From f53de29862193b761f3ef8ec0627d1e70d2fe674 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i@maskray.me>
Date: Thu, 23 Feb 2023 21:45:14 -0800
Subject: [PATCH] [FunctionImport] Change IRMover report_fatal_error to a
 proper error

Conflicting module flags leads to a proper error for regular LTO but a crash
(report_fatal_error) for ThinLTO. Switch to createStringError to fix the crash
and match regular LTO.
---
 llvm/lib/Transforms/IPO/FunctionImport.cpp         |  5 ++--
 .../test/Transforms/FunctionImport/module-flags.ll | 33 ++++++++++++++++++++++
 2 files changed, 36 insertions(+), 2 deletions(-)
 create mode 100644 llvm/test/Transforms/FunctionImport/module-flags.ll

diff --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp
index 7c99465..222b719 100644
--- a/llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -1373,8 +1373,9 @@ Expected<bool> FunctionImporter::importFunctions(
     if (Error Err = Mover.move(std::move(SrcModule),
                                GlobalsToImport.getArrayRef(), nullptr,
                                /*IsPerformingImport=*/true))
-      report_fatal_error(Twine("Function Import: link error: ") +
-                         toString(std::move(Err)));
+      return createStringError(errc::invalid_argument,
+                               Twine("Function Import: link error: ") +
+                                   toString(std::move(Err)));
 
     ImportedCount += GlobalsToImport.size();
     NumImportedModules++;
diff --git a/llvm/test/Transforms/FunctionImport/module-flags.ll b/llvm/test/Transforms/FunctionImport/module-flags.ll
new file mode 100644
index 0000000..662df30
--- /dev/null
+++ b/llvm/test/Transforms/FunctionImport/module-flags.ll
@@ -0,0 +1,33 @@
+; RUN: rm -rf %t && split-file %s %t && cd %t
+; RUN: opt -module-summary 1.ll -o 1.bc
+; RUN: opt -module-summary 2.ll -o 2.bc
+; RUN: llvm-lto -thinlto -o 3 1.bc 2.bc
+; RUN: opt -S -passes=function-import -summary-file 3.thinlto.bc 1.bc 2>&1 | FileCheck %s
+
+; CHECK: Function Import: link error: linking module flags 'Error': IDs have conflicting values in '2.bc' and '1.bc'
+
+;--- 1.ll
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @main() {
+entry:
+  call void () @foo()
+  ret i32 0
+}
+
+declare void @foo()
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 1, !"Error", i32 0}
+
+;--- 2.ll
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @foo() {
+  ret void
+}
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 1, !"Error", i32 1}
-- 
2.7.4