// information to AsmPrinter.
uint8_t NumMemRefs; // Information on memory references.
+ // Note that MemRefs == nullptr, means 'don't know', not 'no memory access'.
+ // Calling code must treat missing information conservatively. If the number
+ // of memory operands required to be precise exceeds the maximum value of
+ // NumMemRefs - currently 256 - we remove the operands entirely. Note also
+ // that this is a non-owning reference to a shared copy on write buffer owned
+ // by the MachineFunction and created via MF.allocateMemRefsArray.
mmo_iterator MemRefs;
DebugLoc debugLoc; // Source line information.
/// Access to memory operands of the instruction
mmo_iterator memoperands_begin() const { return MemRefs; }
mmo_iterator memoperands_end() const { return MemRefs + NumMemRefs; }
+ /// Return true if we don't have any memory operands which described the the
+ /// memory access done by this instruction. If this is true, calling code
+ /// must be conservative.
bool memoperands_empty() const { return NumMemRefs == 0; }
iterator_range<mmo_iterator> memoperands() {
bool isKill() const { return getOpcode() == TargetOpcode::KILL; }
bool isImplicitDef() const { return getOpcode()==TargetOpcode::IMPLICIT_DEF; }
bool isInlineAsm() const { return getOpcode() == TargetOpcode::INLINEASM; }
- bool isMSInlineAsm() const {
+ bool isMSInlineAsm() const {
return getOpcode() == TargetOpcode::INLINEASM && getInlineAsmDialect();
}
bool isStackAligningInlineAsm() const;
assert(NumMemRefs == NewMemRefsEnd - NewMemRefs && "Too many memrefs");
}
- /// Clear this MachineInstr's memory reference descriptor list.
- void clearMemRefs() {
+ /// Clear this MachineInstr's memory reference descriptor list. This resets
+ /// the memrefs to their most conservative state. This should be used only
+ /// as a last resort since it greatly pessimizes our knowledge of the memory
+ /// access performed by the instruction.
+ void dropMemRefs() {
MemRefs = nullptr;
NumMemRefs = 0;
}