Add a libLTO diagnostic handler that supports lto_get_error_message API

This is a follow-up from the previous discussion on the thread:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151019/307763.html

The LibLTO lto_get_error_message() API reads error messages from a std::string
sLastErrorString. Instead of passing this string around as an argument, this
patch creates a diagnostic handler and then sends this handler to the
constructor of LTOCodeGenerator.

Differential Revision: http://reviews.llvm.org/D14313

llvm-svn: 252791

1 files changed, 10 insertions, 2 deletions

diff --git a/llvm/tools/lto/lto.cpp b/llvm/tools/lto/lto.cpp
index 62675081464..0839a566cc5 100644
--- a/llvm/tools/lto/lto.cpp
+++ b/llvm/tools/lto/lto.cpp
@@ -85,13 +85,21 @@ static void lto_initialize() {
 
 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
 // libLTO API semantics, which require that the code generator owns the object
 // file.
 struct LibLTOCodeGenerator : LTOCodeGenerator {
-  LibLTOCodeGenerator() {}
+  LibLTOCodeGenerator() {
+    setDiagnosticHandler(handleLibLTODiagnostic, nullptr); }
   LibLTOCodeGenerator(std::unique_ptr<LLVMContext> Context)
-      : LTOCodeGenerator(std::move(Context)) {}
+      : LTOCodeGenerator(std::move(Context)) {
+    setDiagnosticHandler(handleLibLTODiagnostic, nullptr); }
 
   std::unique_ptr<MemoryBuffer> NativeObjectFile;
 };