Leave hasPHIKill flags alone in LiveInterval::RenumberValues.

It is conservatively correct to keep the hasPHIKill flags, even after
deleting PHI-defs.

The calculation can be very expensive after taildup has created a
quadratic number of indirectbr edges in the CFG, and the hasPHIKill flag
isn't used for anything after RenumberValues().

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139780 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/CodeGen/LiveInterval.h b/include/llvm/CodeGen/LiveInterval.h
index 0daaf82..2df2edd 100644 (file)
--- a/include/llvm/CodeGen/LiveInterval.h
+++ b/include/llvm/CodeGen/LiveInterval.h
@@ -313,7 +313,6 @@ namespace llvm {
 
     /// RenumberValues - Renumber all values in order of appearance and remove
     /// unused values.
-    /// Recalculate phi-kill flags in case any phi-def values were removed.
     void RenumberValues(LiveIntervals &lis);
 
     /// isOnlyLROfValNo - Return true if the specified live range is the only

diff --git a/lib/CodeGen/LiveInterval.cpp b/lib/CodeGen/LiveInterval.cpp
index 2f787f3..b69945a 100644 (file)
--- a/lib/CodeGen/LiveInterval.cpp
+++ b/lib/CodeGen/LiveInterval.cpp
@@ -148,7 +148,6 @@ void LiveInterval::markValNoForDeletion(VNInfo *ValNo) {
 /// remaining unused values.
 void LiveInterval::RenumberValues(LiveIntervals &lis) {
   SmallPtrSet<VNInfo*, 8> Seen;
-  bool seenPHIDef = false;
   valnos.clear();
   for (const_iterator I = begin(), E = end(); I != E; ++I) {
     VNInfo *VNI = I->valno;
@@ -157,26 +156,6 @@ void LiveInterval::RenumberValues(LiveIntervals &lis) {
     assert(!VNI->isUnused() && "Unused valno used by live range");
     VNI->id = (unsigned)valnos.size();
     valnos.push_back(VNI);
-    VNI->setHasPHIKill(false);
-    if (VNI->isPHIDef())
-      seenPHIDef = true;
-  }
-
-  // Recompute phi kill flags.
-  if (!seenPHIDef)
-    return;
-  for (const_vni_iterator I = vni_begin(), E = vni_end(); I != E; ++I) {
-    VNInfo *VNI = *I;
-    if (!VNI->isPHIDef())
-      continue;
-    const MachineBasicBlock *PHIBB = lis.getMBBFromIndex(VNI->def);
-    assert(PHIBB && "No basic block for phi-def");
-    for (MachineBasicBlock::const_pred_iterator PI = PHIBB->pred_begin(),
-         PE = PHIBB->pred_end(); PI != PE; ++PI) {
-      VNInfo *KVNI = getVNInfoAt(lis.getMBBEndIdx(*PI).getPrevSlot());
-      if (KVNI)
-        KVNI->setHasPHIKill(true);
-    }
   }
 }