test: add standalone test for DWARF unwinding with -fomit-frame-pointer

test/standalone.zig

@@ -230,6 +230,10 @@ pub const build_cases = [_]BuildCase{
         .build_root = "test/standalone/zerolength_check",
         .import = @import("standalone/zerolength_check/build.zig"),
     },
+    .{
+        .build_root = "test/standalone/dwarf_unwinding",
+        .import = @import("standalone/dwarf_unwinding/build.zig"),
+    },
 };
 
 const std = @import("std");

test/standalone/dwarf_unwinding/build.zig

@@ -0,0 +1,37 @@
+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const test_step = b.step("test", "Test it");
+    b.default_step = test_step;
+
+    const target = b.standardTargetOptions(.{});
+    const optimize = b.standardOptimizeOption(.{});
+
+    if (!std.debug.StackIterator.supports_context) return;
+
+    const c_shared_lib = b.addSharedLibrary(.{
+        .name = "c_shared_lib",
+        .target = target,
+        .optimize = optimize,
+    });
+
+    if (target.isWindows()) c_shared_lib.defineCMacro("LIB_API", "__declspec(dllexport)");
+
+    c_shared_lib.strip = false;
+    c_shared_lib.addCSourceFile("shared_lib.c", &.{"-fomit-frame-pointer"});
+    c_shared_lib.linkLibC();
+
+    const exe = b.addExecutable(.{
+        .name = "main",
+        .root_source_file = .{ .path = "main.zig" },
+        .target = target,
+        .optimize = optimize,
+    });
+
+    exe.omit_frame_pointer = true;
+    exe.linkLibrary(c_shared_lib);
+    b.installArtifact(exe);
+
+    const run_cmd = b.addRunArtifact(exe);
+    test_step.dependOn(&run_cmd.step);
+}

test/standalone/dwarf_unwinding/main.zig

@@ -0,0 +1,40 @@
+const std = @import("std");
+const debug = std.debug;
+const testing = std.testing;
+
+noinline fn frame4(expected: *[4]usize, unwound: *[4]usize) void {
+    expected[0] = @returnAddress();
+
+    var context: debug.StackTraceContext = undefined;
+    testing.expect(debug.getContext(&context)) catch @panic("failed to getContext");
+
+    var debug_info = debug.getSelfDebugInfo() catch @panic("failed to openSelfDebugInfo");
+    var it = debug.StackIterator.initWithContext(null, debug_info, &context) catch @panic("failed to initWithContext");
+    defer it.deinit();
+
+    for (unwound) |*addr| {
+        if (it.next()) |return_address| addr.* = return_address;
+    }
+}
+
+noinline fn frame3(expected: *[4]usize, unwound: *[4]usize) void {
+    expected[1] = @returnAddress();
+    frame4(expected, unwound);
+}
+
+fn frame2(expected: *[4]usize, unwound: *[4]usize) callconv(.C) void {
+    frame3(expected, unwound);
+}
+
+extern fn frame0(
+    expected: *[4]usize,
+    unwound: *[4]usize,
+    frame_2: *const fn (expected: *[4]usize, unwound: *[4]usize) callconv(.C) void,
+) void;
+
+pub fn main() !void {
+    var expected: [4]usize = undefined;
+    var unwound: [4]usize = undefined;
+    frame0(&expected, &unwound, &frame2);
+    try testing.expectEqual(expected, unwound);
+}

test/standalone/dwarf_unwinding/shared_lib.c

@@ -0,0 +1,24 @@
+#include <stdint.h>
+
+#ifndef LIB_API
+#define LIB_API
+#endif
+
+__attribute__((noinline)) void frame1(
+    void** expected,
+    void** unwound,
+    void (*frame2)(void** expected, void** unwound)) {
+    expected[2] = &&frame_2_ret;
+    frame2(expected, unwound);
+ frame_2_ret:
+}
+
+LIB_API void frame0(
+    void** expected,
+    void** unwound,
+    void (*frame2)(void** expected, void** unwound)) {
+    expected[3] = &&frame_1_ret;
+    frame1(expected, unwound, frame2);
+ frame_1_ret:
+}
+