[llvm] r238008 - Compile time improvements to VirtRegRewriter.

[Puyan Lotfi]

Author: zer0
Date: Fri May 22 03:11:26 2015
New Revision: 238008

URL: http://llvm.org/viewvc/llvm-project?rev=238008&view=rev
Log:
Compile time improvements to VirtRegRewriter.

This change to VirtRegRewriter::addMBBLiveIns adds live-in registers for each
MachineBasicBlock's LiveIns set without isLiveIn checks as they are being added
because doing so is expensive. After all live-in registers are added, the LiveIn
vectors are sorted and uniqued.


Modified:
    llvm/trunk/include/llvm/CodeGen/MachineBasicBlock.h
    llvm/trunk/lib/CodeGen/VirtRegMap.cpp

Modified: llvm/trunk/include/llvm/CodeGen/MachineBasicBlock.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineBasicBlock.h?rev=238008&r1=238007&r2=238008&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineBasicBlock.h (original)
+++ llvm/trunk/include/llvm/CodeGen/MachineBasicBlock.h Fri May 22 03:11:26 2015
@@ -315,9 +315,18 @@ public:
 
   // LiveIn management methods.
 
-  /// addLiveIn - Add the specified register as a live in.  Note that it
-  /// is an error to add the same register to the same set more than once.
-  void addLiveIn(unsigned Reg)  { LiveIns.push_back(Reg); }
+  /// Adds the specified register as a live in. Note that it is an error to add
+  /// the same register to the same set more than once unless the intention is
+  /// to call sortUniqueLiveIns after all registers are added.
+  void addLiveIn(unsigned Reg) { LiveIns.push_back(Reg); }
+
+  /// Sorts and uniques the LiveIns vector. It can be significantly faster to do
+  /// this than repeatedly calling isLiveIn before calling addLiveIn for every
+  /// LiveIn insertion.
+  void sortUniqueLiveIns() {
+    std::sort(LiveIns.begin(), LiveIns.end());
+    LiveIns.erase(std::unique(LiveIns.begin(), LiveIns.end()), LiveIns.end());
+  }
 
   /// Add PhysReg as live in to this block, and ensure that there is a copy of
   /// PhysReg to a virtual register of class RC. Return the virtual register

Modified: llvm/trunk/lib/CodeGen/VirtRegMap.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/VirtRegMap.cpp?rev=238008&r1=238007&r2=238008&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/VirtRegMap.cpp (original)
+++ llvm/trunk/lib/CodeGen/VirtRegMap.cpp Fri May 22 03:11:26 2015
@@ -264,8 +264,7 @@ void VirtRegRewriter::addMBBLiveIns() {
             if ((SubRegLaneMask & S.LaneMask) == 0)
               continue;
             for (unsigned i = 0, e = LiveIn.size(); i != e; ++i) {
-              if (!LiveIn[i]->isLiveIn(SubReg))
-                LiveIn[i]->addLiveIn(SubReg);
+              LiveIn[i]->addLiveIn(SubReg);
             }
           }
           LiveIn.clear();
@@ -277,12 +276,16 @@ void VirtRegRewriter::addMBBLiveIns() {
         if (!Indexes->findLiveInMBBs(Seg.start, Seg.end, LiveIn))
           continue;
         for (unsigned i = 0, e = LiveIn.size(); i != e; ++i)
-          if (!LiveIn[i]->isLiveIn(PhysReg))
-            LiveIn[i]->addLiveIn(PhysReg);
+          LiveIn[i]->addLiveIn(PhysReg);
         LiveIn.clear();
       }
     }
   }
+
+  // Sort and unique MBB LiveIns as we've not checked if SubReg/PhysReg were in
+  // each MBB's LiveIns set before calling addLiveIn on them.
+  for (MachineBasicBlock &MBB : *MF)
+    MBB.sortUniqueLiveIns();
 }
 
 void VirtRegRewriter::rewrite() {