Frontend: Change ComputePreambleBounds to take MemoryBufferRef, NFC

Avoid requiring an actual MemoryBuffer in ComputePreambleBounds, when
a MemoryBufferRef will do just fine.

Differential Revision: https://reviews.llvm.org/D90890

clang-tools-extra/clangd/CodeComplete.cpp

@@ -1104,7 +1104,7 @@ bool semaCodeComplete(std::unique_ptr<CodeCompleteConsumer> Consumer,
   // overriding the preamble will break sema completion. Fortunately we can just
   // skip all includes in this case; these completions are really simple.
   PreambleBounds PreambleRegion =
-      ComputePreambleBounds(*CI->getLangOpts(), ContentsBuffer.get(), 0);
+      ComputePreambleBounds(*CI->getLangOpts(), *ContentsBuffer, 0);
   bool CompletingInPreamble = PreambleRegion.Size > Input.Offset;
   if (Input.Patch)
     Input.Patch->apply(*CI);

clang-tools-extra/clangd/Preamble.cpp

@@ -249,8 +249,7 @@ scanPreamble(llvm::StringRef Contents, const tooling::CompileCommand &Cmd) {
   // This means we're scanning (though not preprocessing) the preamble section
   // twice. However, it's important to precisely follow the preamble bounds used
   // elsewhere.
-  auto Bounds =
-      ComputePreambleBounds(*CI->getLangOpts(), ContentsBuffer.get(), 0);
+  auto Bounds = ComputePreambleBounds(*CI->getLangOpts(), *ContentsBuffer, 0);
   auto PreambleContents =
       llvm::MemoryBuffer::getMemBufferCopy(Contents.substr(0, Bounds.Size));
   auto Clang = prepareCompilerInstance(
@@ -322,8 +321,7 @@ buildPreamble(PathRef FileName, CompilerInvocation CI,
   // without those.
   auto ContentsBuffer =
       llvm::MemoryBuffer::getMemBuffer(Inputs.Contents, FileName);
-  auto Bounds =
-      ComputePreambleBounds(*CI.getLangOpts(), ContentsBuffer.get(), 0);
+  auto Bounds = ComputePreambleBounds(*CI.getLangOpts(), *ContentsBuffer, 0);
 
   trace::Span Tracer("BuildPreamble");
   SPAN_ATTACH(Tracer, "File", FileName);
@@ -376,8 +374,7 @@ bool isPreambleCompatible(const PreambleData &Preamble,
                           const CompilerInvocation &CI) {
   auto ContentsBuffer =
       llvm::MemoryBuffer::getMemBuffer(Inputs.Contents, FileName);
-  auto Bounds =
-      ComputePreambleBounds(*CI.getLangOpts(), ContentsBuffer.get(), 0);
+  auto Bounds = ComputePreambleBounds(*CI.getLangOpts(), *ContentsBuffer, 0);
   auto VFS = Inputs.TFS->view(Inputs.CompileCommand.Directory);
   return compileCommandsAreEqual(Inputs.CompileCommand,
                                  Preamble.CompileCommand) &&

clang/include/clang/Frontend/PrecompiledPreamble.h

@@ -41,7 +41,7 @@ class PCHContainerOperations;
 
 /// Runs lexer to compute suggested preamble bounds.
 PreambleBounds ComputePreambleBounds(const LangOptions &LangOpts,
-                                     const llvm::MemoryBuffer *Buffer,
+                                     const llvm::MemoryBufferRef &Buffer,
                                      unsigned MaxLines);
 
 class PreambleCallbacks;

clang/lib/Frontend/ASTUnit.cpp

@@ -1317,9 +1317,8 @@ ASTUnit::getMainBufferWithPrecompiledPreamble(
   if (!MainFileBuffer)
     return nullptr;
 
-  PreambleBounds Bounds =
-      ComputePreambleBounds(*PreambleInvocationIn.getLangOpts(),
-                            MainFileBuffer.get(), MaxLines);
+  PreambleBounds Bounds = ComputePreambleBounds(
+      *PreambleInvocationIn.getLangOpts(), *MainFileBuffer, MaxLines);
   if (!Bounds.Size)
     return nullptr;
 

clang/lib/Frontend/PrecompiledPreamble.cpp

@@ -303,9 +303,9 @@ template <class T> bool moveOnNoError(llvm::ErrorOr<T> Val, T &Output) {
 } // namespace
 
 PreambleBounds clang::ComputePreambleBounds(const LangOptions &LangOpts,
-                                            const llvm::MemoryBuffer *Buffer,
+                                            const llvm::MemoryBufferRef &Buffer,
                                             unsigned MaxLines) {
-  return Lexer::ComputePreamble(Buffer->getBuffer(), LangOpts, MaxLines);
+  return Lexer::ComputePreamble(Buffer.getBuffer(), LangOpts, MaxLines);
 }
 
 llvm::ErrorOr<PrecompiledPreamble> PrecompiledPreamble::Build(
@@ -621,7 +621,7 @@ void PrecompiledPreamble::AddImplicitPreamble(
 void PrecompiledPreamble::OverridePreamble(
     CompilerInvocation &CI, IntrusiveRefCntPtr<llvm::vfs::FileSystem> &VFS,
     llvm::MemoryBuffer *MainFileBuffer) const {
-  auto Bounds = ComputePreambleBounds(*CI.getLangOpts(), MainFileBuffer, 0);
+  auto Bounds = ComputePreambleBounds(*CI.getLangOpts(), *MainFileBuffer, 0);
   configurePreamble(Bounds, CI, VFS, MainFileBuffer);
 }