From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Sat, 19 May 2012 05:25:56 +0000 (+0000)
Subject: Don't remat during updateRegDefsUses().
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=67ccb29cec06c85210f334cfbdae144460170cd3;p=oota-llvm.git

Don't remat during updateRegDefsUses().

Remaining virtreg->physreg copies were rematerialized during
updateRegDefsUses(), but we already do the same thing in joinCopy() when
visiting the physreg copy instruction.

Eliminate the preserveSrcInt argument to reMaterializeTrivialDef(). It
is now always true.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157103 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp
index 0dbc7b6c659..3204eff9cbb 100644
--- a/lib/CodeGen/RegisterCoalescer.cpp
+++ b/lib/CodeGen/RegisterCoalescer.cpp
@@ -151,9 +151,8 @@ namespace {
 
     /// reMaterializeTrivialDef - If the source of a copy is defined by a
     /// trivial computation, replace the copy by rematerialize the definition.
-    /// If PreserveSrcInt is true, make sure SrcInt is valid after the call.
-    bool reMaterializeTrivialDef(LiveInterval &SrcInt, bool PreserveSrcInt,
-                                 unsigned DstReg, MachineInstr *CopyMI);
+    bool reMaterializeTrivialDef(LiveInterval &SrcInt, unsigned DstReg,
+                                 MachineInstr *CopyMI);
 
     /// canJoinPhys - Return true if a physreg copy should be joined.
     bool canJoinPhys(CoalescerPair &CP);
@@ -784,7 +783,6 @@ bool RegisterCoalescer::removeCopyByCommutingDef(const CoalescerPair &CP,
 /// reMaterializeTrivialDef - If the source of a copy is defined by a trivial
 /// computation, replace the copy by rematerialize the definition.
 bool RegisterCoalescer::reMaterializeTrivialDef(LiveInterval &SrcInt,
-                                                bool preserveSrcInt,
                                                 unsigned DstReg,
                                                 MachineInstr *CopyMI) {
   SlotIndex CopyIdx = LIS->getInstructionIndex(CopyMI).getRegSlot(true);
@@ -872,8 +870,7 @@ bool RegisterCoalescer::reMaterializeTrivialDef(LiveInterval &SrcInt,
   ++NumReMats;
 
   // The source interval can become smaller because we removed a use.
-  if (preserveSrcInt)
-    LIS->shrinkToUses(&SrcInt);
+  LIS->shrinkToUses(&SrcInt);
 
   return true;
 }
@@ -938,20 +935,6 @@ void RegisterCoalescer::updateRegDefsUses(unsigned SrcReg,
   for (MachineRegisterInfo::reg_iterator I = MRI->reg_begin(SrcReg);
        MachineInstr *UseMI = I.skipInstruction();) {
     bool AlreadyJoined = JoinedCopies.count(UseMI);
-
-    // A PhysReg copy that won't be coalesced can perhaps be rematerialized
-    // instead.
-    if (DstIsPhys) {
-      if (UseMI->isFullCopy() &&
-          UseMI->getOperand(1).getReg() == SrcReg &&
-          UseMI->getOperand(0).getReg() != SrcReg &&
-          UseMI->getOperand(0).getReg() != DstReg &&
-          !AlreadyJoined &&
-          reMaterializeTrivialDef(LIS->getInterval(SrcReg), false,
-                                  UseMI->getOperand(0).getReg(), UseMI))
-        continue;
-    }
-
     SmallVector<unsigned,8> Ops;
     bool Reads, Writes;
     tie(Reads, Writes) = UseMI->readsWritesVirtualRegister(SrcReg, &Ops);
@@ -1093,7 +1076,7 @@ bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) {
       // Before giving up coalescing, if definition of source is defined by
       // trivial computation, try rematerializing it.
       if (!CP.isFlipped() &&
-          reMaterializeTrivialDef(LIS->getInterval(CP.getSrcReg()), true,
+          reMaterializeTrivialDef(LIS->getInterval(CP.getSrcReg()),
                                   CP.getDstReg(), CopyMI))
         return true;
       return false;
@@ -1128,7 +1111,7 @@ bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) {
     // If definition of source is defined by trivial computation, try
     // rematerializing it.
     if (!CP.isFlipped() &&
-        reMaterializeTrivialDef(LIS->getInterval(CP.getSrcReg()), true,
+        reMaterializeTrivialDef(LIS->getInterval(CP.getSrcReg()),
                                 CP.getDstReg(), CopyMI))
       return true;