https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119084
Bug ID: 119084
Summary: LoongArch: __builtin_lsx_vldx can be incorrectly
reordered
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: xry111 at gcc dot gnu.org
Target Milestone: ---
typedef signed char V16QI __attribute__ ((vector_size (16)));
static char x[128];
__attribute__ ((noipa)) int
noopt (int x)
{
return x;
}
int
main (void)
{
int t = noopt (32);
x[32] = 1;
#if 0
/* This can work around the issue */
asm("":::"memory");
#endif
V16QI y = __builtin_lsx_vldx (x, t);
if (y[0] != 1)
__builtin_trap ();
}
produces:
la.local $r12,.LANCHOR0
addi.w $r14,$r0,1 # 0x1
vldx $vr0,$r12,$r4
st.b $r14,$r12,32
vpickve2gr.b $r12,$vr0,0
addi.w $r13,$r0,1 # 0x1
bstrpick.w $r12,$r12,7,0
bne $r12,$r13,.L6
Note that st.b is incorrectly reordered after vldx. It's because
(define_insn "lsx_vldx"
[(set (match_operand:V16QI 0 "register_operand" "=f")
(unspec:V16QI [(match_operand:DI 1 "register_operand" "r")
(match_operand:DI 2 "reg_or_0_operand" "rJ")]
UNSPEC_LSX_VLDX))]
"ISA_HAS_LSX"
{
return "vldx\t%w0,%1,%z2";
}
[(set_attr "type" "simd_load")
(set_attr "mode" "V16QI")])
seems (to the compiler) not accessing the memory at all.
