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[CFI] Remove LinkerSubsectionsViaSymbols. 

Since D17854 LinkerSubsectionsViaSymbols is unnecessary.

It is interfering with ThinLTO implementation of CFI-ICall, where
the aliases used on the !LinkerSubsectionsViaSymbols branch are
needed to export jump tables to ThinLTO backends.

This is the second attempt to land this change after fixing PR33316.

llvm-svn: 305031
This commit is contained in:
Evgeniy Stepanov 2017-06-08 23:38:22 +00:00
parent 2aa4d39f5e
commit d02dbf6b1c
2 changed files with 13 additions and 38 deletions
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35
llvm/lib/Transforms/IPO/LowerTypeTests.cpp
View File

@ -235,7 +235,6 @@ class LowerTypeTestsModule {
ModuleSummaryIndex *ExportSummary;
const ModuleSummaryIndex *ImportSummary;
bool LinkerSubsectionsViaSymbols;
Triple::ArchType Arch;
Triple::OSType OS;
Triple::ObjectFormatType ObjectFormat;
@ -475,13 +474,9 @@ void LowerTypeTestsModule::allocateByteArrays() {
// Create an alias instead of RAUW'ing the gep directly. On x86 this ensures
// that the pc-relative displacement is folded into the lea instead of the
// test instruction getting another displacement.
if (LinkerSubsectionsViaSymbols) {
BAI->ByteArray->replaceAllUsesWith(GEP);
} else {
GlobalAlias *Alias = GlobalAlias::create(
Int8Ty, 0, GlobalValue::PrivateLinkage, "bits", GEP, &M);
BAI->ByteArray->replaceAllUsesWith(Alias);
}
GlobalAlias *Alias = GlobalAlias::create(
Int8Ty, 0, GlobalValue::PrivateLinkage, "bits", GEP, &M);
BAI->ByteArray->replaceAllUsesWith(Alias);
BAI->ByteArray->eraseFromParent();
}
@ -502,7 +497,7 @@ Value *LowerTypeTestsModule::createBitSetTest(IRBuilder<> &B,
return createMaskedBitTest(B, TIL.InlineBits, BitOffset);
} else {
Constant *ByteArray = TIL.TheByteArray;
if (!LinkerSubsectionsViaSymbols && AvoidReuse && !ImportSummary) {
if (AvoidReuse && !ImportSummary) {
// Each use of the byte array uses a different alias. This makes the
// backend less likely to reuse previously computed byte array addresses,
// improving the security of the CFI mechanism based on this pass.
@ -697,17 +692,13 @@ void LowerTypeTestsModule::buildBitSetsFromGlobalVariables(
ConstantInt::get(Int32Ty, I * 2)};
Constant *CombinedGlobalElemPtr = ConstantExpr::getGetElementPtr(
NewInit->getType(), CombinedGlobal, CombinedGlobalIdxs);
if (LinkerSubsectionsViaSymbols) {
GV->replaceAllUsesWith(CombinedGlobalElemPtr);
} else {
assert(GV->getType()->getAddressSpace() == 0);
GlobalAlias *GAlias = GlobalAlias::create(NewTy->getElementType(I * 2), 0,
GV->getLinkage(), "",
CombinedGlobalElemPtr, &M);
GAlias->setVisibility(GV->getVisibility());
GAlias->takeName(GV);
GV->replaceAllUsesWith(GAlias);
}
assert(GV->getType()->getAddressSpace() == 0);
GlobalAlias *GAlias =
GlobalAlias::create(NewTy->getElementType(I * 2), 0, GV->getLinkage(),
"", CombinedGlobalElemPtr, &M);
GAlias->setVisibility(GV->getVisibility());
GAlias->takeName(GV);
GV->replaceAllUsesWith(GAlias);
GV->eraseFromParent();
}
}
@ -1183,8 +1174,7 @@ void LowerTypeTestsModule::buildBitSetsFromFunctionsNative(
ArrayRef<Constant *>{ConstantInt::get(IntPtrTy, 0),
ConstantInt::get(IntPtrTy, I)}),
F->getType());
if (LinkerSubsectionsViaSymbols || F->isDeclarationForLinker()) {
if (F->isDeclarationForLinker()) {
if (F->isWeakForLinker())
replaceWeakDeclarationWithJumpTablePtr(F, CombinedGlobalElemPtr);
else
@ -1319,7 +1309,6 @@ LowerTypeTestsModule::LowerTypeTestsModule(
: M(M), ExportSummary(ExportSummary), ImportSummary(ImportSummary) {
assert(!(ExportSummary && ImportSummary));
Triple TargetTriple(M.getTargetTriple());
LinkerSubsectionsViaSymbols = TargetTriple.isMacOSX();
Arch = TargetTriple.getArch();
OS = TargetTriple.getOS();
ObjectFormat = TargetTriple.getObjectFormat();

16
llvm/test/Transforms/LowerTypeTests/simple.ll
View File

@ -1,5 +1,5 @@
; RUN: opt -S -lowertypetests < %s | FileCheck %s
; RUN: opt -S -lowertypetests -mtriple=x86_64-apple-macosx10.8.0 < %s | FileCheck -check-prefix=CHECK-DARWIN %s
; RUN: opt -S -lowertypetests -mtriple=x86_64-apple-macosx10.8.0 < %s | FileCheck %s
; RUN: opt -S -O3 < %s | FileCheck -check-prefix=CHECK-NODISCARD %s
target datalayout = "e-p:32:32"
@ -39,20 +39,6 @@ target datalayout = "e-p:32:32"
; CHECK: @c = protected alias i32, getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 4)
; CHECK: @d = alias [2 x i32], getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 6)
; CHECK-DARWIN: @aptr = constant i32* getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G:@[^ ]*]], i32 0, i32 0)
@aptr = constant i32* @a
; CHECK-DARWIN: @bptr = constant [63 x i32]* getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 2)
@bptr = constant [63 x i32]* @b
; CHECK-DARWIN: @cptr = constant i32* getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 4)
@cptr = constant i32* @c
; CHECK-DARWIN: @dptr = constant [2 x i32]* getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 6)
@dptr = constant [2 x i32]* @d
; CHECK-DARWIN: [[G]] = private constant
; CHECK: @bits{{[0-9]*}} = private alias i8, getelementptr inbounds ([68 x i8], [68 x i8]* [[BA]], i32 0, i32 0)
; CHECK: @bits.{{[0-9]*}} = private alias i8, getelementptr inbounds ([68 x i8], [68 x i8]* [[BA]], i32 0, i32 0)