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VarAction2: Remove constant parameter redirection via variable 7B

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Jonathan G Rennison
2022-05-25 04:12:44 +01:00
parent 08b83352bf
commit db5be4f92e
1 changed files with 14 additions and 0 deletions
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14
src/newgrf.cpp
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@@ -5763,6 +5763,20 @@ static void NewSpriteGroup(ByteReader *buf)
case DSGA_OP_RST: case DSGA_OP_RST:
add_inferences_from_mask(adjust.and_mask); add_inferences_from_mask(adjust.and_mask);
inference |= VA2AIF_PREV_MASK_ADJUST; inference |= VA2AIF_PREV_MASK_ADJUST;
if ((prev_inference & VA2AIF_PREV_MASK_ADJUST) && adjust.variable == 0x7B) {
const DeterministicSpriteGroupAdjust &prev = group->adjusts[group->adjusts.size() - 2];
if (prev.variable == 0x1A) {
/* Extract constant to remove indirect access via variable 7B */
DeterministicSpriteGroupAdjust current = group->adjusts.back();
current.variable = current.parameter;
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;
}
}
break; break;
case DSGA_OP_SHR: case DSGA_OP_SHR:
if ((prev_inference & VA2AIF_PREV_MASK_ADJUST) && adjust.variable == 0x1A && adjust.shift_num == 0) { if ((prev_inference & VA2AIF_PREV_MASK_ADJUST) && adjust.variable == 0x1A && adjust.shift_num == 0) {