Revert "Merge pull request #15995 from mlugg/fix/union-field-ptr-align"

This reverts commit 40cf3f7ae5fbfb84b7af6b27e6296ee858b209ef, reversing
changes made to d98147414d084bc41b00ba9c0be8c7b82ad4e76c.

1 files changed, 7 insertions, 42 deletions

diff --git a/src/Sema.zig b/src/Sema.zig
index c1ec7d1f01..26da430166 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -25879,9 +25879,6 @@ fn structFieldPtrByIndex(
 
     const target = mod.getTarget();
 
-    const parent_align = struct_ptr_ty_info.flags.alignment.toByteUnitsOptional() orelse
-        try sema.typeAbiAlignment(struct_ptr_ty_info.child.toType());
-
     if (struct_obj.layout == .Packed) {
         comptime assert(Type.packed_struct_layout_version == 2);
 
@@ -25903,6 +25900,8 @@ fn structFieldPtrByIndex(
             ptr_ty_data.packed_offset.bit_offset += struct_ptr_ty_info.packed_offset.bit_offset;
         }
 
+        const parent_align = struct_ptr_ty_info.flags.alignment.toByteUnitsOptional() orelse
+            struct_ptr_ty_info.child.toType().abiAlignment(mod);
         ptr_ty_data.flags.alignment = Alignment.fromByteUnits(parent_align);
 
         // If the field happens to be byte-aligned, simplify the pointer type.
@@ -25926,13 +25925,8 @@ fn structFieldPtrByIndex(
                 ptr_ty_data.packed_offset = .{ .host_size = 0, .bit_offset = 0 };
             }
         }
-    } else if (struct_obj.layout == .Extern and field_index == 0) {
-        // This is the first field in memory, so can inherit the struct alignment
-        ptr_ty_data.flags.alignment = Alignment.fromByteUnits(parent_align);
     } else {
-        // Our alignment is capped at the field alignment
-        const field_align = try sema.structFieldAlignment(field, struct_obj.layout);
-        ptr_ty_data.flags.alignment = Alignment.fromByteUnits(@min(field_align, parent_align));
+        ptr_ty_data.flags.alignment = field.abi_align;
     }
 
     const ptr_field_ty = try mod.ptrType(ptr_ty_data);
@@ -26103,7 +26097,6 @@ fn unionFieldPtr(
     assert(unresolved_union_ty.zigTypeTag(mod) == .Union);
 
     const union_ptr_ty = sema.typeOf(union_ptr);
-    const union_ptr_info = union_ptr_ty.ptrInfo(mod);
     const union_ty = try sema.resolveTypeFields(unresolved_union_ty);
     const union_obj = mod.typeToUnion(union_ty).?;
     const field_index = try sema.unionFieldIndex(block, union_ty, field_name, field_name_src);
@@ -26111,16 +26104,10 @@ fn unionFieldPtr(
     const ptr_field_ty = try mod.ptrType(.{
         .child = field.ty.toIntern(),
         .flags = .{
-            .is_const = union_ptr_info.flags.is_const,
-            .is_volatile = union_ptr_info.flags.is_volatile,
-            .address_space = union_ptr_info.flags.address_space,
-            .alignment = if (union_obj.layout == .Auto) blk: {
-                const union_align = union_ptr_info.flags.alignment.toByteUnitsOptional() orelse try sema.typeAbiAlignment(union_ty);
-                const field_align = try sema.unionFieldAlignment(field);
-                break :blk InternPool.Alignment.fromByteUnits(@min(union_align, field_align));
-            } else union_ptr_info.flags.alignment,
-        },
-        .packed_offset = union_ptr_info.packed_offset,
+            .is_const = !union_ptr_ty.ptrIsMutable(mod),
+            .is_volatile = union_ptr_ty.isVolatilePtr(mod),
+            .address_space = union_ptr_ty.ptrAddressSpace(mod),
+        },
     });
     const enum_field_index = @as(u32, @intCast(union_obj.tag_ty.enumFieldIndex(field_name, mod).?));
 
@@ -35987,28 +35974,6 @@ fn unionFieldAlignment(sema: *Sema, field: Module.Union.Field) !u32 {
         field.abi_align.toByteUnitsOptional() orelse try sema.typeAbiAlignment(field.ty)));
 }
 
-/// Keep implementation in sync with `Module.Struct.Field.alignment`.
-fn structFieldAlignment(sema: *Sema, field: Module.Struct.Field, layout: std.builtin.Type.ContainerLayout) !u32 {
-    const mod = sema.mod;
-    if (field.abi_align.toByteUnitsOptional()) |a| {
-        assert(layout != .Packed);
-        return @as(u32, @intCast(a));
-    }
-    switch (layout) {
-        .Packed => return 0,
-        .Auto => if (mod.getTarget().ofmt != .c) {
-            return sema.typeAbiAlignment(field.ty);
-        },
-        .Extern => {},
-    }
-    // extern
-    const ty_abi_align = try sema.typeAbiAlignment(field.ty);
-    if (field.ty.isAbiInt(mod) and field.ty.intInfo(mod).bits >= 128) {
-        return @max(ty_abi_align, 16);
-    }
-    return ty_abi_align;
-}
-
 /// Synchronize logic with `Type.isFnOrHasRuntimeBits`.
 pub fn fnHasRuntimeBits(sema: *Sema, ty: Type) CompileError!bool {
     const mod = sema.mod;