Convert Windows debug information to a PDB/Dwarf union

ziglang · May 9, 2021 · 2258be5 · 2258be5
1 parent abdf39e
commit 2258be5
Showing 1 changed file with 27 additions and 16 deletions.
diff --git a/lib/std/debug.zig b/lib/std/debug.zig
@@ -50,6 +50,11 @@ pub const LineInfo = struct {
     }
 };
 
+const PdbOrDwarf = union(enum) {
+    pdb: pdb.Pdb,
+    dwarf: DW.DwarfInfo,
+};
+
 var stderr_mutex = std.Thread.Mutex{};
 
 /// Deprecated. Use `std.log` functions for logging or `std.debug.print` for
@@ -536,7 +541,7 @@ fn populateModule(di: *ModuleDebugInfo, mod: *Module) !void {
     if (mod.mod_info.C13ByteSize == 0)
         return;
 
-    const modi = di.pdb.getStreamById(mod.mod_info.ModuleSymStream) orelse return error.MissingDebugInfo;
+    const modi = di.debug_data.pdb.getStreamById(mod.mod_info.ModuleSymStream) orelse return error.MissingDebugInfo;
 
     const signature = try modi.reader().readIntLittle(u32);
     if (signature != 4)
@@ -710,8 +715,7 @@ fn readCoffDebugInfo(allocator: *mem.Allocator, coff_file: File) !ModuleDebugInf
         var di = ModuleDebugInfo{
             .base_address = undefined,
             .coff = coff_obj,
-            .pdb = undefined,
-            .dwarf = null,
+            .debug_data = undefined,
             .sect_contribs = undefined,
             .modules = undefined,
         };
@@ -736,7 +740,8 @@ fn readCoffDebugInfo(allocator: *mem.Allocator, coff_file: File) !ModuleDebugInf
                 .debug_ranges = debug_ranges_data,
             };
             try DW.openDwarfDebugInfo(&dwarf, allocator);
-            di.dwarf = dwarf;
+            di.debug_data = PdbOrDwarf{ .dwarf = dwarf };
+            return di;
         }
 
         var path_buf: [windows.MAX_PATH]u8 = undefined;
@@ -745,9 +750,11 @@ fn readCoffDebugInfo(allocator: *mem.Allocator, coff_file: File) !ModuleDebugInf
 
         const path = try fs.path.resolve(allocator, &[_][]const u8{raw_path});
 
-        try di.pdb.openFile(di.coff, path);
+        di.debug_data = PdbOrDwarf{ .pdb = undefined }; // PDB will be populated below in openFile()
+        const pdb_info = &di.debug_data.pdb;
+        try pdb_info.openFile(di.coff, path);
 
-        var pdb_stream = di.pdb.getStream(pdb.StreamType.Pdb) orelse return error.InvalidDebugInfo;
+        var pdb_stream = pdb_info.getStream(pdb.StreamType.Pdb) orelse return error.InvalidDebugInfo;
         const version = try pdb_stream.reader().readIntLittle(u32);
         const signature = try pdb_stream.reader().readIntLittle(u32);
         const age = try pdb_stream.reader().readIntLittle(u32);
@@ -800,10 +807,10 @@ fn readCoffDebugInfo(allocator: *mem.Allocator, coff_file: File) !ModuleDebugInf
             return error.MissingDebugInfo;
         };
 
-        di.pdb.string_table = di.pdb.getStreamById(string_table_index) orelse return error.MissingDebugInfo;
-        di.pdb.dbi = di.pdb.getStream(pdb.StreamType.Dbi) orelse return error.MissingDebugInfo;
+        pdb_info.string_table = pdb_info.getStreamById(string_table_index) orelse return error.MissingDebugInfo;
+        pdb_info.dbi = pdb_info.getStream(pdb.StreamType.Dbi) orelse return error.MissingDebugInfo;
 
-        const dbi = di.pdb.dbi;
+        const dbi = pdb_info.dbi;
 
         // Dbi Header
         const dbi_stream_header = try dbi.reader().readStruct(pdb.DbiStreamHeader);
@@ -1546,8 +1553,7 @@ pub const ModuleDebugInfo = switch (builtin.os.tag) {
     },
     .uefi, .windows => struct {
         base_address: usize,
-        pdb: pdb.Pdb,
-        dwarf: ?DW.DwarfInfo,
+        debug_data: PdbOrDwarf,
         coff: *coff.Coff,
         sect_contribs: []pdb.SectionContribEntry,
         modules: []Module,
@@ -1560,9 +1566,14 @@ pub const ModuleDebugInfo = switch (builtin.os.tag) {
             // Translate the VA into an address into this object
             const relocated_address = address - self.base_address;
 
-            if (self.dwarf) |*dwarf| {
-                const dwarf_address = relocated_address + self.coff.pe_header.image_base;
-                return getSymbolFromDwarf(dwarf_address, dwarf);
+            switch (self.debug_data) {
+                .dwarf => |*dwarf| {
+                    const dwarf_address = relocated_address + self.coff.pe_header.image_base;
+                    return getSymbolFromDwarf(dwarf_address, dwarf);
+                },
+                .pdb => {
+                    // fallthrough to pdb handling
+                },
             }
 
             var coff_section: *coff.Section = undefined;
@@ -1661,8 +1672,8 @@ pub const ModuleDebugInfo = switch (builtin.os.tag) {
                                         const subsect_index = checksum_offset + block_hdr.NameIndex;
                                         const chksum_hdr = @ptrCast(*pdb.FileChecksumEntryHeader, &mod.subsect_info[subsect_index]);
                                         const strtab_offset = @sizeOf(pdb.PDBStringTableHeader) + chksum_hdr.FileNameOffset;
-                                        try self.pdb.string_table.seekTo(strtab_offset);
-                                        const source_file_name = try self.pdb.string_table.readNullTermString(self.allocator());
+                                        try self.debug_data.pdb.string_table.seekTo(strtab_offset);
+                                        const source_file_name = try self.debug_data.pdb.string_table.readNullTermString(self.allocator());
 
                                         const line_entry_idx = line_i - 1;