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broadcom/vc5: Remove no-op MOVs after register allocation.

Browse source 
We emit some MOVs to track lifetimes of payload registers, but we don't
need there to be actual MOV instructions for them.

total instructions in shared programs: 101045 -> 100423 (-0.62%)
instructions in affected programs:     37083 -> 36461 (-1.68%)
This commit is contained in:
Eric Anholt 2018-02-04 21:05:03 +00:00
parent f3978a7380
commit dc78643ace
1 changed files with 60 additions and 1 deletions
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61
src/broadcom/compiler/vir_to_qpu.c
View file

@ -138,6 +138,60 @@ set_src(struct v3d_qpu_instr *instr, enum v3d_qpu_mux *mux, struct qpu_reg src)
}
}
static bool
is_no_op_mov(struct qinst *qinst)
{
static const struct v3d_qpu_sig no_sig = {0};
/* Make sure it's just a lone MOV. */
if (qinst->qpu.type != V3D_QPU_INSTR_TYPE_ALU ||
qinst->qpu.alu.mul.op != V3D_QPU_M_MOV ||
qinst->qpu.alu.add.op != V3D_QPU_A_NOP ||
memcmp(&qinst->qpu.sig, &no_sig, sizeof(no_sig)) != 0) {
return false;
}
/* Check if it's a MOV from a register to itself. */
enum v3d_qpu_waddr waddr = qinst->qpu.alu.mul.waddr;
if (qinst->qpu.alu.mul.magic_write) {
if (waddr < V3D_QPU_WADDR_R0 || waddr > V3D_QPU_WADDR_R4)
return false;
if (qinst->qpu.alu.mul.a !=
V3D_QPU_MUX_R0 + (waddr - V3D_QPU_WADDR_R0)) {
return false;
}
} else {
int raddr;
switch (qinst->qpu.alu.mul.a) {
case V3D_QPU_MUX_A:
raddr = qinst->qpu.raddr_a;
break;
case V3D_QPU_MUX_B:
raddr = qinst->qpu.raddr_b;
break;
default:
return false;
}
if (raddr != waddr)
return false;
}
/* No packing or flags updates, or we need to execute the
* instruction.
*/
if (qinst->qpu.alu.mul.a_unpack != V3D_QPU_UNPACK_NONE ||
qinst->qpu.alu.mul.output_pack != V3D_QPU_PACK_NONE ||
qinst->qpu.flags.mc != V3D_QPU_COND_NONE ||
qinst->qpu.flags.mpf != V3D_QPU_PF_NONE ||
qinst->qpu.flags.muf != V3D_QPU_UF_NONE) {
return false;
}
return true;
}
static void
v3d_generate_code_block(struct v3d_compile *c,
struct qblock *block,
@ -145,7 +199,7 @@ v3d_generate_code_block(struct v3d_compile *c,
{
int last_vpm_read_index = -1;
vir_for_each_inst(qinst, block) {
vir_for_each_inst_safe(qinst, block) {
#if 0
fprintf(stderr, "translating qinst to qpu: ");
vir_dump_inst(c, qinst);
@ -289,6 +343,11 @@ v3d_generate_code_block(struct v3d_compile *c,
qinst->qpu.alu.mul.waddr = dst.index;
qinst->qpu.alu.mul.magic_write = dst.magic;
if (is_no_op_mov(qinst)) {
vir_remove_instruction(c, qinst);
continue;
}
}
} else {
assert(qinst->qpu.type == V3D_QPU_INSTR_TYPE_BRANCH);