-
-namespace {
- struct MSAH : public MachineFunctionPass {
- static char ID;
- MSAH() : MachineFunctionPass(ID) {}
-
- virtual bool runOnMachineFunction(MachineFunction &MF) {
- const X86TargetMachine *TM =
- static_cast<const X86TargetMachine *>(&MF.getTarget());
- const TargetFrameLowering *TFI = TM->getFrameLowering();
- MachineRegisterInfo &RI = MF.getRegInfo();
- X86MachineFunctionInfo *FuncInfo = MF.getInfo<X86MachineFunctionInfo>();
- unsigned StackAlignment = TFI->getStackAlignment();
-
- // Be over-conservative: scan over all vreg defs and find whether vector
- // registers are used. If yes, there is a possibility that vector register
- // will be spilled and thus require dynamic stack realignment.
- for (unsigned i = 0, e = RI.getNumVirtRegs(); i != e; ++i) {
- unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
- if (RI.getRegClass(Reg)->getAlignment() > StackAlignment) {
- FuncInfo->setForceFramePointer(true);
- return true;
- }
- }
- // Nothing to do
- return false;
- }
-
- virtual const char *getPassName() const {
- return "X86 Maximal Stack Alignment Check";
- }
-
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesCFG();
- MachineFunctionPass::getAnalysisUsage(AU);
- }
- };
-
- char MSAH::ID = 0;
-}
-
-FunctionPass*
-llvm::createX86MaxStackAlignmentHeuristicPass() { return new MSAH(); }