Mention Register Size in #[warn(asm_sub_register)]

Fixes #121593

compiler/rustc_hir_analysis/src/check/intrinsicck.rs

@@ -6,7 +6,9 @@
 use rustc_span::def_id::LocalDefId;
 use rustc_span::Symbol;
 use rustc_target::abi::FieldIdx;
-use rustc_target::asm::{InlineAsmReg, InlineAsmRegClass, InlineAsmRegOrRegClass, InlineAsmType};
+use rustc_target::asm::{
+    InlineAsmReg, InlineAsmRegClass, InlineAsmRegOrRegClass, InlineAsmType, ModifierInfo,
+};
 
 pub struct InlineAsmCtxt<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
@@ -253,8 +255,11 @@ fn check_asm_operand_type(
         }
 
         // Check whether a modifier is suggested for using this type.
-        if let Some((suggested_modifier, suggested_result)) =
+        if let Some(ModifierInfo {
-            reg_class.suggest_modifier(asm_arch, asm_ty)
+            modifier: suggested_modifier,
+            result: suggested_result,
+            size: suggested_size,
+        }) = reg_class.suggest_modifier(asm_arch, asm_ty)
         {
             // Search for any use of this operand without a modifier and emit
             // the suggestion for them.
@@ -268,8 +273,11 @@ fn check_asm_operand_type(
                 }
             }
             if !spans.is_empty() {
-                let (default_modifier, default_result) =
+                let ModifierInfo {
-                    reg_class.default_modifier(asm_arch).unwrap();
+                    modifier: default_modifier,
+                    result: default_result,
+                    size: default_size,
+                } = reg_class.default_modifier(asm_arch).unwrap();
                 self.tcx.node_span_lint(
                     lint::builtin::ASM_SUB_REGISTER,
                     expr.hir_id,
@@ -278,10 +286,10 @@ fn check_asm_operand_type(
                     |lint| {
                         lint.span_label(expr.span, "for this argument");
                         lint.help(format!(
-                            "use `{{{idx}:{suggested_modifier}}}` to have the register formatted as `{suggested_result}`",
+                            "use `{{{idx}:{suggested_modifier}}}` to have the register formatted as `{suggested_result}` (for {suggested_size}-bit values)",
                         ));
                         lint.help(format!(
-                            "or use `{{{idx}:{default_modifier}}}` to keep the default formatting of `{default_result}`",
+                            "or use `{{{idx}:{default_modifier}}}` to keep the default formatting of `{default_result}` (for {default_size}-bit values)",
                         ));
                     },
                 );

compiler/rustc_target/src/asm/aarch64.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use crate::spec::{RelocModel, Target};
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_macros::HashStable_Generic;
@@ -27,32 +27,28 @@ pub fn suggest_class(self, _arch: InlineAsmArch, _ty: InlineAsmType) -> Option<S
         None
     }
 
-    pub fn suggest_modifier(
+    pub fn suggest_modifier(self, _arch: InlineAsmArch, ty: InlineAsmType) -> Option<ModifierInfo> {
-        self,
-        _arch: InlineAsmArch,
-        ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
         match self {
             Self::reg => match ty.size().bits() {
                 64 => None,
-                _ => Some(('w', "w0")),
+                _ => Some(('w', "w0", 32).into()),
             },
             Self::vreg | Self::vreg_low16 => match ty.size().bits() {
-                8 => Some(('b', "b0")),
+                8 => Some(('b', "b0", 8).into()),
-                16 => Some(('h', "h0")),
+                16 => Some(('h', "h0", 16).into()),
-                32 => Some(('s', "s0")),
+                32 => Some(('s', "s0", 32).into()),
-                64 => Some(('d', "d0")),
+                64 => Some(('d', "d0", 64).into()),
-                128 => Some(('q', "q0")),
+                128 => Some(('q', "q0", 128).into()),
                 _ => None,
             },
             Self::preg => None,
         }
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         match self {
-            Self::reg => Some(('x', "x0")),
+            Self::reg => Some(('x', "x0", 64).into()),
-            Self::vreg | Self::vreg_low16 => Some(('v', "v0")),
+            Self::vreg | Self::vreg_low16 => Some(('v', "v0", 128).into()),
             Self::preg => None,
         }
     }

compiler/rustc_target/src/asm/arm.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use crate::spec::{RelocModel, Target};
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_macros::HashStable_Generic;
@@ -35,11 +35,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/avr.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 use std::fmt;
@@ -29,11 +29,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/bpf.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 use std::fmt;
@@ -23,11 +23,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/csky.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 use std::fmt;
@@ -23,11 +23,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/hexagon.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 use std::fmt;
@@ -22,11 +22,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/loongarch.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 use std::fmt;
@@ -23,11 +23,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/m68k.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 use std::fmt;
@@ -24,11 +24,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/mips.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 use std::fmt;
@@ -23,11 +23,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/mod.rs

@@ -6,6 +6,18 @@
 use std::fmt;
 use std::str::FromStr;
 
+pub struct ModifierInfo {
+    pub modifier: char,
+    pub result: &'static str,
+    pub size: u64,
+}
+
+impl From<(char, &'static str, u64)> for ModifierInfo {
+    fn from(value: (char, &'static str, u64)) -> Self {
+        Self { modifier: value.0, result: value.1, size: value.2 }
+    }
+}
+
 macro_rules! def_reg_class {
     ($arch:ident $arch_regclass:ident {
         $(
@@ -512,11 +524,7 @@ pub fn suggest_class(self, arch: InlineAsmArch, ty: InlineAsmType) -> Option<Sel
     /// Such suggestions are useful if a type smaller than the full register
     /// size is used and a modifier can be used to point to the subregister of
     /// the correct size.
-    pub fn suggest_modifier(
+    pub fn suggest_modifier(self, arch: InlineAsmArch, ty: InlineAsmType) -> Option<ModifierInfo> {
-        self,
-        arch: InlineAsmArch,
-        ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
         match self {
             Self::X86(r) => r.suggest_modifier(arch, ty),
             Self::Arm(r) => r.suggest_modifier(arch, ty),
@@ -545,7 +553,7 @@ pub fn suggest_modifier(
     /// This is only needed when the register class can suggest a modifier, so
     /// that the user can be shown how to get the default behavior without a
     /// warning.
-    pub fn default_modifier(self, arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, arch: InlineAsmArch) -> Option<ModifierInfo> {
         match self {
             Self::X86(r) => r.default_modifier(arch),
             Self::Arm(r) => r.default_modifier(arch),

compiler/rustc_target/src/asm/msp430.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 use std::fmt;
@@ -22,11 +22,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/nvptx.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 
@@ -23,11 +23,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/powerpc.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 use std::fmt;
@@ -26,11 +26,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/riscv.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use crate::spec::{RelocModel, Target};
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_macros::HashStable_Generic;
@@ -26,11 +26,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/s390x.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 use std::fmt;
@@ -24,11 +24,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/spirv.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 
@@ -21,11 +21,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/wasm.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use rustc_macros::HashStable_Generic;
 use rustc_span::Symbol;
 
@@ -21,11 +21,11 @@ pub fn suggest_modifier(
         self,
         _arch: InlineAsmArch,
         _ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
+    ) -> Option<ModifierInfo> {
         None
     }
 
-    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, _arch: InlineAsmArch) -> Option<ModifierInfo> {
         None
     }
 

compiler/rustc_target/src/asm/x86.rs

@@ -1,4 +1,4 @@
-use super::{InlineAsmArch, InlineAsmType};
+use super::{InlineAsmArch, InlineAsmType, ModifierInfo};
 use crate::spec::{RelocModel, Target};
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_macros::HashStable_Generic;
@@ -53,32 +53,28 @@ pub fn suggest_class(self, _arch: InlineAsmArch, ty: InlineAsmType) -> Option<Se
         }
     }
 
-    pub fn suggest_modifier(
+    pub fn suggest_modifier(self, arch: InlineAsmArch, ty: InlineAsmType) -> Option<ModifierInfo> {
-        self,
-        arch: InlineAsmArch,
-        ty: InlineAsmType,
-    ) -> Option<(char, &'static str)> {
         match self {
             Self::reg => match ty.size().bits() {
-                16 => Some(('x', "ax")),
+                16 => Some(('x', "ax", 16).into()),
-                32 if arch == InlineAsmArch::X86_64 => Some(('e', "eax")),
+                32 if arch == InlineAsmArch::X86_64 => Some(('e', "eax", 32).into()),
                 _ => None,
             },
             Self::reg_abcd => match ty.size().bits() {
-                16 => Some(('x', "ax")),
+                16 => Some(('x', "ax", 16).into()),
-                32 if arch == InlineAsmArch::X86_64 => Some(('e', "eax")),
+                32 if arch == InlineAsmArch::X86_64 => Some(('e', "eax", 32).into()),
                 _ => None,
             },
             Self::reg_byte => None,
             Self::xmm_reg => None,
             Self::ymm_reg => match ty.size().bits() {
                 256 => None,
-                _ => Some(('x', "xmm0")),
+                _ => Some(('x', "xmm0", 128).into()),
             },
             Self::zmm_reg => match ty.size().bits() {
                 512 => None,
-                256 => Some(('y', "ymm0")),
+                256 => Some(('y', "ymm0", 256).into()),
-                _ => Some(('x', "xmm0")),
+                _ => Some(('x', "xmm0", 128).into()),
             },
             Self::kreg | Self::kreg0 => None,
             Self::mmx_reg | Self::x87_reg => None,
@@ -86,19 +82,19 @@ pub fn suggest_modifier(
         }
     }
 
-    pub fn default_modifier(self, arch: InlineAsmArch) -> Option<(char, &'static str)> {
+    pub fn default_modifier(self, arch: InlineAsmArch) -> Option<ModifierInfo> {
         match self {
             Self::reg | Self::reg_abcd => {
                 if arch == InlineAsmArch::X86_64 {
-                    Some(('r', "rax"))
+                    Some(('r', "rax", 64).into())
                 } else {
-                    Some(('e', "eax"))
+                    Some(('e', "eax", 32).into())
                 }
             }
             Self::reg_byte => None,
-            Self::xmm_reg => Some(('x', "xmm0")),
+            Self::xmm_reg => Some(('x', "xmm0", 128).into()),
-            Self::ymm_reg => Some(('y', "ymm0")),
+            Self::ymm_reg => Some(('y', "ymm0", 256).into()),
-            Self::zmm_reg => Some(('z', "zmm0")),
+            Self::zmm_reg => Some(('z', "zmm0", 512).into()),
             Self::kreg | Self::kreg0 => None,
             Self::mmx_reg | Self::x87_reg => None,
             Self::tmm_reg => None,