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nvc0/ir: add support for 64-bit shift lowering on SM20/SM30

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Unfortunately there is no SHF.L/SHF.R instruction pre-SM35. So we have
to do a bit more work to get the job done.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
This commit is contained in:
Ilia Mirkin
2017-02-05 10:03:53 -05:00
parent 1aefd6159c
commit 61d7676df7
1 changed files with 62 additions and 6 deletions
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68
src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp
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@@ -150,21 +150,77 @@ NVC0LegalizeSSA::handleTEXLOD(TexInstruction *i)
void
NVC0LegalizeSSA::handleShift(Instruction *lo)
{
Instruction *hi = new_Instruction(func, lo->op, TYPE_U32);
lo->bb->insertAfter(lo, hi);
Value *shift = lo->getSrc(1);
Value *dst64 = lo->getDef(0);
Value *src[2], *dst[2];
operation op = lo->op;
bld.setPosition(lo, false);
Value *src[2], *dst[2] = {bld.getSSA(), bld.getSSA()};
Value *dst64 = lo->getDef(0), *shift = lo->getSrc(1);
bld.mkSplit(src, 4, lo->getSrc(0));
// SM30 and prior don't have the fancy new SHF.L/R ops. So the logic has to
// be completely emulated. For SM35+, we can use the more directed SHF
// operations.
if (prog->getTarget()->getChipset() < NVISA_GK20A_CHIPSET) {
// The strategy here is to handle shifts >= 32 and less than 32 as
// separate parts.
//
// For SHL:
// If the shift is <= 32, then
// (HI,LO) << x = (HI << x | (LO >> (32 - x)), LO << x)
// If the shift is > 32, then
// (HI,LO) << x = (LO << (x - 32), 0)
//
// For SHR:
// If the shift is <= 32, then
// (HI,LO) >> x = (HI >> x, (HI << (32 - x)) | LO >> x)
// If the shift is > 32, then
// (HI,LO) >> x = (0, HI >> (x - 32))
//
// Note that on NVIDIA hardware, a shift > 32 yields a 0 value, which we
// can use to our advantage. Also note the structural similarities
// between the right/left cases. The main difference is swapping hi/lo
// on input and output.
Value *x32_minus_shift, *pred, *hi1, *hi2;
DataType type = isSignedIntType(lo->dType) ? TYPE_S32 : TYPE_U32;
operation antiop = op == OP_SHR ? OP_SHL : OP_SHR;
if (op == OP_SHR)
std::swap(src[0], src[1]);
bld.mkOp2(OP_ADD, TYPE_U32, (x32_minus_shift = bld.getSSA()), shift, bld.mkImm(0x20))
->src(0).mod = Modifier(NV50_IR_MOD_NEG);
bld.mkCmp(OP_SET, CC_LE, TYPE_U8, (pred = bld.getSSA(1, FILE_PREDICATE)),
TYPE_U32, shift, bld.mkImm(32));
// Compute HI (shift <= 32)
bld.mkOp2(OP_OR, TYPE_U32, (hi1 = bld.getSSA()),
bld.mkOp2v(op, TYPE_U32, bld.getSSA(), src[1], shift),
bld.mkOp2v(antiop, TYPE_U32, bld.getSSA(), src[0], x32_minus_shift))
->setPredicate(CC_P, pred);
// Compute LO (all shift values)
bld.mkOp2(op, type, (dst[0] = bld.getSSA()), src[0], shift);
// Compute HI (shift > 32)
bld.mkOp2(op, type, (hi2 = bld.getSSA()), src[1],
bld.mkOp1v(OP_NEG, TYPE_S32, bld.getSSA(), x32_minus_shift))
->setPredicate(CC_NOT_P, pred);
bld.mkOp2(OP_UNION, TYPE_U32, (dst[1] = bld.getSSA()), hi1, hi2);
if (op == OP_SHR)
std::swap(dst[0], dst[1]);
bld.mkOp2(OP_MERGE, TYPE_U64, dst64, dst[0], dst[1]);
delete_Instruction(prog, lo);
return;
}
Instruction *hi = new_Instruction(func, op, TYPE_U32);
lo->bb->insertAfter(lo, hi);
hi->sType = lo->sType;
lo->dType = TYPE_U32;
hi->setDef(0, dst[1]);
hi->setDef(0, (dst[1] = bld.getSSA()));
if (lo->op == OP_SHR)
hi->subOp |= NV50_IR_SUBOP_SHIFT_HIGH;
lo->setDef(0, dst[0]);
lo->setDef(0, (dst[0] = bld.getSSA()));
bld.setPosition(hi, true);