zig

commit 44b322ce6410a0fab7c3cbdfc35bb1530a31a304 (tree)
parent e3db210cf1007f87930c97c072c54b2fb8ae0b8c
Author: Luuk de Gram <luuk@degram.dev>
Date:   Thu, 15 Jun 2023 20:15:01 +0200

wasm-linker: correctly resolve undefined functions

We now resolve undefined symbols during incremental-compilation
where we discard the current symbol if we detect we found
an existing symbol which is not the one currently being updated.
The symbol will always be discarded in favor of the existing symbol
in such a case.

Diffstat:
M
src/link/Wasm.zig
 | 
13
++++++++++++-
M
test/behavior/bugs/529.zig
 | 
1
-

2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/src/link/Wasm.zig b/src/link/Wasm.zig
@@ -1909,6 +1909,17 @@ pub fn addOrUpdateImport(
         global_gop.value_ptr.* = loc;
         try wasm.resolved_symbols.put(wasm.base.allocator, loc, {});
         try wasm.undefs.putNoClobber(wasm.base.allocator, decl_name_index, loc);
+    } else if (global_gop.value_ptr.*.index != symbol_index) {
+        // We are not updating a symbol, but found an existing global
+        // symbol with the same name. This means we always favor the
+        // existing symbol, regardless whether it's defined or not.
+        // We can also skip storing the import as we will not output
+        // this symbol.
+        return wasm.discarded.put(
+            wasm.base.allocator,
+            .{ .file = null, .index = symbol_index },
+            global_gop.value_ptr.*,
+        );
     }
 
     if (type_index) |ty_index| {
@@ -1924,8 +1935,8 @@ pub fn addOrUpdateImport(
             };
         }
     } else {
+        // non-functions will not be imported from the runtime, but only resolved during link-time
         symbol.tag = .data;
-        return; // non-functions will not be imported from the runtime, but only resolved during link-time
     }
 }
 
diff --git a/test/behavior/bugs/529.zig b/test/behavior/bugs/529.zig
@@ -11,7 +11,6 @@ comptime {
 const builtin = @import("builtin");
 
 test "issue 529 fixed" {
-    if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO