From: Chris Lattner <sabre@nondot.org>
Date: Mon, 25 Apr 2005 21:20:28 +0000 (+0000)
Subject: implement some more logical compares with constants, so that:
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=229ab2e7b24847ea0d248d3d8b3d83adc8e5f5fe;p=oota-llvm.git

implement some more logical compares with constants, so that:

int foo1(int x, int y) {
  int t1 = x >= 0;
  int t2 = y >= 0;
  return t1 & t2;
}
int foo2(int x, int y) {
  int t1 = x == -1;
  int t2 = y == -1;
  return t1 & t2;
}

produces:

_foo1:
        or r2, r4, r3
        srwi r2, r2, 31
        xori r3, r2, 1
        blr
_foo2:
        and r2, r4, r3
        addic r2, r2, 1
        li r2, 0
        addze r3, r2
        blr

instead of:

_foo1:
        srwi r2, r4, 31
        xori r2, r2, 1
        srwi r3, r3, 31
        xori r3, r3, 1
        and r3, r2, r3
        blr
_foo2:
        addic r2, r4, 1
        li r2, 0
        addze r2, r2
        addic r3, r3, 1
        li r3, 0
        addze r3, r3
        and r3, r2, r3
        blr


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21547 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 10b6b76da4d..3e5395bd341 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1060,17 +1060,30 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT,
         SDOperand LR = LHS->getOperand(1), RR = RHS->getOperand(1);
         ISD::CondCode Op2 = RHS->getCondition();
 
-        // (X != 0) | (Y != 0) -> (X|Y != 0)
-        // (X == 0) & (Y == 0) -> (X|Y == 0)
-        // (X <  0) | (Y <  0) -> (X|Y < 0)
         if (LR == RR && isa<ConstantSDNode>(LR) &&
-            cast<ConstantSDNode>(LR)->getValue() == 0 &&
             Op2 == LHS->getCondition() && MVT::isInteger(LL.getValueType())) {
-          if ((Op2 == ISD::SETEQ && Opcode == ISD::AND) ||
-              (Op2 == ISD::SETNE && Opcode == ISD::OR) ||
-              (Op2 == ISD::SETLT && Opcode == ISD::OR))
+          // (X != 0) | (Y != 0) -> (X|Y != 0)
+          // (X == 0) & (Y == 0) -> (X|Y == 0)
+          // (X <  0) | (Y <  0) -> (X|Y < 0)
+          if (cast<ConstantSDNode>(LR)->getValue() == 0 &&
+              ((Op2 == ISD::SETEQ && Opcode == ISD::AND) ||
+               (Op2 == ISD::SETNE && Opcode == ISD::OR) ||
+               (Op2 == ISD::SETLT && Opcode == ISD::OR)))
             return getSetCC(Op2, VT,
                             getNode(ISD::OR, LR.getValueType(), LL, RL), LR);
+
+          if (cast<ConstantSDNode>(LR)->isAllOnesValue()) {
+            // (X == -1) & (Y == -1) -> (X&Y == -1)
+            // (X != -1) | (Y != -1) -> (X&Y != -1)
+            if ((Opcode == ISD::AND && Op2 == ISD::SETEQ) ||
+                (Opcode == ISD::OR  && Op2 == ISD::SETNE))
+              return getSetCC(Op2, VT,
+                            getNode(ISD::AND, LR.getValueType(), LL, RL), LR);
+            // (X >  -1) & (Y >  -1) -> (X|Y > -1)
+            if (Opcode == ISD::AND && Op2 == ISD::SETGT)
+              return getSetCC(Op2, VT,
+                            getNode(ISD::OR, LR.getValueType(), LL, RL), LR);
+          }
         }
 
         // (X op1 Y) | (Y op2 X) -> (X op1 Y) | (X swapop2 Y)