Opened 5 years ago
Last modified 5 years ago
#197 new defect
Generated constructor calls copy ctor twice on tuple elements
| Reported by: | f37yu | Owned by: | |
|---|---|---|---|
| Priority: | major | Component: | cfa-cc |
| Version: | 1.0 | Keywords: | tuple, copy, constructor |
| Cc: |
Description (last modified by )
Compiler generated copy constructor for struct with fields of tuple type does a redundant copy.
The tuple elements are first copied to generated temporary variables, then to the actual destination.
Code that creates the problem:
struct A {};
void ?{}(A& a, A src) { sout | 'A'; }
struct B { [A, A] elem; };
int main() {
B b;
B b1 = b;
}
Correct behavior is the program prints twice. Currently on B b1 = b; it prints four times.
compile this snippet with -n -P resolver, should find the following (note the "maybe constructed"):
?{}: autogenerated cfa static inline function
... with parameters
_dst: reference to instance of struct B with body 1
_src: instance of struct B with body 1
... returning nothing
... with body
CompoundStmt
Implicit Ctor Dtor Statement
... with Ctor/Dtor: Expression Statement:
Tuple Assignment Expression, with stmt expr:
Statement Expression:
CompoundStmt
Declaration of __multassign_L0: reference to instance of struct A with body 1 with initializer (not constructed)
Simple Initializer: Generated Cast of:
Tuple Index Expression, with tuple:
Member Expression, with field:
elem: tuple of types
instance of struct A with body 1
instance of struct A with body 1
... from aggregate:
Generated Cast of:
Variable Expression: _dst: reference to instance of struct B with body 1
... to:
instance of struct B with body 1 with index: 0
... to:
reference to instance of struct A with body 1
Declaration of __multassign_L1: reference to instance of struct A with body 1 with initializer (not constructed)
Simple Initializer: Generated Cast of:
Tuple Index Expression, with tuple:
Member Expression, with field:
elem: tuple of types
instance of struct A with body 1
instance of struct A with body 1
... from aggregate:
Generated Cast of:
Variable Expression: _dst: reference to instance of struct B with body 1
... to:
instance of struct B with body 1 with index: 1
... to:
reference to instance of struct A with body 1
Declaration of __multassign_R0: instance of struct A with body 1 with initializer (maybe constructed)
Constructor initializer:
... initially constructed with Implicit Ctor Dtor Statement
... with Ctor/Dtor: Expression Statement:
Application of
Variable Expression: ?{}: static inline function
... with parameters
_dst: reference to instance of struct A with body 1
_src: instance of struct A with body 1
... returning nothing
... to arguments
Generated Cast of:
Variable Expression: __multassign_R0: instance of struct A with body 1
... to:
reference to instance of struct A with body 1
Tuple Index Expression, with tuple:
Member Expression, with field:
elem: tuple of types
instance of struct A with body 1
instance of struct A with body 1
... from aggregate:
Variable Expression: _src: instance of struct B with body 1 with index: 0
... destructed with Implicit Ctor Dtor Statement
... with Ctor/Dtor: Expression Statement:
Application of
Variable Expression: ^?{}: static inline function
... with parameters
_dst: reference to instance of struct A with body 1
... returning nothing
... to arguments
Generated Cast of:
Variable Expression: __multassign_R0: instance of struct A with body 1
... to:
reference to instance of struct A with body 1
Declaration of __multassign_R1: instance of struct A with body 1 with initializer (maybe constructed)
Constructor initializer:
... initially constructed with Implicit Ctor Dtor Statement
... with Ctor/Dtor: Expression Statement:
Application of
Variable Expression: ?{}: static inline function
... with parameters
_dst: reference to instance of struct A with body 1
_src: instance of struct A with body 1
... returning nothing
... to arguments
Generated Cast of:
Variable Expression: __multassign_R1: instance of struct A with body 1
... to:
reference to instance of struct A with body 1
Tuple Index Expression, with tuple:
Member Expression, with field:
elem: tuple of types
instance of struct A with body 1
instance of struct A with body 1
... from aggregate:
Variable Expression: _src: instance of struct B with body 1 with index: 1
... destructed with Implicit Ctor Dtor Statement
... with Ctor/Dtor: Expression Statement:
Application of
Variable Expression: ^?{}: static inline function
... with parameters
_dst: reference to instance of struct A with body 1
... returning nothing
... to arguments
Generated Cast of:
Variable Expression: __multassign_R1: instance of struct A with body 1
... to:
reference to instance of struct A with body 1
Expression Statement:
Tuple:
Application of
Variable Expression: ?{}: static inline function
... with parameters
_dst: reference to instance of struct A with body 1
_src: instance of struct A with body 1
... returning nothing
... to arguments
Variable Expression: __multassign_L0: reference to instance of struct A with body 1
Variable Expression: __multassign_R0: instance of struct A with body 1
Application of
Variable Expression: ?{}: static inline function
... with parameters
_dst: reference to instance of struct A with body 1
_src: instance of struct A with body 1
... returning nothing
... to arguments
Variable Expression: __multassign_L1: reference to instance of struct A with body 1
Variable Expression: __multassign_R1: instance of struct A with body 1
Change History (2)
comment:1 by , 5 years ago
| Description: | modified (diff) |
|---|
comment:2 by , 5 years ago
| Description: | modified (diff) |
|---|
Note:
See TracTickets
for help on using tickets.
