[llvm-commits] CVS: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

[Chris Lattner]

Changes in directory llvm/lib/CodeGen/SelectionDAG:

SelectionDAG.cpp updated: 1.66 -> 1.67
---
Log message:

add a little peephole optimization.  This allows us to codegen:

int a(short i) {
        return i & 1;
}

as 

_a:
        andi. r3, r3, 1
        blr

instead of:

_a:
        rlwinm r2, r3, 0, 16, 31
        andi. r3, r2, 1
        blr

on ppc.  It should also help the other risc targets.



---
Diffs of the changes:  (+11 -0)

 SelectionDAG.cpp |   11 +++++++++++
 1 files changed, 11 insertions(+)


Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.66 llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.67
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.66	Sat Apr  9 00:15:53 2005
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp	Sat Apr  9 16:43:54 2005
@@ -766,6 +766,17 @@
       if (!C2) return N2;         // X and 0 -> 0
       if (N2C->isAllOnesValue())
 	return N1;                // X and -1 -> X
+
+      // and (zero_extend_inreg x:16:32), 1 -> and x, 1
+      if (N1.getOpcode() == ISD::ZERO_EXTEND_INREG ||
+          N1.getOpcode() == ISD::SIGN_EXTEND_INREG) {
+        // If we are masking out the part of our input that was extended, just
+        // mask the input to the extension directly.
+        unsigned ExtendBits =
+          MVT::getSizeInBits(cast<MVTSDNode>(N1)->getExtraValueType());
+        if ((C2 & (~0ULL << ExtendBits)) == 0)
+          return getNode(ISD::AND, VT, N1.getOperand(0), N2);
+      }
       break;
     case ISD::OR:
       if (!C2)return N1;          // X or 0 -> X