[llvm-commits] [llvm] r106753 - in /llvm/trunk: include/llvm/CodeGen/RegisterCoalescer.h lib/CodeGen/RegisterCoalescer.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Thu Jun 24 11:19:28 2010
New Revision: 106753

URL: http://llvm.org/viewvc/llvm-project?rev=106753&view=rev
Log:
Be more strict about subreg-to-subreg copies in CoalescerPair.

Also keep track of the original DstREg before subregister adjustments.

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

Modified: llvm/trunk/include/llvm/CodeGen/RegisterCoalescer.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/RegisterCoalescer.h?rev=106753&r1=106752&r2=106753&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/RegisterCoalescer.h (original)
+++ llvm/trunk/include/llvm/CodeGen/RegisterCoalescer.h Thu Jun 24 11:19:28 2010
@@ -165,9 +165,15 @@
     /// virtual register.
     unsigned subIdx_;
 
+    /// origDstReg_ - dstReg_ without subreg adjustments.
+    unsigned origDstReg_;
+
     /// partial_ - True when the original copy was a partial subregister copy.
     bool partial_;
 
+    /// crossClass_ - True when both regs are virtual, and newRC is constrained.
+    bool crossClass_;
+
     /// flipped_ - True when DstReg and SrcReg are reversed from the oriignal copy
     /// instruction.
     bool flipped_;
@@ -186,7 +192,8 @@
   public:
     CoalescerPair(const TargetInstrInfo &tii, const TargetRegisterInfo &tri)
       : tii_(tii), tri_(tri), dstReg_(0), srcReg_(0), subIdx_(0),
-        partial_(false), flipped_(false), newRC_(0) {}
+        origDstReg_(0), partial_(false), crossClass_(false), flipped_(false),
+        newRC_(0) {}
 
     /// setRegisters - set registers to match the copy instruction MI. Return
     /// false if MI is not a coalescable copy instruction.
@@ -207,6 +214,9 @@
     /// full register, but was a subreg operation.
     bool isPartial() const { return partial_; }
 
+    /// isCrossClass - Return true if DstReg is virtual and NewRC is a smaller register class than DstReg's.
+    bool isCrossClass() const { return crossClass_; }
+
     /// isFlipped - Return true when getSrcReg is the register being defined by
     /// the original copy instruction.
     bool isFlipped() const { return flipped_; }
@@ -222,6 +232,10 @@
     /// coalesced into, or 0.
     unsigned getSubIdx() const { return subIdx_; }
 
+    /// getOrigDstReg - Return DstReg as it appeared in the original copy
+    /// instruction before any subreg adjustments.
+    unsigned getOrigDstReg() const { return isPhys() ? origDstReg_ : dstReg_; }
+
     /// getNewRC - Return the register class of the coalesced register.
     const TargetRegisterClass *getNewRC() const { return newRC_; }
   };

Modified: llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp?rev=106753&r1=106752&r2=106753&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp Thu Jun 24 11:19:28 2010
@@ -63,7 +63,7 @@
 bool CoalescerPair::setRegisters(const MachineInstr *MI) {
   srcReg_ = dstReg_ = subIdx_ = 0;
   newRC_ = 0;
-  flipped_ = false;
+  flipped_ = crossClass_ = false;
 
   unsigned Src, Dst, SrcSub, DstSub;
   if (!isMoveInstr(MI, Src, Dst, SrcSub, DstSub))
@@ -78,6 +78,7 @@
     std::swap(SrcSub, DstSub);
     flipped_ = true;
   }
+  origDstReg_ = Dst;
 
   const MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
 
@@ -100,11 +101,19 @@
   } else {
     // Both registers are virtual.
 
-    // Identical sub to sub.
-    if (SrcSub == DstSub)
+    // Both registers have subreg indices.
+    if (SrcSub && DstSub) {
+      // For now we only handle the case of identical indices in commensurate
+      // registers: Dreg:ssub_1 + Dreg:ssub_1 -> Dreg
+      // FIXME: Handle Qreg:ssub_3 + Dreg:ssub_1 as QReg:dsub_1 + Dreg.
+      if (SrcSub != DstSub)
+        return false;
+      const TargetRegisterClass *SrcRC = MRI.getRegClass(Src);
+      const TargetRegisterClass *DstRC = MRI.getRegClass(Dst);
+      if (!getCommonSubClass(DstRC, SrcRC))
+        return false;
       SrcSub = DstSub = 0;
-    else if (SrcSub && DstSub)
-      return false; // FIXME: Qreg:ssub_3 + Dreg:ssub_1 => QReg:dsub_1 + Dreg.
+    }
 
     // There can be no SrcSub.
     if (SrcSub) {
@@ -124,6 +133,7 @@
       newRC_ = getCommonSubClass(DstRC, SrcRC);
     if (!newRC_)
       return false;
+    crossClass_ = newRC_ != DstRC || newRC_ != SrcRC;
   }
   // Check our invariants
   assert(TargetRegisterInfo::isVirtualRegister(Src) && "Src must be virtual");