[BOLT] Check MCContext errors

Abort on emission errors to prevent a malformed binary being written.
Example:
```
<unknown>:0: error: Undefined temporary symbol .Ltmp26310
<unknown>:0: error: Undefined temporary symbol .Ltmp26311
<unknown>:0: error: Undefined temporary symbol .Ltmp26312
<unknown>:0: error: Undefined temporary symbol .Ltmp26313
<unknown>:0: error: Undefined temporary symbol .Ltmp26314
<unknown>:0: error: Undefined temporary symbol .Ltmp26315
BOLT-ERROR: Emission failed.
```

Reviewed By: yota9

Differential Revision: https://reviews.llvm.org/D123263

1 files changed, 5 insertions, 1 deletions

diff --git a/bolt/lib/Rewrite/RewriteInstance.cpp b/bolt/lib/Rewrite/RewriteInstance.cpp
index 1db7bd92a4a0..2cac9d74b83e 100644
--- a/bolt/lib/Rewrite/RewriteInstance.cpp
+++ b/bolt/lib/Rewrite/RewriteInstance.cpp
@@ -3108,6 +3108,10 @@ void RewriteInstance::emitAndLink() {
   emitBinaryContext(*Streamer, *BC, getOrgSecPrefix());
 
   Streamer->Finish();
+  if (Streamer->getContext().hadError()) {
+    errs() << "BOLT-ERROR: Emission failed.\n";
+    exit(1);
+  }
 
   //////////////////////////////////////////////////////////////////////////////
   // Assign addresses to new sections.
@@ -3137,7 +3141,7 @@ void RewriteInstance::emitAndLink() {
 
   RTDyld->finalizeWithMemoryManagerLocking();
   if (RTDyld->hasError()) {
-    outs() << "BOLT-ERROR: RTDyld failed: " << RTDyld->getErrorString() << "\n";
+    errs() << "BOLT-ERROR: RTDyld failed: " << RTDyld->getErrorString() << "\n";
     exit(1);
   }