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[stack protector] Look through bitcasts to get global variable

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__stack_chk_guard.

Handle the case where the pointer operand of the load instruction that loads the
stack guard is not a global variable but instead a bitcast.

%StackGuard = load i8** bitcast (i64** @__stack_chk_guard to i8**)
call void @llvm.stackprotector(i8* %StackGuard, i8** %StackGuardSlot)

Original test case provided by Ana Pazos.

This fixes PR20558.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215167 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Akira Hatanaka 2014-08-07 23:08:24 +00:00
parent 7f48f056f7
commit 43f6ce9289
2 changed files with 45 additions and 9 deletions
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28
lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
View File

@ -1814,12 +1814,14 @@ void SelectionDAGBuilder::visitSPDescriptorParent(StackProtectorDescriptor &SPD,
SDValue Guard;
// If useLoadStackGuardNode returns true, retrieve the guard value from
// the virtual register holding the value. Otherwise, emit a volatile load
// to retrieve the stack guard value.
if (TLI->useLoadStackGuardNode())
Guard = DAG.getCopyFromReg(DAG.getEntryNode(), getCurSDLoc(),
SPD.getGuardReg(), PtrTy);
// If GuardReg is set and useLoadStackGuardNode returns true, retrieve the
// guard value from the virtual register holding the value. Otherwise, emit a
// volatile load to retrieve the stack guard value.
unsigned GuardReg = SPD.getGuardReg();
if (GuardReg && TLI->useLoadStackGuardNode())
Guard = DAG.getCopyFromReg(DAG.getEntryNode(), getCurSDLoc(), GuardReg,
PtrTy);
else
Guard = DAG.getLoad(PtrTy, getCurSDLoc(), DAG.getEntryNode(),
GuardPtr, MachinePointerInfo(IRGuard, 0),
@ -5263,13 +5265,21 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
MachineFrameInfo *MFI = MF.getFrameInfo();
EVT PtrTy = TLI->getPointerTy();
SDValue Src, Chain = getRoot();
const Value *Ptr = cast<LoadInst>(I.getArgOperand(0))->getPointerOperand();
const GlobalVariable *GV = dyn_cast<GlobalVariable>(Ptr);
if (TLI->useLoadStackGuardNode()) {
// See if Ptr is a bitcast. If it is, look through it and see if we can get
// global variable __stack_chk_guard.
if (!GV)
if (const Operator *BC = dyn_cast<Operator>(Ptr))
if (BC->getOpcode() == Instruction::BitCast)
GV = dyn_cast<GlobalVariable>(BC->getOperand(0));
if (GV && TLI->useLoadStackGuardNode()) {
// Emit a LOAD_STACK_GUARD node.
MachineSDNode *Node = DAG.getMachineNode(TargetOpcode::LOAD_STACK_GUARD,
sdl, PtrTy, Chain);
LoadInst *LI = cast<LoadInst>(I.getArgOperand(0));
MachinePointerInfo MPInfo(LI->getPointerOperand());
MachinePointerInfo MPInfo(GV);
MachineInstr::mmo_iterator MemRefs = MF.allocateMemRefsArray(1);
unsigned Flags = MachineMemOperand::MOLoad |
MachineMemOperand::MOInvariant;

26
test/CodeGen/AArch64/stack-guard-remat-bitcast.ll Normal file
View File

@ -0,0 +1,26 @@
; RUN: llc < %s -mtriple=arm64-apple-ios -relocation-model=pic | FileCheck %s
@__stack_chk_guard = external global i64*
; PR20558
; CHECK: adrp [[R0:x[0-9]+]], ___stack_chk_guard@GOTPAGE
; CHECK: ldr [[R1:x[0-9]+]], {{\[}}[[R0]], ___stack_chk_guard@GOTPAGEOFF{{\]}}
; CHECK: ldr [[R2:x[0-9]+]], {{\[}}[[R1]]{{\]}}
; CHECK: stur [[R2]], {{\[}}x29, [[SLOT0:[0-9#\-]+]]{{\]}}
; CHECK: ldur [[R3:x[0-9]+]], {{\[}}x29, [[SLOT0]]{{\]}}
; CHECK: sub [[R4:x[0-9]+]], [[R2]], [[R3]]
; CHECK: cbnz [[R4]], LBB
define i32 @test_stack_guard_remat2() {
entry:
%StackGuardSlot = alloca i8*
%StackGuard = load i8** bitcast (i64** @__stack_chk_guard to i8**)
call void @llvm.stackprotector(i8* %StackGuard, i8** %StackGuardSlot)
%container = alloca [32 x i8], align 1
call void @llvm.stackprotectorcheck(i8** bitcast (i64** @__stack_chk_guard to i8**))
ret i32 -1
}
declare void @llvm.stackprotector(i8*, i8**)
declare void @llvm.stackprotectorcheck(i8**)