Auto merge of #88839 - nbdd0121:alignof, r=nagisa

Introduce NullOp::AlignOf

This PR introduces `Rvalue::NullaryOp(NullOp::AlignOf, ty)`, which will be lowered from `align_of`, similar to `size_of` lowering to `Rvalue::NullaryOp(NullOp::SizeOf, ty)`.

The changes are originally part of #88700 but since it's not dependent on other changes and could have performance impact on its own, it's separated into its own PR.

2 files changed, 21 insertions, 15 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs b/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
index 75999225c03..f943157dc66 100644
--- a/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
@@ -104,7 +104,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 }
             }
             sym::pref_align_of
-            | sym::min_align_of
             | sym::needs_drop
             | sym::type_id
             | sym::type_name
diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
index f65af17535a..7403c21a906 100644
--- a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
@@ -486,20 +486,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 )
             }
 
-            mir::Rvalue::NullaryOp(mir::NullOp::SizeOf, ty) => {
-                let ty = self.monomorphize(ty);
-                assert!(bx.cx().type_is_sized(ty));
-                let val = bx.cx().const_usize(bx.cx().layout_of(ty).size.bytes());
-                let tcx = self.cx.tcx();
-                (
-                    bx,
-                    OperandRef {
-                        val: OperandValue::Immediate(val),
-                        layout: self.cx.layout_of(tcx.types.usize),
-                    },
-                )
-            }
-
             mir::Rvalue::NullaryOp(mir::NullOp::Box, content_ty) => {
                 let content_ty = self.monomorphize(content_ty);
                 let content_layout = bx.cx().layout_of(content_ty);
@@ -524,6 +510,27 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 let operand = OperandRef { val: OperandValue::Immediate(val), layout: box_layout };
                 (bx, operand)
             }
+
+            mir::Rvalue::NullaryOp(null_op, ty) => {
+                let ty = self.monomorphize(ty);
+                assert!(bx.cx().type_is_sized(ty));
+                let layout = bx.cx().layout_of(ty);
+                let val = match null_op {
+                    mir::NullOp::SizeOf => layout.size.bytes(),
+                    mir::NullOp::AlignOf => layout.align.abi.bytes(),
+                    mir::NullOp::Box => unreachable!(),
+                };
+                let val = bx.cx().const_usize(val);
+                let tcx = self.cx.tcx();
+                (
+                    bx,
+                    OperandRef {
+                        val: OperandValue::Immediate(val),
+                        layout: self.cx.layout_of(tcx.types.usize),
+                    },
+                )
+            }
+
             mir::Rvalue::ThreadLocalRef(def_id) => {
                 assert!(bx.cx().tcx().is_static(def_id));
                 let static_ = bx.get_static(def_id);