[CacheKey] Fix filelist CAS option

When using a file list inputs to the swift-frontend invocation, the name
of the file is not significant, only the content of the file. Improve
cache key computation so only the content of the input file will affect
cache key, not the file name.

lib/Frontend/CompileJobCacheKey.cpp

@@ -20,6 +20,8 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/CAS/HierarchicalTreeBuilder.h"
 #include "llvm/CAS/ObjectStore.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/MemoryBuffer.h"
 
 using namespace swift;
 
@@ -30,29 +32,45 @@ llvm::Expected<llvm::cas::ObjectRef> swift::createCompileJobBaseCacheKey(
 
   // TODO: Improve this list.
   static const std::vector<std::string> removeArgAndNext = {
-      "-o", "-supplementary-output-file-map", "-serialize-diagnostics-path",
-      "-num-threads", "-cas-path"};
+      "-o",
+      "-output-filelist",
+      "-supplementary-output-file-map",
+      "-index-unit-output-path",
+      "-index-unit-output-path-filelist",
+      "-serialize-diagnostics-path",
+      "-num-threads",
+      "-cas-path"};
 
   // Don't count the `-frontend` in the first location since only frontend
   // invocation can have a cache key.
   if (Args.size() > 1 && StringRef(Args.front()) == "-frontend")
     Args = Args.drop_front();
 
-  bool SkipNext = false;
-  for (StringRef Arg : Args) {
-    if (SkipNext) {
-      SkipNext = false;
-      continue;
-    }
+  for (unsigned I = 0, IE =Args.size(); I < IE; ++I) {
+    StringRef Arg = Args[I];
     if (llvm::is_contained(removeArgAndNext, Arg)) {
-      SkipNext = true;
+      ++I;
       continue;
     }
     // FIXME: Use a heuristic to remove all the flags that affect output paths.
     // Those should not affect compile cache key.
     if (Arg.startswith("-emit-")) {
       if (Arg.endswith("-path"))
-        SkipNext = true;
+        ++I;
+      continue;
+    }
+    // Handle -file-list option. Need to drop the option but adds the file
+    // content instead.
+    // FIXME: will be nice if the same list of files gets the same key no matter
+    // going through command-line or filelist.
+    if (Arg == "-filelist" || Arg == "-primary-filelist") {
+      auto FileList = llvm::MemoryBuffer::getFile(Args[++I]);
+      if (!FileList)
+        return llvm::errorCodeToError(FileList.getError());
+      CommandLine.append(Arg);
+      CommandLine.push_back(0);
+      CommandLine.append((*FileList)->getBuffer());
+      CommandLine.push_back(0);
       continue;
     }
     CommandLine.append(Arg);