Target RegisterInfo: devirtualize TargetFrameLowering

Summary:
The target frame lowering's concrete type is always known in RegisterInfo, yet it's only sometimes devirtualized through a static_cast. This change adds an auto-generated static function <Target>GenRegisterInfo::getFrameLowering(const MachineFunction &MF) which does this devirtualization, and uses this function in all targets which can.

This change was suggested by sunfish in D11070 for WebAssembly, I figure that I may as well improve the other targets while I'm here.

Subscribers: sunfish, ted, llvm-commits, jfb

Differential Revision: http://reviews.llvm.org/D11093

llvm-svn: 241921

1 files changed, 11 insertions, 17 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp b/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
index 656376c641a..2b09b2f625d 100644
--- a/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
@@ -165,8 +165,7 @@ void PPCRegisterInfo::adjustStackMapLiveOutMask(uint32_t *Mask) const {
 BitVector PPCRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
   BitVector Reserved(getNumRegs());
   const PPCSubtarget &Subtarget = MF.getSubtarget<PPCSubtarget>();
-  const PPCFrameLowering *PPCFI =
-      static_cast<const PPCFrameLowering *>(Subtarget.getFrameLowering());
+  const PPCFrameLowering *TFI = getFrameLowering(MF);
 
   // The ZERO register is not really a register, but the representation of r0
   // when used in instructions that treat r0 as the constant 0.
@@ -209,7 +208,7 @@ BitVector PPCRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
     Reserved.set(PPC::X1);
     Reserved.set(PPC::X13);
 
-    if (PPCFI->needsFP(MF))
+    if (TFI->needsFP(MF))
       Reserved.set(PPC::X31);
 
     if (hasBasePointer(MF))
@@ -230,7 +229,7 @@ BitVector PPCRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
     }
   }
 
-  if (PPCFI->needsFP(MF))
+  if (TFI->needsFP(MF))
     Reserved.set(PPC::R31);
 
   if (hasBasePointer(MF)) {
@@ -256,8 +255,7 @@ BitVector PPCRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
 
 unsigned PPCRegisterInfo::getRegPressureLimit(const TargetRegisterClass *RC,
                                               MachineFunction &MF) const {
-  const PPCSubtarget &Subtarget = MF.getSubtarget<PPCSubtarget>();
-  const TargetFrameLowering *TFI = Subtarget.getFrameLowering();
+  const PPCFrameLowering *TFI = getFrameLowering(MF);
   const unsigned DefaultSafety = 1;
 
   switch (RC->getID()) {
@@ -341,7 +339,8 @@ void PPCRegisterInfo::lowerDynamicAlloc(MachineBasicBlock::iterator II) const {
   unsigned FrameSize = MFI->getStackSize();
   
   // Get stack alignments.
-  unsigned TargetAlign = Subtarget.getFrameLowering()->getStackAlignment();
+  const PPCFrameLowering *TFI = getFrameLowering(MF);
+  unsigned TargetAlign = TFI->getStackAlignment();
   unsigned MaxAlign = MFI->getMaxAlignment();
   assert((maxCallFrameSize & (MaxAlign-1)) == 0 &&
          "Maximum call-frame size not sufficiently aligned");
@@ -864,8 +863,7 @@ PPCRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
 }
 
 unsigned PPCRegisterInfo::getFrameRegister(const MachineFunction &MF) const {
-  const PPCSubtarget &Subtarget = MF.getSubtarget<PPCSubtarget>();
-  const TargetFrameLowering *TFI = Subtarget.getFrameLowering();
+  const PPCFrameLowering *TFI = getFrameLowering(MF);
 
   if (!TM.isPPC64())
     return TFI->hasFP(MF) ? PPC::R31 : PPC::R1;
@@ -908,10 +906,10 @@ bool PPCRegisterInfo::canRealignStack(const MachineFunction &MF) const {
 }
 
 bool PPCRegisterInfo::needsStackRealignment(const MachineFunction &MF) const {
-  const PPCSubtarget &Subtarget = MF.getSubtarget<PPCSubtarget>();
+  const PPCFrameLowering *TFI = getFrameLowering(MF);
   const MachineFrameInfo *MFI = MF.getFrameInfo();
   const Function *F = MF.getFunction();
-  unsigned StackAlign = Subtarget.getFrameLowering()->getStackAlignment();
+  unsigned StackAlign = TFI->getStackAlignment();
   bool requiresRealignment = ((MFI->getMaxAlignment() > StackAlign) ||
                               F->hasFnAttribute(Attribute::StackAlignment));
 
@@ -946,11 +944,8 @@ needsFrameBaseReg(MachineInstr *MI, int64_t Offset) const {
 
   MachineBasicBlock &MBB = *MI->getParent();
   MachineFunction &MF = *MBB.getParent();
-  const PPCSubtarget &Subtarget = MF.getSubtarget<PPCSubtarget>();
-  const PPCFrameLowering *PPCFI =
-      static_cast<const PPCFrameLowering *>(Subtarget.getFrameLowering());
-  unsigned StackEst =
-    PPCFI->determineFrameLayout(MF, false, true);
+  const PPCFrameLowering *TFI = getFrameLowering(MF);
+  unsigned StackEst = TFI->determineFrameLayout(MF, false, true);
 
   // If we likely don't need a stack frame, then we probably don't need a
   // virtual base register either.
@@ -1034,4 +1029,3 @@ bool PPCRegisterInfo::isFrameOffsetLegal(const MachineInstr *MI,
          MI->getOpcode() == TargetOpcode::PATCHPOINT ||
          (isInt<16>(Offset) && (!usesIXAddr(*MI) || (Offset & 3) == 0));
 }
-