Files
triton/lib/codegen/reassociate.cpp
Philippe Tillet 38b3771c26 some reassociation
2019-07-23 14:43:18 -07:00

186 lines
6.2 KiB
C++

#include <algorithm>
#include "triton/codegen/reassociate.h"
#include "triton/ir/module.h"
#include "triton/ir/function.h"
#include "triton/ir/basic_block.h"
#include "triton/ir/instructions.h"
#include "triton/ir/cfg.h"
namespace triton {
namespace codegen{
//inline Constant *get_gep_cst_offset(GetElementPtrInst *gep){
// std::vector<Value*> idx_vals;
// std::transform(gep->idx_begin(), gep->idx_end(),
// std::back_inserter(idx_vals),
// [](Value* x){ return x;});
// if(idx_vals.size() > 1)
// return nullptr;
// Value *idx = idx_vals[0];
// if(isa<Constant>(idx))
// return idx;
// if(Instruction *BinOp = is_bin_add(idx)){
// Value *LHS = BinOp->getOperand(0);
// Value *RHS = BinOp->getOperand(1);
// if(Constant* Res = dyn_cast<Constant>(LHS))
// return Res;
// if(Constant* Res = dyn_cast<Constant>(RHS))
// return Res;
// }
// return nullptr;
//}
inline ir::instruction* reassociate::is_bin_add(ir::value *x) {
ir::binary_operator *bin_op = dynamic_cast<ir::binary_operator*>(x);
bool is_bin_add = bin_op && bin_op->get_op()==llvm::Instruction::Add;
if(is_bin_add)
return (ir::instruction*)x;
return nullptr;
}
inline bool is_cst(ir::value *x) {
if(dynamic_cast<ir::constant*>(x))
return true;
if(auto *v = dynamic_cast<ir::retile_inst*>(x))
return is_cst(v->get_operand(0));
return false;
}
inline ir::value *reassociate::reorder_op(ir::value *old_value,
ir::builder &builder,
std::vector<ir::instruction*>& to_delete,
ir::value *&noncst,
ir::value *&cst){
// value doesn't change by default
ir::value* new_value = old_value;
cst = nullptr;
noncst = old_value;
// handle retiling
if(ir::instruction* op = dynamic_cast<ir::retile_inst*>(old_value)){
auto shapes = op->get_type()->get_tile_shapes();
ir::value *old_arg = op->get_operand(0);
ir::value *new_arg = reorder_op(old_arg, builder, to_delete, noncst, cst);
// retile(x + y) = retile(x) + retile(y)
if(ir::instruction* bin_add = is_bin_add(new_arg))
if(cst){
ir::value *old_lhs = bin_add->get_operand(0);
ir::value *old_rhs = bin_add->get_operand(1);
if(dynamic_cast<ir::reshape_inst*>(op)){
builder.set_insert_point(op);
ir::value *new_lhs = builder.create_reshape(old_lhs, shapes);
ir::value *new_rhs = builder.create_reshape(old_rhs, shapes);
new_value = builder.create_add(new_lhs, new_rhs, op->get_name());
}
if(dynamic_cast<ir::broadcast_inst*>(op)){
builder.set_insert_point(op);
ir::value *new_lhs = builder.create_broadcast(old_lhs, shapes);
ir::value *new_rhs = builder.create_broadcast(old_rhs, shapes);
new_value = builder.create_add(new_lhs, new_rhs, op->get_name());
}
if(dynamic_cast<ir::splat_inst*>(op)){
builder.set_insert_point(op);
ir::value *new_lhs = builder.create_splat(old_lhs, shapes);
ir::value *new_rhs = builder.create_splat(old_rhs, shapes);
new_value = builder.create_add(new_lhs, new_rhs, op->get_name());
}
to_delete.push_back(op);
}
}
// handle binary addition
if(ir::instruction* op = is_bin_add(old_value)){
builder.set_insert_point(op);
std::string name = op->get_name();
ir::value *lhs = reorder_op(op->get_operand (0), builder, to_delete, noncst, cst);
ir::value *rhs = reorder_op(op->get_operand(1), builder, to_delete, noncst, cst);
builder.set_insert_point(op);
// (x + y) + z
if(ir::instruction* bin_lhs = is_bin_add(lhs)){
ir::value *llhs = bin_lhs->get_operand(0);
ir::value *rlhs = bin_lhs->get_operand(1);
// (cst + x) + y -> cst + (x + y)
if(is_cst(llhs))
new_value = builder.create_add(llhs, builder.create_add(rlhs, rhs), name);
// (x + cst) + y -> cst + (x + y)
if(is_cst(rlhs))
new_value = builder.create_add(rlhs, builder.create_add(llhs, rhs), name);
if(new_value != op)
to_delete.push_back(bin_lhs);
}
// x + (y + z)
if(ir::instruction* bin_rhs = is_bin_add(rhs)){
ir::value *lrhs = bin_rhs->get_operand(0);
ir::value *rrhs = bin_rhs->get_operand(1);
// x + (cst + y) -> cst + (x + y)
if(is_cst(lrhs))
new_value = builder.create_add(lrhs, builder.create_add(rrhs, lhs), name, cst);
// x + (y + cst) -> cst + (x + y)
if(is_cst(rrhs))
new_value = builder.create_add(rrhs, builder.create_add(lrhs, lhs), name, cst);
if(new_value != op)
to_delete.push_back(bin_rhs);
}
}
// extract constant and non-constant
if(ir::instruction *bin_add = is_bin_add(new_value)){
ir::value *new_lhs = bin_add->get_operand(0);
ir::value *new_rhs = bin_add->get_operand(1);
if(is_cst(new_lhs)){
cst = new_lhs;
noncst = new_rhs;
}
if(is_cst(new_rhs)){
cst = new_rhs;
noncst = new_lhs;
}
}
// clean-up if some re-ordering happened
if(old_value != new_value){
old_value->replace_all_uses_with(new_value);
if(auto *x = dynamic_cast<ir::instruction*>(old_value))
to_delete.push_back(x);
}
return new_value;
}
reassociate::reassociate() {
}
void reassociate::run(ir::module &mod) {
ir::builder &builder = mod.get_builder();
std::vector<ir::instruction*> to_delete;
for(ir::function *fn: mod.get_function_list()){
std::vector<ir::basic_block*> rpo = ir::cfg::reverse_post_order(fn);
bool done = false;
do{
// iterate through blocks
for(ir::basic_block *block: rpo){
// iterate through instruction
for(ir::instruction *i: block->get_inst_list()){
if(auto *gep = dynamic_cast<ir::getelementptr_inst*>(i)){
std::vector<ir::value*> idxs(gep->idx_begin(), gep->idx_end());
ir::value *cst = nullptr;
ir::value *noncst = idxs[0];
reorder_op(noncst, builder, to_delete, noncst, cst);
// std::cout << gep->get_name() << " " << noncst << " " << cst << std::endl;
}
}
done = true;
}
}while(!done);
}
// erase dead code
for(ir::instruction* i: to_delete)
i->erase_from_parent();
}
}
}