[Diagnose] Unify MCContext and LLVMContext diagnosing

The situation with inline asm/MC error reporting is kind of messy at the
moment. The errors from MC layout are not reliably propagated and users
have to specify an inlineasm handler separately to get inlineasm
diagnose. The latter issue is not a correctness issue but could be improved.

* Kill LLVMContext inlineasm diagnose handler and migrate it to use
  DiagnoseInfo/DiagnoseHandler.
* Introduce `DiagnoseInfoSrcMgr` to diagnose SourceMgr backed errors. This
  covers use cases like inlineasm, MC, and any clients using SourceMgr.
* Move AsmPrinter::SrcMgrDiagInfo and its instance to MCContext. The next step
  is to combine MCContext::SrcMgr and MCContext::InlineSrcMgr because in all
  use cases, only one of them is used.
* If LLVMContext is available, let MCContext uses LLVMContext's diagnose
  handler; if LLVMContext is not available, MCContext uses its own default
  diagnose handler which just prints SMDiagnostic.
* Change a few clients(Clang, llc, lldb) to use the new way of reporting.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D97449

1 files changed, 22 insertions, 10 deletions

diff --git a/lldb/source/Expression/IRExecutionUnit.cpp b/lldb/source/Expression/IRExecutionUnit.cpp
index 538935da52ee..b19c1d787093 100644
--- a/lldb/source/Expression/IRExecutionUnit.cpp
+++ b/lldb/source/Expression/IRExecutionUnit.cpp
@@ -9,6 +9,8 @@
 #include "llvm/ExecutionEngine/ExecutionEngine.h"
 #include "llvm/ExecutionEngine/ObjectCache.h"
 #include "llvm/IR/Constants.h"
+#include "llvm/IR/DiagnosticHandler.h"
+#include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Support/SourceMgr.h"
@@ -200,16 +202,26 @@ Status IRExecutionUnit::DisassembleFunction(Stream &stream,
   return ret;
 }
 
-static void ReportInlineAsmError(const llvm::SMDiagnostic &diagnostic,
-                                 void *Context, unsigned LocCookie) {
-  Status *err = static_cast<Status *>(Context);
+namespace {
+struct IRExecDiagnosticHandler : public llvm::DiagnosticHandler {
+  Status *err;
+  IRExecDiagnosticHandler(Status *err) : err(err) {}
+  bool handleDiagnostics(const llvm::DiagnosticInfo &DI) override {
+    if (DI.getKind() == llvm::DK_SrcMgr) {
+      const auto &DISM = llvm::cast<llvm::DiagnosticInfoSrcMgr>(DI);
+      if (err && err->Success()) {
+        err->SetErrorToGenericError();
+        err->SetErrorStringWithFormat(
+            "Inline assembly error: %s",
+            DISM.getSMDiag().getMessage().str().c_str());
+      }
+      return true;
+    }
 
-  if (err && err->Success()) {
-    err->SetErrorToGenericError();
-    err->SetErrorStringWithFormat("Inline assembly error: %s",
-                                  diagnostic.getMessage().str().c_str());
+    return false;
   }
-}
+};
+} // namespace
 
 void IRExecutionUnit::ReportSymbolLookupError(ConstString name) {
   m_failed_lookups.push_back(name);
@@ -257,8 +269,8 @@ void IRExecutionUnit::GetRunnableInfo(Status &error, lldb::addr_t &func_addr,
     LLDB_LOGF(log, "Module being sent to JIT: \n%s", s.c_str());
   }
 
-  m_module_up->getContext().setInlineAsmDiagnosticHandler(ReportInlineAsmError,
-                                                          &error);
+  m_module_up->getContext().setDiagnosticHandler(
+      std::make_unique<IRExecDiagnosticHandler>(&error));
 
   llvm::EngineBuilder builder(std::move(m_module_up));
   llvm::Triple triple(m_module->getTargetTriple());