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i965: Avoid generating MOVs for assignments of expressions. 

No statistically significant difference measured in 3dbenchmark
egypt/pro.  It does reduce fragment shader instructions across
shader-db by 0.3%.
This commit is contained in:
Eric Anholt 2011-04-26 17:58:04 -07:00
parent 1791857d7d
commit 53c89c67f3
2 changed files with 75 additions and 12 deletions
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82
src/mesa/drivers/dri/i965/brw_fs.cpp
View File

@ -818,6 +818,7 @@ fs_visitor::try_emit_saturate(ir_expression *ir)
if (!sat_val)
return false;
this->result = reg_undef;
sat_val->accept(this);
fs_reg src = this->result;
@ -864,7 +865,11 @@ fs_visitor::visit(ir_expression *ir)
if (try_emit_saturate(ir))
return;
/* This is where our caller would like us to put the result, if possible. */
fs_reg saved_result_storage = this->result;
for (operand = 0; operand < ir->get_num_operands(); operand++) {
this->result = reg_undef;
ir->operands[operand]->accept(this);
if (this->result.file == BAD_FILE) {
ir_print_visitor v;
@ -882,10 +887,14 @@ fs_visitor::visit(ir_expression *ir)
assert(!ir->operands[operand]->type->is_vector());
}
/* Storage for our result. If our result goes into an assignment, it will
* just get copy-propagated out, so no worries.
/* Inherit storage from our parent if possible, and otherwise we
* alloc a temporary.
*/
this->result = fs_reg(this, ir->type);
if (saved_result_storage.file == BAD_FILE) {
this->result = fs_reg(this, ir->type);
} else {
this->result = saved_result_storage;
}
switch (ir->operation) {
case ir_unop_logic_not:
@ -906,6 +915,9 @@ fs_visitor::visit(ir_expression *ir)
case ir_unop_sign:
temp = fs_reg(this, ir->type);
/* Unalias the destination. (imagine a = sign(a)) */
this->result = fs_reg(this, ir->type);
emit(BRW_OPCODE_MOV, this->result, fs_reg(0.0f));
inst = emit(BRW_OPCODE_CMP, reg_null_f, op[0], fs_reg(0.0f));
@ -1054,6 +1066,9 @@ fs_visitor::visit(ir_expression *ir)
break;
case ir_binop_min:
/* Unalias the destination */
this->result = fs_reg(this, ir->type);
inst = emit(BRW_OPCODE_CMP, this->result, op[0], op[1]);
inst->conditional_mod = BRW_CONDITIONAL_L;
@ -1061,6 +1076,9 @@ fs_visitor::visit(ir_expression *ir)
inst->predicated = true;
break;
case ir_binop_max:
/* Unalias the destination */
this->result = fs_reg(this, ir->type);
inst = emit(BRW_OPCODE_CMP, this->result, op[0], op[1]);
inst->conditional_mod = BRW_CONDITIONAL_G;
@ -1106,8 +1124,10 @@ fs_visitor::emit_assignment_writes(fs_reg &l, fs_reg &r,
l.type = brw_type_for_base_type(type);
r.type = brw_type_for_base_type(type);
fs_inst *inst = emit(BRW_OPCODE_MOV, l, r);
inst->predicated = predicated;
if (predicated || !l.equals(&r)) {
fs_inst *inst = emit(BRW_OPCODE_MOV, l, r);
inst->predicated = predicated;
}
l.reg_offset++;
r.reg_offset++;
@ -1142,9 +1162,21 @@ fs_visitor::visit(ir_assignment *ir)
fs_inst *inst;
/* FINISHME: arrays on the lhs */
this->result = reg_undef;
ir->lhs->accept(this);
l = this->result;
/* If we're doing a direct assignment, an RHS expression could
* drop its result right into our destination. Otherwise, tell it
* not to.
*/
if (ir->condition ||
!(ir->lhs->type->is_scalar() ||
(ir->lhs->type->is_vector() &&
ir->write_mask == (1 << ir->lhs->type->vector_elements) - 1))) {
this->result = reg_undef;
}
ir->rhs->accept(this);
r = this->result;
@ -1159,9 +1191,13 @@ fs_visitor::visit(ir_assignment *ir)
ir->lhs->type->is_vector()) {
for (int i = 0; i < ir->lhs->type->vector_elements; i++) {
if (ir->write_mask & (1 << i)) {
inst = emit(BRW_OPCODE_MOV, l, r);
if (ir->condition)
if (ir->condition) {
inst = emit(BRW_OPCODE_MOV, l, r);
inst->predicated = true;
} else if (!l.equals(&r)) {
inst = emit(BRW_OPCODE_MOV, l, r);
}
r.reg_offset++;
}
l.reg_offset++;
@ -1202,16 +1238,19 @@ fs_visitor::emit_texture_gen4(ir_texture *ir, fs_reg dst, fs_reg coordinate,
emit(BRW_OPCODE_MOV, fs_reg(MRF, base_mrf + mlen), fs_reg(0.0f));
mlen++;
} else if (ir->op == ir_txb) {
this->result = reg_undef;
ir->lod_info.bias->accept(this);
emit(BRW_OPCODE_MOV, fs_reg(MRF, base_mrf + mlen), this->result);
mlen++;
} else {
assert(ir->op == ir_txl);
this->result = reg_undef;
ir->lod_info.lod->accept(this);
emit(BRW_OPCODE_MOV, fs_reg(MRF, base_mrf + mlen), this->result);
mlen++;
}
this->result = reg_undef;
ir->shadow_comparitor->accept(this);
emit(BRW_OPCODE_MOV, fs_reg(MRF, base_mrf + mlen), this->result);
mlen++;
@ -1246,10 +1285,12 @@ fs_visitor::emit_texture_gen4(ir_texture *ir, fs_reg dst, fs_reg coordinate,
mlen += 6;
if (ir->op == ir_txb) {
this->result = reg_undef;
ir->lod_info.bias->accept(this);
emit(BRW_OPCODE_MOV, fs_reg(MRF, base_mrf + mlen), this->result);
mlen++;
} else {
this->result = reg_undef;
ir->lod_info.lod->accept(this);
emit(BRW_OPCODE_MOV, fs_reg(MRF, base_mrf + mlen), this->result);
mlen++;
@ -1341,6 +1382,7 @@ fs_visitor::emit_texture_gen5(ir_texture *ir, fs_reg dst, fs_reg coordinate,
if (ir->shadow_comparitor) {
mlen = MAX2(mlen, header_present + 4 * reg_width);
this->result = reg_undef;
ir->shadow_comparitor->accept(this);
emit(BRW_OPCODE_MOV, fs_reg(MRF, base_mrf + mlen), this->result);
mlen += reg_width;
@ -1352,6 +1394,7 @@ fs_visitor::emit_texture_gen5(ir_texture *ir, fs_reg dst, fs_reg coordinate,
inst = emit(FS_OPCODE_TEX, dst);
break;
case ir_txb:
this->result = reg_undef;
ir->lod_info.bias->accept(this);
mlen = MAX2(mlen, header_present + 4 * reg_width);
emit(BRW_OPCODE_MOV, fs_reg(MRF, base_mrf + mlen), this->result);
@ -1361,6 +1404,7 @@ fs_visitor::emit_texture_gen5(ir_texture *ir, fs_reg dst, fs_reg coordinate,
break;
case ir_txl:
this->result = reg_undef;
ir->lod_info.lod->accept(this);
mlen = MAX2(mlen, header_present + 4 * reg_width);
emit(BRW_OPCODE_MOV, fs_reg(MRF, base_mrf + mlen), this->result);
@ -1464,6 +1508,7 @@ fs_visitor::visit(ir_texture *ir)
int sampler;
fs_inst *inst = NULL;
this->result = reg_undef;
ir->coordinate->accept(this);
fs_reg coordinate = this->result;
@ -1609,6 +1654,7 @@ fs_visitor::visit(ir_texture *ir)
void
fs_visitor::visit(ir_swizzle *ir)
{
this->result = reg_undef;
ir->val->accept(this);
fs_reg val = this->result;
@ -1671,6 +1717,7 @@ fs_visitor::visit(ir_constant *ir)
const unsigned size = type_size(ir->type->fields.array);
for (unsigned i = 0; i < ir->type->length; i++) {
this->result = reg_undef;
ir->array_elements[i]->accept(this);
fs_reg src_reg = this->result;
@ -1686,6 +1733,7 @@ fs_visitor::visit(ir_constant *ir)
ir_instruction *const field = (ir_instruction *) node;
const unsigned size = type_size(field->type);
this->result = reg_undef;
field->accept(this);
fs_reg src_reg = this->result;
@ -1736,6 +1784,7 @@ fs_visitor::emit_bool_to_cond_code(ir_rvalue *ir)
for (unsigned int i = 0; i < expr->get_num_operands(); i++) {
assert(expr->operands[i]->type->is_scalar());
this->result = reg_undef;
expr->operands[i]->accept(this);
op[i] = this->result;
}
@ -1800,6 +1849,7 @@ fs_visitor::emit_bool_to_cond_code(ir_rvalue *ir)
return;
}
this->result = reg_undef;
ir->accept(this);
if (intel->gen >= 6) {
@ -1829,6 +1879,7 @@ fs_visitor::emit_if_gen6(ir_if *ir)
for (unsigned int i = 0; i < expr->get_num_operands(); i++) {
assert(expr->operands[i]->type->is_scalar());
this->result = reg_undef;
expr->operands[i]->accept(this);
op[i] = this->result;
}
@ -1890,6 +1941,7 @@ fs_visitor::emit_if_gen6(ir_if *ir)
return;
}
this->result = reg_undef;
ir->condition->accept(this);
fs_inst *inst = emit(BRW_OPCODE_IF, reg_null_d, this->result, fs_reg(0));
@ -1922,7 +1974,7 @@ fs_visitor::visit(ir_if *ir)
foreach_iter(exec_list_iterator, iter, ir->then_instructions) {
ir_instruction *ir = (ir_instruction *)iter.get();
this->base_ir = ir;
this->result = reg_undef;
ir->accept(this);
}
@ -1932,7 +1984,7 @@ fs_visitor::visit(ir_if *ir)
foreach_iter(exec_list_iterator, iter, ir->else_instructions) {
ir_instruction *ir = (ir_instruction *)iter.get();
this->base_ir = ir;
this->result = reg_undef;
ir->accept(this);
}
}
@ -1955,10 +2007,14 @@ fs_visitor::visit(ir_loop *ir)
counter = *(variable_storage(ir->counter));
if (ir->from) {
this->result = counter;
this->base_ir = ir->from;
this->result = counter;
ir->from->accept(this);
emit(BRW_OPCODE_MOV, counter, this->result);
if (!this->result.equals(&counter))
emit(BRW_OPCODE_MOV, counter, this->result);
}
}
@ -1966,6 +2022,7 @@ fs_visitor::visit(ir_loop *ir)
if (ir->to) {
this->base_ir = ir->to;
this->result = reg_undef;
ir->to->accept(this);
fs_inst *inst = emit(BRW_OPCODE_CMP, reg_null_cmp, counter, this->result);
@ -1979,11 +2036,13 @@ fs_visitor::visit(ir_loop *ir)
ir_instruction *ir = (ir_instruction *)iter.get();
this->base_ir = ir;
this->result = reg_undef;
ir->accept(this);
}
if (ir->increment) {
this->base_ir = ir->increment;
this->result = reg_undef;
ir->increment->accept(this);
emit(BRW_OPCODE_ADD, counter, counter, this->result);
}
@ -2033,7 +2092,7 @@ fs_visitor::visit(ir_function *ir)
foreach_iter(exec_list_iterator, iter, sig->body) {
ir_instruction *ir = (ir_instruction *)iter.get();
this->base_ir = ir;
this->result = reg_undef;
ir->accept(this);
}
}
@ -4117,6 +4176,7 @@ fs_visitor::run()
foreach_iter(exec_list_iterator, iter, *shader->ir) {
ir_instruction *ir = (ir_instruction *)iter.get();
base_ir = ir;
this->result = reg_undef;
ir->accept(this);
}

5
src/mesa/drivers/dri/i965/brw_fs.h
View File

@ -571,7 +571,10 @@ public:
bool failed;
/* Result of last visit() method. */
/* On entry to a visit() method, this is the storage for the
* result. On exit, the visit() called may have changed it, in
* which case the parent must use the new storage instead.
*/
fs_reg result;
fs_reg pixel_x;