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aco/spill: keep loop-carried variables spilled at merge blocks

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If loop-carried variables are partially spilled at some predecessor,
keep them spilled without extra instruction.

Also slightly refactors the code for better readability.

Totals from 13 (0.02% of 79395) affected shaders: (GFX11)

Instrs: 259129 -> 258194 (-0.36%)
CodeSize: 1337604 -> 1331768 (-0.44%)
SpillSGPRs: 561 -> 560 (-0.18%)
SpillVGPRs: 146 -> 140 (-4.11%)
Latency: 2410886 -> 2408560 (-0.10%)
InvThroughput: 759229 -> 758416 (-0.11%)
VClause: 4178 -> 4154 (-0.57%)
SClause: 7217 -> 7219 (+0.03%)
Copies: 32411 -> 32174 (-0.73%)
Branches: 9426 -> 9296 (-1.38%)
VALU: 144602 -> 144098 (-0.35%)
SALU: 30582 -> 30405 (-0.58%)
VMEM: 6961 -> 6908 (-0.76%)
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27774>
This commit is contained in:
Daniel Schürmann
2024-02-22 17:21:05 +01:00
committed by Marge Bot
parent 971407bd2f
commit 31f6aebb2c
1 changed files with 14 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/amd/compiler/aco_spill.cpp
+14 -10
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@@ -661,10 +661,13 @@ init_live_in_vars(spill_ctx& ctx, Block* block, unsigned block_idx)
* it. Otherwise, if any predecessor reloads it, ensure it's reloaded on all other
* predecessors. The idea is that it's better in practice to rematerialize redundantly than to
* create lots of phis. */
/* TODO: test this idea with more than Dawn of War III shaders (the current pipeline-db
* doesn't seem to exercise this path much) */
bool remat = ctx.remat.count(pair.first);
bool spill = !remat;
const bool remat = ctx.remat.count(pair.first);
/* If the variable is spilled at the current loop-header, spilling is essentially for free
* while reloading is not. Thus, keep them spilled if they are at least partially spilled.
*/
const bool avoid_respill = block->loop_nest_depth && ctx.loop.back().spills.count(pair.first);
bool spill = true;
bool partial_spill = false;
uint32_t spill_id = 0;
for (unsigned pred_idx : preds) {
/* variable is not even live at the predecessor: probably from a phi */
@@ -673,22 +676,22 @@ init_live_in_vars(spill_ctx& ctx, Block* block, unsigned block_idx)
break;
}
if (!ctx.spills_exit[pred_idx].count(pair.first)) {
partial_spills.emplace(pair.first, false);
if (!remat)
spill = false;
spill = false;
} else {
partial_spills[pair.first] = true;
partial_spill = true;
/* it might be that on one incoming path, the variable has a different spill_id, but
* add_couple_code() will take care of that. */
spill_id = ctx.spills_exit[pred_idx][pair.first];
if (remat)
spill = true;
}
}
spill |= (remat && partial_spill);
spill |= (avoid_respill && partial_spill);
if (spill) {
ctx.spills_entry[block_idx][pair.first] = spill_id;
partial_spills.erase(pair.first);
spilled_registers += pair.first;
} else {
partial_spills[pair.first] = partial_spill;
}
}
@@ -716,6 +719,7 @@ init_live_in_vars(spill_ctx& ctx, Block* block, unsigned block_idx)
/* The phi is spilled at all predecessors. Keep it spilled. */
ctx.add_to_spills(phi->definitions[0].getTemp(), ctx.spills_entry[block_idx]);
spilled_registers += phi->definitions[0].getTemp();
partial_spills.erase(phi->definitions[0].getTemp());
} else {
/* Phis might increase the register pressure. */
partial_spills[phi->definitions[0].getTemp()] = is_partial_spill;