Post RA scheduler changes. Introduce a hazard recognizer that uses the target schedule information to accurately model the pipeline. Update the scheduler to correctly handle multi-issue targets.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78563 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/PostRASchedulerList.cpp b/lib/CodeGen/PostRASchedulerList.cpp
index 3cd8847..5de5e76 100644
--- a/lib/CodeGen/PostRASchedulerList.cpp
+++ b/lib/CodeGen/PostRASchedulerList.cpp
@@ -19,6 +19,8 @@
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "post-RA-sched"
+#include "ExactHazardRecognizer.h"
+#include "SimpleHazardRecognizer.h"
#include "ScheduleDAGInstrs.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/LatencyPriorityQueue.h"
@@ -49,8 +51,8 @@
static cl::opt<bool>
EnablePostRAHazardAvoidance("avoid-hazards",
- cl::desc("Enable simple hazard-avoidance"),
- cl::init(true), cl::Hidden);
+ cl::desc("Enable exact hazard avoidance"),
+ cl::init(false), cl::Hidden);
namespace {
class VISIBILITY_HIDDEN PostRAScheduler : public MachineFunctionPass {
@@ -156,62 +158,6 @@
void ListScheduleTopDown();
bool BreakAntiDependencies();
};
-
- /// SimpleHazardRecognizer - A *very* simple hazard recognizer. It uses
- /// a coarse classification and attempts to avoid that instructions of
- /// a given class aren't grouped too densely together.
- class SimpleHazardRecognizer : public ScheduleHazardRecognizer {
- /// Class - A simple classification for SUnits.
- enum Class {
- Other, Load, Store
- };
-
- /// Window - The Class values of the most recently issued
- /// instructions.
- Class Window[8];
-
- /// getClass - Classify the given SUnit.
- Class getClass(const SUnit *SU) {
- const MachineInstr *MI = SU->getInstr();
- const TargetInstrDesc &TID = MI->getDesc();
- if (TID.mayLoad())
- return Load;
- if (TID.mayStore())
- return Store;
- return Other;
- }
-
- /// Step - Rotate the existing entries in Window and insert the
- /// given class value in position as the most recent.
- void Step(Class C) {
- std::copy(Window+1, array_endof(Window), Window);
- Window[array_lengthof(Window)-1] = C;
- }
-
- public:
- SimpleHazardRecognizer() : Window() {}
-
- virtual HazardType getHazardType(SUnit *SU) {
- Class C = getClass(SU);
- if (C == Other)
- return NoHazard;
- unsigned Score = 0;
- for (unsigned i = 0; i != array_lengthof(Window); ++i)
- if (Window[i] == C)
- Score += i + 1;
- if (Score > array_lengthof(Window) * 2)
- return Hazard;
- return NoHazard;
- }
-
- virtual void EmitInstruction(SUnit *SU) {
- Step(getClass(SU));
- }
-
- virtual void AdvanceCycle() {
- Step(Other);
- }
- };
}
/// isSchedulingBoundary - Test if the given instruction should be
@@ -241,9 +187,10 @@
const MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
const MachineDominatorTree &MDT = getAnalysis<MachineDominatorTree>();
+ const InstrItineraryData &InstrItins = Fn.getTarget().getInstrItineraryData();
ScheduleHazardRecognizer *HR = EnablePostRAHazardAvoidance ?
- new SimpleHazardRecognizer :
- new ScheduleHazardRecognizer();
+ (ScheduleHazardRecognizer *)new ExactHazardRecognizer(InstrItins) :
+ (ScheduleHazardRecognizer *)new SimpleHazardRecognizer();
SchedulePostRATDList Scheduler(Fn, MLI, MDT, HR);
@@ -289,6 +236,9 @@
// Call the superclass.
ScheduleDAGInstrs::StartBlock(BB);
+ // Reset the hazard recognizer.
+ HazardRec->Reset();
+
// Clear out the register class data.
std::fill(Classes, array_endof(Classes),
static_cast<const TargetRegisterClass *>(0));
@@ -380,6 +330,9 @@
}
}
+ DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
+ SUnits[su].dumpAll(this));
+
AvailableQueue.initNodes(SUnits);
ListScheduleTopDown();
@@ -872,13 +825,6 @@
MinDepth = PendingQueue[i]->getDepth();
}
- // If there are no instructions available, don't try to issue anything, and
- // don't advance the hazard recognizer.
- if (AvailableQueue.empty()) {
- CurCycle = MinDepth != ~0u ? MinDepth : CurCycle + 1;
- continue;
- }
-
SUnit *FoundSUnit = 0;
bool HasNoopHazards = false;
@@ -909,10 +855,14 @@
ScheduleNodeTopDown(FoundSUnit, CurCycle);
HazardRec->EmitInstruction(FoundSUnit);
- // If this is a pseudo-op node, we don't want to increment the current
- // cycle.
- if (FoundSUnit->Latency) // Don't increment CurCycle for pseudo-ops!
- ++CurCycle;
+ // If we are using the target-specific hazards, then don't
+ // advance the cycle time just because we schedule a node. If
+ // the target allows it we can schedule multiple nodes in the
+ // same cycle.
+ if (!EnablePostRAHazardAvoidance) {
+ if (FoundSUnit->Latency) // Don't increment CurCycle for pseudo-ops!
+ ++CurCycle;
+ }
} else if (!HasNoopHazards) {
// Otherwise, we have a pipeline stall, but no other problem, just advance
// the current cycle and try again.