Use Operand::constant() in a couple of places

Also reduce visibility of a function

Author: bjorn3

src/constant.rs

@@ -228,7 +228,7 @@ fn pointer_for_allocation<'tcx>(
     crate::pointer::Pointer::new(global_ptr)
 }
 
-pub(crate) fn data_id_for_alloc_id(
+fn data_id_for_alloc_id(
     cx: &mut ConstantCx,
     module: &mut dyn Module,
     alloc_id: AllocId,

src/intrinsics/llvm_x86.rs

@@ -202,9 +202,10 @@ pub(super) fn codegen_x86_llvm_intrinsic_call<'tcx>(
             };
             let x = codegen_operand(fx, &x.node);
             let y = codegen_operand(fx, &y.node);
-            let kind = match &kind.node {
-                Operand::Constant(const_) => crate::constant::eval_mir_constant(fx, const_).0,
-                Operand::Copy(_) | Operand::Move(_) => unreachable!("{kind:?}"),
+            let kind = if let Some(const_) = kind.node.constant() {
+                crate::constant::eval_mir_constant(fx, const_).0
+            } else {
+                unreachable!("{kind:?}")
             };
 
             let flt_cc = match kind

src/intrinsics/simd.rs

@@ -205,9 +205,10 @@ pub(super) fn codegen_simd_intrinsic_call<'tcx>(
             // Find a way to reuse `immediate_const_vector` from `codegen_ssa` instead.
             let indexes = {
                 use rustc_middle::mir::interpret::*;
-                let idx_const = match &idx.node {
-                    Operand::Constant(const_) => crate::constant::eval_mir_constant(fx, const_).0,
-                    Operand::Copy(_) | Operand::Move(_) => unreachable!("{idx:?}"),
+                let idx_const = if let Some(const_) = idx.node.constant() {
+                    crate::constant::eval_mir_constant(fx, const_).0
+                } else {
+                    unreachable!("{idx:?}")
                 };
 
                 let idx_bytes = match idx_const {