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PPCRec: Update spill cost calculation

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This commit is contained in:
Exzap 2024-10-25 19:00:11 +02:00
parent 8e78371005
commit 547cf501d0
5 changed files with 103 additions and 90 deletions
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79
src/Cafe/HW/Espresso/Recompiler/IML/IMLRegisterAllocatorRanges.cpp
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@ -642,7 +642,7 @@ void PPCRecRA_updateOrAddSubrangeLocation(raLivenessRange* subrange, sint32 inde
subrange->list_locations.emplace_back(index, isRead, isWrite);
}
sint32 PPCRecRARange_getReadWriteCost(IMLSegment* imlSegment)
sint32 IMLRA_GetSegmentReadWriteCost(IMLSegment* imlSegment)
{
sint32 v = imlSegment->loopDepth + 1;
v *= 5;
@ -668,13 +668,13 @@ sint32 PPCRecRARange_estimateTotalCost(std::span<raLivenessRange*> ranges)
if (!subrange->interval2.ExtendsPreviousSegment())
{
//cost += PPCRecRARange_getReadWriteCost(subrange->imlSegment);
mostExpensiveRead = std::max(mostExpensiveRead, PPCRecRARange_getReadWriteCost(subrange->imlSegment));
mostExpensiveRead = std::max(mostExpensiveRead, IMLRA_GetSegmentReadWriteCost(subrange->imlSegment));
readCount++;
}
if (!subrange->interval2.ExtendsIntoNextSegment())
{
//cost += PPCRecRARange_getReadWriteCost(subrange->imlSegment);
mostExpensiveWrite = std::max(mostExpensiveWrite, PPCRecRARange_getReadWriteCost(subrange->imlSegment));
mostExpensiveWrite = std::max(mostExpensiveWrite, IMLRA_GetSegmentReadWriteCost(subrange->imlSegment));
writeCount++;
}
}
@ -683,21 +683,34 @@ sint32 PPCRecRARange_estimateTotalCost(std::span<raLivenessRange*> ranges)
return cost;
}
// calculate cost of range that it would have after calling PPCRecRA_explodeRange() on it
sint32 PPCRecRARange_estimateCostAfterRangeExplode(raLivenessRange* subrange)
// calculate additional cost of range that it would have after calling _ExplodeRange() on it
sint32 IMLRA_CalculateAdditionalCostOfRangeExplode(raLivenessRange* subrange)
{
auto ranges = subrange->GetAllSubrangesInCluster();
sint32 cost = -PPCRecRARange_estimateTotalCost(ranges);
sint32 cost = 0;//-PPCRecRARange_estimateTotalCost(ranges);
for (auto& subrange : ranges)
{
if (subrange->list_locations.empty())
continue;
cost += PPCRecRARange_getReadWriteCost(subrange->imlSegment) * 2; // we assume a read and a store
continue; // this range would be deleted and thus has no cost
sint32 segmentLoadStoreCost = IMLRA_GetSegmentReadWriteCost(subrange->imlSegment);
bool hasAdditionalLoad = subrange->interval2.ExtendsPreviousSegment();
bool hasAdditionalStore = subrange->interval2.ExtendsIntoNextSegment();
if(hasAdditionalLoad && !subrange->list_locations.front().isRead && subrange->list_locations.front().isWrite) // if written before read, then a load isn't necessary
{
cost += segmentLoadStoreCost;
}
if(hasAdditionalStore)
{
bool hasWrite = std::find_if(subrange->list_locations.begin(), subrange->list_locations.end(), [](const raLivenessLocation_t& loc) { return loc.isWrite; }) != subrange->list_locations.end();
if(!hasWrite) // ranges which don't modify their value do not need to be stored
cost += segmentLoadStoreCost;
}
}
// todo - properly calculating all the data-flow dependency based costs is more complex so this currently is an approximation
return cost;
}
sint32 PPCRecRARange_estimateAdditionalCostAfterSplit(raLivenessRange* subrange, raInstructionEdge splitPosition)
sint32 IMLRA_CalculateAdditionalCostAfterSplit(raLivenessRange* subrange, raInstructionEdge splitPosition)
{
// validation
#ifdef CEMU_DEBUG_ASSERT
@ -719,9 +732,53 @@ sint32 PPCRecRARange_estimateAdditionalCostAfterSplit(raLivenessRange* subrange,
if (splitInstructionIndex > subrange->list_locations.back().index)
return 0;
// todo - determine exact cost of split subranges
// this can be optimized, but we should change list_locations to track instruction edges instead of instruction indices
std::vector<raLivenessLocation_t> headLocations;
std::vector<raLivenessLocation_t> tailLocations;
for (auto& location : subrange->list_locations)
{
if(location.GetReadPos() < splitPosition || location.GetWritePos() < splitPosition)
headLocations.push_back(location);
if(location.GetReadPos() >= splitPosition || location.GetWritePos() >= splitPosition)
tailLocations.push_back(location);
}
// fixup locations
if(!headLocations.empty() && headLocations.back().GetWritePos() >= splitPosition)
{
headLocations.back().isWrite = false;
if(!headLocations.back().isRead && !headLocations.back().isWrite)
headLocations.pop_back();
}
if(!tailLocations.empty() && tailLocations.front().GetReadPos() < splitPosition)
{
tailLocations.front().isRead = false;
if(!tailLocations.front().isRead && !tailLocations.front().isWrite)
tailLocations.erase(tailLocations.begin());
}
cost += PPCRecRARange_getReadWriteCost(subrange->imlSegment) * 2; // currently we assume that the additional region will require a read and a store
// based on
sint32 segmentLoadStoreCost = IMLRA_GetSegmentReadWriteCost(subrange->imlSegment);
auto CalculateCostFromLocationRange = [segmentLoadStoreCost](const std::vector<raLivenessLocation_t>& locations, bool trackLoadCost = true, bool trackStoreCost = true) -> sint32
{
if(locations.empty())
return 0;
sint32 cost = 0;
if(locations.front().isRead && trackLoadCost)
cost += segmentLoadStoreCost; // not overwritten, so there is a load cost
bool hasWrite = std::find_if(locations.begin(), locations.end(), [](const raLivenessLocation_t& loc) { return loc.isWrite; }) != locations.end();
if(hasWrite && trackStoreCost)
cost += segmentLoadStoreCost; // modified, so there is a store cost
return cost;
};
sint32 baseCost = CalculateCostFromLocationRange(subrange->list_locations);
bool tailOverwritesValue = !tailLocations.empty() && !tailLocations.front().isRead && tailLocations.front().isWrite;
sint32 newCost = CalculateCostFromLocationRange(headLocations) + CalculateCostFromLocationRange(tailLocations, !tailOverwritesValue, true);
cemu_assert_debug(newCost >= baseCost);
cost = newCost - baseCost;
return cost;
}