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fold (conv (load x)) -> (load (conv*)x). 

This allows us to compile this:
void foo(double);
void bar(double *X) { foo(*X); }

To this:

bar:
        save -96, %o6, %o6
        ld [%i0+4], %o1
        ld [%i0], %o0
        call foo
        nop
        restore %g0, %g0, %g0
        retl
        nop

instead of this:

bar:
        save -104, %o6, %o6
        ldd [%i0], %f0
        std %f0, [%i6+-8]
        ld [%i6+-4], %o1
        ld [%i6+-8], %o0
        call foo
        nop
        restore %g0, %g0, %g0
        retl
        nop

on SparcV8.

llvm-svn: 24982
This commit is contained in:
Chris Lattner 2005-12-23 05:44:41 +00:00
parent efbbedbf4a
commit 54560f6887
1 changed files with 10 additions and 0 deletions
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10
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -1760,6 +1760,16 @@ SDOperand DAGCombiner::visitBIT_CONVERT(SDNode *N) {
if (N0.getOpcode() == ISD::BIT_CONVERT) // conv(conv(x,t1),t2) -> conv(x,t2)
return DAG.getNode(ISD::BIT_CONVERT, VT, N0.getOperand(0));
// fold (conv (load x)) -> (load (conv*)x)
if (N0.getOpcode() == ISD::LOAD && N0.hasOneUse()) {
SDOperand Load = DAG.getLoad(VT, N0.getOperand(0), N0.getOperand(1),
N0.getOperand(2));
WorkList.push_back(N);
CombineTo(N0.Val, DAG.getNode(ISD::BIT_CONVERT, N0.getValueType(), Load),
Load.getValue(1));
return Load;
}
return SDOperand();
}