[llvm] [LegacyLTO] Emit the error message that was silently dropped (PR #152172)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lto

Author: Steven Wu (cachemeifyoucan)

<details>
<summary>Changes</summary>

Using LLVMContext to emit the error from `TargetRegistry::lookupTarget`
that was silently ignored and not propagated. This allows user to better
identify the kind of error occured.

rdar://157542119


---
Full diff: https://github.com/llvm/llvm-project/pull/152172.diff


1 Files Affected:

- (modified) llvm/lib/LTO/LTOModule.cpp (+3-1) 


``````````diff
diff --git a/llvm/lib/LTO/LTOModule.cpp b/llvm/lib/LTO/LTOModule.cpp
index e0a975806a31d..7dd06118e2a57 100644
--- a/llvm/lib/LTO/LTOModule.cpp
+++ b/llvm/lib/LTO/LTOModule.cpp
@@ -203,8 +203,10 @@ LTOModule::makeLTOModule(MemoryBufferRef Buffer, const TargetOptions &options,
   // find machine architecture for this module
   std::string errMsg;
   const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
-  if (!march)
+  if (!march) {
+    Context.emitError(errMsg);
     return make_error_code(object::object_error::arch_not_found);
+  }
 
   // construct LTOModule, hand over ownership of module and target
   SubtargetFeatures Features;

``````````

</details>


https://github.com/llvm/llvm-project/pull/152172