[llvm] r322226 - LiveRangeEdit: Simplify code; NFC

[Matthias Braun via llvm-commits]

Author: matze
Date: Wed Jan 10 13:41:02 2018
New Revision: 322226

URL: http://llvm.org/viewvc/llvm-project?rev=322226&view=rev
Log:
LiveRangeEdit: Simplify code; NFC

Simplify the code slightly: Instead of creating empty subranges in one
case and immediately removing them, do not create them in the first
place.

Modified:
    llvm/trunk/include/llvm/CodeGen/LiveRangeEdit.h
    llvm/trunk/lib/CodeGen/LiveRangeEdit.cpp

Modified: llvm/trunk/include/llvm/CodeGen/LiveRangeEdit.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/LiveRangeEdit.h?rev=322226&r1=322225&r2=322226&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/LiveRangeEdit.h (original)
+++ llvm/trunk/include/llvm/CodeGen/LiveRangeEdit.h Wed Jan 10 13:41:02 2018
@@ -121,6 +121,9 @@ private:
   /// main live range of \p LI or in one of the matching subregister ranges.
   bool useIsKill(const LiveInterval &LI, const MachineOperand &MO) const;
 
+  /// Create a new empty interval based on OldReg.
+  LiveInterval &createEmptyIntervalFrom(unsigned OldReg, bool createSubRanges);
+
 public:
   /// Create a LiveRangeEdit for breaking down parent into smaller pieces.
   /// @param parent The register being spilled or split.
@@ -174,16 +177,13 @@ public:
     return makeArrayRef(NewRegs).slice(FirstNew);
   }
 
-  /// createEmptyIntervalFrom - Create a new empty interval based on OldReg.
-  LiveInterval &createEmptyIntervalFrom(unsigned OldReg);
-
   /// createFrom - Create a new virtual register based on OldReg.
   unsigned createFrom(unsigned OldReg);
 
   /// create - Create a new register with the same class and original slot as
   /// parent.
   LiveInterval &createEmptyInterval() {
-    return createEmptyIntervalFrom(getReg());
+    return createEmptyIntervalFrom(getReg(), true);
   }
 
   unsigned create() { return createFrom(getReg()); }

Modified: llvm/trunk/lib/CodeGen/LiveRangeEdit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/LiveRangeEdit.cpp?rev=322226&r1=322225&r2=322226&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/LiveRangeEdit.cpp (original)
+++ llvm/trunk/lib/CodeGen/LiveRangeEdit.cpp Wed Jan 10 13:41:02 2018
@@ -31,21 +31,24 @@ STATISTIC(NumFracRanges,     "Number of
 
 void LiveRangeEdit::Delegate::anchor() { }
 
-LiveInterval &LiveRangeEdit::createEmptyIntervalFrom(unsigned OldReg) {
+LiveInterval &LiveRangeEdit::createEmptyIntervalFrom(unsigned OldReg,
+                                                     bool createSubRanges) {
   unsigned VReg = MRI.createVirtualRegister(MRI.getRegClass(OldReg));
-  if (VRM) {
+  if (VRM)
     VRM->setIsSplitFromReg(VReg, VRM->getOriginal(OldReg));
-  }
+
   LiveInterval &LI = LIS.createEmptyInterval(VReg);
   if (Parent && !Parent->isSpillable())
     LI.markNotSpillable();
-  // Create empty subranges if the OldReg's interval has them. Do not create
-  // the main range here---it will be constructed later after the subranges
-  // have been finalized.
-  LiveInterval &OldLI = LIS.getInterval(OldReg);
-  VNInfo::Allocator &Alloc = LIS.getVNInfoAllocator();
-  for (LiveInterval::SubRange &S : OldLI.subranges())
-    LI.createSubRange(Alloc, S.LaneMask);
+  if (createSubRanges) {
+    // Create empty subranges if the OldReg's interval has them. Do not create
+    // the main range here---it will be constructed later after the subranges
+    // have been finalized.
+    LiveInterval &OldLI = LIS.getInterval(OldReg);
+    VNInfo::Allocator &Alloc = LIS.getVNInfoAllocator();
+    for (LiveInterval::SubRange &S : OldLI.subranges())
+      LI.createSubRange(Alloc, S.LaneMask);
+  }
   return LI;
 }
 
@@ -357,8 +360,7 @@ void LiveRangeEdit::eliminateDeadDef(Mac
     // LiveRangeEdit::DeadRemats and will be deleted after all the
     // allocations of the func are done.
     if (isOrigDef && DeadRemats && TII.isTriviallyReMaterializable(*MI, AA)) {
-      LiveInterval &NewLI = createEmptyIntervalFrom(Dest);
-      NewLI.removeEmptySubRanges();
+      LiveInterval &NewLI = createEmptyIntervalFrom(Dest, false);
       VNInfo *VNI = NewLI.getNextValue(Idx, LIS.getVNInfoAllocator());
       NewLI.addSegment(LiveInterval::Segment(Idx, Idx.getDeadSlot(), VNI));
       pop_back();