[Mesa-dev] [PATCH 14/12] i965/fs: Copy propagate partial reads.
Jason Ekstrand
jason at jlekstrand.net
Fri Sep 26 12:24:54 PDT 2014
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 at intel.com>
---
src/mesa/drivers/dri/i965/brw_fs.h | 1 +
.../drivers/dri/i965/brw_fs_copy_propagation.cpp | 83 ++++++++++++++++------
2 files changed, 64 insertions(+), 20 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_fs.h b/src/mesa/drivers/dri/i965/brw_fs.h
index 50b5fc1..9b63114 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.h
+++ b/src/mesa/drivers/dri/i965/brw_fs.h
@@ -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();
diff --git a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
index e5816df..a97dc04 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
@@ -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))
--
2.1.0
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