[PATCH] D17094: [safestack] Add -safe-stack-subr-acc-as-unsafe option

[Michael LeMay via llvm-commits]

mlemay-intel updated this revision to Diff 53926.
mlemay-intel added a comment.

Check for the separate-stack-seg feature instead of defining a new command line option.


http://reviews.llvm.org/D17094

Files:
  include/llvm/Target/TargetLowering.h
  lib/CodeGen/SafeStack.cpp
  lib/Target/X86/X86ISelLowering.cpp
  lib/Target/X86/X86ISelLowering.h

Index: lib/Target/X86/X86ISelLowering.h
===================================================================
--- lib/Target/X86/X86ISelLowering.h
+++ lib/Target/X86/X86ISelLowering.h
@@ -655,6 +655,7 @@
 
     unsigned getJumpTableEncoding() const override;
     bool useSoftFloat() const override;
+    bool useOnlyLocalStackPointers() const override;
 
     MVT getScalarShiftAmountTy(const DataLayout &, EVT) const override {
       return MVT::i8;
Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -1985,6 +1985,10 @@
   return Subtarget.useSoftFloat();
 }
 
+bool X86TargetLowering::useOnlyLocalStackPointers() const {
+  return Subtarget.useSeparateStackSeg();
+}
+
 const MCExpr *
 X86TargetLowering::LowerCustomJumpTableEntry(const MachineJumpTableInfo *MJTI,
                                              const MachineBasicBlock *MBB,
Index: lib/CodeGen/SafeStack.cpp
===================================================================
--- lib/CodeGen/SafeStack.cpp
+++ lib/CodeGen/SafeStack.cpp
@@ -308,6 +308,11 @@
       case Instruction::Invoke: {
         ImmutableCallSite CS(I);
 
+        // FIXME: A more precise solution may consider whether particular types
+        // of intrinsics necessitate moving allocations to the unsafe stack.
+        if (TL->useOnlyLocalStackPointers())
+          return false;
+
         if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
           if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
               II->getIntrinsicID() == Intrinsic::lifetime_end)
Index: include/llvm/Target/TargetLowering.h
===================================================================
--- include/llvm/Target/TargetLowering.h
+++ include/llvm/Target/TargetLowering.h
@@ -169,6 +169,13 @@
 
   virtual bool useSoftFloat() const { return false; }
 
+  /// A target may require that no pointer passed from one function to another
+  /// points to the main stack.  Such a target must override this function to
+  /// return true.  SafeStack must always be used for such a target, to move
+  /// any stack allocation to the unsafe stack that is the target of a pointer
+  /// passed to a subroutine.
+  virtual bool useOnlyLocalStackPointers() const { return false; }
+
   /// Return the pointer type for the given address space, defaults to
   /// the pointer type from the data layout.
   /// FIXME: The default needs to be removed once all the code is updated.


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