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VarAction2: Detect equality comparisons

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Remove redundant equality with 0 comparison before ternary
This commit is contained in:
Jonathan G Rennison
2022-05-25 02:23:25 +01:00
parent 7283825638
commit 012d73ef34
3 changed files with 31 additions and 1 deletions
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20
src/newgrf.cpp
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@@ -5666,6 +5666,15 @@ static void NewSpriteGroup(ByteReader *buf)
if (adjust.and_mask <= 1) inference = VA2AIF_SIGNED_NON_NEGATIVE | VA2AIF_ONE_OR_ZERO;
break;
case DSGA_OP_AND:
if ((prev_inference & VA2AIF_SIGNED_NON_NEGATIVE) && adjust.variable == 0x1A && adjust.shift_num == 0 && adjust.and_mask == 1) {
DeterministicSpriteGroupAdjust &prev = group->adjusts[group->adjusts.size() - 2];
if (prev.operation == DSGA_OP_SCMP || prev.operation == DSGA_OP_UCMP) {
prev.operation = DSGA_OP_EQ;
group->adjusts.pop_back();
inference = VA2AIF_SIGNED_NON_NEGATIVE | VA2AIF_ONE_OR_ZERO;
break;
}
}
if (adjust.and_mask <= 1) {
inference = VA2AIF_SIGNED_NON_NEGATIVE | VA2AIF_ONE_OR_ZERO;
} else if ((adjust.and_mask & (1 << ((varsize * 8) - 1))) == 0) {
@@ -5700,6 +5709,17 @@ static void NewSpriteGroup(ByteReader *buf)
}
break;
}
if (group->adjusts.size() > 1) {
/* Remove redundant comparison with 0 if applicable */
const DeterministicSpriteGroupAdjust &prev = group->adjusts[group->adjusts.size() - 2];
if (prev.type == DSGA_TYPE_NONE && prev.operation == DSGA_OP_EQ && prev.variable == 0x1A && prev.shift_num == 0 && prev.and_mask == 0) {
DeterministicSpriteGroupAdjust current = group->adjusts.back();
group->adjusts.pop_back();
group->adjusts.pop_back();
std::swap(current.and_mask, current.add_val);
group->adjusts.push_back(current);
}
}
inference = VA2AIF_PREV_TERNARY;
}
break;