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Added llvm.module flag for strict vtable pointers 

It is dangerous to do LTO on code with strict-vtable-pointers, because
one module has invariant.group.barriers, and the other one not.

In the future I want to just strip all invariant.group metadata from
vptrs loads/stores and get rid of invariant.group.barrier calls.

http://reviews.llvm.org/D12580

llvm-svn: 247724
This commit is contained in:
Piotr Padlewski 2015-09-15 21:46:50 +00:00
parent 338c9d0ade
commit 9d0ecf27a7
2 changed files with 25 additions and 0 deletions
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16
clang/lib/CodeGen/CodeGenModule.cpp
View File

@ -398,6 +398,22 @@ void CodeGenModule::Release() {
// Indicate that we want CodeView in the metadata.
getModule().addModuleFlag(llvm::Module::Warning, "CodeView", 1);
}
if (CodeGenOpts.OptimizationLevel > 0 && CodeGenOpts.StrictVTablePointers) {
// We don't support LTO with 2 with different StrictVTablePointers
// FIXME: we could support it by stripping all the information introduced
// by StrictVTablePointers.
getModule().addModuleFlag(llvm::Module::Error, "StrictVTablePointers",1);
llvm::Metadata *Ops[2] = {
llvm::MDString::get(VMContext, "StrictVTablePointers"),
llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
llvm::Type::getInt32Ty(VMContext), 1))};
getModule().addModuleFlag(llvm::Module::Require,
"StrictVTablePointersRequirement",
llvm::MDNode::get(VMContext, Ops));
}
if (DebugInfo)
// We support a single version in the linked module. The LLVM
// parser will drop debug info with a different version number

9
clang/test/CodeGenCXX/strict-vtable-pointers.cpp
View File

@ -2,6 +2,7 @@
// RUN: FileCheck --check-prefix=CHECK-CTORS %s < %t.ll
// RUN: FileCheck --check-prefix=CHECK-NEW %s < %t.ll
// RUN: FileCheck --check-prefix=CHECK-DTORS %s < %t.ll
// RUN: FileCheck --check-prefix=CHECK-LINK-REQ %s < %t.ll
typedef __typeof__(sizeof(0)) size_t;
void *operator new(size_t, void*) throw();
@ -191,3 +192,11 @@ struct DynamicFromStatic;
// CHECK-DTORS-LABEL: define linkonce_odr void @_ZN14DynamicDerivedD2Ev
// CHECK-DTORS-NOT: call i8* @llvm.invariant.group.barrier(
// CHECK-DTORS-LABEL: }
// CHECK-LINK-REQ: !llvm.module.flags = !{![[FIRST:.*]], ![[SEC:.*]]{{.*}}}
// CHECK-LINK-REQ: ![[FIRST]] = !{i32 1, !"StrictVTablePointers", i32 1}
// CHECK-LINK-REQ: ![[SEC]] = !{i32 3, !"StrictVTablePointersRequirement", ![[META:.*]]}
// CHECK-LINK-REQ: ![[META]] = !{!"StrictVTablePointers", i32 1}