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Add naive cache for provers #1972

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Merged
zasdfgbnm merged 3 commits into from
Mar 21, 2024
Merged

Add naive cache for provers #1972

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2e85fc5
Add naive cache for provers
zasdfgbnm Mar 20, 2024
1d3159c
Merge branch 'main' into naive-cache-provers
zasdfgbnm Mar 21, 2024
922475a
rename macro
zasdfgbnm Mar 21, 2024
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71 changes: 55 additions & 16 deletions csrc/expr_simplifier.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,18 @@
#include <unordered_set>
#include <vector>

namespace std {
template <typename X, typename Y>
struct hash<std::pair<X, Y>> {
std::size_t operator()(const std::pair<X, Y>& pair) const {
std::size_t h1 = std::hash<X>()(pair.first);
std::size_t h2 = std::hash<Y>()(pair.second);
nvfuser::hashCombine(h1, h2);
return h1;
}
};
} // namespace std

namespace nvfuser {

namespace debug_print {
Expand Down Expand Up @@ -251,6 +263,9 @@ class Context {
return less_equal_;
}

mutable std::unordered_map<std::pair<Val*, Val*>, bool> less_than_cache_;
mutable std::unordered_map<std::pair<Val*, Val*>, bool> less_equal_cache_;

private:
void assume(Val* a) {
auto def = a->definition();
Expand Down Expand Up @@ -1527,77 +1542,99 @@ bool hasCompatibleSign(Val* x, Val* y, const Context& context) {
return isNonNegative(x, context) && isNonNegative(y, context);
}

#define CACHE_AND_RETURN_LT(value) \
context.less_than_cache_.emplace(std::make_pair(x, y), value); \
return value

bool lessThan(Val* x, Val* y, const Context& context) {
auto cache_it = context.less_than_cache_.find({x, y});
if (cache_it != context.less_than_cache_.end()) {
return cache_it->second;
}

x = foldConstants(x);
y = foldConstants(y);
if (x->value().hasValue() && y->value().hasValue()) {
return x->value() < y->value();
bool result = x->value() < y->value();
CACHE_AND_RETURN_LT(result);
}
x = maybeUnwrapMagicZero(x);
y = maybeUnwrapMagicZero(y);
if (x->isZero() && isPositiveHelper(y, context)) {
return true;
CACHE_AND_RETURN_LT(true);
}
// i1 % i2 < i2
if (auto bop = dynamic_cast<BinaryOp*>(x->definition());
bop != nullptr && bop->getBinaryOpType() == BinaryOpType::Mod) {
auto denominator = bop->rhs();
if (denominator->sameAs(y) && isValidDenominator(denominator, context) &&
isNonNegative(y, context)) {
return true;
CACHE_AND_RETURN_LT(true);
}
}
// x <= a & a < b & b <= y --> x < y
for (const auto& [a, b] : context.getKnownLessThan()) {
if (lessEqual(x, a, context) && lessEqual(b, y, context)) {
return true;
CACHE_AND_RETURN_LT(true);
}
}
return false;
CACHE_AND_RETURN_LT(false);
}

#undef CACHE_AND_RETURN_LT

#define CACHE_AND_RETURN_LE(value) \
context.less_equal_cache_.emplace(std::make_pair(x, y), value); \
return value

bool lessEqual(Val* x, Val* y, const Context& context) {
auto cache_it = context.less_equal_cache_.find({x, y});
if (cache_it != context.less_equal_cache_.end()) {
return cache_it->second;
}

x = foldConstants(x);
y = foldConstants(y);
if (x->value().hasValue() && y->value().hasValue()) {
return x->value() <= y->value();
bool result = x->value() <= y->value();
CACHE_AND_RETURN_LE(result);
}
x = maybeUnwrapMagicZero(x);
y = maybeUnwrapMagicZero(y);
// x == y -> x <= y
if (x->sameAs(y)) {
return true;
CACHE_AND_RETURN_LE(true);
}
if (x->isZero() && isNonNegativeHelper(y, context)) {
return true;
CACHE_AND_RETURN_LE(true);
}
for (const auto& [a, b] : context.getKnownLessThan()) {
// x < y --> x <= y
if (a->sameAs(x) && b->sameAs(y)) {
return true;
CACHE_AND_RETURN_LE(true);
}
}
for (const auto& [a, b] : context.getKnownLessEqual()) {
if (a->sameAs(x) && b->sameAs(y)) {
return true;
CACHE_AND_RETURN_LE(true);
}
}
for (const auto& [a, b] : context.getKnownLessThan()) {
// x < b & b <= y --> x <= y
if (a->sameAs(x) && lessEqual(b, y, context)) {
return true;
CACHE_AND_RETURN_LE(true);
}
}
for (const auto& [a, b] : context.getKnownLessEqual()) {
// x <= b & b <= y --> x <= y
if (a->sameAs(x) && lessEqual(b, y, context)) {
return true;
CACHE_AND_RETURN_LE(true);
}
}
// if i is an integer, i > 0, then i >= 1
if (x->isOneInt() && y->isIntegralScalar()) {
if (isPositiveHelper(y, context)) {
return true;
CACHE_AND_RETURN_LE(true);
}
}
// if a >= 0, b >= 1, then a <= a * b
Expand All @@ -1619,7 +1656,7 @@ bool lessEqual(Val* x, Val* y, const Context& context) {
maybeFlattenedOpOf(BinaryOpType::Mul, std::move(remaining_inputs));
auto one = IrBuilder::create<Val>(1L, *remaining->getDataType());
if (lessEqual(one, remaining, context)) {
return true;
CACHE_AND_RETURN_LE(true);
}
}
}
Expand All @@ -1643,14 +1680,16 @@ bool lessEqual(Val* x, Val* y, const Context& context) {
maybeFlattenedOpOf(BinaryOpType::Mul, std::move(remaining_inputs));
auto one = IrBuilder::create<Val>(1L, *remaining->getDataType());
if (lessEqual(one, remaining, context)) {
return true;
CACHE_AND_RETURN_LE(true);
}
}
}
}
return false;
CACHE_AND_RETURN_LE(false);
}

#undef CACHE_AND_RETURN_LE

} // namespace prove

namespace {
Expand Down