mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-11-10 17:07:06 +00:00
c8bfd1d78f
flags. They are still not enable in this revision. Added TargetInstrInfo::isZeroCost() to fix a fundamental problem with the scheduler's model of operand latency in the selection DAG. Generalized unit tests to work with sched-cycles. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123969 91177308-0d34-0410-b5e6-96231b3b80d8
94 lines
3.5 KiB
C++
94 lines
3.5 KiB
C++
//=- llvm/CodeGen/ScheduleHazardRecognizer.h - Scheduling Support -*- 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 the ScheduleHazardRecognizer class, which implements
|
|
// hazard-avoidance heuristics for scheduling.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_CODEGEN_SCHEDULEHAZARDRECOGNIZER_H
|
|
#define LLVM_CODEGEN_SCHEDULEHAZARDRECOGNIZER_H
|
|
|
|
namespace llvm {
|
|
|
|
class SUnit;
|
|
|
|
/// HazardRecognizer - This determines whether or not an instruction can be
|
|
/// issued this cycle, and whether or not a noop needs to be inserted to handle
|
|
/// the hazard.
|
|
class ScheduleHazardRecognizer {
|
|
protected:
|
|
/// MaxLookAhead - Indicate the number of cycles in the scoreboard
|
|
/// state. Important to restore the state after backtracking. Additionally,
|
|
/// MaxLookAhead=0 identifies a fake recognizer, allowing the client to
|
|
/// bypass virtual calls. Currently the PostRA scheduler ignores it.
|
|
unsigned MaxLookAhead;
|
|
|
|
public:
|
|
ScheduleHazardRecognizer(): MaxLookAhead(0) {}
|
|
virtual ~ScheduleHazardRecognizer();
|
|
|
|
enum HazardType {
|
|
NoHazard, // This instruction can be emitted at this cycle.
|
|
Hazard, // This instruction can't be emitted at this cycle.
|
|
NoopHazard // This instruction can't be emitted, and needs noops.
|
|
};
|
|
|
|
unsigned getMaxLookAhead() const { return MaxLookAhead; }
|
|
|
|
bool isEnabled() const { return MaxLookAhead != 0; }
|
|
|
|
/// atIssueLimit - Return true if no more instructions may be issued in this
|
|
/// cycle.
|
|
virtual bool atIssueLimit() const { return false; }
|
|
|
|
/// getHazardType - Return the hazard type of emitting this node. There are
|
|
/// three possible results. Either:
|
|
/// * NoHazard: it is legal to issue this instruction on this cycle.
|
|
/// * Hazard: issuing this instruction would stall the machine. If some
|
|
/// other instruction is available, issue it first.
|
|
/// * NoopHazard: issuing this instruction would break the program. If
|
|
/// some other instruction can be issued, do so, otherwise issue a noop.
|
|
virtual HazardType getHazardType(SUnit *m, int Stalls) {
|
|
return NoHazard;
|
|
}
|
|
|
|
/// Reset - This callback is invoked when a new block of
|
|
/// instructions is about to be schedule. The hazard state should be
|
|
/// set to an initialized state.
|
|
virtual void Reset() {}
|
|
|
|
/// EmitInstruction - This callback is invoked when an instruction is
|
|
/// emitted, to advance the hazard state.
|
|
virtual void EmitInstruction(SUnit *) {}
|
|
|
|
/// AdvanceCycle - This callback is invoked whenever the next top-down
|
|
/// instruction to be scheduled cannot issue in the current cycle, either
|
|
/// because of latency or resource conflicts. This should increment the
|
|
/// internal state of the hazard recognizer so that previously "Hazard"
|
|
/// instructions will now not be hazards.
|
|
virtual void AdvanceCycle() {}
|
|
|
|
/// RecedeCycle - This callback is invoked whenever the next bottom-up
|
|
/// instruction to be scheduled cannot issue in the current cycle, either
|
|
/// because of latency or resource conflicts.
|
|
virtual void RecedeCycle() {}
|
|
|
|
/// EmitNoop - This callback is invoked when a noop was added to the
|
|
/// instruction stream.
|
|
virtual void EmitNoop() {
|
|
// Default implementation: count it as a cycle.
|
|
AdvanceCycle();
|
|
}
|
|
};
|
|
|
|
}
|
|
|
|
#endif
|