Added -stress-sched flag in the Asserts build.

Added a test case for handling physreg aliases during pre-RA-sched.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133063 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/ScheduleDAG.h

@@ -497,6 +497,12 @@ namespace llvm {
     SUnit EntrySU;                        // Special node for the region entry.
     SUnit ExitSU;                         // Special node for the region exit.
 
+#ifdef NDEBUG
+    static const bool StressSched = false;
+#else
+    bool StressSched;
+#endif
+
     explicit ScheduleDAG(MachineFunction &mf);
 
     virtual ~ScheduleDAG();

lib/CodeGen/ScheduleDAG.cpp

@@ -19,17 +19,27 @@
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 #include <climits>
 using namespace llvm;
 
+#ifndef NDEBUG
+cl::opt<bool> StressSchedOpt(
+  "stress-sched", cl::Hidden, cl::init(false),
+  cl::desc("Stress test instruction scheduling"));
+#endif
+
 ScheduleDAG::ScheduleDAG(MachineFunction &mf)
   : TM(mf.getTarget()),
     TII(TM.getInstrInfo()),
     TRI(TM.getRegisterInfo()),
     MF(mf), MRI(mf.getRegInfo()),
     EntrySU(), ExitSU() {
+#ifndef NDEBUG
+  StressSched = StressSchedOpt;
+#endif
 }
 
 ScheduleDAG::~ScheduleDAG() {}
@@ -307,6 +317,8 @@ void SUnit::dumpAll(const ScheduleDAG *G) const {
       if (I->isArtificial())
         dbgs() << " *";
       dbgs() << ": Latency=" << I->getLatency();
+      if (I->isAssignedRegDep())
+        dbgs() << " Reg=" << G->TRI->getName(I->getReg());
       dbgs() << "\n";
     }
   }

lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp

@@ -1369,6 +1369,21 @@ struct queue_sort : public std::binary_function<SUnit*, SUnit*, bool> {
   bool isReady(SUnit* SU, unsigned CurCycle) const { return true; }
 };
 
+#ifndef NDEBUG
+template<class SF>
+struct reverse_sort : public queue_sort {
+  SF &SortFunc;
+  reverse_sort(SF &sf) : SortFunc(sf) {}
+  reverse_sort(const reverse_sort &RHS) : SortFunc(RHS.SortFunc) {}
+
+  bool operator()(SUnit* left, SUnit* right) const {
+    // reverse left/right rather than simply !SortFunc(left, right)
+    // to expose different paths in the comparison logic.
+    return SortFunc(right, left);
+  }
+};
+#endif // NDEBUG
+
 /// bu_ls_rr_sort - Priority function for bottom up register pressure
 // reduction scheduler.
 struct bu_ls_rr_sort : public queue_sort {
@@ -1569,20 +1584,33 @@ protected:
 };
 
 template<class SF>
-class RegReductionPriorityQueue : public RegReductionPQBase {
-  static SUnit *popFromQueue(std::vector<SUnit*> &Q, SF &Picker) {
-    std::vector<SUnit *>::iterator Best = Q.begin();
-    for (std::vector<SUnit *>::iterator I = llvm::next(Q.begin()),
-           E = Q.end(); I != E; ++I)
-      if (Picker(*Best, *I))
-        Best = I;
-    SUnit *V = *Best;
-    if (Best != prior(Q.end()))
-      std::swap(*Best, Q.back());
-    Q.pop_back();
-    return V;
-  }
+static SUnit *popFromQueueImpl(std::vector<SUnit*> &Q, SF &Picker) {
+  std::vector<SUnit *>::iterator Best = Q.begin();
+  for (std::vector<SUnit *>::iterator I = llvm::next(Q.begin()),
+         E = Q.end(); I != E; ++I)
+    if (Picker(*Best, *I))
+      Best = I;
+  SUnit *V = *Best;
+  if (Best != prior(Q.end()))
+    std::swap(*Best, Q.back());
+  Q.pop_back();
+  return V;
+}
 
+template<class SF>
+SUnit *popFromQueue(std::vector<SUnit*> &Q, SF &Picker, ScheduleDAG *DAG) {
+#ifndef NDEBUG
+  if (DAG->StressSched) {
+    reverse_sort<SF> RPicker(Picker);
+    return popFromQueueImpl(Q, RPicker);
+  }
+#endif
+  (void)DAG;
+  return popFromQueueImpl(Q, Picker);
+}
+
+template<class SF>
+class RegReductionPriorityQueue : public RegReductionPQBase {
   SF Picker;
 
 public:
@@ -1603,7 +1631,7 @@ public:
   SUnit *pop() {
     if (Queue.empty()) return NULL;
 
-    SUnit *V = popFromQueue(Queue, Picker);
+    SUnit *V = popFromQueue(Queue, Picker, scheduleDAG);
     V->NodeQueueId = 0;
     return V;
   }
@@ -1613,7 +1641,7 @@ public:
     std::vector<SUnit*> DumpQueue = Queue;
     SF DumpPicker = Picker;
     while (!DumpQueue.empty()) {
-      SUnit *SU = popFromQueue(DumpQueue, DumpPicker);
+      SUnit *SU = popFromQueue(DumpQueue, DumpPicker, scheduleDAG);
       if (isBottomUp())
         dbgs() << "Height " << SU->getHeight() << ": ";
       else

lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp

@@ -435,7 +435,7 @@ void ScheduleDAGSDNodes::AddSchedEdges() {
         // it requires a cross class copy (cost < 0). That means we are only
         // treating "expensive to copy" register dependency as physical register
         // dependency. This may change in the future though.
-        if (Cost >= 0)
+        if (Cost >= 0 && !StressSched)
           PhysReg = 0;
 
         // If this is a ctrl dep, latency is 1.

test/CodeGen/X86/2011-06-14-PreschedRegalias.ll

@@ -0,0 +1,17 @@
+; RUN: llc < %s -march=x86-64 -stress-sched | FileCheck %s
+; Test interference between physreg aliases during preRAsched.
+; mul wants an operand in AL, but call clobbers it.
+
+define i8 @f(i8 %v1, i8 %v2) nounwind {
+entry:
+; CHECK: callq
+; CHECK: movb %{{.*}}, %al
+; CHECK: mulb
+; CHECK: mulb
+        %rval = tail call i8 @bar() nounwind
+        %m1 = mul i8 %v1, %v2
+        %m2 = mul i8 %m1, %rval
+        ret i8 %m2
+}
+
+declare i8 @bar()