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i965/fs: Copy propagate partial reads.

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This commit reworks copy propagation a bit to support propagating the
copying of partial registers.  This comes up every time we have pull
constants because we do a pull constant read immediately followed by a move
to splat the one component of the out to 8 or 16-wide.  This allows us to
eliminate the copy and simply use the one component of the register.

Shader DB results:

total instructions in shared programs: 5044937 -> 5044428 (-0.01%)
instructions in affected programs:     66112 -> 65603 (-0.77%)
GAINED:                                0
LOST:                                  0

Signed-off-by: Jason Ekstrand <jason.ekstrand@intel.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
This commit is contained in:
Jason Ekstrand 2014-09-23 17:22:09 -07:00
parent 4d5f0eb048
commit 1728e74957
2 changed files with 64 additions and 20 deletions
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1
src/mesa/drivers/dri/i965/brw_fs.h
View file

@ -337,6 +337,7 @@ public:
bool opt_cse_local(bblock_t *block);
bool opt_copy_propagate();
bool try_copy_propagate(fs_inst *inst, int arg, acp_entry *entry);
bool try_constant_propagate(fs_inst *inst, acp_entry *entry);
bool opt_copy_propagate_local(void *mem_ctx, bblock_t *block,
exec_list *acp);
void opt_drop_redundant_mov_to_flags();

83
src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
View file

@ -277,24 +277,30 @@ is_logic_op(enum opcode opcode)
bool
fs_visitor::try_copy_propagate(fs_inst *inst, int arg, acp_entry *entry)
{
if (inst->src[arg].file != GRF)
return false;
if (entry->src.file == IMM)
return false;
assert(entry->src.file == GRF || entry->src.file == UNIFORM);
if (entry->opcode == SHADER_OPCODE_LOAD_PAYLOAD &&
inst->opcode == SHADER_OPCODE_LOAD_PAYLOAD)
return false;
/* Bail if inst is reading more than entry is writing. */
if ((inst->regs_read(this, arg) * inst->src[arg].stride *
type_sz(inst->src[arg].type)) > type_sz(entry->dst.type))
assert(entry->dst.file == GRF);
if (inst->src[arg].reg != entry->dst.reg)
return false;
if (inst->src[arg].file != entry->dst.file ||
inst->src[arg].reg != entry->dst.reg ||
inst->src[arg].reg_offset != entry->dst.reg_offset ||
inst->src[arg].subreg_offset != entry->dst.subreg_offset) {
/* Bail if inst is reading a range that isn't contained in the range
* that entry is writing.
*/
int reg_size = dispatch_width * sizeof(float);
if (inst->src[arg].reg_offset < entry->dst.reg_offset ||
(inst->src[arg].reg_offset * reg_size + inst->src[arg].subreg_offset +
inst->regs_read(this, arg) * inst->src[arg].stride * reg_size) >
(entry->dst.reg_offset + 1) * reg_size)
return false;
}
/* See resolve_ud_negate() and comment in brw_fs_emit.cpp. */
if (inst->conditional_mod &&
@ -361,11 +367,39 @@ fs_visitor::try_copy_propagate(fs_inst *inst, int arg, acp_entry *entry)
inst->src[arg].file = entry->src.file;
inst->src[arg].reg = entry->src.reg;
inst->src[arg].reg_offset = entry->src.reg_offset;
inst->src[arg].subreg_offset = entry->src.subreg_offset;
inst->src[arg].stride *= entry->src.stride;
inst->saturate = inst->saturate || entry->saturate;
switch (entry->src.file) {
case BAD_FILE:
case HW_REG:
case UNIFORM:
inst->src[arg].reg_offset = entry->src.reg_offset;
inst->src[arg].subreg_offset = entry->src.subreg_offset;
break;
case GRF:
{
/* In this case, we have to deal with mapping parts of vgrfs to
* other parts of vgrfs so we have to do some reg_offset magic.
*/
/* Compute the offset of inst->src[arg] relative to inst->dst */
assert(entry->dst.subreg_offset == 0);
int rel_offset = inst->src[arg].reg_offset - entry->dst.reg_offset;
int rel_suboffset = inst->src[arg].subreg_offset;
/* Compute the final register offset (in bytes) */
int offset = entry->src.reg_offset * reg_size + entry->src.subreg_offset;
offset += rel_offset * reg_size + rel_suboffset;
inst->src[arg].reg_offset = offset / reg_size;
inst->src[arg].subreg_offset = offset % reg_size;
}
break;
default:
unreachable("Invalid register file");
break;
}
if (!inst->src[arg].abs) {
inst->src[arg].abs = entry->src.abs;
inst->src[arg].negate ^= entry->src.negate;
@ -375,9 +409,8 @@ fs_visitor::try_copy_propagate(fs_inst *inst, int arg, acp_entry *entry)
}
static bool
try_constant_propagate(struct brw_context *brw, fs_inst *inst,
acp_entry *entry)
bool
fs_visitor::try_constant_propagate(fs_inst *inst, acp_entry *entry)
{
bool progress = false;
@ -385,12 +418,22 @@ try_constant_propagate(struct brw_context *brw, fs_inst *inst,
return false;
for (int i = inst->sources - 1; i >= 0; i--) {
if (inst->src[i].file != entry->dst.file ||
inst->src[i].reg != entry->dst.reg ||
inst->src[i].reg_offset != entry->dst.reg_offset ||
inst->src[i].subreg_offset != entry->dst.subreg_offset ||
inst->src[i].type != entry->dst.type ||
inst->src[i].stride > 1)
if (inst->src[i].file != GRF)
continue;
assert(entry->dst.file == GRF);
if (inst->src[i].reg != entry->dst.reg ||
inst->src[i].type != entry->dst.type)
continue;
/* Bail if inst is reading a range that isn't contained in the range
* that entry is writing.
*/
int reg_size = dispatch_width * sizeof(float);
if (inst->src[i].reg_offset < entry->dst.reg_offset ||
(inst->src[i].reg_offset * reg_size + inst->src[i].subreg_offset +
inst->regs_read(this, i) * inst->src[i].stride * reg_size) >
(entry->dst.reg_offset + 1) * reg_size)
continue;
/* Don't bother with cases that should have been taken care of by the
@ -546,7 +589,7 @@ fs_visitor::opt_copy_propagate_local(void *copy_prop_ctx, bblock_t *block,
continue;
foreach_in_list(acp_entry, entry, &acp[inst->src[i].reg % ACP_HASH_SIZE]) {
if (try_constant_propagate(brw, inst, entry))
if (try_constant_propagate(inst, entry))
progress = true;
if (try_copy_propagate(inst, i, entry))