+namespace {
+ struct MaximalStackAlignmentCalculator : public MachineFunctionPass {
+ static char ID;
+ MaximalStackAlignmentCalculator() : MachineFunctionPass(&ID) {}
+
+ virtual bool runOnMachineFunction(MachineFunction &MF) {
+ MachineFrameInfo *FFI = MF.getFrameInfo();
+ MachineRegisterInfo &RI = MF.getRegInfo();
+
+ // Calculate max stack alignment of all already allocated stack objects.
+ unsigned MaxAlign = calculateMaxStackAlignment(FFI);
+
+ // Be over-conservative: scan over all vreg defs and find, whether vector
+ // registers are used. If yes - there is probability, that vector register
+ // will be spilled and thus stack needs to be aligned properly.
+ for (unsigned RegNum = TargetRegisterInfo::FirstVirtualRegister;
+ RegNum < RI.getLastVirtReg(); ++RegNum)
+ MaxAlign = std::max(MaxAlign, RI.getRegClass(RegNum)->getAlignment());
+
+ if (FFI->getMaxAlignment() == MaxAlign)
+ return false;
+
+ FFI->setMaxAlignment(MaxAlign);
+ return true;
+ }
+
+ virtual const char *getPassName() const {
+ return "ARM Stack Required Alignment Auto-Detector";
+ }
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+ MachineFunctionPass::getAnalysisUsage(AU);
+ }
+ };
+
+ char MaximalStackAlignmentCalculator::ID = 0;
+}
+
+FunctionPass*
+llvm::createARMMaxStackAlignmentCalculatorPass() {
+ return new MaximalStackAlignmentCalculator();
+}
+