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Pull and through and/or/xor. This compiles some bitfield code to: 

mov EAX, DWORD PTR [ESP + 4]
        mov ECX, DWORD PTR [EAX]
        mov EDX, ECX
        add EDX, EDX
        or EDX, ECX
        and EDX, -2147483648
        and ECX, 2147483647
        or EDX, ECX
        mov DWORD PTR [EAX], EDX
        ret

instead of:

        sub ESP, 4
        mov DWORD PTR [ESP], ESI
        mov EAX, DWORD PTR [ESP + 8]
        mov ECX, DWORD PTR [EAX]
        mov EDX, ECX
        add EDX, EDX
        mov ESI, ECX
        and ESI, -2147483648
        and EDX, -2147483648
        or EDX, ESI
        and ECX, 2147483647
        or EDX, ECX
        mov DWORD PTR [EAX], EDX
        mov ESI, DWORD PTR [ESP]
        add ESP, 4
        ret

llvm-svn: 28122
This commit is contained in:
Chris Lattner 2006-05-05 06:10:43 +00:00
parent 812646aa0c
commit 5ac4293606
1 changed files with 6 additions and 4 deletions
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10
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -1069,11 +1069,13 @@ SDOperand DAGCombiner::SimplifyBinOpWithSameOpcodeHands(SDNode *N) {
return DAG.getNode(ISD::TRUNCATE, VT, ORNode);
}
// fold (and (shl/srl/sra x), (shl/srl/sra y)) -> (shl/srl/sra (and x, y))
// fold (or (shl/srl/sra x), (shl/srl/sra y)) -> (shl/srl/sra (or x, y))
// fold (xor (shl/srl/sra x), (shl/srl/sra y)) -> (shl/srl/sra (xor x, y))
// For each of OP in SHL/SRL/SRA/AND...
// fold (and (OP x, z), (OP y, z)) -> (OP (and x, y), z)
// fold (or (OP x, z), (OP y, z)) -> (OP (or x, y), z)
// fold (xor (OP x, z), (OP y, z)) -> (OP (xor x, y), z)
if ((N0.getOpcode() == ISD::SHL || N0.getOpcode() == ISD::SRL ||
N0.getOpcode() == ISD::SRA) &&
N0.getOpcode() == ISD::SRA || N0.getOpcode() == ISD::AND) &&
N0.getOperand(1) == N1.getOperand(1)) {
SDOperand ORNode = DAG.getNode(N->getOpcode(),
N0.getOperand(0).getValueType(),