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VarAction2: Detect and replace signed relational comparisons

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This commit is contained in:
Jonathan G Rennison
2022-05-25 23:58:44 +01:00
parent e732042785
commit 90a2aa57fc
3 changed files with 70 additions and 9 deletions
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55
src/newgrf.cpp
View File

@@ -5722,8 +5722,44 @@ static void NewSpriteGroup(ByteReader *buf)
} else {
switch (adjust.operation) {
case DSGA_OP_SMIN:
if (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_SGE;
group->adjusts.pop_back();
inference = VA2AIF_SIGNED_NON_NEGATIVE | VA2AIF_ONE_OR_ZERO;
break;
}
if (group->adjusts.size() >= 3 && prev.operation == DSGA_OP_XOR && prev.type == DSGA_TYPE_NONE && prev.variable == 0x1A &&
prev.shift_num == 0 && prev.and_mask == 2) {
DeterministicSpriteGroupAdjust &prev2 = group->adjusts[group->adjusts.size() - 3];
if (prev2.operation == DSGA_OP_SCMP) {
prev2.operation = DSGA_OP_SLE;
group->adjusts.pop_back();
group->adjusts.pop_back();
inference = VA2AIF_SIGNED_NON_NEGATIVE | VA2AIF_ONE_OR_ZERO;
break;
}
}
}
if (adjust.and_mask <= 1 && (prev_inference & VA2AIF_SIGNED_NON_NEGATIVE)) inference = VA2AIF_SIGNED_NON_NEGATIVE | VA2AIF_ONE_OR_ZERO;
break;
case DSGA_OP_SMAX:
if (adjust.variable == 0x1A && adjust.shift_num == 0 && adjust.and_mask == 0) {
DeterministicSpriteGroupAdjust &prev = group->adjusts[group->adjusts.size() - 2];
if (group->adjusts.size() >= 3 && prev.operation == DSGA_OP_SUB && prev.type == DSGA_TYPE_NONE && prev.variable == 0x1A &&
prev.shift_num == 0 && prev.and_mask == 1) {
DeterministicSpriteGroupAdjust &prev2 = group->adjusts[group->adjusts.size() - 3];
if (prev2.operation == DSGA_OP_SCMP) {
prev2.operation = DSGA_OP_SGT;
group->adjusts.pop_back();
group->adjusts.pop_back();
inference = VA2AIF_SIGNED_NON_NEGATIVE | VA2AIF_ONE_OR_ZERO;
break;
}
}
}
break;
case DSGA_OP_UMIN:
if (adjust.and_mask <= 1) inference = VA2AIF_SIGNED_NON_NEGATIVE | VA2AIF_ONE_OR_ZERO;
break;
@@ -5737,7 +5773,7 @@ static void NewSpriteGroup(ByteReader *buf)
group->adjusts.pop_back();
break;
}
if ((prev_inference & VA2AIF_SIGNED_NON_NEGATIVE) && adjust.variable == 0x1A && adjust.shift_num == 0 && adjust.and_mask == 1) {
if (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;
@@ -5753,7 +5789,18 @@ static void NewSpriteGroup(ByteReader *buf)
}
break;
case DSGA_OP_OR:
if (adjust.and_mask <= 1) inference = prev_inference & (VA2AIF_SIGNED_NON_NEGATIVE | VA2AIF_ONE_OR_ZERO);
break;
case DSGA_OP_XOR:
if (adjust.variable == 0x1A && adjust.shift_num == 0 && adjust.and_mask == 1) {
DeterministicSpriteGroupAdjust &prev = group->adjusts[group->adjusts.size() - 2];
if (prev.operation == DSGA_OP_SLT || prev.operation == DSGA_OP_SGE || prev.operation == DSGA_OP_SLE || prev.operation == DSGA_OP_SGT) {
prev.operation = (DeterministicSpriteGroupAdjustOperation)(prev.operation ^ 1);
group->adjusts.pop_back();
inference = VA2AIF_SIGNED_NON_NEGATIVE | VA2AIF_ONE_OR_ZERO;
break;
}
}
if (adjust.and_mask <= 1) inference = prev_inference & (VA2AIF_SIGNED_NON_NEGATIVE | VA2AIF_ONE_OR_ZERO);
break;
case DSGA_OP_MUL: {
@@ -5804,12 +5851,6 @@ static void NewSpriteGroup(ByteReader *buf)
break;
}
case DSGA_OP_SCMP:
inference = VA2AIF_SIGNED_NON_NEGATIVE;
/* Convert to UCMP if possible to make other analysis operations easier */
if ((prev_inference & VA2AIF_SIGNED_NON_NEGATIVE) && adjust.variable == 0x1A && adjust.shift_num == 0 && (adjust.and_mask & get_sign_bit()) == 0) {
adjust.operation = DSGA_OP_UCMP;
}
break;
case DSGA_OP_UCMP:
inference = VA2AIF_SIGNED_NON_NEGATIVE;
break;

17
src/newgrf_spritegroup.cpp
View File

@@ -184,6 +184,10 @@ static U EvalAdjustT(const DeterministicSpriteGroupAdjust &adjust, ScopeResolver
case DSGA_OP_SAR: return (int32)(S)last_value >> ((U)value & 0x1F);
case DSGA_OP_TERNARY: return (last_value != 0) ? value : adjust.add_val;
case DSGA_OP_EQ: return (last_value == value) ? 1 : 0;
case DSGA_OP_SLT: return ((S)last_value < (S)value) ? 1 : 0;
case DSGA_OP_SGE: return ((S)last_value >= (S)value) ? 1 : 0;
case DSGA_OP_SLE: return ((S)last_value <= (S)value) ? 1 : 0;
case DSGA_OP_SGT: return ((S)last_value > (S)value) ? 1 : 0;
default: return value;
}
}
@@ -544,6 +548,16 @@ static const char *_dsg_op_names[] {
};
static_assert(lengthof(_dsg_op_names) == DSGA_OP_END);
static const char *_dsg_op_special_names[] {
"TERNARY",
"EQ",
"SLT",
"SGE",
"SLE",
"SGT",
};
static_assert(lengthof(_dsg_op_special_names) == DSGA_OP_SPECIAL_END - DSGA_OP_TERNARY);
static const char *_sg_scope_names[] {
"SELF",
"PARENT",
@@ -560,8 +574,7 @@ static const char *_sg_size_names[] {
static const char *GetAdjustOperationName(DeterministicSpriteGroupAdjustOperation operation)
{
if (operation < DSGA_OP_END) return _dsg_op_names[operation];
if (operation == DSGA_OP_TERNARY) return "TERNARY";
if (operation == DSGA_OP_EQ) return "EQ";
if (operation >= DSGA_OP_TERNARY && operation < DSGA_OP_SPECIAL_END) return _dsg_op_special_names[operation - DSGA_OP_TERNARY];
return "???";
}

7
src/newgrf_spritegroup.h
View File

@@ -164,10 +164,17 @@ enum DeterministicSpriteGroupAdjustOperation {
DSGA_OP_TERNARY = 0x80, ///< a == 0 ? b : c,
DSGA_OP_EQ, ///< a == b ? 1 : 0,
DSGA_OP_SLT, ///< (signed) a < b ? 1 : 0,
DSGA_OP_SGE, ///< (signed) a >= b ? 1 : 0,
DSGA_OP_SLE, ///< (signed) a <= b ? 1 : 0,
DSGA_OP_SGT, ///< (signed) a > b ? 1 : 0,
DSGA_OP_SPECIAL_END,
};
static_assert((DSGA_OP_SLT ^ 1) == DSGA_OP_SGE);
static_assert((DSGA_OP_SLE ^ 1) == DSGA_OP_SGT);
inline bool IsEvalAdjustWithZeroRemovable(DeterministicSpriteGroupAdjustOperation op)
{
switch (op) {