[LTO] Fix error reporting when a file passed to libLTO is invalid or non-existent

This addresses PR26060 where function lto_module_create() could return nullptr
but lto_get_error_message() returned an empty string.

The error() call after LTOModule::createFromFile() in llvm-lto is then removed
because any error from this function should go through the diagnostic handler in
llvm-lto which will exit the program. The error() call was added because this
previously did not happen when the file was non-existent. This is fixed by the
patch. (The situation that llvm-lto reports an error when the input file does
not exist is tested by llvm/tools/llvm-lto/error.ll).

Differential Revision: http://reviews.llvm.org/D16106

llvm-svn: 258298

3 files changed, 9 insertions, 6 deletions

diff --git a/llvm/lib/LTO/LTOModule.cpp b/llvm/lib/LTO/LTOModule.cpp
index 409b9490233..4806f903bdf 100644
--- a/llvm/lib/LTO/LTOModule.cpp
+++ b/llvm/lib/LTO/LTOModule.cpp
@@ -105,8 +105,10 @@ LTOModule::createFromFile(LLVMContext &Context, const char *path,
                           TargetOptions options) {
   ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
       MemoryBuffer::getFile(path);
-  if (std::error_code EC = BufferOrErr.getError())
+  if (std::error_code EC = BufferOrErr.getError()) {
+    Context.emitError(EC.message());
     return EC;
+  }
   std::unique_ptr<MemoryBuffer> Buffer = std::move(BufferOrErr.get());
   return makeLTOModule(Buffer->getMemBufferRef(), options, &Context);
 }
@@ -123,8 +125,10 @@ LTOModule::createFromOpenFileSlice(LLVMContext &Context, int fd,
                                    off_t offset, TargetOptions options) {
   ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
       MemoryBuffer::getOpenFileSlice(fd, path, map_size, offset);
-  if (std::error_code EC = BufferOrErr.getError())
+  if (std::error_code EC = BufferOrErr.getError()) {
+    Context.emitError(EC.message());
     return EC;
+  }
   std::unique_ptr<MemoryBuffer> Buffer = std::move(BufferOrErr.get());
   return makeLTOModule(Buffer->getMemBufferRef(), options, &Context);
 }
@@ -158,8 +162,10 @@ parseBitcodeFileImpl(MemoryBufferRef Buffer, LLVMContext &Context,
   // Find the buffer.
   ErrorOr<MemoryBufferRef> MBOrErr =
       IRObjectFile::findBitcodeInMemBuffer(Buffer);
-  if (std::error_code EC = MBOrErr.getError())
+  if (std::error_code EC = MBOrErr.getError()) {
+    Context.emitError(EC.message());
     return EC;
+  }
 
   if (!ShouldBeLazy) {
     // Parse the full file.
diff --git a/llvm/tools/llvm-lto/llvm-lto.cpp b/llvm/tools/llvm-lto/llvm-lto.cpp
index 55c0f48aead..e83ac279f83 100644
--- a/llvm/tools/llvm-lto/llvm-lto.cpp
+++ b/llvm/tools/llvm-lto/llvm-lto.cpp
@@ -294,7 +294,6 @@ int main(int argc, char **argv) {
     CurrentActivity = "loading file '" + InputFilenames[i] + "'";
     ErrorOr<std::unique_ptr<LTOModule>> ModuleOrErr =
         LTOModule::createFromFile(Context, InputFilenames[i].c_str(), Options);
-    error(ModuleOrErr, "error " + CurrentActivity);
     std::unique_ptr<LTOModule> &Module = *ModuleOrErr;
     CurrentActivity = "";
 
diff --git a/llvm/tools/lto/lto.cpp b/llvm/tools/lto/lto.cpp
index d8f99c050a3..e7062b59d52 100644
--- a/llvm/tools/lto/lto.cpp
+++ b/llvm/tools/lto/lto.cpp
@@ -81,7 +81,6 @@ static void diagnosticHandler(const DiagnosticInfo &DI, void *Context) {
     DiagnosticPrinterRawOStream DP(Stream);
     DI.print(DP);
   }
-  sLastErrorString += '\n';
 }
 
 // Initialize the configured targets if they have not been initialized.
@@ -111,7 +110,6 @@ namespace {
 static void handleLibLTODiagnostic(lto_codegen_diagnostic_severity_t Severity,
                                    const char *Msg, void *) {
   sLastErrorString = Msg;
-  sLastErrorString += "\n";
 }
 
 // This derived class owns the native object file. This helps implement the