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brw: Remove brw_inst::no_dd_check/no_dd_clear

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These dependency hints were primarily useful for the vec4 backend, where
it was common to write subsets of a vec4's components across multiple
instructions.  In the scalar backend, we rarely used them.  They also no
longer exist on Tigerlake and later in favor of software scoreboarding.

Dropping this allows us to clean up the IR a bit.

We still use the hardware hints in the generator in a couple places:

   - Gfx9-12.0 scratch headers
   - Quad swizzles
   - Indirect MOV lowering

In theory we might want them back if we moved that lowering to the IR.
For scratch at least, I suspect it won't have a huge impact, as we're
already incurring the cost of spills/fills.  The others are fairly rare
as well, so it may not be worth keeping.

Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36730>
This commit is contained in:
Kenneth Graunke
2025-08-13 14:05:43 -07:00
committed by Marge Bot
parent b26c68e40a
commit 6281a12822
5 changed files with 45 additions and 64 deletions
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src/intel/compiler/brw_analysis_performance.cpp
+16 -18
View File
@@ -936,26 +936,24 @@ namespace {
}
/* Stall on any write dependencies. */
if (!inst->no_dd_check) {
if (inst->dst.file != BAD_FILE && !inst->dst.is_null()) {
for (unsigned j = 0; j < regs_written(inst); j++)
stall_on_dependency(
st, reg_dependency_id(devinfo, inst->dst, j));
}
if (inst->dst.file != BAD_FILE && !inst->dst.is_null()) {
for (unsigned j = 0; j < regs_written(inst); j++)
stall_on_dependency(
st, reg_dependency_id(devinfo, inst->dst, j));
}
if (inst->writes_accumulator_implicitly(devinfo)) {
for (unsigned j = accum_reg_of_channel(devinfo, inst, info.tx, 0);
j <= accum_reg_of_channel(devinfo, inst, info.tx,
inst->exec_size - 1); j++)
stall_on_dependency(
st, reg_dependency_id(devinfo, brw_acc_reg(8), j));
}
if (inst->writes_accumulator_implicitly(devinfo)) {
for (unsigned j = accum_reg_of_channel(devinfo, inst, info.tx, 0);
j <= accum_reg_of_channel(devinfo, inst, info.tx,
inst->exec_size - 1); j++)
stall_on_dependency(
st, reg_dependency_id(devinfo, brw_acc_reg(8), j));
}
if (const unsigned mask = inst->flags_written(devinfo)) {
for (unsigned i = 0; i < sizeof(mask) * CHAR_BIT; i++) {
if (mask & (1 << i))
stall_on_dependency(st, flag_dependency_id(i));
}
if (const unsigned mask = inst->flags_written(devinfo)) {
for (unsigned i = 0; i < sizeof(mask) * CHAR_BIT; i++) {
if (mask & (1 << i))
stall_on_dependency(st, flag_dependency_id(i));
}
}