[CodeGen] Refactor MachineMemOperand::Flags's target-specific flags.

Summary:
Make the target-specific flags in MachineMemOperand::Flags real, bona
fide enum values.  This simplifies users, prevents various constants
from going out of sync, and avoids the false sense of security provided
by declaring static members in classes and then forgetting to define
them inside of cpp files.

Reviewers: MatzeB

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D22372

llvm-svn: 275451

llvm/include/llvm/CodeGen/MachineMemOperand.h

@@ -89,32 +89,27 @@ struct MachinePointerInfo {
 ///
 class MachineMemOperand {
 public:
-  // This is the number of bits we need to represent flags.
-  static LLVM_CONSTEXPR unsigned MOMaxBits = 8;
-
-  // Target hints allow target passes to annotate memory operations.
-  static LLVM_CONSTEXPR unsigned MOTargetStartBit = 5;
-  static LLVM_CONSTEXPR unsigned MOTargetNumBits = 3;
-
   /// Flags values. These may be or'd together.
   enum Flags : uint16_t {
     // No flags set.
     MONone = 0,
     /// The memory access reads data.
-    MOLoad = 1,
+    MOLoad = 1u << 0,
     /// The memory access writes data.
-    MOStore = 2,
+    MOStore = 1u << 1,
     /// The memory access is volatile.
-    MOVolatile = 4,
+    MOVolatile = 1u << 2,
     /// The memory access is non-temporal.
-    MONonTemporal = 8,
+    MONonTemporal = 1u << 3,
     /// The memory access is invariant.
-    MOInvariant = 16,
+    MOInvariant = 1u << 4,
 
-    // Maximum MemOperandFlag value (inclusive).
-    MOMaxFlag = (1 << MOMaxBits) - 1,
+    // Reserved for use by target-specific passes.
+    MOTargetFlag1 = 1u << 5,
+    MOTargetFlag2 = 1u << 6,
+    MOTargetFlag3 = 1u << 7,
 
-    LLVM_MARK_AS_BITMASK_ENUM(MOMaxFlag)
+    LLVM_MARK_AS_BITMASK_ENUM(/* LargestFlag = */ MOTargetFlag3)
   };
 
 private:

llvm/lib/CodeGen/MachineInstr.cpp

@@ -503,8 +503,6 @@ MachineMemOperand::MachineMemOperand(MachinePointerInfo ptrinfo, Flags f,
                                      const MDNode *Ranges)
     : PtrInfo(ptrinfo), Size(s), FlagVals(f), BaseAlignLog2(Log2_32(a) + 1),
       AAInfo(AAInfo), Ranges(Ranges) {
-  assert(MOMaxFlag == (1 << MOMaxBits) - 1 &&
-         "MOMaxFlag and MOMaxBits have fallen out of sync.");
   assert((PtrInfo.V.isNull() || PtrInfo.V.is<const PseudoSourceValue*>() ||
           isa<PointerType>(PtrInfo.V.get<const Value*>()->getType())) &&
          "invalid pointer value");

llvm/lib/Target/AArch64/AArch64InstrInfo.cpp

@@ -29,6 +29,9 @@ using namespace llvm;
 #define GET_INSTRINFO_CTOR_DTOR
 #include "AArch64GenInstrInfo.inc"
 
+static constexpr MachineMemOperand::Flags MOSuppressPair =
+    MachineMemOperand::MOTargetFlag1;
+
 AArch64InstrInfo::AArch64InstrInfo(const AArch64Subtarget &STI)
     : AArch64GenInstrInfo(AArch64::ADJCALLSTACKDOWN, AArch64::ADJCALLSTACKUP),
       RI(STI.getTargetTriple()), Subtarget(STI) {}
@@ -1449,27 +1452,16 @@ bool AArch64InstrInfo::isScaledAddr(const MachineInstr &MI) const {
 
 /// Check all MachineMemOperands for a hint to suppress pairing.
 bool AArch64InstrInfo::isLdStPairSuppressed(const MachineInstr &MI) const {
-  static_assert(MOSuppressPair < (1 << MachineMemOperand::MOTargetNumBits),
-                "Too many target MO flags");
-  for (auto *MM : MI.memoperands()) {
-    if (MM->getFlags() &
-        (MOSuppressPair << MachineMemOperand::MOTargetStartBit)) {
-      return true;
-    }
-  }
-  return false;
+  return any_of(MI.memoperands(), [](MachineMemOperand *MMO) {
+    return MMO->getFlags() & MOSuppressPair;
+  });
 }
 
 /// Set a flag on the first MachineMemOperand to suppress pairing.
 void AArch64InstrInfo::suppressLdStPair(MachineInstr &MI) const {
   if (MI.memoperands_empty())
     return;
-
-  static_assert(MOSuppressPair < (1 << MachineMemOperand::MOTargetNumBits),
-                "Too many target MO flags");
-  (*MI.memoperands_begin())
-      ->setFlags(static_cast<MachineMemOperand::Flags>(
-          MOSuppressPair << MachineMemOperand::MOTargetStartBit));
+  (*MI.memoperands_begin())->setFlags(MOSuppressPair);
 }
 
 bool AArch64InstrInfo::isUnscaledLdSt(unsigned Opc) const {

llvm/lib/Target/AArch64/AArch64InstrInfo.h

@@ -28,12 +28,6 @@ class AArch64Subtarget;
 class AArch64TargetMachine;
 
 class AArch64InstrInfo : public AArch64GenInstrInfo {
-  // Reserve bits in the MachineMemOperand target hint flags, starting at 1.
-  // They will be shifted into MOTargetHintStart when accessed.
-  enum TargetMemOperandFlags {
-    MOSuppressPair = 1
-  };
-
   const AArch64RegisterInfo RI;
   const AArch64Subtarget &Subtarget;