Strongly mitigates the harm from the previous commit, which made many
integer multiplications much more heavy on the register and instruction
count.
total instructions in shared programs : 5839715 -> 5801926 (-0.65%)
total gprs used in shared programs : 670553 -> 669853 (-0.10%)
total shared used in shared programs : 548832 -> 548832 (0.00%)
total local used in shared programs : 21164 -> 21068 (-0.45%)
local shared gpr inst bytes
helped 1 0 408 2522 2522
hurt 0 0 232 23 23
Signed-off-by: Rhys Perry <pendingchao...@gmail.com>
---
.../drivers/nouveau/codegen/nv50_ir_peephole.cpp | 126 ++++++++++++++++++---
1 file changed, 112 insertions(+), 14 deletions(-)
diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
index a6ddb284b8..e5d033c9b0 100644
--- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
+++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
@@ -379,6 +379,10 @@ private:
CmpInstruction *findOriginForTestWithZero(Value *);
+ Value *createMulMethod1(Value *a, unsigned b, Value *c);
+ Value *createMulMethod2(Value *a, unsigned b, Value *c);
+ Value *createMul(Value *a, unsigned b, Value *c);
+
unsigned int foldCount;
BuildUtil bld;
@@ -953,6 +957,88 @@ ConstantFolding::opnd3(Instruction *i, ImmediateValue
&imm2)
}
}
+Value *
+ConstantFolding::createMulMethod1(Value *a, unsigned b, Value *c)
+{
+ // basically constant folded shift and add multiplication.
+ Value *res = c ? c : bld.loadImm(NULL, 0u);
+ bool resZero = !c;
+ unsigned ashift = 0;
+ while (b) {
+ if ((b & 1) && ashift) {
+ Value *sh = bld.loadImm(NULL, ashift);
+ if (resZero)
+ res = bld.mkOp2v(OP_SHL, TYPE_U32, bld.getSSA(), a, sh);
+ else
+ res = bld.mkOp3v(OP_SHLADD, TYPE_U32, bld.getSSA(), a, sh, res);
+ resZero = false;
+ } else if (b & 1) {
+ if (resZero)
+ res = a;
+ else
+ res = bld.mkOp2v(OP_ADD, TYPE_U32, bld.getSSA(), res, a);
+ resZero = false;
+ }
+ b >>= 1;
+ ashift++;
+ }
+ return res;
+}
+
+Value *
+ConstantFolding::createMulMethod2(Value *a, unsigned b, Value *c)
+{
+ // basically does a * b2 - a * (b2 - b) + c
+ uint64_t b2 = util_next_power_of_two64(b);
+ unsigned b2shift = ffsll(b2) - 1;
+
+ Value *mul1 = createMulMethod1(a, b2 - b, NULL);
+
+ Value *res;
+ if (b2shift < 32) {
+ Instruction *i = bld.mkOp3(OP_SHLADD, TYPE_U32, bld.getSSA(),
+ a, bld.loadImm(NULL, b2shift), mul1);
+ res = i->getDef(0);
+
+ // all targets supporting OP_SHLADD should pass this
+ assert(bld.getProgram()->getTarget()->isModSupported(i, 2,
NV50_IR_MOD_NEG));
+ i->src(2).mod *= Modifier(NV50_IR_MOD_NEG);
+ } else {
+ res = bld.mkOp1v(OP_NEG, TYPE_U32, bld.getSSA(), mul1);
+ }
+
+ if (c)
+ res = bld.mkOp2v(OP_ADD, TYPE_U32, bld.getSSA(), res, c);
+
+ return res;
+}
+
+Value *
+ConstantFolding::createMul(Value *a, unsigned b, Value *c)
+{
+ unsigned cost[2];
+
+ // estimate cost for first method (a << i) + (b << j) + ...
+ cost[0] = util_bitcount64(b >> 1);
+
+ // estimate cost for second method (a << i) - ((a << j) + (a << k) + ...)
+ uint64_t rounded_b = util_next_power_of_two64(b);
+ cost[1] = rounded_b == b ? 1 : (util_bitcount64((rounded_b - b) >> 1) + 1);
+ if (c) cost[1]++;
+
+ // The general method, multiplication by XMADs, costs three instructions.
+ // So nothing much larger than that or it could be making things worse.
+ if (cost[0] > 3 && cost[1] > 3)
+ return NULL;
+
+ // the cost is the same for both methods with powers of twos
+ // but method 1 creates more optimizable code
+ if (cost[0] <= cost[1])
+ return createMulMethod1(a, b, c);
+ else
+ return createMulMethod2(a, b, c);
+}
+
void
ConstantFolding::opnd(Instruction *i, ImmediateValue &imm0, int s)
{
@@ -1040,13 +1126,25 @@ ConstantFolding::opnd(Instruction *i, ImmediateValue
&imm0, int s)
i->setSrc(s, i->getSrc(t));
i->src(s).mod = i->src(t).mod;
} else
- if (!isFloatType(i->sType) && !imm0.isNegative() && imm0.isPow2()) {
- i->op = OP_SHL;
- imm0.applyLog2();
- i->setSrc(0, i->getSrc(t));
- i->src(0).mod = i->src(t).mod;
- i->setSrc(1, new_ImmediateValue(prog, imm0.reg.data.u32));
- i->src(1).mod = 0;
+ if (!isFloatType(i->dType)) {
+ bool optimized = false;
+ if (target->isOpSupported(OP_SHLADD, TYPE_U32)) {
+ bld.setPosition(i, false);
+ Value *val = createMul(i->getSrc(t), imm0.reg.data.u32, NULL);
+ if (val) {
+ i->def(0).replace(val, false);
+ delete_Instruction(prog, i);
+ optimized = true;
+ }
+ }
+ if (!optimized && !imm0.isNegative() && imm0.isPow2()) {
+ i->op = OP_SHL;
+ imm0.applyLog2();
+ i->setSrc(0, i->getSrc(t));
+ i->src(0).mod = i->src(t).mod;
+ i->setSrc(1, new_ImmediateValue(prog, imm0.reg.data.u32));
+ i->src(1).mod = 0;
+ }
} else
if (i->postFactor && i->sType == TYPE_F32) {
/* Can't emit a postfactor with an immediate, have to fold it in */
@@ -1079,13 +1177,13 @@ ConstantFolding::opnd(Instruction *i, ImmediateValue
&imm0, int s)
i->setSrc(2, NULL);
i->op = OP_ADD;
} else
- if (s == 1 && !imm0.isNegative() && imm0.isPow2() &&
- !isFloatType(i->dType) &&
- target->isOpSupported(OP_SHLADD, i->dType) &&
- !i->subOp) {
- i->op = OP_SHLADD;
- imm0.applyLog2();
- i->setSrc(1, new_ImmediateValue(prog, imm0.reg.data.u32));
+ if (!isFloatType(i->dType) && target->isOpSupported(OP_SHLADD, TYPE_U32)
&& !i->subOp) {
+ bld.setPosition(i, false);
+ Value *val = createMul(i->getSrc(t), imm0.reg.data.u32, i->getSrc(2));
+ if (val) {
+ i->def(0).replace(val, false);
+ delete_Instruction(prog, i);
+ }
}
break;
case OP_SUB:
--
2.14.4
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