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Fix expansion of shifts by exactly NVT bits on arch's (like X86) that have 

masking shifts.

This fixes the miscompilation of this:

long long test1(unsigned A, unsigned B) {
        return ((unsigned long long)A << 32) | B;
}

into this:

test1:
        movl 4(%esp), %edx
        movl %edx, %eax
        orl 8(%esp), %eax
        ret

allowing us to generate this instead:

test1:
        movl 4(%esp), %edx
        movl 8(%esp), %eax
        ret

llvm-svn: 21230
This commit is contained in:
Chris Lattner 2005-04-11 20:08:52 +00:00
parent 607bd26b38
commit edd197062f
1 changed files with 10 additions and 0 deletions
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10
llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
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@ -1500,6 +1500,9 @@ bool SelectionDAGLegalize::ExpandShift(unsigned Opc, SDOperand Op,SDOperand Amt,
} else if (Cst > NVTBits) {
Lo = DAG.getConstant(0, NVT);
Hi = DAG.getNode(ISD::SHL, NVT, InL, DAG.getConstant(Cst-NVTBits,ShTy));
} else if (Cst == NVTBits) {
Lo = DAG.getConstant(0, NVT);
Hi = InL;
} else {
Lo = DAG.getNode(ISD::SHL, NVT, InL, DAG.getConstant(Cst, ShTy));
Hi = DAG.getNode(ISD::OR, NVT,
@ -1514,6 +1517,9 @@ bool SelectionDAGLegalize::ExpandShift(unsigned Opc, SDOperand Op,SDOperand Amt,
} else if (Cst > NVTBits) {
Lo = DAG.getNode(ISD::SRL, NVT, InH, DAG.getConstant(Cst-NVTBits,ShTy));
Hi = DAG.getConstant(0, NVT);
} else if (Cst == NVTBits) {
Lo = InH;
Hi = DAG.getConstant(0, NVT);
} else {
Lo = DAG.getNode(ISD::OR, NVT,
DAG.getNode(ISD::SRL, NVT, InL, DAG.getConstant(Cst, ShTy)),
@ -1530,6 +1536,10 @@ bool SelectionDAGLegalize::ExpandShift(unsigned Opc, SDOperand Op,SDOperand Amt,
DAG.getConstant(Cst-NVTBits, ShTy));
Hi = DAG.getNode(ISD::SRA, NVT, InH,
DAG.getConstant(NVTBits-1, ShTy));
} else if (Cst == NVTBits) {
Lo = InH;
Hi = DAG.getNode(ISD::SRA, NVT, InH,
DAG.getConstant(NVTBits-1, ShTy));
} else {
Lo = DAG.getNode(ISD::OR, NVT,
DAG.getNode(ISD::SRL, NVT, InL, DAG.getConstant(Cst, ShTy)),