From: Nate Begeman <natebegeman@mac.com>
Date: Wed, 24 Aug 2005 00:21:28 +0000 (+0000)
Subject: Fix optimization of select_cc seteq X, 0, 1, 0 -> srl (ctlz X), log2 X size
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=0750a40a4ff494a2dec24f5761149b8b00e642c5;p=oota-llvm.git

Fix optimization of select_cc seteq X, 0, 1, 0 -> srl (ctlz X), log2 X size


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22995 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 3ebaaa465f6..c7687e3c618 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -854,9 +854,9 @@ SDOperand SelectionDAG::SimplifySelectCC(SDOperand N1, SDOperand N2,
   }
   
   // Check to see if this is the equivalent of seteq X, 0.
-  // select_cc seteq X, 0, 1, 0 -> setcc X, 0, seteq -> srl (ctlz X), size(X)-1
+  // select_cc eq X, 0, 1, 0 -> setcc X, 0, eq -> srl (ctlz X), log2(size(X))
   if (N2C && N2C->isNullValue() && N4C && N4C->isNullValue() &&
-      N3C && (N3C->getValue() == 1)) {
+      N3C && (N3C->getValue() == 1ULL) && CC == ISD::SETEQ) {
     MVT::ValueType XType = N1.getValueType();
     if (TLI.getOperationAction(ISD::SETCC, TLI.getSetCCResultTy()) == 
         TargetLowering::Legal) {
@@ -865,7 +865,7 @@ SDOperand SelectionDAG::SimplifySelectCC(SDOperand N1, SDOperand N2,
     if (TLI.getOperationAction(ISD::CTLZ, XType) == TargetLowering::Legal) {
       SDOperand Ctlz = getNode(ISD::CTLZ, XType, N1);
       return getNode(ISD::SRL, XType, Ctlz, 
-                     getConstant(MVT::getSizeInBits(XType)-1,
+                     getConstant(Log2_32(MVT::getSizeInBits(XType)),
                                  TLI.getShiftAmountTy()));
     }
   }