Merge pull request #603 from swiftlang/owenv/modulewrap-fix

Fix the criteria for enabling modulewrap in release builds

Author: owenv

Sources/SWBCore/SpecImplementations/Tools/SwiftCompiler.swift

@@ -2162,11 +2162,6 @@ public final class SwiftCompilerSpec : CompilerSpec, SpecIdentifierType, SwiftDi
                 return (inputs, outputs)
             }()
 
-            if cbc.scope.evaluate(BuiltinMacros.PLATFORM_REQUIRES_SWIFT_MODULEWRAP) && cbc.scope.evaluate(BuiltinMacros.GCC_GENERATE_DEBUGGING_SYMBOLS) {
-                let moduleWrapOutput = Path(moduleFilePath.withoutSuffix + ".o")
-                moduleOutputPaths.append(moduleWrapOutput)
-            }
-
             // Add const metadata outputs to extra compilation outputs
             if await supportConstSupplementaryMetadata(cbc, delegate, compilationMode: compilationMode) {
                 // If using whole module optimization then we use the -primary.swiftconstvalues file from the sole compilation task.
@@ -2254,6 +2249,7 @@ public final class SwiftCompilerSpec : CompilerSpec, SpecIdentifierType, SwiftDi
                 return nil
             }()
 
+            let emittingModuleSeparately: Bool
             if eagerCompilationEnabled(args: args, scope: cbc.scope, compilationMode: compilationMode, isUsingWholeModuleOptimization: isUsingWholeModuleOptimization) {
                 if isUsingWholeModuleOptimization {
                     args += ["-emit-module-separately-wmo"]
@@ -2262,8 +2258,24 @@ public final class SwiftCompilerSpec : CompilerSpec, SpecIdentifierType, SwiftDi
                 }
                 // Cross-module optimization is not supported when emitting the swiftmodule separately.
                 args += ["-disable-cmo"]
+                emittingModuleSeparately = true
             } else if isUsingWholeModuleOptimization && !usingLegacyDriver {
                 args += ["-no-emit-module-separately-wmo"]
+                emittingModuleSeparately = false
+            } else {
+                // Conservatively assume we're not emitting a module separately in the fallback case.
+                emittingModuleSeparately = false
+            }
+
+            // Conditions which all must be met to enable module wrapping:
+            // 1. The platform must require it
+            // 2. We must be compiling with debug info
+            // 3. We must be emitting a module separately
+            if cbc.scope.evaluate(BuiltinMacros.PLATFORM_REQUIRES_SWIFT_MODULEWRAP) &&
+                cbc.scope.evaluate(BuiltinMacros.GCC_GENERATE_DEBUGGING_SYMBOLS) &&
+                emittingModuleSeparately {
+                let moduleWrapOutput = Path(moduleFilePath.withoutSuffix + ".o")
+                moduleOutputPaths.append(moduleWrapOutput)
             }
 
             // The rule info.

Tests/SWBBuildSystemTests/BuildOperationTests.swift

@@ -30,8 +30,8 @@ import SWBTestSupport
 
 @Suite(.requireXcode16())
 fileprivate struct BuildOperationTests: CoreBasedTests {
-    @Test(.requireSDKs(.host), arguments: ["clang", "swiftc"])
-    func commandLineTool(linkerDriver: String) async throws {
+    @Test(.requireSDKs(.host), arguments: [("clang", "-Onone"), ("swiftc", "-Onone"), ("swiftc", "-Owholemodule")])
+    func commandLineTool(linkerDriver: String, optimizationLevel: String) async throws {
         try await withTemporaryDirectory { (tmpDir: Path) in
             let testProject = try await TestProject(
                 "TestProject",
@@ -55,6 +55,7 @@ fileprivate struct BuildOperationTests: CoreBasedTests {
                         "SUPPORTED_PLATFORMS": "$(HOST_PLATFORM)",
                         "SWIFT_VERSION": swiftVersion,
                         "LINKER_DRIVER": linkerDriver,
+                        "SWIFT_OPTIMIZATION_LEVEL": optimizationLevel,
                     ])
                 ],
                 targets: [