From 10caa6ecedb5e8c12da0a0b9fb94bd8af383b24e Mon Sep 17 00:00:00 2001
From: Yuta Saito <kateinoigakukun@gmail.com>
Date: Tue, 15 Oct 2024 13:29:18 +0000
Subject: [PATCH] Unlock `-profile-generate` for WebAssembly targets

We added support for `-profile-generate` in the latest LLVM, but it is
explicitly banned for WebAssembly targets now. Unlock the feature by
adding the necessary runtime library to the link command line as well as
other platforms.
---
 .../WebAssemblyToolchain+LinkerSupport.swift  |  7 +++++--
 Tests/SwiftDriverTests/SwiftDriverTests.swift | 21 +++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/Sources/SwiftDriver/Jobs/WebAssemblyToolchain+LinkerSupport.swift b/Sources/SwiftDriver/Jobs/WebAssemblyToolchain+LinkerSupport.swift
index a0c0a02a0..085f27f8f 100644
--- a/Sources/SwiftDriver/Jobs/WebAssemblyToolchain+LinkerSupport.swift
+++ b/Sources/SwiftDriver/Jobs/WebAssemblyToolchain+LinkerSupport.swift
@@ -160,8 +160,11 @@ extension WebAssemblyToolchain {
         throw Error.sanitizersUnsupportedForTarget(targetTriple.triple)
       }
 
-      guard !parsedOptions.hasArgument(.profileGenerate) else {
-        throw Error.profilingUnsupportedForTarget(targetTriple.triple)
+      if parsedOptions.hasArgument(.profileGenerate) {
+        let libProfile = VirtualPath.lookup(targetInfo.runtimeResourcePath.path)
+          .appending(components: "clang", "lib", targetTriple.osName,
+                                 "libclang_rt.profile-\(targetTriple.archName).a")
+        commandLine.appendPath(libProfile)
       }
 
       if let lto = lto {
diff --git a/Tests/SwiftDriverTests/SwiftDriverTests.swift b/Tests/SwiftDriverTests/SwiftDriverTests.swift
index 1fc27396b..118a9830e 100644
--- a/Tests/SwiftDriverTests/SwiftDriverTests.swift
+++ b/Tests/SwiftDriverTests/SwiftDriverTests.swift
@@ -4463,6 +4463,27 @@ final class SwiftDriverTests: XCTestCase {
     }
     #endif
 
+    // -profile-generate should add libclang_rt.profile for WebAssembly targets
+    try withTemporaryDirectory { resourceDir in
+      try localFileSystem.writeFileContents(resourceDir.appending(components: "wasi", "static-executable-args.lnk")) {
+        $0.send("garbage")
+      }
+
+      for triple in ["wasm32-unknown-wasi", "wasm32-unknown-wasip1-threads"] {
+        var driver = try Driver(args: [
+          "swiftc", "-profile-generate", "-target", triple, "test.swift",
+          "-resource-dir", resourceDir.pathString
+        ])
+        let plannedJobs = try driver.planBuild().removingAutolinkExtractJobs()
+
+        XCTAssertEqual(plannedJobs.count, 2)
+        XCTAssertEqual(plannedJobs[0].kind, .compile)
+
+        XCTAssertEqual(plannedJobs[1].kind, .link)
+        XCTAssert(plannedJobs[1].commandLine.containsPathWithBasename("libclang_rt.profile-wasm32.a"))
+      }
+    }
+
     for explicitUseLd in [true, false] {
       var args = ["swiftc", "-profile-generate", "-target", "x86_64-unknown-windows-msvc", "test.swift"]
       if explicitUseLd {