[PATCH] D79140: [ThinLTO] return error instead of crashing on invalid input

[Sergei Trofimovich via Phabricator via llvm-commits]

trofi created this revision.
trofi added a reviewer: lattner.
Herald added subscribers: llvm-commits, dexonsmith, hiraditya, inglorion.
Herald added a project: LLVM.

In https://bugs.llvm.org/show_bug.cgi?id=45636 firefox was linked
against stale object files that don't match profiled build.

Before the change `ld.lld` was crashing with a backtrace as:

  LLVM ERROR: Function Import: link error:
    linking module flags 'ProfileSummary':
      IDs have conflicting values in 'Mutex_posix.o' and 'nsBrowserApp.o'
    PLEASE submit a bug report to https://bugs.llvm.org/ and include the
    crash backtrace.
  
   #0 0x000055b58915b86a llvm::sys::PrintStackTrace(llvm::raw_ostream&)
     llvm/lib/Support/Unix/Signals.inc:564:22
   ...
   #11 0x000055b589111f89 llvm::report_fatal_error(llvm::Twine const&, bool)
     llvm/lib/Support/ErrorHandling.cpp:113:27
   #12 0x000055b5891120e1 llvm/lib/Support/ErrorHandling.cpp:87:21
   #13 0x000055b58a22611f llvm::FunctionImporter::importFunctions(...)
     llvm/lib/Transforms/IPO/FunctionImport.cpp:1250:25

After the change `ld.lld` collects all errors during ThinLTO and reports
them as usual:

  ld.lld: error: Function Import: link error:
    linking module flags 'ProfileSummary':
      IDs have conflicting values in 'Mutex_posix.o' and 'nsBrowserApp.o'


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D79140

Files:
  llvm/lib/Transforms/IPO/FunctionImport.cpp


Index: llvm/lib/Transforms/IPO/FunctionImport.cpp
===================================================================
--- llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -39,6 +39,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/Errc.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
@@ -1247,8 +1248,9 @@
             std::move(SrcModule), GlobalsToImport.getArrayRef(),
             [](GlobalValue &, IRMover::ValueAdder) {},
             /*IsPerformingImport=*/true))
-      report_fatal_error("Function Import: link error: " +
-                         toString(std::move(Err)));
+      return createStringError(errc::invalid_argument,
+                               "Function Import: link error: %s",
+                               toString(std::move(Err)).c_str());
 
     ImportedCount += GlobalsToImport.size();
     NumImportedModules++;


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