mirror/zig
1
0
Fork 0
mirror of https://github.com/ziglang/zig.git synced 2026-01-10 17:35:12 +00:00
Code Issues Packages Projects Releases Wiki Activity

optimize >>= operator for common case

Browse Source
This commit is contained in:
Josh Wolfe 2017-09-20 18:37:36 -07:00
parent 0228f8c9fd
commit e2f8bec7ac
1 changed files with 62 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

108
src/parsec.cpp
View File

@ -987,59 +987,75 @@ static AstNode *trans_compound_assign_operator(Context *c, bool result_used, Ast
return nullptr;
case BO_ShrAssign: {
BinOpType bin_op = BinOpTypeBitShiftRight;
// c: lhs >>= rhs;
// zig: {
// zig: const _ref = &lhs;
// zig: *_ref = result_type(operation_type(*_ref) >> u5(rhs));
// zig: *_ref
// zig: };
// where u5 is the appropriate type
// TODO: avoid mess when we don't need the assignment value for chained assignments or anything.
AstNode *child_block = trans_create_node(c, NodeTypeBlock);
// const _ref = &lhs;
AstNode *lhs = trans_expr(c, true, child_block, stmt->getLHS(), TransLValue);
if (lhs == nullptr) return nullptr;
AstNode *addr_of_lhs = trans_create_node_addr_of(c, false, false, lhs);
// TODO: avoid name collisions with generated variable names
Buf* tmp_var_name = buf_create_from_str("_ref");
AstNode *tmp_var_decl = trans_create_node_var_decl_local(c, true, tmp_var_name, nullptr, addr_of_lhs);
child_block->data.block.statements.append(tmp_var_decl);
// *_ref = result_type(operation_type(*_ref) >> u5(rhs));
AstNode *rhs = trans_expr(c, true, child_block, stmt->getRHS(), TransRValue);
if (rhs == nullptr) return nullptr;
const SourceLocation &rhs_location = stmt->getRHS()->getLocStart();
AstNode *rhs_type = qual_type_to_log2_int_ref(c, stmt->getComputationLHSType(), rhs_location);
AstNode *assign_statement = trans_create_node_bin_op(c,
trans_create_node_prefix_op(c, PrefixOpDereference,
trans_create_node_symbol(c, tmp_var_name)),
BinOpTypeAssign,
trans_c_cast(c, rhs_location,
stmt->getComputationResultType(),
trans_create_node_bin_op(c,
trans_c_cast(c, rhs_location,
stmt->getComputationLHSType(),
trans_create_node_prefix_op(c, PrefixOpDereference,
trans_create_node_symbol(c, tmp_var_name))),
bin_op,
trans_create_node_fn_call_1(c,
rhs_type,
rhs))));
child_block->data.block.statements.append(assign_statement);
bool use_intermediate_casts = stmt->getComputationLHSType().getTypePtr() != stmt->getComputationResultType().getTypePtr();
if (!use_intermediate_casts && !result_used) {
// simple common case, where the C and Zig are identical:
// lhs >>= rh* s
AstNode *lhs = trans_expr(c, true, block, stmt->getLHS(), TransLValue);
if (lhs == nullptr) return nullptr;
if (result_used) {
// *_ref
child_block->data.block.statements.append(
AstNode *rhs = trans_expr(c, true, block, stmt->getRHS(), TransRValue);
if (rhs == nullptr) return nullptr;
AstNode *coerced_rhs = trans_create_node_fn_call_1(c, rhs_type, rhs);
return trans_create_node_bin_op(c, lhs, BinOpTypeAssignBitShiftRight, coerced_rhs);
} else {
// need more complexity. worst case, this looks like this:
// c: lhs >>= rhs
// zig: {
// zig: const _ref = &lhs;
// zig: *_ref = result_type(operation_type(*_ref) >> u5(rhs));
// zig: *_ref
// zig: }
// where u5 is the appropriate type
// TODO: avoid mess when we don't need the assignment value for chained assignments or anything.
AstNode *child_block = trans_create_node(c, NodeTypeBlock);
// const _ref = &lhs;
AstNode *lhs = trans_expr(c, true, child_block, stmt->getLHS(), TransLValue);
if (lhs == nullptr) return nullptr;
AstNode *addr_of_lhs = trans_create_node_addr_of(c, false, false, lhs);
// TODO: avoid name collisions with generated variable names
Buf* tmp_var_name = buf_create_from_str("_ref");
AstNode *tmp_var_decl = trans_create_node_var_decl_local(c, true, tmp_var_name, nullptr, addr_of_lhs);
child_block->data.block.statements.append(tmp_var_decl);
// *_ref = result_type(operation_type(*_ref) >> u5(rhs));
AstNode *rhs = trans_expr(c, true, child_block, stmt->getRHS(), TransRValue);
if (rhs == nullptr) return nullptr;
AstNode *coerced_rhs = trans_create_node_fn_call_1(c, rhs_type, rhs);
AstNode *assign_statement = trans_create_node_bin_op(c,
trans_create_node_prefix_op(c, PrefixOpDereference,
trans_create_node_symbol(c, tmp_var_name)));
child_block->data.block.last_statement_is_result_expression = true;
}
trans_create_node_symbol(c, tmp_var_name)),
BinOpTypeAssign,
trans_c_cast(c, rhs_location,
stmt->getComputationResultType(),
trans_create_node_bin_op(c,
trans_c_cast(c, rhs_location,
stmt->getComputationLHSType(),
trans_create_node_prefix_op(c, PrefixOpDereference,
trans_create_node_symbol(c, tmp_var_name))),
bin_op,
coerced_rhs)));
child_block->data.block.statements.append(assign_statement);
return child_block;
if (result_used) {
// *_ref
child_block->data.block.statements.append(
trans_create_node_prefix_op(c, PrefixOpDereference,
trans_create_node_symbol(c, tmp_var_name)));
child_block->data.block.last_statement_is_result_expression = true;
}
return child_block;
}
}
case BO_AndAssign:
emit_warning(c, stmt->getLocStart(), "TODO handle more C compound assign operators: BO_AndAssign");