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[stackprotector] Use analysis from the StackProtector pass for stack layout in PEI a nd LocalStackSlot passes.

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This changes the MachineFrameInfo API to use the new SSPLayoutKind information
produced by the StackProtector pass (instead of a boolean flag) and updates a
few pass dependencies (to preserve the SSP analysis).

The stack layout follows the same approach used prior to this change - i.e.,
only LargeArray stack objects will be placed near the canary and everything
else will be laid out normally.  After this change, structures containing large
arrays will also be placed near the canary - a case previously missed by the
old implementation.

Out of tree targets will need to update their usage of
MachineFrameInfo::CreateStackObject to remove the MayNeedSP argument. 

The next patch will implement the rules for sspstrong and sspreq.  The end goal
is to support ssp-strong stack layout rules.

WIP.

Differential Revision: http://llvm-reviews.chandlerc.com/D2158


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197653 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Josh Magee
2013-12-19 03:17:11 +00:00
parent 629f3b229e
commit 5b6af7163d
18 changed files with 559 additions and 54 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/CodeGen/LocalStackSlotAllocation.cpp
+51 -9
View File
@@ -17,12 +17,14 @@
#define DEBUG_TYPE "localstackalloc"
#include "llvm/CodeGen/Passes.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/StackProtector.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instructions.h"
@@ -60,18 +62,27 @@ namespace {
class LocalStackSlotPass: public MachineFunctionPass {
SmallVector<int64_t,16> LocalOffsets;
/// StackObjSet - A set of stack object indexes
typedef SmallSetVector<int, 8> StackObjSet;
void AdjustStackOffset(MachineFrameInfo *MFI, int FrameIdx, int64_t &Offset,
bool StackGrowsDown, unsigned &MaxAlign);
void AssignProtectedObjSet(const StackObjSet &UnassignedObjs,
SmallSet<int, 16> &ProtectedObjs,
MachineFrameInfo *MFI, bool StackGrowsDown,
int64_t &Offset, unsigned &MaxAlign);
void calculateFrameObjectOffsets(MachineFunction &Fn);
bool insertFrameReferenceRegisters(MachineFunction &Fn);
public:
static char ID; // Pass identification, replacement for typeid
explicit LocalStackSlotPass() : MachineFunctionPass(ID) { }
explicit LocalStackSlotPass() : MachineFunctionPass(ID) {
initializeLocalStackSlotPassPass(*PassRegistry::getPassRegistry());
}
bool runOnMachineFunction(MachineFunction &MF);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<StackProtector>();
MachineFunctionPass::getAnalysisUsage(AU);
}
@@ -81,8 +92,12 @@ namespace {
char LocalStackSlotPass::ID = 0;
char &llvm::LocalStackSlotAllocationID = LocalStackSlotPass::ID;
INITIALIZE_PASS(LocalStackSlotPass, "localstackalloc",
"Local Stack Slot Allocation", false, false)
INITIALIZE_PASS_BEGIN(LocalStackSlotPass, "localstackalloc",
"Local Stack Slot Allocation", false, false)
INITIALIZE_PASS_DEPENDENCY(StackProtector)
INITIALIZE_PASS_END(LocalStackSlotPass, "localstackalloc",
"Local Stack Slot Allocation", false, false)
bool LocalStackSlotPass::runOnMachineFunction(MachineFunction &MF) {
MachineFrameInfo *MFI = MF.getFrameInfo();
@@ -145,6 +160,22 @@ void LocalStackSlotPass::AdjustStackOffset(MachineFrameInfo *MFI,
++NumAllocations;
}
/// AssignProtectedObjSet - Helper function to assign large stack objects (i.e.,
/// those required to be close to the Stack Protector) to stack offsets.
void LocalStackSlotPass::AssignProtectedObjSet(const StackObjSet &UnassignedObjs,
SmallSet<int, 16> &ProtectedObjs,
MachineFrameInfo *MFI,
bool StackGrowsDown, int64_t &Offset,
unsigned &MaxAlign) {
for (StackObjSet::const_iterator I = UnassignedObjs.begin(),
E = UnassignedObjs.end(); I != E; ++I) {
int i = *I;
AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign);
ProtectedObjs.insert(i);
}
}
/// calculateFrameObjectOffsets - Calculate actual frame offsets for all of the
/// abstract stack objects.
///
@@ -156,11 +187,13 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
TFI.getStackGrowthDirection() == TargetFrameLowering::StackGrowsDown;
int64_t Offset = 0;
unsigned MaxAlign = 0;
StackProtector *SP = &getAnalysis<StackProtector>();
// Make sure that the stack protector comes before the local variables on the
// stack.
SmallSet<int, 16> LargeStackObjs;
SmallSet<int, 16> ProtectedObjs;
if (MFI->getStackProtectorIndex() >= 0) {
StackObjSet LargeArrayObjs;
AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), Offset,
StackGrowsDown, MaxAlign);
@@ -170,12 +203,21 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
continue;
if (MFI->getStackProtectorIndex() == (int)i)
continue;
if (!MFI->MayNeedStackProtector(i))
continue;
AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign);
LargeStackObjs.insert(i);
switch (SP->getSSPLayout(MFI->getObjectAllocation(i))) {
case StackProtector::SSPLK_None:
case StackProtector::SSPLK_SmallArray:
case StackProtector::SSPLK_AddrOf:
continue;
case StackProtector::SSPLK_LargeArray:
LargeArrayObjs.insert(i);
continue;
}
llvm_unreachable("Unexpected SSPLayoutKind.");
}
AssignProtectedObjSet(LargeArrayObjs, ProtectedObjs, MFI, StackGrowsDown,
Offset, MaxAlign);
}
// Then assign frame offsets to stack objects that are not used to spill
@@ -185,7 +227,7 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
continue;
if (MFI->getStackProtectorIndex() == (int)i)
continue;
if (LargeStackObjs.count(i))
if (ProtectedObjs.count(i))
continue;
AdjustStackOffset(MFI, i, Offset, StackGrowsDown, MaxAlign);