[stackprotector] Implement the sspstrong rules for stack layout.

This changes the PrologueEpilogInserter and LocalStackSlotAllocation passes to
follow the extended stack layout rules for sspstrong and sspreq.

The sspstrong layout rules are:
 1. Large arrays and structures containing large arrays (>= ssp-buffer-size)
are closest to the stack protector.
 2. Small arrays and structures containing small arrays (< ssp-buffer-size) are
2nd closest to the protector.
 3. Variables that have had their address taken are 3rd closest to the
protector.


Differential Revision: http://llvm-reviews.chandlerc.com/D2546

llvm-svn: 200601

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp b/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp
index f521548b213..08f0cc2f011 100644
--- a/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp
+++ b/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp
@@ -194,6 +194,9 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
   SmallSet<int, 16> ProtectedObjs;
   if (MFI->getStackProtectorIndex() >= 0) {
     StackObjSet LargeArrayObjs;
+    StackObjSet SmallArrayObjs;
+    StackObjSet AddrOfObjs;
+
     AdjustStackOffset(MFI, MFI->getStackProtectorIndex(), Offset,
                       StackGrowsDown, MaxAlign);
 
@@ -206,8 +209,12 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
 
       switch (SP->getSSPLayout(MFI->getObjectAllocation(i))) {
       case StackProtector::SSPLK_None:
+        continue;
       case StackProtector::SSPLK_SmallArray:
+        SmallArrayObjs.insert(i);
+        continue;
       case StackProtector::SSPLK_AddrOf:
+        AddrOfObjs.insert(i);
         continue;
       case StackProtector::SSPLK_LargeArray:
         LargeArrayObjs.insert(i);
@@ -218,6 +225,10 @@ void LocalStackSlotPass::calculateFrameObjectOffsets(MachineFunction &Fn) {
 
     AssignProtectedObjSet(LargeArrayObjs, ProtectedObjs, MFI, StackGrowsDown,
                           Offset, MaxAlign);
+    AssignProtectedObjSet(SmallArrayObjs, ProtectedObjs, MFI, StackGrowsDown,
+                          Offset, MaxAlign);
+    AssignProtectedObjSet(AddrOfObjs, ProtectedObjs, MFI, StackGrowsDown,
+                          Offset, MaxAlign);
   }
 
   // Then assign frame offsets to stack objects that are not used to spill