On 11/12/20 3:53 PM, Richard Biener wrote:
On November 12, 2020 9:43:52 PM GMT+01:00, Andrew MacLeod via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
So I spent some time tracking down a ranger issue, and in the end, it
boiled down to the range-op handler not being picked up properly.
The handler is picked up by:
if ((gimple_code (s) == GIMPLE_ASSIGN) || (gimple_code (s) ==
GIMPLE_COND))
return range_op_handler (gimple_expr_code (s), gimple_expr_type
(s));
IMHO this should use more specific functions. Gimple_expr_code should go away
similar to gimple_expr_type.
gimple_expr_type is quite pervasive.. and each consumer is going to have
to roll their own version of it. Why do we want to get rid of it?
If we are trying to save a few bytes by storing the information in
different places, then we're going to need some sort of accessing
function like that
where it is indexing the table with the gimple_expr_code..
the stmt being processed was for a pointer assignment,
_5 = _33
and it was coming back with a gimple_expr_code of VAR_DECL instead of
an SSA_NAME... which confused me greatly.
gimple_expr_code (const gimple *stmt)
{
enum gimple_code code = gimple_code (stmt);
if (code == GIMPLE_ASSIGN || code == GIMPLE_COND)
return (enum tree_code) stmt->subcode;
A little more digging shows this:
static inline enum tree_code
gimple_assign_rhs_code (const gassign *gs)
{
enum tree_code code = (enum tree_code) gs->subcode;
/* While we initially set subcode to the TREE_CODE of the rhs for
GIMPLE_SINGLE_RHS assigns we do not update that subcode to stay
in sync when we rewrite stmts into SSA form or do SSA
propagations. */
if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS)
code = TREE_CODE (gs->op[1]);
return code;
}
Fascinating comment.
... 😬
But it means that gimple_expr_code() isn't returning the correct result
for GIMPLE_SINGLE_RHS....
It depends. A SSA name isn't an expression code either. As said, the generic
gimple_expr_code should be used with extreme care.
what is an expression code? It seems like its just a tree_code
representing what is on the RHS? Im not sure I understand why one
needs to be careful with it. It only applies to COND, ASSIGN and CALL.
and its current right for everything except GIMPLE_SINGLE_RHS?
If we dont fix gimple_expr_code, then Im basically going to be
reimplementing it myself... which seems kind of pointless.
Andrew
