Mesa (master): aco: improve waitcnt insertion around loops
GitLab Mirror
gitlab-mirror at kemper.freedesktop.org
Thu Nov 21 21:13:40 UTC 2019
Module: Mesa
Branch: master
Commit: d1b9deeea89f70ea5a4f2cb6c82785d3179e5ad2
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=d1b9deeea89f70ea5a4f2cb6c82785d3179e5ad2
Author: Rhys Perry <pendingchaos02 at gmail.com>
Date: Mon Oct 21 21:36:41 2019 +0100
aco: improve waitcnt insertion around loops
Do this by repeating processing of loops until no progress is made.
Totals from affected shaders:
SGPRS: 162576 -> 162576 (0.00 %)
VGPRS: 145228 -> 145228 (0.00 %)
Spilled SGPRs: 668 -> 668 (0.00 %)
Spilled VGPRs: 0 -> 0 (0.00 %)
Private memory VGPRs: 0 -> 0 (0.00 %)
Scratch size: 0 -> 0 (0.00 %) dwords per thread
Code Size: 15778640 -> 15771336 (-0.05 %) bytes
LDS: 146 -> 146 (0.00 %) blocks
Max Waves: 6087 -> 6087 (0.00 %)
v2: use block_kind_loop_header/block_kind_loop_exit to repeat at the end
of loops instead of at each continue
Signed-off-by: Rhys Perry <pendingchaos02 at gmail.com>
Reviewed-by: Daniel Schürmann <daniel at schuermann.dev>
---
src/amd/compiler/aco_insert_waitcnt.cpp | 153 ++++++++++++++++++++++----------
1 file changed, 108 insertions(+), 45 deletions(-)
diff --git a/src/amd/compiler/aco_insert_waitcnt.cpp b/src/amd/compiler/aco_insert_waitcnt.cpp
index 1f4733ed356..5d65ae253ff 100644
--- a/src/amd/compiler/aco_insert_waitcnt.cpp
+++ b/src/amd/compiler/aco_insert_waitcnt.cpp
@@ -24,6 +24,7 @@
#include <algorithm>
#include <map>
+#include <stack>
#include "aco_ir.h"
#include "vulkan/radv_shader.h"
@@ -34,8 +35,9 @@ namespace {
/**
* The general idea of this pass is:
- * The CFG is traversed in reverse postorder (forward).
- * Per BB one wait_ctx is maintained.
+ * The CFG is traversed in reverse postorder (forward) and loops are processed
+ * several times until no progress is made.
+ * Per BB two wait_ctx is maintained: an in-context and out-context.
* The in-context is the joined out-contexts of the predecessors.
* The context contains a map: gpr -> wait_entry
* consisting of the information about the cnt values to be waited for.
@@ -114,6 +116,19 @@ struct wait_imm {
wait_imm(uint16_t vm_, uint16_t exp_, uint16_t lgkm_, uint16_t vs_) :
vm(vm_), exp(exp_), lgkm(lgkm_), vs(vs_) {}
+ wait_imm(enum chip_class chip, uint16_t packed) : vs(unset_counter)
+ {
+ vm = packed & 0xf;
+ if (chip >= GFX9)
+ vm |= (packed >> 10) & 0x30;
+
+ exp = (packed >> 4) & 0x7;
+
+ lgkm = (packed >> 8) & 0xf;
+ if (chip >= GFX10)
+ lgkm |= (packed >> 8) & 0x30;
+ }
+
uint16_t pack(enum chip_class chip) const
{
uint16_t imm = 0;
@@ -142,12 +157,14 @@ struct wait_imm {
return imm;
}
- void combine(const wait_imm& other)
+ bool combine(const wait_imm& other)
{
+ bool changed = other.vm < vm || other.exp < exp || other.lgkm < lgkm || other.vs < vs;
vm = std::min(vm, other.vm);
exp = std::min(exp, other.exp);
lgkm = std::min(lgkm, other.lgkm);
vs = std::min(vs, other.vs);
+ return changed;
}
bool empty() const
@@ -168,13 +185,17 @@ struct wait_entry {
: imm(imm), events(event), counters(get_counters_for_event(event)),
wait_on_read(wait_on_read), logical(logical) {}
- void join(const wait_entry& other)
+ bool join(const wait_entry& other)
{
+ bool changed = (other.events & ~events) ||
+ (other.counters & ~counters) ||
+ (other.wait_on_read && !wait_on_read);
events |= other.events;
counters |= other.counters;
- imm.combine(other.imm);
+ changed |= imm.combine(other.imm);
wait_on_read = wait_on_read || other.wait_on_read;
assert(logical == other.logical);
+ return changed;
}
void remove_counter(counter_type counter)
@@ -237,8 +258,15 @@ struct wait_ctx {
max_vs_cnt(program_->chip_class >= GFX10 ? 62 : 0),
unordered_events(event_smem | (program_->chip_class < GFX10 ? event_flat : 0)) {}
- void join(const wait_ctx* other, bool logical)
+ bool join(const wait_ctx* other, bool logical)
{
+ bool changed = other->exp_cnt > exp_cnt ||
+ other->vm_cnt > vm_cnt ||
+ other->lgkm_cnt > lgkm_cnt ||
+ other->vs_cnt > vs_cnt ||
+ (other->pending_flat_lgkm && !pending_flat_lgkm) ||
+ (other->pending_flat_vm && !pending_flat_vm);
+
exp_cnt = std::max(exp_cnt, other->exp_cnt);
vm_cnt = std::max(vm_cnt, other->vm_cnt);
lgkm_cnt = std::max(lgkm_cnt, other->lgkm_cnt);
@@ -253,14 +281,18 @@ struct wait_ctx {
if (entry.second.logical != logical)
continue;
- if (it != gpr_map.end())
- it->second.join(entry.second);
- else
+ if (it != gpr_map.end()) {
+ changed |= it->second.join(entry.second);
+ } else {
gpr_map.insert(entry);
+ changed = true;
+ }
}
for (unsigned i = 0; i < barrier_count; i++)
- barrier_imm[i].combine(other->barrier_imm[i]);
+ changed |= barrier_imm[i].combine(other->barrier_imm[i]);
+
+ return changed;
}
};
@@ -319,12 +351,27 @@ wait_imm check_instr(Instruction* instr, wait_ctx& ctx)
return wait;
}
+wait_imm parse_wait_instr(wait_ctx& ctx, Instruction *instr)
+{
+ if (instr->opcode == aco_opcode::s_waitcnt_vscnt &&
+ instr->definitions[0].physReg() == sgpr_null) {
+ wait_imm imm;
+ imm.vs = std::min<uint8_t>(imm.vs, static_cast<SOPK_instruction*>(instr)->imm);
+ return imm;
+ } else if (instr->opcode == aco_opcode::s_waitcnt) {
+ return wait_imm(ctx.chip_class, static_cast<SOPK_instruction*>(instr)->imm);
+ }
+ return wait_imm();
+}
+
wait_imm kill(Instruction* instr, wait_ctx& ctx)
{
wait_imm imm;
if (ctx.exp_cnt || ctx.vm_cnt || ctx.lgkm_cnt)
imm.combine(check_instr(instr, ctx));
+ imm.combine(parse_wait_instr(ctx, instr));
+
if (ctx.chip_class >= GFX10) {
/* Seems to be required on GFX10 to achieve correct behaviour.
* It shouldn't cost anything anyways since we're about to do s_endpgm.
@@ -665,39 +712,23 @@ void handle_block(Program *program, Block& block, wait_ctx& ctx)
{
std::vector<aco_ptr<Instruction>> new_instructions;
+ wait_imm queued_imm;
for (aco_ptr<Instruction>& instr : block.instructions) {
- wait_imm imm = kill(instr.get(), ctx);
+ bool is_wait = !parse_wait_instr(ctx, instr.get()).empty();
- if (!imm.empty())
- emit_waitcnt(ctx, new_instructions, imm);
+ queued_imm.combine(kill(instr.get(), ctx));
gen(instr.get(), ctx);
- if (instr->format != Format::PSEUDO_BARRIER)
+ if (instr->format != Format::PSEUDO_BARRIER && !is_wait) {
+ if (!queued_imm.empty()) {
+ emit_waitcnt(ctx, new_instructions, queued_imm);
+ queued_imm = wait_imm();
+ }
new_instructions.emplace_back(std::move(instr));
- }
-
- /* check if this block is at the end of a loop */
- for (unsigned succ_idx : block.linear_succs) {
- /* eliminate any remaining counters */
- if (succ_idx <= block.index && (ctx.vm_cnt || ctx.exp_cnt || ctx.lgkm_cnt || ctx.vs_cnt)) {
- // TODO: we could do better if we only wait if the regs between the block and other predecessors differ
-
- aco_ptr<Instruction> branch = std::move(new_instructions.back());
- new_instructions.pop_back();
-
- wait_imm imm(ctx.vm_cnt ? 0 : wait_imm::unset_counter,
- ctx.exp_cnt ? 0 : wait_imm::unset_counter,
- ctx.lgkm_cnt ? 0 : wait_imm::unset_counter,
- ctx.vs_cnt ? 0 : wait_imm::unset_counter);
- emit_waitcnt(ctx, new_instructions, imm);
-
- new_instructions.push_back(std::move(branch));
-
- ctx = wait_ctx(program);
- break;
}
}
+
block.instructions.swap(new_instructions);
}
@@ -705,23 +736,55 @@ void handle_block(Program *program, Block& block, wait_ctx& ctx)
void insert_wait_states(Program* program)
{
- wait_ctx out_ctx[program->blocks.size()]; /* per BB ctx */
+ /* per BB ctx */
+ std::vector<bool> done(program->blocks.size());
+ wait_ctx in_ctx[program->blocks.size()];
+ wait_ctx out_ctx[program->blocks.size()];
for (unsigned i = 0; i < program->blocks.size(); i++)
- out_ctx[i] = wait_ctx(program);
-
- for (unsigned i = 0; i < program->blocks.size(); i++) {
- Block& current = program->blocks[i];
- wait_ctx& in = out_ctx[current.index];
+ in_ctx[i] = wait_ctx(program);
+ std::stack<unsigned> loop_header_indices;
+ unsigned loop_progress = 0;
+
+ for (unsigned i = 0; i < program->blocks.size();) {
+ Block& current = program->blocks[i++];
+ wait_ctx ctx = in_ctx[current.index];
+
+ if (current.kind & block_kind_loop_header) {
+ loop_header_indices.push(current.index);
+ } else if (current.kind & block_kind_loop_exit) {
+ bool repeat = false;
+ if (loop_progress == loop_header_indices.size()) {
+ i = loop_header_indices.top();
+ repeat = true;
+ }
+ loop_header_indices.pop();
+ loop_progress = std::min<unsigned>(loop_progress, loop_header_indices.size());
+ if (repeat)
+ continue;
+ }
+ bool changed = false;
for (unsigned b : current.linear_preds)
- in.join(&out_ctx[b], false);
+ changed |= ctx.join(&out_ctx[b], false);
for (unsigned b : current.logical_preds)
- in.join(&out_ctx[b], true);
+ changed |= ctx.join(&out_ctx[b], true);
+
+ in_ctx[current.index] = ctx;
+
+ if (done[current.index] && !changed)
+ continue;
- if (current.instructions.empty())
+ if (current.instructions.empty()) {
+ out_ctx[current.index] = ctx;
continue;
+ }
+
+ loop_progress = std::max<unsigned>(loop_progress, current.loop_nest_depth);
+ done[current.index] = true;
+
+ handle_block(program, current, ctx);
- handle_block(program, current, in);
+ out_ctx[current.index] = ctx;
}
}
More information about the mesa-commit
mailing list