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broadcom/compiler: remove unused leading ldunifa

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This requires that we go back to the unifa write and update the address
to jump over the unused leading component.

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9128>
This commit is contained in:
Iago Toral Quiroga 2021-02-16 12:08:05 +01:00 • committed by Marge Bot
parent 9d16d2d0be
commit 89de085055
1 changed files with 80 additions and 2 deletions
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82
src/broadcom/compiler/vir_opt_dead_code.c
View file

@ -91,7 +91,9 @@ vir_dce_flags(struct v3d_compile *c, struct qinst *inst)
}
static bool
is_last_ldunifa(struct v3d_compile *c, struct qinst *inst, struct qblock *block)
check_last_ldunifa(struct v3d_compile *c,
struct qinst *inst,
struct qblock *block)
{
if (!inst->qpu.sig.ldunifa && !inst->qpu.sig.ldunifarf)
return false;
@ -116,6 +118,66 @@ is_last_ldunifa(struct v3d_compile *c, struct qinst *inst, struct qblock *block)
return true;
}
static bool
check_first_ldunifa(struct v3d_compile *c,
struct qinst *inst,
struct qblock *block,
struct qinst **unifa)
{
if (!inst->qpu.sig.ldunifa && !inst->qpu.sig.ldunifarf)
return false;
list_for_each_entry_from_rev(struct qinst, scan_inst, inst->link.prev,
&block->instructions, link) {
/* If we find a write to unifa, then this was the first
* ldunifa in its sequence and is safe to remove.
*/
if (scan_inst->dst.file == QFILE_MAGIC &&
scan_inst->dst.index == V3D_QPU_WADDR_UNIFA) {
*unifa = scan_inst;
return true;
}
/* If we find another ldunifa in the same sequence then we
* can't remove it.
*/
if (scan_inst->qpu.sig.ldunifa || scan_inst->qpu.sig.ldunifarf)
return false;
}
unreachable("could not find starting unifa for ldunifa sequence");
}
static bool
increment_unifa_address(struct v3d_compile *c, struct qinst *unifa)
{
if (unifa->qpu.type == V3D_QPU_INSTR_TYPE_ALU &&
unifa->qpu.alu.mul.op == V3D_QPU_M_MOV) {
c->cursor = vir_after_inst(unifa);
struct qreg unifa_reg = vir_reg(QFILE_MAGIC, V3D_QPU_WADDR_UNIFA);
vir_ADD_dest(c, unifa_reg, unifa->src[0], vir_uniform_ui(c, 4u));
vir_remove_instruction(c, unifa);
return true;
}
/* FIXME: we can optimize this further by implementing a constant
* ALU pass in the backend, for the case where we are skipping
* multiple leading ldunifa.
*/
if (unifa->qpu.type == V3D_QPU_INSTR_TYPE_ALU &&
unifa->qpu.alu.add.op == V3D_QPU_A_ADD) {
c->cursor = vir_after_inst(unifa);
struct qreg unifa_reg = vir_reg(QFILE_MAGIC, V3D_QPU_WADDR_UNIFA);
struct qreg tmp =
vir_ADD(c, unifa->src[1], vir_uniform_ui(c, 4u));
vir_ADD_dest(c, unifa_reg, unifa->src[0], tmp);
vir_remove_instruction(c, unifa);
return true;
}
return false;
}
bool
vir_opt_dead_code(struct v3d_compile *c)
{
@ -151,8 +213,15 @@ vir_opt_dead_code(struct v3d_compile *c)
continue;
}
const bool is_last_ldunifa =
check_last_ldunifa(c, inst, block);
struct qinst *unifa = NULL;
const bool is_first_ldunifa =
check_first_ldunifa(c, inst, block, &unifa);
if (vir_has_side_effects(c, inst) &&
!is_last_ldunifa(c, inst, block)) {
!is_last_ldunifa && !is_first_ldunifa) {
continue;
}
@ -195,6 +264,15 @@ vir_opt_dead_code(struct v3d_compile *c)
continue;
}
/* If we are removing the first ldunifa in a sequence
* we need to update the unifa address.
*/
if (is_first_ldunifa) {
assert(unifa);
if (!increment_unifa_address(c, unifa))
continue;
}
assert(inst != last_flags_write);
dce(c, inst);
progress = true;