Revert "Reapply 91184 with fixes and an addition to the testcase to cover the

[oota-llvm.git] / lib / CodeGen / LiveIntervalAnalysis.cpp

diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 4d73b509246007ca2375bb40af5121bc42a6ec90..8806439f543902b768e42300379d9d11431c6d06 100644 (file)
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -745,8 +745,16 @@ unsigned LiveIntervals::getVNInfoSourceReg(const VNInfo *VNI) const {
   if (VNI->getCopy()->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG) {
     // If it's extracting out of a physical register, return the sub-register.
     unsigned Reg = VNI->getCopy()->getOperand(1).getReg();
-    if (TargetRegisterInfo::isPhysicalRegister(Reg))
+    if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
+      unsigned SrcSubReg = VNI->getCopy()->getOperand(2).getImm();
+      unsigned DstSubReg = VNI->getCopy()->getOperand(0).getSubReg();
+      if (SrcSubReg == DstSubReg)
+        // %reg1034:3<def> = EXTRACT_SUBREG %EDX, 3
+        // reg1034 can still be coalesced to EDX.
+        return Reg;
+      assert(DstSubReg == 0);
       Reg = tri_->getSubReg(Reg, VNI->getCopy()->getOperand(2).getImm());
+    }
     return Reg;
   } else if (VNI->getCopy()->getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
              VNI->getCopy()->getOpcode() == TargetInstrInfo::SUBREG_TO_REG)