nv50/ir: fold MAD when one of the multiplicands is const

Fold MAD dst, src0, immed, src2 (or src0/immed swapped) when
 - immed = 0 -> MOV dst, src2
 - immed = +/- 1 -> ADD dst, src0, src2

These types of MAD patterns were observed in some st/nine shaders.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
This commit is contained in:
Ilia Mirkin 2015-01-01 01:01:13 -05:00
parent 290553b6d6
commit 9e94b87b60

View file

@ -784,6 +784,29 @@ ConstantFolding::opnd(Instruction *i, ImmediateValue &imm0, int s)
i->src(1).mod = 0;
}
break;
case OP_MAD:
if (imm0.isInteger(0)) {
i->setSrc(0, i->getSrc(2));
i->src(0).mod = i->src(2).mod;
i->setSrc(1, NULL);
i->setSrc(2, NULL);
i->op = i->src(0).mod.getOp();
if (i->op != OP_CVT)
i->src(0).mod = 0;
} else
if (imm0.isInteger(1) || imm0.isInteger(-1)) {
if (imm0.isNegative())
i->src(t).mod = i->src(t).mod ^ Modifier(NV50_IR_MOD_NEG);
if (s == 0) {
i->setSrc(0, i->getSrc(1));
i->src(0).mod = i->src(1).mod;
}
i->setSrc(1, i->getSrc(2));
i->src(1).mod = i->src(2).mod;
i->setSrc(2, NULL);
i->op = OP_ADD;
}
break;
case OP_ADD:
if (i->usesFlags())
break;