TargetLowering: Add finalizeLowering() function; NFC

Adds a new method finalizeLowering to TargetLoweringBase. This is in
preparation for an upcoming commit.

This function is meant for target specific adjustments to
MachineFrameInfo or register reservations.

Move the freezeRegisters() and the hasCopyImplyingStackAdjustment()
handling into the new function to prove the concept. As an added bonus
GlobalISel no longer missed the hasCopyImplyingStackAdjustment()
handling with this.

Differential Revision: https://reviews.llvm.org/D32621

llvm-svn: 301679

llvm/include/llvm/Target/TargetLowering.h

@@ -2097,6 +2097,12 @@ class TargetLoweringBase {
     return LibcallCallingConvs[Call];
   }
 
+  /// Execute target specific actions to finalize target lowering.
+  /// This is used to set extra flags in MachineFrameInformation and freezing
+  /// the set of reserved registers.
+  /// The default implementation just freezes the set of reserved registers.
+  virtual void finalizeLowering(MachineFunction &MF) const;
+
 private:
   const TargetMachine &TM;
 
@@ -2655,12 +2661,6 @@ class TargetLowering : public TargetLoweringBase {
     return false;
   }
 
-  /// Return true if the MachineFunction contains a COPY which would imply
-  /// HasCopyImplyingStackAdjustment.
-  virtual bool hasCopyImplyingStackAdjustment(MachineFunction *MF) const {
-    return false;
-  }
-
   /// Perform necessary initialization to handle a subset of CSRs explicitly
   /// via copies. This function is called at the beginning of instruction
   /// selection.

llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp

@@ -1199,9 +1199,7 @@ bool IRTranslator::runOnMachineFunction(MachineFunction &CurMF) {
 
   finishPendingPhis();
 
-  // Now that the MachineFrameInfo has been configured, no further changes to
-  // the reserved registers are possible.
-  MRI->freezeReservedRegs(*MF);
+  TLI->finalizeLowering(*MF);
 
   // Merge the argument lowering and constants block with its single
   // successor, the LLVM-IR entry block.  We want the basic block to

llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

@@ -593,13 +593,7 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
     MRI.replaceRegWith(From, To);
   }
 
-  if (TLI->hasCopyImplyingStackAdjustment(MF))
-    MFI.setHasCopyImplyingStackAdjustment(true);
-
-  // Freeze the set of reserved registers now that MachineFrameInfo has been
-  // set up. All the information required by getReservedRegs() should be
-  // available now.
-  MRI.freezeReservedRegs(*MF);
+  TLI->finalizeLowering(*MF);
 
   // Release function-specific state. SDB and CurDAG are already cleared
   // at this point.

llvm/lib/CodeGen/TargetLoweringBase.cpp

@@ -21,6 +21,7 @@
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineJumpTableInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/StackMaps.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/DerivedTypes.h"
@@ -2108,3 +2109,7 @@ int TargetLoweringBase::getDivRefinementSteps(EVT VT,
                                               MachineFunction &MF) const {
   return getOpRefinementSteps(false, VT, getRecipEstimateForFunc(MF));
 }
+
+void TargetLoweringBase::finalizeLowering(MachineFunction &MF) const {
+  MF.getRegInfo().freezeReservedRegs(MF);
+}

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -35169,14 +35169,21 @@ bool X86TargetLowering::isTypeDesirableForOp(unsigned Opc, EVT VT) const {
 /// know that the code that lowers COPY of EFLAGS has to use the stack, and if
 /// we don't adjust the stack we clobber the first frame index.
 /// See X86InstrInfo::copyPhysReg.
-bool X86TargetLowering::hasCopyImplyingStackAdjustment(
-    MachineFunction *MF) const {
-  const MachineRegisterInfo &MRI = MF->getRegInfo();
-
+static bool hasCopyImplyingStackAdjustment(const MachineFunction &MF) {
+  const MachineRegisterInfo &MRI = MF.getRegInfo();
   return any_of(MRI.reg_instructions(X86::EFLAGS),
                 [](const MachineInstr &RI) { return RI.isCopy(); });
 }
 
+void X86TargetLowering::finalizeLowering(MachineFunction &MF) const {
+  if (hasCopyImplyingStackAdjustment(MF)) {
+    MachineFrameInfo &MFI = MF.getFrameInfo();
+    MFI.setHasCopyImplyingStackAdjustment(true);
+  }
+
+  TargetLoweringBase::finalizeLowering(MF);
+}
+
 /// This method query the target whether it is beneficial for dag combiner to
 /// promote the specified node. If true, it should return the desired promotion
 /// type by reference.

llvm/lib/Target/X86/X86ISelLowering.h

@@ -773,10 +773,6 @@ namespace llvm {
     /// and some i16 instructions are slow.
     bool IsDesirableToPromoteOp(SDValue Op, EVT &PVT) const override;
 
-    /// Return true if the MachineFunction contains a COPY which would imply
-    /// HasOpaqueSPAdjustment.
-    bool hasCopyImplyingStackAdjustment(MachineFunction *MF) const override;
-
     MachineBasicBlock *
     EmitInstrWithCustomInserter(MachineInstr &MI,
                                 MachineBasicBlock *MBB) const override;
@@ -1065,6 +1061,9 @@ namespace llvm {
                               ArrayRef<ShuffleVectorInst *> Shuffles,
                               ArrayRef<unsigned> Indices,
                               unsigned Factor) const override;
+
+    void finalizeLowering(MachineFunction &MF) const override;
+
   protected:
     std::pair<const TargetRegisterClass *, uint8_t>
     findRepresentativeClass(const TargetRegisterInfo *TRI,