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VarAction2: Remove redundant variable loads

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This commit is contained in:
Jonathan G Rennison
2022-06-03 12:51:58 +01:00
parent 4660169b1f
commit c2fde53495
1 changed files with 27 additions and 2 deletions
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29
src/newgrf.cpp
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@@ -5601,6 +5601,7 @@ enum VarAction2AdjustInferenceFlags {
VA2AIF_PREV_MASK_ADJUST = 0x08,
VA2AIF_PREV_STORE_TMP = 0x10,
VA2AIF_HAVE_CONSTANT = 0x20,
VA2AIF_SINGLE_LOAD = 0x40,
VA2AIF_PREV_MASK = VA2AIF_PREV_TERNARY | VA2AIF_PREV_MASK_ADJUST | VA2AIF_PREV_STORE_TMP,
};
@@ -5710,6 +5711,31 @@ static void OptimiseVarAction2Adjust(VarAction2OptimiseState &state, const GrfSp
}
}
if ((prev_inference & VA2AIF_SINGLE_LOAD) && adjust.operation == DSGA_OP_RST && adjust.variable != 0x1A && adjust.variable != 0x7D && adjust.variable != 0x7E) {
/* See if this is a repeated load of a variable (not constant, temp store load or procedure call) */
for (int i = (int)group->adjusts.size() - 2; i >= 0; i--) {
const DeterministicSpriteGroupAdjust &prev = group->adjusts[i];
if (MemCmpT<DeterministicSpriteGroupAdjust>(&prev, &adjust) == 0) {
group->adjusts.pop_back();
state.inference = prev_inference;
return;
} else if (prev.operation == DSGA_OP_STO) {
if (prev.type == DSGA_TYPE_NONE && prev.variable == 0x1A && prev.shift_num == 0 && prev.and_mask < 0x100) {
/* Temp store */
continue;
} else {
/* Special register store or unpredictable store, don't try to optimise following load */
break;
}
} else if (prev.operation == DSGA_OP_STOP) {
/* Permanent storage store */
continue;
} else {
break;
}
}
}
if ((prev_inference & VA2AIF_PREV_TERNARY) && adjust.variable == 0x1A && IsEvalAdjustUsableForConstantPropagation(adjust.operation)) {
/* Propagate constant operation back into previous ternary */
DeterministicSpriteGroupAdjust &prev = group->adjusts[group->adjusts.size() - 2];
@@ -5982,7 +6008,7 @@ static void OptimiseVarAction2Adjust(VarAction2OptimiseState &state, const GrfSp
}
}
add_inferences_from_mask(adjust.and_mask);
state.inference |= VA2AIF_PREV_MASK_ADJUST;
state.inference |= VA2AIF_PREV_MASK_ADJUST | VA2AIF_SINGLE_LOAD;
if ((prev_inference & VA2AIF_PREV_MASK_ADJUST) && adjust.variable == 0x7B) {
const DeterministicSpriteGroupAdjust &prev = group->adjusts[group->adjusts.size() - 2];
if (prev.variable == 0x1A) {
@@ -5992,7 +6018,6 @@ static void OptimiseVarAction2Adjust(VarAction2OptimiseState &state, const GrfSp
current.parameter = (UINT_MAX >> prev.shift_num) & prev.and_mask;
group->adjusts.pop_back();
group->adjusts.pop_back();
if (group->adjusts.empty()) current.operation = DSGA_OP_ADD;
group->adjusts.push_back(current);
break;
}