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ThinLTOBitcodeWriter: Include globals associated with type metadata globals in the merged module. 

Globals that are associated with globals with type metadata need to appear
in the merged module because they will reference the global's section directly.

Differential Revision: https://reviews.llvm.org/D65312

llvm-svn: 367242
This commit is contained in:
Peter Collingbourne 2019-07-29 17:22:40 +00:00
parent 6a253d378b
commit dd9682196b
2 changed files with 25 additions and 3 deletions
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14
llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
View File

@ -218,10 +218,18 @@ void splitAndWriteThinLTOBitcode(
promoteTypeIds(M, ModuleId);
// Returns whether a global has attached type metadata. Such globals may
// participate in CFI or whole-program devirtualization, so they need to
// appear in the merged module instead of the thin LTO module.
// Returns whether a global or its associated global has attached type
// metadata. The former may participate in CFI or whole-program
// devirtualization, so they need to appear in the merged module instead of
// the thin LTO module. Similarly, globals that are associated with globals
// with type metadata need to appear in the merged module because they will
// reference the global's section directly.
auto HasTypeMetadata = [](const GlobalObject *GO) {
if (MDNode *MD = GO->getMetadata(LLVMContext::MD_associated))
if (auto *AssocVM = dyn_cast_or_null<ValueAsMetadata>(MD->getOperand(0)))
if (auto *AssocGO = dyn_cast<GlobalObject>(AssocVM->getValue()))
if (AssocGO->hasMetadata(LLVMContext::MD_type))
return true;
return GO->hasMetadata(LLVMContext::MD_type);
};

14
llvm/test/Transforms/ThinLTOBitcodeWriter/associated.ll Normal file
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@ -0,0 +1,14 @@
; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s
; M0: @g = external constant
; M0-NOT: @assoc
; M1: @g = constant i8 1
; M1: @assoc = private constant i8 2
@g = constant i8 1, !type !0
@assoc = private constant i8 2, !associated !1
!0 = !{i32 0, !"typeid"}
!1 = !{i8* @g}