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

[Chris Lattner]

Changes in directory llvm/lib/CodeGen/SelectionDAG:

DAGCombiner.cpp updated: 1.71 -> 1.72
SelectionDAG.cpp updated: 1.231 -> 1.232
---
Log message:

Fold bitconv(bitconv(x)) -> x.  We now compile this:

void foo(double);
void bar(double X) { foo(X); }

to this:

bar:
        save -96, %o6, %o6
        or %g0, %i0, %o0
        or %g0, %i1, %o1
        call foo
        nop
        restore %g0, %g0, %g0
        retl
        nop

instead of this:

bar:
        save -112, %o6, %o6
        st %i1, [%i6+-4]
        st %i0, [%i6+-8]
        ldd [%i6+-8], %f0
        std %f0, [%i6+-16]
        ld [%i6+-12], %o1
        ld [%i6+-16], %o0
        call foo
        nop
        restore %g0, %g0, %g0
        retl
        nop

on V8.



---
Diffs of the changes:  (+5 -0)

 DAGCombiner.cpp  |    3 +++
 SelectionDAG.cpp |    2 ++
 2 files changed, 5 insertions(+)


Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.71 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.72
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.71	Thu Dec 22 23:30:37 2005
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp	Thu Dec 22 23:37:50 2005
@@ -1757,6 +1757,9 @@
     if (Res.Val != N) return Res;
   }
   
+  if (N0.getOpcode() == ISD::BIT_CONVERT)  // conv(conv(x,t1),t2) -> conv(x,t2)
+    return DAG.getNode(ISD::BIT_CONVERT, VT, N0.getOperand(0));
+  
   return SDOperand();
 }
 


Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.231 llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.232
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.231	Thu Dec 22 23:30:37 2005
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp	Thu Dec 22 23:37:50 2005
@@ -916,6 +916,8 @@
     assert(MVT::getSizeInBits(VT)==MVT::getSizeInBits(Operand.getValueType()) &&
            "Cannot BIT_CONVERT between two different types!");
     if (VT == Operand.getValueType()) return Operand;  // noop conversion.
+    if (OpOpcode == ISD::BIT_CONVERT)  // bitconv(bitconv(x)) -> bitconv(x)
+      return getNode(ISD::BIT_CONVERT, VT, Operand.getOperand(0));
     break;
   case ISD::FNEG:
     if (OpOpcode == ISD::FSUB)   // -(X-Y) -> (Y-X)