samitolvanen updated this revision to Diff 494756.
samitolvanen added a comment.
This revision is now accepted and ready to land.
Herald added subscribers: ormris, steven_wu.
Don't drop type hashes from VisibleToRegularObj symbols.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D138337/new/
https://reviews.llvm.org/D138337
Files:
llvm/include/llvm/CodeGen/AsmPrinter.h
llvm/include/llvm/IR/Function.h
llvm/include/llvm/LTO/LTO.h
llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
llvm/lib/LTO/LTO.cpp
llvm/lib/Target/X86/X86AsmPrinter.cpp
llvm/test/LTO/Resolution/X86/kcfi-seal.ll
Index: llvm/test/LTO/Resolution/X86/kcfi-seal.ll
===================================================================
--- /dev/null
+++ llvm/test/LTO/Resolution/X86/kcfi-seal.ll
@@ -0,0 +1,33 @@
+; RUN: opt %s -o %t1.o
+; RUN: llvm-lto2 run -O0 -o %t2.o %t1.o -r %t1.o,a,px -r %t1.o,b,p -r %t1.o,c,p -r %t1.o,p,p
+; RUN: llvm-nm --numeric-sort %t2.o.0 | FileCheck %s
+
+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"
+
+;; VisibleToRegularObj && !AddressTaken
+; CHECK: T __cfi_a
+; CHECK: T a
+define void @a() !kcfi_type !1 {
+ ret void
+}
+
+;; !VisibleToRegularObj && !AddressTaken
+; CHECK-NOT: __cfi_b
+; CHECK: t b
+define void @b() !kcfi_type !1 {
+ ret void
+}
+
+;; !VisibleToRegularObj && AddressTaken
+; CHECK: t __cfi_c
+; CHECK: t c
+define void @c() !kcfi_type !1 {
+ ret void
+}
+
+@p = global ptr @c
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 4, !"kcfi", i32 1}
+!1 = !{i32 12345678}
Index: llvm/lib/Target/X86/X86AsmPrinter.cpp
===================================================================
--- llvm/lib/Target/X86/X86AsmPrinter.cpp
+++ llvm/lib/Target/X86/X86AsmPrinter.cpp
@@ -156,8 +156,9 @@
return;
ConstantInt *Type = nullptr;
- if (const MDNode *MD = F.getMetadata(LLVMContext::MD_kcfi_type))
- Type = mdconst::extract<ConstantInt>(MD->getOperand(0));
+ if (needsKCFITypeId(MF))
+ if (const MDNode *MD = F.getMetadata(LLVMContext::MD_kcfi_type))
+ Type = mdconst::extract<ConstantInt>(MD->getOperand(0));
// If we don't have a type to emit, just emit padding if needed to maintain
// the same alignment for all functions.
Index: llvm/lib/LTO/LTO.cpp
===================================================================
--- llvm/lib/LTO/LTO.cpp
+++ llvm/lib/LTO/LTO.cpp
@@ -601,6 +601,7 @@
GlobalRes.VisibleOutsideSummary |=
(Res.VisibleToRegularObj || Sym.isUsed() || !InSummary);
+ GlobalRes.VisibleToRegularObj |= Res.VisibleToRegularObj;
GlobalRes.ExportDynamic |= Res.ExportDynamic;
}
}
@@ -1164,6 +1165,9 @@
: GlobalValue::UnnamedAddr::None);
if (EnableLTOInternalization && R.second.Partition == 0)
GV->setLinkage(GlobalValue::InternalLinkage);
+
+ if (auto *F = dyn_cast<Function>(GV))
+ F->setIsVisibleToRegularObj(R.second.VisibleToRegularObj);
}
RegularLTO.CombinedModule->addModuleFlag(Module::Error, "LTOPostLink", 1);
Index: llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -1386,7 +1386,31 @@
OutStreamer->popSection();
}
+bool AsmPrinter::needsKCFITypeId(const MachineFunction &MF) {
+ const Function &F = MF.getFunction();
+ const Module &M = *F.getParent();
+
+ if (!F.hasMetadata(LLVMContext::MD_kcfi_type))
+ return false;
+
+ // With LTO, we can drop type information from globals that are not
+ // address-taken, as long as they are not visible to regular objects.
+ if (!M.getModuleFlag("LTOPostLink") || F.isVisibleToRegularObj())
+ return true;
+
+ // Disable the optimization for ThinLTO as the address-taken property
+ // is not combined.
+ if (auto *MD =
+ mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
+ if (MD->getZExtValue())
+ return true;
+
+ return F.hasAddressTaken();
+}
+
void AsmPrinter::emitKCFITypeId(const MachineFunction &MF) {
+ if (!needsKCFITypeId(MF))
+ return;
const Function &F = MF.getFunction();
if (const MDNode *MD = F.getMetadata(LLVMContext::MD_kcfi_type))
emitGlobalConstant(F.getParent()->getDataLayout(),
Index: llvm/include/llvm/LTO/LTO.h
===================================================================
--- llvm/include/llvm/LTO/LTO.h
+++ llvm/include/llvm/LTO/LTO.h
@@ -342,6 +342,9 @@
/// summary).
bool VisibleOutsideSummary = false;
+ /// This symbol is visible to regular objects.
+ bool VisibleToRegularObj = false;
+
/// The symbol was exported dynamically, and therefore could be referenced
/// by a shared library not visible to the linker.
bool ExportDynamic = false;
Index: llvm/include/llvm/IR/Function.h
===================================================================
--- llvm/include/llvm/IR/Function.h
+++ llvm/include/llvm/IR/Function.h
@@ -93,6 +93,8 @@
enum {
/// Whether this function is materializable.
IsMaterializableBit = 0,
+ /// Whether this function is visible to regular objects with LTO,
+ IsVisibleToRegularObjBit,
};
friend class SymbolTableListTraits<Function>;
@@ -195,6 +197,15 @@
(V ? Mask : 0u));
}
+ bool isVisibleToRegularObj() const {
+ return getGlobalObjectSubClassData() & (1 << IsVisibleToRegularObjBit);
+ }
+ void setIsVisibleToRegularObj(bool V) {
+ unsigned Mask = 1 << IsVisibleToRegularObjBit;
+ setGlobalObjectSubClassData((~Mask & getGlobalObjectSubClassData()) |
+ (V ? Mask : 0u));
+ }
+
/// getIntrinsicID - This method returns the ID number of the specified
/// function, or Intrinsic::not_intrinsic if the function is not an
/// intrinsic, or if the pointer is null. This value is always defined to be
Index: llvm/include/llvm/CodeGen/AsmPrinter.h
===================================================================
--- llvm/include/llvm/CodeGen/AsmPrinter.h
+++ llvm/include/llvm/CodeGen/AsmPrinter.h
@@ -420,6 +420,7 @@
void emitBBAddrMapSection(const MachineFunction &MF);
void emitKCFITrapEntry(const MachineFunction &MF, const MCSymbol *Symbol);
+ bool needsKCFITypeId(const MachineFunction &MF);
virtual void emitKCFITypeId(const MachineFunction &MF);
void emitPseudoProbe(const MachineInstr &MI);
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