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VarAction2: Fix jump insertion moving past special stores which could affect the jump variable

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See: #672
This commit is contained in:
Jonathan G Rennison
2024-03-17 00:50:18 +00:00
parent 57db9a41f1
commit 109d31a350
1 changed files with 9 additions and 2 deletions
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11
src/newgrf_optimiser.cpp
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@@ -172,6 +172,12 @@ static bool IsVariableVeryCheap(uint16_t variable, GrfSpecFeature scope_feature)
return false;
}
static bool IsVariableIndependentOfSpecialTempStorage(uint16_t variable)
{
/* This is a very conservative whitelist */
return variable < 0x40 || variable == 0x7C || variable == 0x7D;
}
static bool IsFeatureUsableForDSE(GrfSpecFeature feature)
{
return true;
@@ -2247,7 +2253,7 @@ static uint OptimiseVarAction2InsertSpecialStoreOps(DeterministicSpriteGroup *gr
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 (!IsVariableIndependentOfSpecialTempStorage(next.variable)) break; // crude whitelist of variables which will never read special registers
}
if (skip) continue;
DeterministicSpriteGroupAdjust store = {};
@@ -2393,7 +2399,7 @@ static void OptimiseVarAction2DeterministicSpriteGroupInsertJumps(DeterministicS
/* Don't try to skip over: unpredictable or unusable special stores, unskippable procedure calls, permanent stores, or another jump */
if (prev.operation == DSGA_OP_STO && (prev.type != DSGA_TYPE_NONE || prev.variable != 0x1A || prev.shift_num != 0 || prev.and_mask >= 0x100)) break;
if (prev.operation == DSGA_OP_STO_NC && prev.divmod_val >= 0x100) {
if (prev.divmod_val < 0x110 && prev.type == DSGA_TYPE_NONE && prev.variable == 0x1A && prev.shift_num == 0) {
if (prev.divmod_val < 0x110 && prev.type == DSGA_TYPE_NONE && prev.variable == 0x1A && prev.shift_num == 0 && IsVariableIndependentOfSpecialTempStorage(adjust.variable)) {
/* Storing a constant in a special register */
if (!HasBit(special_stores_mask, prev.divmod_val - 0x100)) {
special_stores[prev.divmod_val - 0x100] = prev.and_mask;
@@ -2408,6 +2414,7 @@ static void OptimiseVarAction2DeterministicSpriteGroupInsertJumps(DeterministicS
if (prev.variable == 0x7E) {
const VarAction2ProcedureCallVarReadAnnotation &anno = _varaction2_proc_call_var_read_annotations[prev.jump];
if (anno.unskippable) break;
if (anno.anno->special_register_mask != 0 && !IsVariableIndependentOfSpecialTempStorage(adjust.variable)) break;
if ((anno.relevant_stores & ~ok_stores).any()) break;
ok_stores |= anno.last_reads;