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VarAction2: Allow DSE to remove procedure calls

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This commit is contained in:
Jonathan G Rennison
2022-08-10 00:04:32 +01:00
parent 30ecdfe140
commit 00e32162a1
1 changed files with 78 additions and 13 deletions
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91
src/newgrf.cpp
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@@ -7754,6 +7754,38 @@ static VarAction2ProcedureAnnotation *OptimiseVarAction2GetFilledProcedureAnnota
return anno;
}
static uint OptimiseVarAction2InsertSpecialStoreOps(DeterministicSpriteGroup *group, uint offset, uint32 values[16], uint16 mask)
{
uint added = 0;
for (uint8 bit : SetBitIterator(mask)) {
bool skip = false;
for (size_t i = offset; i < group->adjusts.size(); i++) {
const DeterministicSpriteGroupAdjust &next = group->adjusts[i];
if (next.operation == DSGA_OP_STO_NC && next.divmod_val == 0x100u + bit) {
skip = true;
break;
}
if (next.operation == DSGA_OP_STO && next.variable == 0x1A && next.type == DSGA_TYPE_NONE && next.shift_num == 0 && next.and_mask == 0x100u + bit) {
skip = true;
break;
}
if (next.variable == 0x7D && next.parameter == 0x100u + bit) break;
if (next.variable >= 0x40 && next.variable != 0x7D && next.variable != 0x7C) break; // crude whitelist of variables which will never read special registers
}
if (skip) continue;
DeterministicSpriteGroupAdjust store = {};
store.operation = DSGA_OP_STO_NC;
store.variable = 0x1A;
store.type = DSGA_TYPE_NONE;
store.shift_num = 0;
store.and_mask = values[bit];
store.divmod_val = 0x100 + bit;
group->adjusts.insert(group->adjusts.begin() + offset + added, store);
added++;
}
return added;
}
struct VarAction2ProcedureCallVarReadAnnotation {
const SpriteGroup *subroutine;
VarAction2ProcedureAnnotation *anno;
@@ -7918,18 +7950,7 @@ static void OptimiseVarAction2DeterministicSpriteGroupInsertJumps(DeterministicS
adj.adjust_flags |= DSGAF_END_BLOCK;
adj.jump = inc;
if (special_stores_mask) {
uint added = 0;
for (uint8 bit : SetBitIterator(special_stores_mask)) {
DeterministicSpriteGroupAdjust store = {};
store.operation = DSGA_OP_STO_NC;
store.variable = 0x1A;
store.type = DSGA_TYPE_NONE;
store.shift_num = 0;
store.and_mask = special_stores[bit];
store.divmod_val = 0x100 + bit;
group->adjusts.insert(group->adjusts.begin() + index + 1, store);
added++;
}
uint added = OptimiseVarAction2InsertSpecialStoreOps(group, index + 1, special_stores, special_stores_mask);
/* Fixup offsets */
if (i > (int)index) i += added;
@@ -8169,6 +8190,7 @@ static std::bitset<256> HandleVarAction2DeadStoreElimination(DeterministicSprite
std::bitset<256> bits;
std::vector<uint> substitution_candidates;
if (var_tracking != nullptr) bits = var_tracking->out;
bool need_var1C = false;
auto abandon_substitution_candidates = [&]() {
for (uint value : substitution_candidates) {
@@ -8217,6 +8239,7 @@ static std::bitset<256> HandleVarAction2DeadStoreElimination(DeterministicSprite
bits.reset();
}
substitution_candidates.clear();
need_var1C = false;
};
const DeterministicSpriteGroupAdjust &adjust = group->adjusts[i];
if (adjust.operation == DSGA_OP_STO) {
@@ -8370,8 +8393,35 @@ static std::bitset<256> HandleVarAction2DeadStoreElimination(DeterministicSprite
bits.set(adjust.parameter, true);
}
}
if (adjust.variable == 0x1C) {
need_var1C = true;
}
if (adjust.variable == 0x7E) {
/* procedure call */
VarAction2ProcedureAnnotation *anno = OptimiseVarAction2GetFilledProcedureAnnotation(adjust.subroutine);
bool may_remove = !need_var1C;
if (may_remove && anno->unskippable) may_remove = false;
if (may_remove && (anno->stores & bits).any()) may_remove = false;
if (may_remove) {
if ((i + 1 < (int)group->adjusts.size() && group->adjusts[i + 1].operation == DSGA_OP_RST && group->adjusts[i + 1].variable != 0x7B) ||
(i + 1 == (int)group->adjusts.size() && group->ranges.empty() && !group->calculated_result)) {
/* Procedure is skippable, makes no stores we need, and the return value is also not needed */
erase_adjust(i);
if (anno->special_register_mask) {
OptimiseVarAction2InsertSpecialStoreOps(group, i, anno->special_register_values, anno->special_register_mask);
restart();
} else {
i--;
}
continue;
}
}
need_var1C = false;
auto handle_group = y_combinator([&](auto handle_group, const SpriteGroup *sg) -> void {
if (sg == nullptr) return;
if (sg->type == SGT_RANDOMIZED) {
@@ -8383,10 +8433,25 @@ static std::bitset<256> HandleVarAction2DeadStoreElimination(DeterministicSprite
const DeterministicSpriteGroup *sub = static_cast<const DeterministicSpriteGroup *>(sg);
VarAction2GroupVariableTracking *var_tracking = _cur.GetVarAction2GroupVariableTracking(sub, false);
if (var_tracking != nullptr) bits |= var_tracking->in;
if (sub->dsg_flags & DSGF_REQUIRES_VAR1C) need_var1C = true;
}
});
handle_group(adjust.subroutine);
abandon_substitution_candidates();
if (anno->unskippable || anno->special_register_mask) {
abandon_substitution_candidates();
} else {
/* Flush any substitution candidates which reference stores made in the procedure */
for (size_t j = 0; j < substitution_candidates.size();) {
uint8 idx = substitution_candidates[j] & 0xFF;
if (anno->stores[idx]) {
bits.set(idx, true);
substitution_candidates[j] = substitution_candidates.back();
substitution_candidates.pop_back();
} else {
j++;
}
}
}
}
i--;
}