Commit c93e0d86187cb589d6726acd36f741f3d87a96be | zig

author	Matthew Lugg <mlugg@mlugg.co.uk> 2023-03-09 21:34:06+00:00
committer	Veikka Tuominen <git@vexu.eu> 2023-03-12 18:55:23+02:00
log	c93e0d86187cb589d6726acd36f741f3d87a96be
tree	3e812c1fcd520086b45cc22cbc890fb24f432b57
parent	948926c513befd95dc1ff90fe05329245f1c81db

Sema: @extern fixes

* There was an edge case where the arena could be destroyed twice on
  error: once from the arena itself and once from the decl destruction.

* The type of the created decl was incorrect (it should have been the
  pointer child type), but it's not required anyway, so it's now just
  initialized to anyopaque (which more accurately reflects what's
  actually at that memory, since e.g. [*]T may correspond to nothing).

* A runtime bitcast of the pointer was performed, meaning @extern didn't
  work at comptime. This is unnecessary: the decl_ref can just be
  initialized with the correct pointer type.

5 files changed, 84 insertions(+), 29 deletions(-)

src
- Sema.zig
test
- standalone.zig
- standalone
  - extern
    build.zig
    exports.zig
    main.zig

src/Sema.zig+30-29

 @@ -22287,7 +22287,6 @@ fn zirBuiltinExtern(
     extended: Zir.Inst.Extended.InstData,
 ) CompileError!Air.Inst.Ref {
     const extra = sema.code.extraData(Zir.Inst.BinNode, extended.operand).data;
-    const src = LazySrcLoc.nodeOffset(extra.node);
     const ty_src: LazySrcLoc = .{ .node_offset_builtin_call_arg0 = extra.node };
     const options_src: LazySrcLoc = .{ .node_offset_builtin_call_arg1 = extra.node };
 @@ -22315,39 +22314,41 @@ fn zirBuiltinExtern(
     const new_decl = sema.mod.declPtr(new_decl_index);
     new_decl.name = try sema.gpa.dupeZ(u8, options.name);
-    var new_decl_arena = std.heap.ArenaAllocator.init(sema.gpa);
+    {
-    errdefer new_decl_arena.deinit();
+        var new_decl_arena = std.heap.ArenaAllocator.init(sema.gpa);
-    const new_decl_arena_allocator = new_decl_arena.allocator();
+        errdefer new_decl_arena.deinit();
+        const new_decl_arena_allocator = new_decl_arena.allocator();
-    const new_var = try new_decl_arena_allocator.create(Module.Var);
+        const new_var = try new_decl_arena_allocator.create(Module.Var);
-    errdefer new_decl_arena_allocator.destroy(new_var);
+        new_var.* = .{
+            .owner_decl = sema.owner_decl_index,
+            .init = Value.initTag(.unreachable_value),
+            .is_extern = true,
+            .is_mutable = false,
+            .is_threadlocal = options.is_thread_local,
+            .is_weak_linkage = options.linkage == .Weak,
+            .lib_name = null,
+        };
-    new_var.* = .{
+        new_decl.src_line = sema.owner_decl.src_line;
-        .owner_decl = sema.owner_decl_index,
+        // We only access this decl through the decl_ref with the correct type created
-        .init = Value.initTag(.unreachable_value),
+        // below, so this type doesn't matter
-        .is_extern = true,
+        new_decl.ty = Type.Tag.init(.anyopaque);
-        .is_mutable = false,
+        new_decl.val = try Value.Tag.variable.create(new_decl_arena_allocator, new_var);
-        .is_threadlocal = options.is_thread_local,
+        new_decl.@"align" = 0;
-        .is_weak_linkage = options.linkage == .Weak,
+        new_decl.@"linksection" = null;
-        .lib_name = null,
+        new_decl.has_tv = true;
-    };
+        new_decl.analysis = .complete;
+        new_decl.generation = sema.mod.generation;
-    new_decl.src_line = sema.owner_decl.src_line;
+        try new_decl.finalizeNewArena(&new_decl_arena);
-    new_decl.ty = try ty.copy(new_decl_arena_allocator);
+    }
-    new_decl.val = try Value.Tag.variable.create(new_decl_arena_allocator, new_var);
-    new_decl.@"align" = 0;
-    new_decl.@"linksection" = null;
-    new_decl.has_tv = true;
-    new_decl.analysis = .complete;
-    new_decl.generation = sema.mod.generation;
-    const arena_state = try new_decl_arena_allocator.create(std.heap.ArenaAllocator.State);
+    try sema.mod.declareDeclDependency(sema.owner_decl_index, new_decl_index);
-    arena_state.* = new_decl_arena.state;
+    try sema.ensureDeclAnalyzed(new_decl_index);
-    new_decl.value_arena = arena_state;
-    const ref = try sema.analyzeDeclRef(new_decl_index);
+    const ref = try Value.Tag.decl_ref.create(sema.arena, new_decl_index);
-    try sema.requireRuntimeBlock(block, src, null);
+    return sema.addConstant(ty, ref);
-    return block.addBitCast(ty, ref);
 }
 fn requireRuntimeBlock(sema: *Sema, block: *Block, src: LazySrcLoc, runtime_src: ?LazySrcLoc) !void {

test/standalone.zig+1

...	@@ -107,6 +107,7 @@ pub fn addCases(cases: *tests.StandaloneContext) void {	...	@@ -107,6 +107,7 @@ pub fn addCases(cases: *tests.StandaloneContext) void {
107	cases.addBuildFile("test/standalone/emit_asm_and_bin/build.zig", .{});	107	cases.addBuildFile("test/standalone/emit_asm_and_bin/build.zig", .{});
108	cases.addBuildFile("test/standalone/issue_12588/build.zig", .{});	108	cases.addBuildFile("test/standalone/issue_12588/build.zig", .{});
109	cases.addBuildFile("test/standalone/embed_generated_file/build.zig", .{});	109	cases.addBuildFile("test/standalone/embed_generated_file/build.zig", .{});
		110	cases.addBuildFile("test/standalone/extern/build.zig", .{});
110		111
111	cases.addBuildFile("test/standalone/dep_diamond/build.zig", .{});	112	cases.addBuildFile("test/standalone/dep_diamond/build.zig", .{});
112	cases.addBuildFile("test/standalone/dep_triangle/build.zig", .{});	113	cases.addBuildFile("test/standalone/dep_triangle/build.zig", .{});

test/standalone/extern/build.zig created+20

...	@@ -0,0 +1,20 @@
1	const std = @import("std");
2
3	pub fn build(b: *std.Build) void {
4	const optimize = b.standardOptimizeOption(.{});
5
6	const obj = b.addObject(.{
7	.name = "exports",
8	.root_source_file = .{ .path = "exports.zig" },
9	.target = .{},
10	.optimize = optimize,
11	});
12	const main = b.addTest(.{
13	.root_source_file = .{ .path = "main.zig" },
14	.optimize = optimize,
15	});
16	main.addObject(obj);
17
18	const test_step = b.step("test", "Test it");
19	test_step.dependOn(&main.step);
20	}

test/standalone/extern/exports.zig created+12

...	@@ -0,0 +1,12 @@
1	var hidden: u32 = 0;
2	export fn updateHidden(val: u32) void {
3	hidden = val;
4	}
5	export fn getHidden() u32 {
6	return hidden;
7	}
8
9	const T = extern struct { x: u32 };
10
11	export var mut_val: f64 = 1.23;
12	export const const_val: T = .{ .x = 42 };

test/standalone/extern/main.zig created+21

...	@@ -0,0 +1,21 @@
1	const assert = @import("std").debug.assert;
2
3	const updateHidden = @extern(*const fn (u32) callconv(.C) void, .{ .name = "updateHidden" });
4	const getHidden = @extern(*const fn () callconv(.C) u32, .{ .name = "getHidden" });
5
6	const T = extern struct { x: u32 };
7
8	test {
9	var mut_val_ptr = @extern(*f64, .{ .name = "mut_val" });
10	var const_val_ptr = @extern(*const T, .{ .name = "const_val" });
11
12	assert(getHidden() == 0);
13	updateHidden(123);
14	assert(getHidden() == 123);
15
16	assert(mut_val_ptr.* == 1.23);
17	mut_val_ptr.* = 10.0;
18	assert(mut_val_ptr.* == 10.0);
19
20	assert(const_val_ptr.x == 42);
21	}