Simplify store(bitconv(x)) to store(x). This allows us to compile this:

void bar(double Y, double *X) {
  *X = Y;
}

to this:

bar:
        save -96, %o6, %o6
        st %i1, [%i2+4]
        st %i0, [%i2]
        restore %g0, %g0, %g0
        retl
        nop

instead of this:

bar:
        save -104, %o6, %o6
        st %i1, [%i6+-4]
        st %i0, [%i6+-8]
        ldd [%i6+-8], %f0
        std  %f0, [%i2]
        restore %g0, %g0, %g0
        retl
        nop

on sparcv8.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24983 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index f08fd10413cbd06919622530bd9e75f77e3f9fe3..52e8391f37273fa1190bd57e4ba4997e54fa35c2 100644 (file)
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2081,6 +2081,11 @@ SDOperand DAGCombiner::visitSTORE(SDNode *N) {
     return SDOperand(N, 0);
   }
   
+  // If this is a store of a bit convert, store the input value.
+  if (Value.getOpcode() == ISD::BIT_CONVERT)
+    return DAG.getNode(ISD::STORE, MVT::Other, Chain, Value.getOperand(0),
+                       Ptr, SrcValue);
+  
   return SDOperand();
 }