Pass UseCASBackend flag to replayCachedResult.

When using MCCAS, the replay on a cache hit needs to materialize the
object file by calling into MCCAS's serializeObjectFile function. Pass
the UseCASBackend flag from the CodeGenOpts to replayCachedResult to
make sure it knows when to invoke MCCAS serialization.

(cherry picked from commit 1fe3f3a)

Author: rastogishubham

clang/include/clang/Frontend/CompileJobCache.h

@@ -81,12 +81,13 @@ class CompileJobCache {
   /// \returns true if finished successfully.
   bool finishComputedResult(CompilerInstance &Clang, bool Success);
 
-  static llvm::Expected<std::optional<int>> replayCachedResult(
-      std::shared_ptr<CompilerInvocation> Invok, StringRef WorkingDir,
-      const llvm::cas::CASID &CacheKey,
-      cas::CompileJobCacheResult &CachedResult, SmallVectorImpl<char> &DiagText,
-      bool WriteOutputAsCASID = false, bool UseCASBackend = false,
-      std::optional<llvm::cas::CASID> *MCOutputID = nullptr);
+  static llvm::Expected<std::optional<int>>
+  replayCachedResult(std::shared_ptr<CompilerInvocation> Invok,
+                     StringRef WorkingDir, const llvm::cas::CASID &CacheKey,
+                     cas::CompileJobCacheResult &CachedResult,
+                     SmallVectorImpl<char> &DiagText,
+                     bool WriteOutputAsCASID = false,
+                     std::optional<llvm::cas::CASID> *MCOutputID = nullptr);
 
   class CachingOutputs;
 

clang/lib/Frontend/CompileJobCache.cpp

@@ -542,7 +542,7 @@ Expected<std::optional<int>> CompileJobCache::replayCachedResult(
     std::shared_ptr<CompilerInvocation> Invok, StringRef WorkingDir,
     const llvm::cas::CASID &CacheKey, cas::CompileJobCacheResult &CachedResult,
     SmallVectorImpl<char> &DiagText, bool WriteOutputAsCASID,
-    bool UseCASBackend, std::optional<llvm::cas::CASID> *OutMCOutputID) {
+    std::optional<llvm::cas::CASID> *OutMCOutputID) {
   CompilerInstance Clang;
   Clang.setInvocation(std::move(Invok));
   llvm::raw_svector_ostream DiagOS(DiagText);
@@ -573,7 +573,7 @@ Expected<std::optional<int>> CompileJobCache::replayCachedResult(
   std::optional<llvm::cas::CASID> MCOutputID;
   ObjectStoreCachingOutputs CachingOutputs(
       Clang, WorkingDir, std::move(PrefixMapper), WriteOutputAsCASID,
-      UseCASBackend, MCOutputID,
+      Clang.getInvocation().getCodeGenOpts().UseCASBackend, MCOutputID,
       /*CAS*/ nullptr, /*Cache*/ nullptr);
   if (OutMCOutputID)
     *OutMCOutputID = std::move(MCOutputID);

clang/test/CAS/mccas-replay.c

@@ -0,0 +1,20 @@
+// RUN: rm -rf %t && mkdir %t
+
+// RUN: %clang -cc1depscan -o %t/args.rsp  -cc1-args -cc1 \
+// RUN:    -debug-info-kind=standalone -dwarf-version=4 -debugger-tuning=lldb \
+// RUN:    -emit-obj -fcas-backend  -fcas-path %t/cas       %s -o - > /dev/null
+
+// RUN: %clang @%t/args.rsp -o %t/output1.o -Rcompile-job-cache 2> %t/output1.txt
+
+// RUN: cat %t/output1.txt | grep llvmcas | sed \
+// RUN:       -e "s/^.*miss for '//" \
+// RUN:       -e "s/' .*$//" > %t/cache-key 
+
+// RUN: c-index-test core -replay-cached-job -cas-path %t/cas @%t/cache-key \
+// RUN:       -working-dir %t  -- @%t/args.rsp -o %t/output2.o
+
+// RUN: diff %t/output1.o %t/output2.o 
+
+int foo(int x) {
+    return x+1;
+}