+ SDB->SPDescriptor.resetPerFunctionState();
+}
+
+/// Given that the input MI is before a partial terminator sequence TSeq, return
+/// true if M + TSeq also a partial terminator sequence.
+///
+/// A Terminator sequence is a sequence of MachineInstrs which at this point in
+/// lowering copy vregs into physical registers, which are then passed into
+/// terminator instructors so we can satisfy ABI constraints. A partial
+/// terminator sequence is an improper subset of a terminator sequence (i.e. it
+/// may be the whole terminator sequence).
+static bool MIIsInTerminatorSequence(const MachineInstr *MI) {
+ // If we do not have a copy or an implicit def, we return true if and only if
+ // MI is a debug value.
+ if (!MI->isCopy() && !MI->isImplicitDef())
+ // Sometimes DBG_VALUE MI sneak in between the copies from the vregs to the
+ // physical registers if there is debug info associated with the terminator
+ // of our mbb. We want to include said debug info in our terminator
+ // sequence, so we return true in that case.
+ return MI->isDebugValue();
+
+ // We have left the terminator sequence if we are not doing one of the
+ // following:
+ //
+ // 1. Copying a vreg into a physical register.
+ // 2. Copying a vreg into a vreg.
+ // 3. Defining a register via an implicit def.
+
+ // OPI should always be a register definition...
+ MachineInstr::const_mop_iterator OPI = MI->operands_begin();
+ if (!OPI->isReg() || !OPI->isDef())
+ return false;
+
+ // Defining any register via an implicit def is always ok.
+ if (MI->isImplicitDef())
+ return true;
+
+ // Grab the copy source...
+ MachineInstr::const_mop_iterator OPI2 = OPI;
+ ++OPI2;
+ assert(OPI2 != MI->operands_end()
+ && "Should have a copy implying we should have 2 arguments.");
+
+ // Make sure that the copy dest is not a vreg when the copy source is a
+ // physical register.
+ if (!OPI2->isReg() ||
+ (!TargetRegisterInfo::isPhysicalRegister(OPI->getReg()) &&
+ TargetRegisterInfo::isPhysicalRegister(OPI2->getReg())))
+ return false;
+
+ return true;
+}
+
+/// Find the split point at which to splice the end of BB into its success stack
+/// protector check machine basic block.
+///
+/// On many platforms, due to ABI constraints, terminators, even before register
+/// allocation, use physical registers. This creates an issue for us since
+/// physical registers at this point can not travel across basic
+/// blocks. Luckily, selectiondag always moves physical registers into vregs
+/// when they enter functions and moves them through a sequence of copies back
+/// into the physical registers right before the terminator creating a
+/// ``Terminator Sequence''. This function is searching for the beginning of the
+/// terminator sequence so that we can ensure that we splice off not just the
+/// terminator, but additionally the copies that move the vregs into the
+/// physical registers.
+static MachineBasicBlock::iterator
+FindSplitPointForStackProtector(MachineBasicBlock *BB, DebugLoc DL) {
+ MachineBasicBlock::iterator SplitPoint = BB->getFirstTerminator();
+ //
+ if (SplitPoint == BB->begin())
+ return SplitPoint;
+
+ MachineBasicBlock::iterator Start = BB->begin();
+ MachineBasicBlock::iterator Previous = SplitPoint;
+ --Previous;
+
+ while (MIIsInTerminatorSequence(Previous)) {
+ SplitPoint = Previous;
+ if (Previous == Start)
+ break;
+ --Previous;
+ }
+
+ return SplitPoint;