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constant fold FP_ROUND_INREG, ZERO_EXTEND_INREG, and SIGN_EXTEND_INREG

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This allows the alpha backend to compile:

bool %test(uint %P) {
        %c = seteq uint %P, 0
        ret bool %c
}

into:

test:
        ldgp $29, 0($27)
        ZAP $16,240,$0
        CMPEQ $0,0,$0
        AND $0,1,$0
        ret $31,($26),1

instead of:

test:
        ldgp $29, 0($27)
        ZAP $16,240,$0
        ldiq $1,0
        ZAP $1,240,$1
        CMPEQ $0,$1,$0
        AND $0,1,$0
        ret $31,($26),1

... and fixes PR534.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20534 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-03-09 18:37:12 +00:00
parent 76da61621c
commit 14723c264d
1 changed files with 12 additions and 0 deletions
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12
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@ -946,6 +946,9 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT,SDOperand N1,
"Cannot FP_ROUND_INREG integer types");
if (EVT == VT) return N1; // Not actually rounding
assert(EVT < VT && "Not rounding down!");
if (isa<ConstantFPSDNode>(N1))
return getNode(ISD::FP_EXTEND, VT, getNode(ISD::FP_ROUND, EVT, N1));
break;
case ISD::ZERO_EXTEND_INREG:
case ISD::SIGN_EXTEND_INREG:
@ -955,6 +958,15 @@ SDOperand SelectionDAG::getNode(unsigned Opcode, MVT::ValueType VT,SDOperand N1,
if (EVT == VT) return N1; // Not actually extending
assert(EVT < VT && "Not extending!");
// Extending a constant? Just return the constant.
if (ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val)) {
SDOperand Tmp = getNode(ISD::TRUNCATE, EVT, N1);
if (N1.getOpcode() == ISD::ZERO_EXTEND_INREG)
return getNode(ISD::ZERO_EXTEND, VT, Tmp);
else
return getNode(ISD::SIGN_EXTEND, VT, Tmp);
}
// If we are sign extending an extension, use the original source.
if (N1.getOpcode() == ISD::ZERO_EXTEND_INREG ||
N1.getOpcode() == ISD::SIGN_EXTEND_INREG) {