https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98991
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |accepts-invalid
Component|c++ |inline-asm
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
it looks reduced ad absurdum but the issue must lie in
asm("":"=rmf"(f),"=d"([t(reinterpret_cast<int>(0))]{}):"0"(((0))),""((0)));
which I can't really parse but we expand from
int {anonymous}::n ()
{
int D.2351;
struct ._anon_1 t;
float f;
int D.2422;
struct ._anon_0 D.2374;
register int * D.2360;
void * _1;
int _5;
;; basic block 2, loop depth 0
;; pred: ENTRY
D.2374.__t = 0;
__asm__("" : "=rmf" f, "=d" D.2374 : "0" 0, "" 0);
likely D.2374 is not re-loadable into DREG. The zero seems to be SFmode:
(insn 6 2 7 2 (set (reg:SI 86)
(const_int 0 [0])) "t.ii":1:163 75 {*movsi_internal}
(nil))
(insn 7 6 11 2 (parallel [
(set (mem/c:SF (plus:DI (reg/f:DI 19 frame)
(const_int -4 [0xfffffffffffffffc])) [1 f+0 S4 A32])
(asm_operands:SF ("") ("=rmf") 0 [
(reg:SI 86)
(const_int 0 [0])
]
[
(asm_input:SI ("0") t.ii:1)
(asm_input:SI ("") t.ii:1)
]
[] t.ii:1))
(set (reg:SI 84 [ D.2374 ])
(asm_operands:SI ("") ("=d") 1 [
(reg:SI 86)
(const_int 0 [0])
]
[
(asm_input:SI ("0") t.ii:1)
(asm_input:SI ("") t.ii:1)
]
[] t.ii:1))
(clobber (reg:CC 17 flags))
]) "t.ii":1:163 -1
(expr_list:REG_DEAD (reg:SI 86)
(expr_list:REG_UNUSED (reg:SI 84 [ D.2374 ])
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil)))))
and we fail to reload. It _looks_ similar to
void foo(float f)
{
struct { float f; } x;
asm("": "=f" (f), "=d" (x) : "0" (0), "" (0));
}
but we reject this via
t.i: In function 'void foo(float)':
t.i:4:3: error: inconsistent operand constraints in an 'asm'
4 | asm("": "=f" (f), "=d" (x) : "0" (0), "" (0));
| ^~~
