Support deterministic checking in explicit module build

Author: cachemeifyoucan

lib/Frontend/ModuleInterfaceLoader.cpp

@@ -1360,19 +1360,25 @@ bool ModuleInterfaceLoader::buildExplicitSwiftModuleFromSwiftInterface(
     ArrayRef<std::string> CompiledCandidates,
     DependencyTracker *tracker) {
 
-  // First, check if the expected output already exists and possibly up-to-date w.r.t.
-  // all of the dependencies it was built with. If so, early exit.
-  UpToDateModuleCheker checker(Instance.getASTContext(),
-                               RequireOSSAModules_t(Instance.getSILOptions()));
-  ModuleRebuildInfo rebuildInfo;
-  SmallVector<FileDependency, 3> allDeps;
-  std::unique_ptr<llvm::MemoryBuffer> moduleBuffer;
-  if (checker.swiftModuleIsUpToDate(outputPath, rebuildInfo, allDeps, moduleBuffer)) {
-    if (Instance.getASTContext().LangOpts.EnableSkipExplicitInterfaceModuleBuildRemarks) {
-      Instance.getDiags().diagnose(SourceLoc(),
-                                   diag::explicit_interface_build_skipped, outputPath);
+  if (!Instance.getInvocation().getIRGenOptions().AlwaysCompile) {
+    // First, check if the expected output already exists and possibly
+    // up-to-date w.r.t. all of the dependencies it was built with. If so, early
+    // exit.
+    UpToDateModuleCheker checker(
+        Instance.getASTContext(),
+        RequireOSSAModules_t(Instance.getSILOptions()));
+    ModuleRebuildInfo rebuildInfo;
+    SmallVector<FileDependency, 3> allDeps;
+    std::unique_ptr<llvm::MemoryBuffer> moduleBuffer;
+    if (checker.swiftModuleIsUpToDate(outputPath, rebuildInfo, allDeps,
+                                      moduleBuffer)) {
+      if (Instance.getASTContext()
+              .LangOpts.EnableSkipExplicitInterfaceModuleBuildRemarks) {
+        Instance.getDiags().diagnose(
+            SourceLoc(), diag::explicit_interface_build_skipped, outputPath);
+      }
+      return false;
     }
-    return false;
   }
 
   // Read out the compiler version.

test/Frontend/output_determinism_check.swift

@@ -7,10 +7,21 @@
 /// object files should match when forcing object generation.
 // RUN: %target-swift-frontend -module-name test -c -o %t/test.o -primary-file %s -enable-swift-deterministic-check -always-compile-output-files 2>&1 | %FileCheck %s --check-prefix=OBJECT_OUTPUT
 
+/// Explicit module build. Check building swiftmodule from interface file.
+/// TODO: Implicit module build use a different compiler instance so it doesn't support checking yet.
+// RUN: %target-swift-frontend -typecheck -emit-module-interface-path %t/test.swiftinterface %s -O -enable-swift-deterministic-check 2>&1 | %FileCheck %s --check-prefix=INTERFACE_OUTPUT
+/// Hit cache and not emit the second time.
+// RUN: rm %t/test.swiftmodule
+// RUN: not %target-swift-frontend -compile-module-from-interface %t/test.swiftinterface -explicit-interface-module-build -o %t/test.swiftmodule -enable-swift-deterministic-check 2>&1 | %FileCheck --check-prefix=MODULE_MISMATCH %s
+/// Force swiftmodule generation.
+// RUN: %target-swift-frontend -compile-module-from-interface %t/test.swiftinterface -explicit-interface-module-build -o %t/test.swiftmodule -enable-swift-deterministic-check -always-compile-output-files 2>&1 | %FileCheck --check-prefix=MODULE_OUTPUT %s
+
 // MODULE_OUTPUT: remark: produced matching output file '{{.*}}{{/|\\}}test.swiftmodule'
 // SIB_OUTPUT: remark: produced matching output file '{{.*}}{{/|\\}}test.sib'
 // OBJECT_OUTPUT: remark: produced matching output file '{{.*}}{{/|\\}}test.o'
 // OBJECT_MISMATCH: error: output file '{{.*}}{{/|\\}}test.o' is missing from second compilation for deterministic check
+// INTERFACE_OUTPUT: remark: produced matching output file '{{.*}}{{/|\\}}test.swiftinterface'
+// MODULE_MISMATCH: error: output file '{{.*}}{{/|\\}}test.swiftmodule' is missing from second compilation for deterministic check
 
 public var x = 1
 public func test() {}