feat: Wire up LLD tests via wild-linker/lld-tests submodule

.gitmodules

@@ -4,3 +4,6 @@
 [submodule "wild/tests/bins"]
 	path = wild/tests/bins
 	url = https://github.com/wild-linker/test-files
+[submodule "external_test_suites/lld"]
+	path = external_test_suites/lld
+	url = https://github.com/wild-linker/lld-tests

.typos.toml

@@ -4,6 +4,7 @@ rela = "rela"
 ot = "ot"
 FRE = "FRE"
 aranges = "aranges"
+preemptable = "preemptable"
 
 [files]
 extend-exclude = ["external_test_suites", "wild/tests/bins"]

wild/tests/external_tests/lld_skip_tests.toml

@@ -0,0 +1,104 @@
+[skipped_groups.lld_specific]
+reason = "Test exercises an lld-specific flag or behavior not applicable to Wild"
+tests = ["x86-64-branch-to-branch.s"]
+
+[skipped_groups.requires_newer_lld]
+reason = "Test requires a newer lld/relocation type than our local llvm-mc supports"
+tests = [
+  "x86-64-gotpc-no-relax-err.s",
+  "x86-64-gotpc-relax.s",
+  "x86-64-gotpc-relax-nopic.s",
+  "x86-64-plt-high-addr.s",
+  "x86-64-tlsdesc-gd.s",
+  "x86-64-tls-ie-err.s",
+  "x86-64-tls-ie-local.s",
+]
+
+[skipped_groups.design_differences]
+reason = "Wild intentionally differs from lld's PLT/GOT layout and relocation binding strategy (immediate binding vs lazy binding)"
+tests = [
+  "x86-64-tlsdesc-ld.s",
+  "x86-64-tlsdesc-gd-mixed.s",
+  "x86-64-reloc-gotoff64.s",
+  "x86-64-reloc-gotpc64.s",
+  "x86-64-reloc-pltoff64.s",
+  "x86-64-static-tls-model.s",
+  "x86-64-combined-dynrel.s",
+  "x86-64-got-plt-header.s",
+  "x86-64-plt.s",
+  "x86-64-rela.s",
+  "x86-64-tls-gd-local.s",
+  "x86-64-tls-ld-local.s",
+  "x86-64-zrel-zrela.s",
+]
+
+[skipped_groups.error_message_wording]
+reason = "Wild correctly errors but with different message wording than lld"
+tests = [
+  "x86-64-reloc-tpoff32-error.s",
+  "x86-64-pc32-overflow-large.s",
+  "x86-64-reloc-error2.s",
+  "x86-64-reloc-debug-overflow.s",
+  "x86-64-reloc-range-debug-loc.s",
+  "x86-64-tls-ie-opt-local.s",
+]
+
+[skipped_groups.gc_sections_behavior]
+reason = "Test relies on lld's default --gc-sections behavior differing from Wild's"
+tests = ["x86-64-reloc-error.s"]
+
+[skipped_groups.noinhibit_exec_unsupported]
+reason = "Test relies on --noinhibit-exec, which Wild does not support"
+tests = ["x86-64-reloc-range.s", "x86-64-tls-le-undef.s"]
+
+[skipped_groups.unsupported_features]
+reason = "Feature not yet implemented in Wild"
+tests = [
+  "x86-64-feature-cet.s",
+  "x86-64-dyn-rel-error.s",
+  "x86-64-dyn-rel-error3.s",
+  "x86-64-dyn-rel-error5.s",
+  "x86-64-relax-got-abs.s",
+  "x86-64-reloc-size.s",
+  "x86-64-retpoline.s",
+  "x86-64-retpoline-linkerscript.s",
+  "x86-64-retpoline-znow.s",
+  "x86-64-retpoline-znow-linkerscript.s",
+  "x86-64-retpoline-znow-static-iplt.s",
+  "x86-64-section-layout.s",
+  "x86-64-split-stack-prologue-adjust-fail.s",
+  "x86-64-split-stack-prologue-adjust-shared.s",
+  "x86-64-split-stack-prologue-adjust-silent.s",
+  "x86-64-tls-gd-got.s",
+  "x86-64-tls-opt-noplt.s",
+  "x86-64-tls-pie.s",
+]
+
+[skipped_groups.missing_flag_support]
+reason = "Wild does not yet recognize the --image-base flag used by this test"
+tests = ["x86-64-reloc-32.s"]
+
+[skipped_groups.previously_believed_working]
+reason = "Manual testing previously suggested Wild handles this correctly, but it fails under this harness's exact FileCheck comparison. Needs investigation to reconcile: possible regression, an imprecise manual check, or a local tooling gap (e.g. objdump missing x86_64 target support)."
+tests = [
+  "x86-64-tls-le-align.s",
+  "x86-64-tls-ie.s",
+  "x86-64-tls-gdie.s",
+  "x86-64-reloc-8-16.s",
+  "x86-64-tls-ld-preemptable.s",
+  "x86-64-relax-offset.s",
+  "x86-64-gotpc-relax-too-far.s",
+  "x86-64-gotpc-relax-und-dso.s",
+  "x86-64-tls-dynamic.s",
+  "x86-64-reloc-pc32.s",
+  "x86-64-split-stack-prologue-adjust-success.s",
+]
+
+[skipped_groups.untriaged]
+reason = "Not yet manually triaged against Wild"
+tests = [
+  "x86-64-gotpc-offset.s",
+  "x86-64-gotpc-relax-too-far-relr.s",
+  "x86-64-relax-jump-tables.s",
+  "x86-64-reloc-size-shared.s",
+]

wild/tests/external_tests/lld_tests.rs

@@ -7,11 +7,37 @@
 use crate::Result;
 use libtest_mimic::Failed;
 use libtest_mimic::Trial;
+use serde::Deserialize;
+use std::collections::HashMap;
+use std::fs;
 use std::path::Path;
 use std::process::Command;
+use std::sync::OnceLock;
+
+#[derive(Deserialize)]
+struct Config {
+    skipped_groups: HashMap<String, SkippedGroup>,
+}
+
+#[derive(Deserialize)]
+struct SkippedGroup {
+    tests: Vec<String>,
+}
+
+static SKIP_TESTS_NAME: OnceLock<Option<Vec<String>>> = OnceLock::new();
 
 const PREFIX: &str = "external_test_suites/lld";
 
+/// Architecture prefixes used by LLD's test file naming convention
+/// (e.g. `x86-64-pcrel.s`, `aarch64-abs16.s`).
+const SUPPORTED_ARCH_PREFIXES: &[&str] = &["x86-64-"];
+
+fn is_supported_arch_test(file_name: &str) -> bool {
+    SUPPORTED_ARCH_PREFIXES
+        .iter()
+        .any(|prefix| file_name.starts_with(prefix))
+}
+
 pub(crate) fn collect_tests(tests: &mut Vec<Trial>, filter: &crate::Filter) -> Result {
     if filter.excludes(PREFIX) {
         return Ok(());
@@ -21,23 +47,48 @@ pub(crate) fn collect_tests(tests: &mut Vec<Trial>, filter: &crate::Filter) -> R
     if !test_dir.exists() {
         return Ok(());
     }
-
     let dir = std::fs::read_dir(&test_dir)?;
     for ent in dir {
         let ent = ent?;
         let path = ent.path();
         if path.extension().is_some_and(|ext| ext == "s") {
             let file_name =
                 String::from_utf8_lossy(path.file_name().unwrap().as_encoded_bytes()).to_string();
+
+            // Other architectures (aarch64, riscv64, ...) are left for a
+            // TODO.
+            if !is_supported_arch_test(&file_name) {
+                continue;
+            }
+
             let name = format!("{PREFIX}/test/ELF/{file_name}");
-            tests.push(Trial::test(name, move || {
-                run_lld_test(&path).map_err(|e| Failed::from(e.to_string()))
-            }));
+
+            if !should_skip_lld_test(&path) {
+                tests.push(Trial::test(name, move || {
+                    run_lld_test(&path).map_err(|e| Failed::from(e.to_string()))
+                }));
+            } else {
+                tests.push(Trial::test(format!("{name}/expect_failure"), move || {
+                    verify_skipped_lld_test_still_fails(&path)
+                        .map_err(|e| Failed::from(e.to_string()))
+                }));
+            }
         }
     }
     Ok(())
 }
 
+fn verify_skipped_lld_test_still_fails(test_file: &Path) -> Result {
+    if run_lld_test(test_file).is_ok() {
+        return Err(format!(
+            "Test `{}` is in the skip list but now passes. Should be removed from skip list.",
+            test_file.display()
+        )
+        .into());
+    }
+    Ok(())
+}
+
 fn run_lld_test(test_file: &Path) -> Result {
     let llvm_mc = find_tool("llvm-mc")?;
     let filecheck = find_tool("FileCheck")?;
@@ -97,9 +148,11 @@ fn extract_run_lines(content: &str) -> Vec<String> {
 }
 
 fn substitute_vars(cmd: &str, test_file: &Path, tmpdir: &Path) -> String {
+    let dir = test_file.parent().unwrap().display().to_string();
     cmd.replace("%s", &test_file.display().to_string())
         .replace("%t", &tmpdir.join("test").display().to_string())
-        .replace("%p", &test_file.parent().unwrap().display().to_string())
+        .replace("%S", &dir)
+        .replace("%p", &dir)
 }
 
 fn substitute_tools(cmd: &str, llvm_mc: &str, filecheck: &str) -> String {
@@ -128,3 +181,41 @@ fn execute_command(cmd: &str) -> Result {
     }
     Ok(())
 }
+
+fn load_skip_tests_config() -> &'static Option<Vec<String>> {
+    SKIP_TESTS_NAME.get_or_init(|| {
+        let skip_tests_path = std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
+            .join("tests")
+            .join("external_tests")
+            .join("lld_skip_tests.toml");
+
+        fs::read_to_string(&skip_tests_path)
+            .map(|content| {
+                let config: Config =
+                    toml::from_str(&content).expect("Failed to parse lld_skip_tests.toml");
+
+                config
+                    .skipped_groups
+                    .into_values()
+                    .flat_map(|group| group.tests)
+                    .collect()
+            })
+            .ok()
+    })
+}
+
+fn should_skip_lld_test(path: &Path) -> bool {
+    let file_name = path
+        .file_name()
+        .expect("Must be a valid filename")
+        .to_str()
+        .expect("Expected valid string name");
+
+    if crate::external_tests::should_not_ignore_tests("lld") {
+        return false;
+    }
+
+    load_skip_tests_config()
+        .as_ref()
+        .is_some_and(|skip_list| skip_list.contains(&file_name.to_string()))
+}