[NFC] Add the getSizeInBytes() interface for MachineConstantPoolValue

Current implementation assumes that, each MachineConstantPoolValue takes
up sizeof(MachineConstantPoolValue::Ty) bytes. For PowerPC, we want to
lump all the constants with the same type as one MachineConstantPoolValue
to save the cost that calculate the TOC entry for each const. So, we need
to extend the MachineConstantPoolValue that break this assumption.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D89108

include/llvm/CodeGen/MachineConstantPool.h

@@ -41,10 +41,10 @@ public:
   explicit MachineConstantPoolValue(Type *ty) : Ty(ty) {}
   virtual ~MachineConstantPoolValue() = default;
 
-  /// getType - get type of this MachineConstantPoolValue.
-  ///
   Type *getType() const { return Ty; }
 
+  virtual unsigned getSizeInBytes(const DataLayout &DL) const;
+
   virtual int getExistingMachineCPValue(MachineConstantPool *CP,
                                         Align Alignment) = 0;
 
@@ -94,7 +94,7 @@ public:
 
   Align getAlign() const { return Alignment; }
 
-  Type *getType() const;
+  unsigned getSizeInBytes(const DataLayout &DL) const;
 
   /// This method classifies the entry according to whether or not it may
   /// generate a relocation entry.  This must be conservative, so if it might

lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -1970,8 +1970,7 @@ void AsmPrinter::emitConstantPool() {
       unsigned NewOffset = alignTo(Offset, CPE.getAlign());
       OutStreamer->emitZeros(NewOffset - Offset);
 
-      Type *Ty = CPE.getType();
-      Offset = NewOffset + getDataLayout().getTypeAllocSize(Ty);
+      Offset = NewOffset + CPE.getSizeInBytes(getDataLayout());
 
       OutStreamer->emitLabel(Sym);
       if (CPE.isMachineConstantPoolEntry())

lib/CodeGen/MachineFunction.cpp

@@ -1107,10 +1107,14 @@ Printable llvm::printJumpTableEntryReference(unsigned Idx) {
 
 void MachineConstantPoolValue::anchor() {}
 
-Type *MachineConstantPoolEntry::getType() const {
+unsigned MachineConstantPoolValue::getSizeInBytes(const DataLayout &DL) const {
+  return DL.getTypeAllocSize(Ty);
+}
+
+unsigned MachineConstantPoolEntry::getSizeInBytes(const DataLayout &DL) const {
   if (isMachineConstantPoolEntry())
-    return Val.MachineCPVal->getType();
-  return Val.ConstVal->getType();
+    return Val.MachineCPVal->getSizeInBytes(DL);
+  return DL.getTypeAllocSize(Val.ConstVal->getType());
 }
 
 bool MachineConstantPoolEntry::needsRelocation() const {
@@ -1123,7 +1127,7 @@ SectionKind
 MachineConstantPoolEntry::getSectionKind(const DataLayout *DL) const {
   if (needsRelocation())
     return SectionKind::getReadOnlyWithRel();
-  switch (DL->getTypeAllocSize(getType())) {
+  switch (getSizeInBytes(*DL)) {
   case 4:
     return SectionKind::getMergeableConst4();
   case 8:

lib/Target/ARM/ARMConstantIslandPass.cpp

@@ -514,7 +514,7 @@ ARMConstantIslands::doInitialConstPlacement(std::vector<MachineInstr*> &CPEMIs)
 
   const DataLayout &TD = MF->getDataLayout();
   for (unsigned i = 0, e = CPs.size(); i != e; ++i) {
-    unsigned Size = TD.getTypeAllocSize(CPs[i].getType());
+    unsigned Size = CPs[i].getSizeInBytes(TD);
     Align Alignment = CPs[i].getAlign();
     // Verify that all constant pool entries are a multiple of their alignment.
     // If not, we would have to pad them out so that instructions stay aligned.

lib/Target/Mips/MipsConstantIslandPass.cpp

@@ -552,7 +552,7 @@ MipsConstantIslands::doInitialPlacement(std::vector<MachineInstr*> &CPEMIs) {
 
   const DataLayout &TD = MF->getDataLayout();
   for (unsigned i = 0, e = CPs.size(); i != e; ++i) {
-    unsigned Size = TD.getTypeAllocSize(CPs[i].getType());
+    unsigned Size = CPs[i].getSizeInBytes(TD);
     assert(Size >= 4 && "Too small constant pool entry");
     Align Alignment = CPs[i].getAlign();
     // Verify that all constant pool entries are a multiple of their alignment.

lib/Target/X86/X86MCInstLower.cpp

@@ -1784,10 +1784,7 @@ static const Constant *getConstantFromPool(const MachineInstr &MI,
   if (ConstantEntry.isMachineConstantPoolEntry())
     return nullptr;
 
-  const Constant *C = ConstantEntry.Val.ConstVal;
-  assert((!C || ConstantEntry.getType() == C->getType()) &&
-         "Expected a constant of the same type!");
-  return C;
+  return ConstantEntry.Val.ConstVal;
 }
 
 static std::string getShuffleComment(const MachineInstr *MI, unsigned SrcOp1Idx,