[SYCL][Driver] Fix printing internal defines in SYCL mode (#2188)

clang++ -fsycl -dM -E -x c++ /dev/null is not able to print internal defines, the patch aims to fix this issue. 
It will emit the output to terminal as well as produce the bundled .ii file.

Signed-off-by: haonanya <[email protected]>

Author: haonanya

clang/lib/Driver/Driver.cpp

@@ -5740,6 +5740,7 @@ InputInfo Driver::BuildJobsForActionNoCache(
 
   // Only use pipes when there is exactly one input.
   InputInfoList InputInfos;
+  bool JobForPreprocessToStdout = false;
   for (const Action *Input : Inputs) {
     // Treat dsymutil and verify sub-jobs as being at the top-level too, they
     // shouldn't get temporary output names.
@@ -5750,6 +5751,11 @@ InputInfo Driver::BuildJobsForActionNoCache(
         C, Input, TC, BoundArch, SubJobAtTopLevel, MultipleArchs, LinkingOutput,
         CachedResults, A->getOffloadingDeviceKind()));
   }
+  // Check if we are in sub-work for preprocessing for host side. If so we will
+  // add another job to print information to terminal later.
+  if (!AtTopLevel && A->getKind() == Action::PreprocessJobClass &&
+      C.getJobs().size() == 1)
+    JobForPreprocessToStdout = true;
 
   // Always use the first input as the base input.
   const char *BaseInput = InputInfos[0].getBaseInput();
@@ -5784,6 +5790,7 @@ InputInfo Driver::BuildJobsForActionNoCache(
 
   // Determine the place to write output to, if any.
   InputInfo Result;
+  InputInfo ResultForPreprocessToStdout;
   InputInfoList UnbundlingResults;
   if (auto *UA = dyn_cast<OffloadUnbundlingJobAction>(JA)) {
     // If we have an unbundling job, we need to create results for all the
@@ -5945,6 +5952,8 @@ InputInfo Driver::BuildJobsForActionNoCache(
                                              AtTopLevel, MultipleArchs,
                                              OffloadingPrefix),
                        BaseInput);
+    if (JobForPreprocessToStdout)
+      ResultForPreprocessToStdout = InputInfo(A, "-", BaseInput);
   }
 
   if (CCCPrintBindings && !CCGenDiagnostics) {
@@ -5967,12 +5976,19 @@ InputInfo Driver::BuildJobsForActionNoCache(
       llvm::errs() << "] \n";
     }
   } else {
-    if (UnbundlingResults.empty())
+    if (UnbundlingResults.empty()) {
       T->ConstructJob(
           C, *JA, Result, InputInfos,
           C.getArgsForToolChain(TC, BoundArch, JA->getOffloadingDeviceKind()),
           LinkingOutput);
-    else
+      // Add another job to print information to terminal for host side.
+      if (JobForPreprocessToStdout) {
+        T->ConstructJob(
+            C, *JA, ResultForPreprocessToStdout, InputInfos,
+            C.getArgsForToolChain(TC, BoundArch, JA->getOffloadingDeviceKind()),
+            LinkingOutput);
+      }
+    } else
       T->ConstructJobMultipleOutputs(
           C, *JA, UnbundlingResults, InputInfos,
           C.getArgsForToolChain(TC, BoundArch, JA->getOffloadingDeviceKind()),

clang/test/Driver/print-internal-defines-for-sycl.c

@@ -0,0 +1,5 @@
+// Test if clang is able to print internal defines in SYCL mode
+//
+// RUN: %clangxx -fsycl -dM -E -x c++ %s 2>&1 \
+// RUN: | FileCheck --check-prefix CHECK-PRINT-INTERNAL-DEFINES %s
+// CHECK-PRINT-INTERNAL-DEFINES: #define