z`
+   = note: the `vreg` register class supports the following template modifiers: `b`, `h`, `s`, `d`, `q`, and `v`
 
 error: invalid asm template modifier `r` for this register class
   --> $DIR/bad-reg.rs:26:15
@@ -40,7 +40,7 @@ LL |         asm!("{:r}", in(vreg_low16) foo);
    |               |
    |               template modifier
    |
-   = note: the `vreg_low16` register class supports the following template modifiers: `b`, `h`, `s`, `d`, `q`, `v`, and `z`
+   = note: the `vreg_low16` register class supports the following template modifiers: `b`, `h`, `s`, `d`, `q`, and `v`
 
 error: asm template modifiers are not allowed for `const` arguments
   --> $DIR/bad-reg.rs:28:15

tests/ui/feature-gates/feature-gate-asm_experimental_reg.aarch64.stderr

@@ -8,6 +8,32 @@ LL |     asm!("/* {0} */", in(preg) p);
    = help: add `#![feature(asm_experimental_reg)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
+error[E0658]: invalid asm template modifier `z` for this register class
+  --> $DIR/feature-gate-asm_experimental_reg.rs:53:24
+   |
+LL |     unsafe { asm!("mov {1:z}.d, {0:z}.d", in(vreg) x, out(vreg) y) };
+   |                        ^^^^^ template modifier        ----------- argument
+   |
+   = note: the `vreg` register class only supports the following template modifiers on stable: `b`, `h`, `s`, `d`, `q`, and `v`
+   = note: enabling the `asm_experimental_reg` feature will allow using: `b`, `h`, `s`, `d`, `q`, `v`, and `z`
+   = note: see issue #133416 <https://github.com/rust-lang/rust/issues/133416> for more information
+   = help: add `#![feature(asm_experimental_reg)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0658]: invalid asm template modifier `z` for this register class
+  --> $DIR/feature-gate-asm_experimental_reg.rs:53:33
+   |
+LL |     unsafe { asm!("mov {1:z}.d, {0:z}.d", in(vreg) x, out(vreg) y) };
+   |                                 ^^^^^     ---------- argument
+   |                                 |
+   |                                 template modifier
+   |
+   = note: the `vreg` register class only supports the following template modifiers on stable: `b`, `h`, `s`, `d`, `q`, and `v`
+   = note: enabling the `asm_experimental_reg` feature will allow using: `b`, `h`, `s`, `d`, `q`, `v`, and `z`
+   = note: see issue #133416 <https://github.com/rust-lang/rust/issues/133416> for more information
+   = help: add `#![feature(asm_experimental_reg)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
 error[E0658]: type `svint32_t` cannot be used with this register class in stable
   --> $DIR/feature-gate-asm_experimental_reg.rs:33:32
    |
@@ -48,6 +74,6 @@ LL |     asm!("/* {0} */", in(preg) p);
    = help: add `#![feature(asm_experimental_reg)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error: aborting due to 5 previous errors
+error: aborting due to 7 previous errors
 
 For more information about this error, try `rustc --explain E0658`.

tests/ui/feature-gates/feature-gate-asm_experimental_reg.loongarch.stderr

@@ -1,5 +1,5 @@
 error[E0658]: register class `vreg` can only be used as a clobber in stable
-  --> $DIR/feature-gate-asm_experimental_reg.rs:60:41
+  --> $DIR/feature-gate-asm_experimental_reg.rs:69:41
    |
 LL |     asm!("xvadd.h {1:u}, {0:u}, {0:u}", out(vreg) y, in(vreg) x);
    |                                         ^^^^^^^^^^^
@@ -9,7 +9,7 @@ LL |     asm!("xvadd.h {1:u}, {0:u}, {0:u}", out(vreg) y, in(vreg) x);
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: register class `vreg` can only be used as a clobber in stable
-  --> $DIR/feature-gate-asm_experimental_reg.rs:60:54
+  --> $DIR/feature-gate-asm_experimental_reg.rs:69:54
    |
 LL |     asm!("xvadd.h {1:u}, {0:u}, {0:u}", out(vreg) y, in(vreg) x);
    |                                                      ^^^^^^^^^^
@@ -19,7 +19,7 @@ LL |     asm!("xvadd.h {1:u}, {0:u}, {0:u}", out(vreg) y, in(vreg) x);
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: type `i8x16` cannot be used with this register class in stable
-  --> $DIR/feature-gate-asm_experimental_reg.rs:60:51
+  --> $DIR/feature-gate-asm_experimental_reg.rs:69:51
    |
 LL |     asm!("xvadd.h {1:u}, {0:u}, {0:u}", out(vreg) y, in(vreg) x);
    |                                                   ^
@@ -29,7 +29,7 @@ LL |     asm!("xvadd.h {1:u}, {0:u}, {0:u}", out(vreg) y, in(vreg) x);
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0658]: type `i8x16` cannot be used with this register class in stable
-  --> $DIR/feature-gate-asm_experimental_reg.rs:60:63
+  --> $DIR/feature-gate-asm_experimental_reg.rs:69:63
    |
 LL |     asm!("xvadd.h {1:u}, {0:u}, {0:u}", out(vreg) y, in(vreg) x);
    |                                                               ^

tests/ui/feature-gates/feature-gate-asm_experimental_reg.rs

@@ -47,6 +47,15 @@ unsafe fn predicate(p: svbool_t) {
     //[aarch64]~| ERROR type `svbool_t` cannot be used with this register class in stable
 }
 
+#[cfg(aarch64)]
+unsafe fn modifier(x: f64) -> f64 {
+    let y: f64;
+    unsafe { asm!("mov {1:z}.d, {0:z}.d", in(vreg) x, out(vreg) y) };
+    //[aarch64]~^ ERROR invalid asm template modifier `z` for this register class
+    //[aarch64]~| ERROR invalid asm template modifier `z` for this register class
+    y
+}
+
 #[cfg(loongarch)]
 #[repr(simd)]
 pub struct i8x16([i8; 16]);