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llvm-mirror/lib/CodeGen/AllocationOrder.h
Jonas Paulsson 1b514619dd [RegAlloc, SystemZ] Increase number of LOCRs by passing "hard" regalloc hints.
* The method getRegAllocationHints() is now of bool type instead of void. If
true is returned, regalloc (AllocationOrder) will *only* try to allocate the
hints, as opposed to merely trying them before non-hinted registers.

* TargetRegisterInfo::getRegAllocationHints() is implemented for SystemZ with
an increase in number of LOCRs.

In this case, it is desired to force the hints even though there is a slight
increase in spilling, because if a non-hinted register would be allocated,
the LOCRMux pseudo would have to be expanded with a jump sequence. The LOCR
(Load On Condition) SystemZ instruction must have both operands in either the
low or high part of the 64 bit register.

Reviewers: Quentin Colombet and Ulrich Weigand
https://reviews.llvm.org/D36795

llvm-svn: 317879
2017-11-10 08:46:26 +00:00

97 lines
2.9 KiB
C++

//===-- llvm/CodeGen/AllocationOrder.h - Allocation Order -*- C++ -*-------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements an allocation order for virtual registers.
//
// The preferred allocation order for a virtual register depends on allocation
// hints and target hooks. The AllocationOrder class encapsulates all of that.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_CODEGEN_ALLOCATIONORDER_H
#define LLVM_LIB_CODEGEN_ALLOCATIONORDER_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/MC/MCRegisterInfo.h"
namespace llvm {
class RegisterClassInfo;
class VirtRegMap;
class LiveRegMatrix;
class LLVM_LIBRARY_VISIBILITY AllocationOrder {
SmallVector<MCPhysReg, 16> Hints;
ArrayRef<MCPhysReg> Order;
int Pos;
// If HardHints is true, *only* Hints will be returned.
bool HardHints;
public:
/// Create a new AllocationOrder for VirtReg.
/// @param VirtReg Virtual register to allocate for.
/// @param VRM Virtual register map for function.
/// @param RegClassInfo Information about reserved and allocatable registers.
AllocationOrder(unsigned VirtReg,
const VirtRegMap &VRM,
const RegisterClassInfo &RegClassInfo,
const LiveRegMatrix *Matrix);
/// Get the allocation order without reordered hints.
ArrayRef<MCPhysReg> getOrder() const { return Order; }
/// Return the next physical register in the allocation order, or 0.
/// It is safe to call next() again after it returned 0, it will keep
/// returning 0 until rewind() is called.
unsigned next(unsigned Limit = 0) {
if (Pos < 0)
return Hints.end()[Pos++];
if (HardHints)
return 0;
if (!Limit)
Limit = Order.size();
while (Pos < int(Limit)) {
unsigned Reg = Order[Pos++];
if (!isHint(Reg))
return Reg;
}
return 0;
}
/// As next(), but allow duplicates to be returned, and stop before the
/// Limit'th register in the RegisterClassInfo allocation order.
///
/// This can produce more than Limit registers if there are hints.
unsigned nextWithDups(unsigned Limit) {
if (Pos < 0)
return Hints.end()[Pos++];
if (HardHints)
return 0;
if (Pos < int(Limit))
return Order[Pos++];
return 0;
}
/// Start over from the beginning.
void rewind() { Pos = -int(Hints.size()); }
/// Return true if the last register returned from next() was a preferred register.
bool isHint() const { return Pos <= 0; }
/// Return true if PhysReg is a preferred register.
bool isHint(unsigned PhysReg) const { return is_contained(Hints, PhysReg); }
};
} // end namespace llvm
#endif