Merge pull request #15520 from davidungar/PR-18-15-num-threads-fix

[Batch mode] Harden compiler against -num-threads or -import-objc-header and -enable-batch-mode.

Author: David Ungar

include/swift/AST/DiagnosticsFrontend.def

@@ -83,6 +83,8 @@ ERROR(error_unknown_arg,none,
   "unknown argument: '%0'", (StringRef))
 ERROR(error_invalid_arg_value,none,
   "invalid value '%1' in '%0'", (StringRef, StringRef))
+WARNING(warning_cannot_multithread_batch_mode,none,
+  "ignoring -num-threads argument; cannot multithread batch mode", ())
 ERROR(error_unsupported_option_argument,none,
   "unsupported argument '%1' to option '%0'", (StringRef, StringRef))
 ERROR(error_immediate_mode_missing_stdlib,none,

include/swift/Driver/Driver.h

@@ -242,7 +242,8 @@ class Driver {
   /// information.
   void buildOutputInfo(const ToolChain &TC,
                        const llvm::opt::DerivedArgList &Args,
-                       const InputFileList &Inputs, OutputInfo &OI) const;
+                       const bool BatchMode, const InputFileList &Inputs,
+                       OutputInfo &OI) const;
 
   /// Construct the list of Actions to perform for the given arguments,
   /// which are only done for a single architecture.

lib/Driver/Compilation.cpp

@@ -1154,6 +1154,9 @@ static bool writeFilelistIfNecessary(const Job *job, const ArgList &args,
       else {
         // The normal case for non-single-compile jobs.
         for (const Action *A : job->getSource().getInputs()) {
+          // A could be a GeneratePCHJobAction
+          if (!isa<InputAction>(A))
+            continue;
           const auto *IA = cast<InputAction>(A);
           out << IA->getInputArg().getValue() << "\n";
         }

lib/Driver/Driver.cpp

@@ -588,7 +588,7 @@ Driver::buildCompilation(const ToolChain &TC,
 
   // Determine the OutputInfo for the driver.
   OutputInfo OI;
-  buildOutputInfo(TC, *TranslatedArgList, Inputs, OI);
+  buildOutputInfo(TC, *TranslatedArgList, BatchMode, Inputs, OI);
 
   if (Diags.hadAnyError())
     return nullptr;
@@ -1093,7 +1093,7 @@ static bool isSDKTooOld(StringRef sdkPath, const llvm::Triple &target) {
 }
 
 void Driver::buildOutputInfo(const ToolChain &TC, const DerivedArgList &Args,
-                             const InputFileList &Inputs,
+                             const bool BatchMode, const InputFileList &Inputs,
                              OutputInfo &OI) const {
   // By default, the driver does not link its output; this will be updated
   // appropriately below if linking is required.
@@ -1113,7 +1113,9 @@ void Driver::buildOutputInfo(const ToolChain &TC, const DerivedArgList &Args,
   }
 
   if (const Arg *A = Args.getLastArg(options::OPT_num_threads)) {
-    if (StringRef(A->getValue()).getAsInteger(10, OI.numThreads)) {
+    if (BatchMode) {
+      Diags.diagnose(SourceLoc(), diag::warning_cannot_multithread_batch_mode);
+    } else if (StringRef(A->getValue()).getAsInteger(10, OI.numThreads)) {
       Diags.diagnose(SourceLoc(), diag::error_invalid_arg_value,
                      A->getAsString(Args), A->getValue());
     }
@@ -2304,6 +2306,15 @@ void Driver::computeMainOutput(
       file_types::isAfterLLVM(JA->getType())) {
     // Multi-threaded compilation: A single frontend command produces multiple
     // output file: one for each input files.
+
+    // In batch mode, the driver will try to reserve multiple differing main
+    // outputs to a bridging header. Another assertion will trip, but the cause
+    // will be harder to track down. Since the driver now ignores -num-threads
+    // in batch mode, the user should never be able to falsify this assertion.
+    assert(!C.getBatchModeEnabled() && "Batch mode produces only one main "
+                                       "output per input action, cannot have "
+                                       "batch mode & num-threads");
+
     auto OutputFunc = [&](StringRef Base, StringRef Primary) {
       const TypeToPathMap *OMForInput = nullptr;
       if (OFM)

test/Driver/batch_mode_with_num-threads.swift

@@ -0,0 +1,13 @@
+// RUN: %empty-directory(%t)
+// RUN: echo 'print("Hello, World!")' >%t/main.swift
+// RUN: touch %t/bridgingHeader.h
+//
+// Make sure the proper warning is emitted:
+//
+// RUN: %swiftc_driver -enable-batch-mode -num-threads 2 %t/main.swift -import-objc-header %t/bridgingHeader.h -### 2>&1 | %FileCheck %s
+//
+// CHECK: ignoring -num-threads argument; cannot multithread batch mode
+//
+// Make sure that it actually works. (The link step fails if -num-threads is not ignored.)
+//
+// RUN: %swiftc_driver -enable-batch-mode -num-threads 2 %t/main.swift -import-objc-header %t/bridgingHeader.h

test/Driver/batch_mode_with_pch.swift

@@ -0,0 +1,5 @@
+// RUN: %empty-directory(%t)
+// RUN: echo 'print("Hello, World!")' >%t/main.swift
+// RUN: touch %t/bridgingHeader.h
+//
+// RUN: %swiftc_driver -driver-use-filelists -enable-batch-mode -num-threads 2 %t/main.swift -import-objc-header %t/bridgingHeader.h