make bit_width return u64, consistently with other sizes in the compiler

Author: RalfJung

src/librustc_ast/ast.rs

@@ -1614,7 +1614,7 @@ impl FloatTy {
         }
     }
 
-    pub fn bit_width(self) -> usize {
+    pub fn bit_width(self) -> u64 {
         match self {
             FloatTy::F32 => 32,
             FloatTy::F64 => 64,
@@ -1663,7 +1663,7 @@ impl IntTy {
         format!("{}{}", val as u128, self.name_str())
     }
 
-    pub fn bit_width(&self) -> Option<usize> {
+    pub fn bit_width(&self) -> Option<u64> {
         Some(match *self {
             IntTy::Isize => return None,
             IntTy::I8 => 8,
@@ -1725,7 +1725,7 @@ impl UintTy {
         format!("{}{}", val, self.name_str())
     }
 
-    pub fn bit_width(&self) -> Option<usize> {
+    pub fn bit_width(&self) -> Option<u64> {
         Some(match *self {
             UintTy::Usize => return None,
             UintTy::U8 => 8,

src/librustc_codegen_llvm/intrinsic.rs

@@ -1172,8 +1172,8 @@ fn generic_simd_intrinsic(
         let m_len = match in_ty.kind {
             // Note that this `.unwrap()` crashes for isize/usize, that's sort
             // of intentional as there's not currently a use case for that.
-            ty::Int(i) => i.bit_width().unwrap() as u64,
-            ty::Uint(i) => i.bit_width().unwrap() as u64,
+            ty::Int(i) => i.bit_width().unwrap(),
+            ty::Uint(i) => i.bit_width().unwrap(),
             _ => return_error!("`{}` is not an integral type", in_ty),
         };
         require_simd!(arg_tys[1], "argument");
@@ -1354,20 +1354,18 @@ fn generic_simd_intrinsic(
         // trailing bits.
         let expected_int_bits = in_len.max(8);
         match ret_ty.kind {
-            ty::Uint(i) if i.bit_width() == Some(expected_int_bits as usize) => (),
+            ty::Uint(i) if i.bit_width() == Some(expected_int_bits) => (),
             _ => return_error!("bitmask `{}`, expected `u{}`", ret_ty, expected_int_bits),
         }
 
         // Integer vector <i{in_bitwidth} x in_len>:
         let (i_xn, in_elem_bitwidth) = match in_elem.kind {
-            ty::Int(i) => (
-                args[0].immediate(),
-                i.bit_width().unwrap_or(bx.data_layout().pointer_size.bits() as _),
-            ),
-            ty::Uint(i) => (
-                args[0].immediate(),
-                i.bit_width().unwrap_or(bx.data_layout().pointer_size.bits() as _),
-            ),
+            ty::Int(i) => {
+                (args[0].immediate(), i.bit_width().unwrap_or(bx.data_layout().pointer_size.bits()))
+            }
+            ty::Uint(i) => {
+                (args[0].immediate(), i.bit_width().unwrap_or(bx.data_layout().pointer_size.bits()))
+            }
             _ => return_error!(
                 "vector argument `{}`'s element type `{}`, expected integer element type",
                 in_ty,
@@ -1378,16 +1376,16 @@ fn generic_simd_intrinsic(
         // Shift the MSB to the right by "in_elem_bitwidth - 1" into the first bit position.
         let shift_indices =
             vec![
-                bx.cx.const_int(bx.type_ix(in_elem_bitwidth as _), (in_elem_bitwidth - 1) as _);
+                bx.cx.const_int(bx.type_ix(in_elem_bitwidth), (in_elem_bitwidth - 1) as _);
                 in_len as _
             ];
         let i_xn_msb = bx.lshr(i_xn, bx.const_vector(shift_indices.as_slice()));
         // Truncate vector to an <i1 x N>
-        let i1xn = bx.trunc(i_xn_msb, bx.type_vector(bx.type_i1(), in_len as _));
+        let i1xn = bx.trunc(i_xn_msb, bx.type_vector(bx.type_i1(), in_len));
         // Bitcast <i1 x N> to iN:
-        let i_ = bx.bitcast(i1xn, bx.type_ix(in_len as _));
+        let i_ = bx.bitcast(i1xn, bx.type_ix(in_len));
         // Zero-extend iN to the bitmask type:
-        return Ok(bx.zext(i_, bx.type_ix(expected_int_bits as _)));
+        return Ok(bx.zext(i_, bx.type_ix(expected_int_bits)));
     }
 
     fn simd_simple_float_intrinsic(
@@ -2099,7 +2097,7 @@ fn int_type_width_signed(ty: Ty<'_>, cx: &CodegenCx<'_, '_>) -> Option<(u64, boo
     match ty.kind {
         ty::Int(t) => Some((
             match t {
-                ast::IntTy::Isize => cx.tcx.sess.target.ptr_width as u64,
+                ast::IntTy::Isize => u64::from(cx.tcx.sess.target.ptr_width),
                 ast::IntTy::I8 => 8,
                 ast::IntTy::I16 => 16,
                 ast::IntTy::I32 => 32,
@@ -2110,7 +2108,7 @@ fn int_type_width_signed(ty: Ty<'_>, cx: &CodegenCx<'_, '_>) -> Option<(u64, boo
         )),
         ty::Uint(t) => Some((
             match t {
-                ast::UintTy::Usize => cx.tcx.sess.target.ptr_width as u64,
+                ast::UintTy::Usize => u64::from(cx.tcx.sess.target.ptr_width),
                 ast::UintTy::U8 => 8,
                 ast::UintTy::U16 => 16,
                 ast::UintTy::U32 => 32,
@@ -2127,7 +2125,7 @@ fn int_type_width_signed(ty: Ty<'_>, cx: &CodegenCx<'_, '_>) -> Option<(u64, boo
 // Returns None if the type is not a float
 fn float_type_width(ty: Ty<'_>) -> Option<u64> {
     match ty.kind {
-        ty::Float(t) => Some(t.bit_width() as u64),
+        ty::Float(t) => Some(t.bit_width()),
         _ => None,
     }
 }

src/librustc_mir/interpret/cast.rs

@@ -228,17 +228,16 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         match dest_ty.kind {
             // float -> uint
             Uint(t) => {
-                // FIXME: can we make `bit_width` return a type more compatible with `Size::bits`?
-                let width = t.bit_width().unwrap_or_else(|| self.pointer_size().bits() as usize);
-                let v = f.to_u128(width).value;
+                let width = t.bit_width().unwrap_or_else(|| self.pointer_size().bits());
+                let v = f.to_u128(usize::try_from(width).unwrap()).value;
                 // This should already fit the bit width
-                Ok(Scalar::from_uint(v, Size::from_bits(width as u64)))
+                Ok(Scalar::from_uint(v, Size::from_bits(width)))
             }
             // float -> int
             Int(t) => {
-                let width = t.bit_width().unwrap_or_else(|| self.pointer_size().bits() as usize);
-                let v = f.to_i128(width).value;
-                Ok(Scalar::from_int(v, Size::from_bits(width as u64)))
+                let width = t.bit_width().unwrap_or_else(|| self.pointer_size().bits());
+                let v = f.to_i128(usize::try_from(width).unwrap()).value;
+                Ok(Scalar::from_int(v, Size::from_bits(width)))
             }
             // float -> f32
             Float(FloatTy::F32) => Ok(Scalar::from_f32(f.convert(&mut false).value)),