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Only allocate an output vreg if the instruction actually wants one.

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This commit is contained in:
David Given 2016-10-08 12:15:21 +02:00
parent 2198db69b1
commit 637aeed70a
1 changed files with 9 additions and 12 deletions
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21
mach/proto/mcg/pass_instructionselection.c
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@ -88,6 +88,13 @@ static void constrain_input_reg(int child, int attr)
static void constrain_output_reg(int attr) static void constrain_output_reg(int attr)
{ {
struct vreg* vreg = current_hop->output;
if (!vreg)
current_hop->output = vreg = new_vreg();
array_appendu(&current_hop->outs, vreg);
vreg->defined = current_hop;
} }
static const struct burm_emitter_data emitter_data = static const struct burm_emitter_data emitter_data =
@ -161,22 +168,12 @@ static struct insn* walk_instructions(struct burm_node* node, int goal)
case ir_to_esn(IR_NOP, 0): case ir_to_esn(IR_NOP, 0):
vreg = node->left->ir->result; vreg = node->left->ir->result;
break; break;
default:
/* FIXME: some instructions don't emit anything, so
* allocating a register for them is a waste of time. */
vreg = new_vreg();
} }
insn->hop = current_hop = new_hop(current_bb, insn->ir); insn->hop = current_hop = new_hop(current_bb, insn->ir);
insn->hop->output = vreg; current_hop->output = vreg;
if (vreg)
{
array_appendu(&current_hop->outs, vreg);
vreg->defined = current_hop;
}
emit(insn); emit(insn);
hop_print('I', current_hop); hop_print('I', current_hop);
array_append(&current_bb->hops, current_hop); array_append(&current_bb->hops, current_hop);