Add a "probe-stack" attribute

[Zoxc]

Summary

Split from http://reviews.llvm.org/D4717

[Zoxc]

A newer version was posted to the mailing list.

include/llvm/CodeGen/MachineFunction.h

   /// Should we be emitting segmented stack stuff for the function
   bool shouldSplitStack();
 
+  /// Should we be probing the stack for the function.
+  /// Probing the stack means that we must read or write to the stack on every
+  /// page. This is to ensure that a guard page will be hit and stack overflow
+  /// can be detected. We insert instructions to do this when allocating from
+  /// the stack.
+  bool shouldProbeStack();
+
   /// getNumBlockIDs - Return the number of MBB ID's allocated.
   ///
   unsigned getNumBlockIDs() const { return (unsigned)MBBNumbering.size(); }

lib/CodeGen/MachineFunction.cpp

   return getFunction()->hasFnAttribute("split-stack");
 }
 
+/// Should we be probing the stack for the function.
+/// Probing the stack means that we must read or write to the stack on every
+/// page. This is to ensure that a guard page will be hit and stack overflow
+/// can be detected. We insert instructions to do this when allocating from
+/// the stack.
+bool MachineFunction::shouldProbeStack() {
+  return getFunction()->hasFnAttribute("probe-stack");
+}
+
 /// RenumberBlocks - This discards all of the MachineBasicBlock numbers and
 /// recomputes them.  This guarantees that the MBB numbers are sequential,
 /// dense, and match the ordering of the blocks within the function.  If a

lib/Transforms/IPO/Inliner.cpp

 
   AdjustCallerSSPLevel(Caller, Callee);
 
+  // If the callee requires stack probes, we ensure that the caller will
+  // require those too
+  if (Callee->hasFnAttribute("probe-stack")) {
+    Caller->addFnAttr("probe-stack", "");
+  }
+
   // Look at all of the allocas that we inlined through this call site.  If we
   // have already inlined other allocas through other calls into this function,
   // then we know that they have disjoint lifetimes and that we can merge them.