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Flesh out GEP support 

llvm-svn: 13421
This commit is contained in:
Brian Gaeke 2004-05-08 05:27:20 +00:00
parent d18b330605
commit 7a66e5fff9
1 changed files with 53 additions and 3 deletions
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56
llvm/lib/Target/SparcV8/InstSelectSimple.cpp
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@ -477,12 +477,62 @@ void V8ISel::visitBranchInst(BranchInst &I) {
/// emitGEPOperation - Common code shared between visitGetElementPtrInst and
/// constant expression GEP support.
///
void V8ISel::emitGEPOperation (MachineBasicBlock *BB,
void V8ISel::emitGEPOperation (MachineBasicBlock *MBB,
MachineBasicBlock::iterator IP,
Value *Src, User::op_iterator IdxBegin,
User::op_iterator IdxEnd, unsigned TargetReg) {
std::cerr << "Sorry, GEPs not yet supported\n";
abort ();
const TargetData &TD = TM.getTargetData ();
const Type *Ty = Src->getType ();
unsigned basePtrReg = getReg (Src);
// GEPs have zero or more indices; we must perform a struct access
// or array access for each one.
for (GetElementPtrInst::op_iterator oi = IdxBegin, oe = IdxEnd; oi != oe;
++oi) {
Value *idx = *oi;
unsigned nextBasePtrReg = makeAnotherReg (Type::UIntTy);
if (const StructType *StTy = dyn_cast<StructType> (Ty)) {
// It's a struct access. idx is the index into the structure,
// which names the field. Use the TargetData structure to
// pick out what the layout of the structure is in memory.
// Use the (constant) structure index's value to find the
// right byte offset from the StructLayout class's list of
// structure member offsets.
unsigned fieldIndex = cast<ConstantUInt> (idx)->getValue ();
unsigned memberOffset =
TD.getStructLayout (StTy)->MemberOffsets[fieldIndex];
// Emit an ADD to add memberOffset to the basePtr.
BuildMI (*MBB, IP, V8::ADDri, 2,
nextBasePtrReg).addReg (basePtrReg).addZImm (memberOffset);
// The next type is the member of the structure selected by the
// index.
Ty = StTy->getElementType (fieldIndex);
} else if (const SequentialType *SqTy = dyn_cast<SequentialType> (Ty)) {
// It's an array or pointer access: [ArraySize x ElementType].
// We want to add basePtrReg to (idxReg * sizeof ElementType). First, we
// must find the size of the pointed-to type (Not coincidentally, the next
// type is the type of the elements in the array).
Ty = SqTy->getElementType ();
unsigned elementSize = TD.getTypeSize (Ty);
unsigned idxReg = getReg (idx, MBB, IP);
unsigned OffsetReg = makeAnotherReg (Type::IntTy);
unsigned elementSizeReg = makeAnotherReg (Type::UIntTy);
BuildMI (*MBB, IP, V8::ORri, 2,
elementSizeReg).addZImm (elementSize).addReg (V8::G0);
// Emit a SMUL to multiply the register holding the index by
// elementSize, putting the result in OffsetReg.
BuildMI (*MBB, IP, V8::SMULrr, 2,
OffsetReg).addReg (elementSizeReg).addReg (idxReg);
// Emit an ADD to add OffsetReg to the basePtr.
BuildMI (*MBB, IP, V8::ADDrr, 2,
nextBasePtrReg).addReg (basePtrReg).addReg (OffsetReg);
}
basePtrReg = nextBasePtrReg;
}
// After we have processed all the indices, the result is left in
// basePtrReg. Move it to the register where we were expected to
// put the answer.
BuildMI (BB, V8::ORrr, 1, TargetReg).addReg (V8::G0).addReg (basePtrReg);
}
void V8ISel::visitGetElementPtrInst (GetElementPtrInst &I) {