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#pragma once
#include <torch/csrc/jit/tensorexpr/codegen.h>
#include <torch/csrc/jit/tensorexpr/ir.h>
#include <torch/csrc/jit/tensorexpr/ir_visitor.h>
#include <torch/csrc/jit/tensorexpr/tensor.h>
namespace torch::jit::tensorexpr {
// Walk the Statement looking for Half size loads/stores.
class HalfChecker : public IRVisitor {
public:
HalfChecker(const std::vector<CodeGen::BufferArg>& args) {
for (const auto& BA : args) {
hasHalf_ |= BA.dtype().scalar_type() == ScalarType::Half;
}
}
bool hasHalf() const {
return hasHalf_;
}
bool hasBFloat16() const {
return hasBFloat16_;
}
void visit(const LoadPtr& v) override {
hasHalf_ |= v->dtype().scalar_type() == ScalarType::Half;
hasBFloat16_ |= v->dtype().scalar_type() == ScalarType::BFloat16;
IRVisitor::visit(v);
}
void visit(const StorePtr& v) override {
hasHalf_ |= v->buf()->dtype().scalar_type() == ScalarType::Half;
hasBFloat16_ |= v->buf()->dtype().scalar_type() == ScalarType::BFloat16;
IRVisitor::visit(v);
}
void visit(const HalfImmPtr& v) override {
hasHalf_ = true;
}
void visit(const BFloat16ImmPtr& v) override {
hasBFloat16_ = true;
}
void visit(const CastPtr& v) override {
hasHalf_ |= v->dtype().scalar_type() == ScalarType::Half;
hasBFloat16_ |= v->dtype().scalar_type() == ScalarType::BFloat16;
IRVisitor::visit(v);
}
private:
bool hasHalf_{false};
bool hasBFloat16_{false};
};
class HalfRewriter : public IRMutator {
ExprPtr mutate(const LoadPtr& v) override {
ExprPtr child = IRMutator::mutate(v);
if (!isHalf(child)) {
return child;
}
ExprPtr ret = alloc<Cast>(
child->dtype().cloneWithScalarType(ScalarType::Float), child);
inserted_half_casts_.insert(ret);
return ret;
}
StmtPtr mutate(const StorePtr& v) override {
// Since mutation changes the `value()` expression in-place, we need to
// get the dtype of the `value()` before that is mutated.
auto newType = v->value()->dtype();
ExprPtr new_val = v->value()->accept_mutator(this);
auto bufType = v->buf()->dtype();
if (isHalf(newType.scalar_type())) {
new_val = alloc<Cast>(newType, new_val);
inserted_half_casts_.insert(new_val);
}
// The scalar_type of value is not Half while the buf is Half
if (!isHalf(newType.scalar_type()) && isHalf(bufType.scalar_type())) {
new_val = alloc<Cast>(
newType.cloneWithScalarType(bufType.scalar_type()), new_val);
inserted_half_casts_.insert(new_val);
}
v->set_value(new_val);
return v;
}
ExprPtr mutate(const HalfImmPtr& v) override {
return alloc<Cast>(kFloat, v);
}
ExprPtr mutate(const BFloat16ImmPtr& v) override {
return alloc<Cast>(kFloat, v);
}
ExprPtr mutate(const CastPtr& v) override {
ExprPtr child = v->src_value()->accept_mutator(this);
// just don't allow half casts we didn't insert.
if (isHalf(v)) {
if (inserted_half_casts_.count(v) < 1) {
v->set_src_value(child);
v->set_dtype(v->dtype().cloneWithScalarType(c10::kFloat));
return v;
}
}
// Remove Half(Float()) and friends.
CastPtr cast_child = to<Cast>(child);
if (cast_child) {
auto cast_to_double = v->dtype().scalar_type() == ScalarType::Double;
auto from_half = isHalf(cast_child->src_value());
// Cannot simplify the double(float(half)) to double(half) as NNC does
// not support cast BF16 to double directly.
auto not_cast_half_to_doulbe = !(cast_to_double && from_half);
if (v->dtype().is_floating_point() &&
cast_child->dtype().is_floating_point() && not_cast_half_to_doulbe) {
return alloc<Cast>(v->dtype(), cast_child->src_value());
}
}
if (child == v->src_value()) {
return v;
}
return alloc<Cast>(v->dtype(), child);
}
StmtPtr mutate(const LetPtr& v) override {
if (isHalf(v->var()->dtype().scalar_type())) {
VarPtr load_new_var = alloc<Var>(v->var()->name_hint(), kFloat);
ExprPtr new_value = alloc<Cast>(
v->var()->dtype().cloneWithScalarType(ScalarType::Float),
v->value()->accept_mutator(this));
var_map[v->var()] = load_new_var;
return alloc<Let>(load_new_var, new_value);
}
return IRMutator::mutate(v);
}
ExprPtr mutate(const VarPtr& v) override {
auto it = var_map.find(v);
if (it != var_map.end()) {
return it->second;
}
return v;
}
template <typename T>
ExprPtr mutateArithmetic(T v) {
IRMutator::mutate(v);
if (isHalf(v)) {
v->set_dtype(v->dtype().cloneWithScalarType(c10::kFloat));
}
return v;
}
ExprPtr mutate(const AddPtr& v) override {
return mutateArithmetic(v);
}
ExprPtr mutate(const SubPtr& v) override {
return mutateArithmetic(v);
}
ExprPtr mutate(const MulPtr& v) override {
return mutateArithmetic(v);
}
ExprPtr mutate(const DivPtr& v) override {
return mutateArithmetic(v);
}
ExprPtr mutate(const MaxPtr& v) override {
return mutateArithmetic(v);
}
ExprPtr mutate(const MinPtr& v) override {
return mutateArithmetic(v);
}
ExprPtr mutate(const CompareSelectPtr& v) override {
return mutateArithmetic(v);
}
ExprPtr mutate(const BroadcastPtr& v) override {
return mutateArithmetic(v);
}
ExprPtr mutate(const IfThenElsePtr& v) override {
return mutateArithmetic(v);
}
ExprPtr mutate(const IntrinsicsPtr& v) override {
return mutateArithmetic(v);
}
private:
static bool isHalf(ScalarType st) {
return st == ScalarType::Half || st == ScalarType::BFloat16;
}
static bool isHalf(const ExprPtr& v) {
return isHalf(v->dtype().scalar_type());
}
std::unordered_set<ExprPtr> inserted_half_casts_;
std::unordered_map<VarPtr, VarPtr> var_map;
};
} // namespace torch::jit::tensorexpr
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