Merge pull request #21758 from kcbanner/dll_storage_class

Add `is_dll_import` to @extern, to support `__declspec(dllimport)` with the MSVC ABI

2 files changed, 17 insertions, 9 deletions

diff --git a/src/codegen/llvm.zig b/src/codegen/llvm.zig
index d83e5b4e0a..f19577cac8 100644
--- a/src/codegen/llvm.zig
+++ b/src/codegen/llvm.zig
@@ -3260,10 +3260,10 @@ pub const Object = struct {
         const ip = &zcu.intern_pool;
         const nav = ip.getNav(nav_index);
         const resolved = nav.status.resolved;
-        const is_extern, const is_threadlocal, const is_weak_linkage = switch (ip.indexToKey(resolved.val)) {
-            .variable => |variable| .{ false, variable.is_threadlocal, variable.is_weak_linkage },
-            .@"extern" => |@"extern"| .{ true, @"extern".is_threadlocal, @"extern".is_weak_linkage },
-            else => .{ false, false, false },
+        const is_extern, const is_threadlocal, const is_weak_linkage, const is_dll_import = switch (ip.indexToKey(resolved.val)) {
+            .variable => |variable| .{ false, variable.is_threadlocal, variable.is_weak_linkage, false },
+            .@"extern" => |@"extern"| .{ true, @"extern".is_threadlocal, @"extern".is_weak_linkage, @"extern".is_dll_import },
+            else => .{ false, false, false, false },
         };
 
         const variable_index = try o.builder.addVariable(
@@ -3280,6 +3280,7 @@ pub const Object = struct {
             if (is_threadlocal and !zcu.navFileScope(nav_index).mod.single_threaded)
                 variable_index.setThreadLocal(.generaldynamic, &o.builder);
             if (is_weak_linkage) variable_index.setLinkage(.extern_weak, &o.builder);
+            if (is_dll_import) variable_index.setDllStorageClass(.dllimport, &o.builder);
         } else {
             variable_index.setLinkage(.internal, &o.builder);
             variable_index.setUnnamedAddr(.unnamed_addr, &o.builder);
@@ -4810,10 +4811,10 @@ pub const NavGen = struct {
         const nav = ip.getNav(nav_index);
         const resolved = nav.status.resolved;
 
-        const is_extern, const lib_name, const is_threadlocal, const is_weak_linkage, const is_const, const init_val, const owner_nav = switch (ip.indexToKey(resolved.val)) {
-            .variable => |variable| .{ false, variable.lib_name, variable.is_threadlocal, variable.is_weak_linkage, false, variable.init, variable.owner_nav },
-            .@"extern" => |@"extern"| .{ true, @"extern".lib_name, @"extern".is_threadlocal, @"extern".is_weak_linkage, @"extern".is_const, .none, @"extern".owner_nav },
-            else => .{ false, .none, false, false, true, resolved.val, nav_index },
+        const is_extern, const lib_name, const is_threadlocal, const is_weak_linkage, const is_dll_import, const is_const, const init_val, const owner_nav = switch (ip.indexToKey(resolved.val)) {
+            .variable => |variable| .{ false, variable.lib_name, variable.is_threadlocal, variable.is_weak_linkage, false, false, variable.init, variable.owner_nav },
+            .@"extern" => |@"extern"| .{ true, @"extern".lib_name, @"extern".is_threadlocal, @"extern".is_weak_linkage, @"extern".is_dll_import, @"extern".is_const, .none, @"extern".owner_nav },
+            else => .{ false, .none, false, false, false, true, resolved.val, nav_index },
         };
         const ty = Type.fromInterned(nav.typeOf(ip));
 
@@ -4888,8 +4889,11 @@ pub const NavGen = struct {
             try global_index.rename(decl_name, &o.builder);
             global_index.setLinkage(.external, &o.builder);
             global_index.setUnnamedAddr(.default, &o.builder);
-            if (zcu.comp.config.dll_export_fns)
+            if (is_dll_import) {
+                global_index.setDllStorageClass(.dllimport, &o.builder);
+            } else if (zcu.comp.config.dll_export_fns) {
                 global_index.setDllStorageClass(.default, &o.builder);
+            }
 
             if (is_weak_linkage) global_index.setLinkage(.extern_weak, &o.builder);
         }
diff --git a/src/codegen/llvm/Builder.zig b/src/codegen/llvm/Builder.zig
index bcc93d79b9..ce4040c127 100644
--- a/src/codegen/llvm/Builder.zig
+++ b/src/codegen/llvm/Builder.zig
@@ -2541,6 +2541,10 @@ pub const Variable = struct {
             return self.ptrConst(builder).global.setLinkage(linkage, builder);
         }
 
+        pub fn setDllStorageClass(self: Index, class: DllStorageClass, builder: *Builder) void {
+            return self.ptrConst(builder).global.setDllStorageClass(class, builder);
+        }
+
         pub fn setUnnamedAddr(self: Index, unnamed_addr: UnnamedAddr, builder: *Builder) void {
             return self.ptrConst(builder).global.setUnnamedAddr(unnamed_addr, builder);
         }