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ConstProp: drop const pool heuristic

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slightly worse for compile time, slightly better output, honestly I'll take the
win because this is easier to reason about.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
This commit is contained in:
Alyssa Rosenzweig 2024-06-03 14:28:09 -04:00
parent be1a5cea8e
commit aa7dcffcea
1 changed files with 4 additions and 27 deletions
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31
FEXCore/Source/Interface/IR/Passes/ConstProp.cpp
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@ -86,11 +86,7 @@ private:
void ConstantPropagation(IREmitter* IREmit, const IRListView& CurrentIR, Ref CodeNode, IROp_Header* IROp);
void ConstantInlining(IREmitter* IREmit, const IRListView& CurrentIR);
struct ConstPoolData {
Ref Node;
IR::NodeID NodeID;
};
fextl::unordered_map<uint64_t, ConstPoolData> ConstPool;
fextl::unordered_map<uint64_t, Ref> ConstPool;
// Pool inline constant generation. These are typically very small and pool efficiently.
fextl::robin_map<uint64_t, Ref> InlineConstantGen;
@ -104,11 +100,6 @@ private:
}
bool SupportsTSOImm9 {};
const FEXCore::CPUIDEmu* CPUID;
// This is a heuristic to limit constant pool live ranges to reduce RA interference pressure.
// If the range is unbounded then RA interference pressure seems to increase to the point
// that long blocks of constant usage can slow to a crawl.
// See https://github.com/FEX-Emu/FEX/issues/2688 for more information.
constexpr static uint32_t CONSTANT_POOL_RANGE_LIMIT = 500;
void InlineMemImmediate(IREmitter* IREmit, const IRListView& IR, Ref CodeNode, IROp_Header* IROp, OrderedNodeWrapper Offset,
MemOffsetType OffsetType, const size_t Offset_Index, uint8_t& OffsetScale, bool TSO) {
@ -142,27 +133,13 @@ void ConstProp::HandleConstantPools(IREmitter* IREmit, const IRListView& Current
for (auto [CodeNode, IROp] : CurrentIR.GetCode(BlockNode)) {
if (IROp->Op == OP_CONSTANT) {
auto Op = IROp->C<IR::IROp_Constant>();
const auto NewNodeID = CurrentIR.GetID(CodeNode);
auto it = ConstPool.find(Op->Constant);
if (it != ConstPool.end()) {
const auto OldNodeID = it->second.NodeID;
if ((NewNodeID.Value - OldNodeID.Value) > CONSTANT_POOL_RANGE_LIMIT) {
// Don't reuse if the live range is beyond the heurstic range.
// Update the tracked value to this new constant.
it->second.Node = CodeNode;
it->second.NodeID = NewNodeID;
continue;
}
auto CodeIter = CurrentIR.at(CodeNode);
IREmit->ReplaceUsesWithAfter(CodeNode, it->second.Node, CodeIter);
IREmit->ReplaceUsesWithAfter(CodeNode, it->second, CodeIter);
} else {
ConstPool[Op->Constant] = ConstPoolData {
.Node = CodeNode,
.NodeID = NewNodeID,
};
ConstPool[Op->Constant] = CodeNode;
}
}
}