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When using a 4 byte jump table on a 64 bit machine, 

do an extending load of the 4 bytes rather than a
potentially illegal (type) i32 load followed by a
sign extend.

llvm-svn: 60945
This commit is contained in:
Duncan Sands 2008-12-12 08:13:38 +00:00
parent dd6f3dbd05
commit e4bcb8e2dd
1 changed files with 3 additions and 11 deletions
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14
llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
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@ -1951,23 +1951,15 @@ SDValue SelectionDAGLegalize::LegalizeOp(SDValue Op) {
unsigned EntrySize = MF.getJumpTableInfo()->getEntrySize();
Index= DAG.getNode(ISD::MUL, PTy, Index, DAG.getConstant(EntrySize, PTy));
SDValue Addr = DAG.getNode(ISD::ADD, PTy, Index, Table);
SDValue LD;
switch (EntrySize) {
default: assert(0 && "Size of jump table not supported yet."); break;
case 4: LD = DAG.getLoad(MVT::i32, Chain, Addr,
PseudoSourceValue::getJumpTable(), 0); break;
case 8: LD = DAG.getLoad(MVT::i64, Chain, Addr,
PseudoSourceValue::getJumpTable(), 0); break;
}
MVT MemVT = MVT::getIntegerVT(EntrySize * 8);
SDValue LD = DAG.getExtLoad(ISD::SEXTLOAD, PTy, Chain, Addr,
PseudoSourceValue::getJumpTable(), 0, MemVT);
Addr = LD;
if (TLI.getTargetMachine().getRelocationModel() == Reloc::PIC_) {
// For PIC, the sequence is:
// BRIND(load(Jumptable + index) + RelocBase)
// RelocBase can be JumpTable, GOT or some sort of global base.
if (PTy != MVT::i32)
Addr = DAG.getNode(ISD::SIGN_EXTEND, PTy, Addr);
Addr = DAG.getNode(ISD::ADD, PTy, Addr,
TLI.getPICJumpTableRelocBase(Table, DAG));
}