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Partialexecuter perf #351

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Merged
alexp-sssup merged 3 commits into from
Mar 16, 2026
Merged

Partialexecuter perf #351

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9118eb9
PartialExecuter: Prefer binary search to linear lookup
alexp-sssup Mar 15, 2026
7388bb5
PartialExecuter: Avoid redundant application of GV alignment requirem…
alexp-sssup Mar 15, 2026
21d4b07
PartialExecuter: Micro optimizations
alexp-sssup Mar 15, 2026
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18 changes: 13 additions & 5 deletions llvm/lib/CheerpWriter/PartialExecuter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -121,7 +121,7 @@ class PartialInterpreter : public llvm::Interpreter {
// TODO(carlo): this can easily be memoized since there is no state
if (!isa<Constant>(V))
return false;
if (const GlobalVariable* GVar = dyn_cast_or_null<GlobalVariable>(V))
if (const GlobalVariable* GVar = dyn_cast<GlobalVariable>(V))
{
const bool res = isGlobalVariablePartiallyExecutable(*GVar);
if (res)
Expand All @@ -135,7 +135,7 @@ class PartialInterpreter : public llvm::Interpreter {
}
return res;
}
if (const ConstantExpr* CE = dyn_cast_or_null<ConstantExpr>(V))
else if (const ConstantExpr* CE = dyn_cast<ConstantExpr>(V))
{
for (auto& op : CE->operands())
{
Expand Down Expand Up @@ -433,6 +433,7 @@ class PartialInterpreter : public llvm::Interpreter {
{
for (auto& pair : newAlignmentData)
moduleAlignmentData.insert(pair);
newAlignmentData.clear();
}
//We are going to interpret a CallInst, we need to add a stack frame and forward the known arguments
void forwardArgumentsToNextFrame(CallInst& CI)
Expand Down Expand Up @@ -509,11 +510,15 @@ class PartialInterpreter : public llvm::Interpreter {
GenericValue SRC = getOperandValue(LI.getPointerOperand());
GenericValue *Ptr = (GenericValue*)GVTORP(SRC);

const long long loadPtr = (long long)Ptr;
const long long loadSize = getDataLayout().getTypeAllocSize(LI.getType());

for (const auto& interval : immutableLoadIntervals)
{
if ((long long)Ptr >= interval.first && ((long long)Ptr+loadSize) <= interval.second)
// immutableLoadIntervals sorted by .first; find first interval with .first > loadPtr
auto it = std::upper_bound(immutableLoadIntervals.begin(), immutableLoadIntervals.end(), loadPtr,
[](long long p, const std::pair<long long, long long>& interval) { return p < interval.first; });
if (it != immutableLoadIntervals.begin()) {
const auto& interval = *--it;
if (loadPtr + loadSize <= interval.second)
return false;
}

Expand Down Expand Up @@ -584,6 +589,9 @@ class PartialInterpreter : public llvm::Interpreter {
immutableLoadIntervals.push_back({(long long)Ptr, ((long long)Ptr)+getDataLayout().getTypeAllocSize(GV->getInitializer()->getType())});
}

// Sort by start for O(log n) lookup in hasToBeSkipped Load case
std::sort(immutableLoadIntervals.begin(), immutableLoadIntervals.end());

// detach the 'virtual' call frame
popCallFrame();
}
Expand Down
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