From 7b3392326c40c3c20697816acae597ba7b3144eb Mon Sep 17 00:00:00 2001
From: dim <dim@FreeBSD.org>
Date: Thu, 20 Oct 2011 21:10:27 +0000
Subject: Vendor import of llvm release_30 branch r142614:
 http://llvm.org/svn/llvm-project/llvm/branches/release_30@142614

---
 lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp | 36 +++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

(limited to 'lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp')

diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
index 12b1838..e757def 100644
--- a/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
@@ -2621,6 +2621,39 @@ bool RegReductionPQBase::canClobber(const SUnit *SU, const SUnit *Op) {
   return false;
 }
 
+/// canClobberReachingPhysRegUse - True if SU would clobber one of it's
+/// successor's explicit physregs whose definition can reach DepSU.
+/// i.e. DepSU should not be scheduled above SU.
+static bool canClobberReachingPhysRegUse(const SUnit *DepSU, const SUnit *SU,
+                                         ScheduleDAGRRList *scheduleDAG,
+                                         const TargetInstrInfo *TII,
+                                         const TargetRegisterInfo *TRI) {
+  const unsigned *ImpDefs
+    = TII->get(SU->getNode()->getMachineOpcode()).getImplicitDefs();
+  if(!ImpDefs)
+    return false;
+
+  for (SUnit::const_succ_iterator SI = SU->Succs.begin(), SE = SU->Succs.end();
+       SI != SE; ++SI) {
+    SUnit *SuccSU = SI->getSUnit();
+    for (SUnit::const_pred_iterator PI = SuccSU->Preds.begin(),
+           PE = SuccSU->Preds.end(); PI != PE; ++PI) {
+      if (!PI->isAssignedRegDep())
+        continue;
+
+      for (const unsigned *ImpDef = ImpDefs; *ImpDef; ++ImpDef) {
+        // Return true if SU clobbers this physical register use and the
+        // definition of the register reaches from DepSU. IsReachable queries a
+        // topological forward sort of the DAG (following the successors).
+        if (TRI->regsOverlap(*ImpDef, PI->getReg()) &&
+            scheduleDAG->IsReachable(DepSU, PI->getSUnit()))
+          return true;
+      }
+    }
+  }
+  return false;
+}
+
 /// canClobberPhysRegDefs - True if SU would clobber one of SuccSU's
 /// physical register defs.
 static bool canClobberPhysRegDefs(const SUnit *SuccSU, const SUnit *SU,
@@ -2837,7 +2870,8 @@ void RegReductionPQBase::AddPseudoTwoAddrDeps() {
             SuccOpc == TargetOpcode::INSERT_SUBREG ||
             SuccOpc == TargetOpcode::SUBREG_TO_REG)
           continue;
-        if ((!canClobber(SuccSU, DUSU) ||
+        if (!canClobberReachingPhysRegUse(SuccSU, SU, scheduleDAG, TII, TRI) &&
+            (!canClobber(SuccSU, DUSU) ||
              (isLiveOut && !hasOnlyLiveOutUses(SuccSU)) ||
              (!SU->isCommutable && SuccSU->isCommutable)) &&
             !scheduleDAG->IsReachable(SuccSU, SU)) {
-- 
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