On Thu, Jul 23, 2026 at 9:08 AM Uros Bizjak <[email protected]> wrote:
> I took the liberty and rewrite comments to be more comprehensible:
... and pointed AI to them to make comments even more readable:
--cut here--
/* PAT is a SET that stores into OP, a MEM linked to parameter BASE.
Return true if PAT stores BASE's argument register into OP. This
is a spill: the callee saves its own register argument to the
stack. It is not a stack argument set up by the caller:
(set (mem/c:V2DI (plus:DI (reg/f:DI 7 sp)
(const_int -16 [0xfffffffffffffff0])) [4 a1+0 S16 A128])
(reg:V2DI 20 xmm0 [ a1 ]))
*/
static bool
ix86_spill_register_argument_p (const_rtx set, const_rtx op, tree base)
{
rtx src = SET_SRC (set);
/* Not a hard register store, so not a spill. */
if (!REG_P (src) || !HARD_REGISTER_P (src))
return false;
rtx dest = SET_DEST (set);
tree reg_expr = REG_EXPR (src);
return dest == op && reg_expr == base;
}
/* Return true if OP, found in PAT, is a stack argument set up by the
caller. Return false if OP is a register argument that the callee
spilled to its own stack frame. Both cases share the same
MEM_EXPR, so we must check PAT to tell them apart. */
static bool
ix86_argument_passed_on_stack_p (const_rtx op, const_rtx pat)
{
tree mem_expr = MEM_EXPR (op);
if (!mem_expr)
return false;
tree var = get_base_address (mem_expr);
if (TREE_CODE (var) != PARM_DECL)
return false;
/* PAT is always a single SET here: note_stores splits PARALLEL
patterns into separate SETs before calling this function. */
if (GET_CODE (pat) == SET)
return !ix86_spill_register_argument_p (pat, op, var);
return true;
}
--cut here--
Uros.
