[LTO] Always mark regular LTO units with EnableSplitLTOUnit=1

Summary:
Regular LTO modules do not need LTO Unit splitting, only ThinLTO does
(they must be consistently split into regular and Thin units for
optimizations such as whole program devirtualization and lower type
tests). In order to avoid spurious errors from LTO when combining with
split ThinLTO modules, always set this flag for regular LTO modules.

Reviewers: pcc

Subscribers: mehdi_amini, Prazek, inglorion, steven_wu, dexonsmith, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D65009

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@366623 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/BackendUtil.cpp b/lib/CodeGen/BackendUtil.cpp
index 850b3db6213cb151735435f23d0d9a0be0db681c..b53d7a6ddfa3c06cacdd433b93f3a41866be1b2c 100644 (file)
--- a/lib/CodeGen/BackendUtil.cpp
+++ b/lib/CodeGen/BackendUtil.cpp
@@ -852,7 +852,7 @@ void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
         if (!TheModule->getModuleFlag("ThinLTO"))
           TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
         TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
-                                 CodeGenOpts.EnableSplitLTOUnit);
+                                 uint32_t(1));
       }
 
       PerModulePasses.add(createBitcodeWriterPass(

diff --git a/test/CodeGen/split-lto-unit.c b/test/CodeGen/split-lto-unit.c
new file mode 100644 (file)
index 0000000..8e83eba
--- /dev/null
+++ b/test/CodeGen/split-lto-unit.c
@@ -0,0 +1,12 @@
+// ; Check that -flto=thin without -fsplit-lto-unit has EnableSplitLTOUnit = 0
+// RUN: %clang_cc1 -flto=thin -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s
+// CHECK: !{i32 1, !"EnableSplitLTOUnit", i32 0}
+//
+// ; Check that -flto=thin with -fsplit-lto-unit has EnableSplitLTOUnit = 1
+// RUN: %clang_cc1 -flto=thin -fsplit-lto-unit -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s --check-prefix=SPLIT
+// SPLIT: !{i32 1, !"EnableSplitLTOUnit", i32 1}
+//
+// ; Check that regular LTO has EnableSplitLTOUnit = 1
+// RUN: %clang_cc1 -flto -triple x86_64-pc-linux-gnu -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s --implicit-check-not="EnableSplitLTOUnit" --check-prefix=SPLIT
+
+int main() {}