On Thu, 2023-08-31 at 10:46 +0800, chenxiaolong wrote:
> +;; Implement __builtin_fabs128 function.
> +
> +(define_expand "abstf2"
> + [(match_operand:TF 0 "register_operand")
> + (match_operand:TF 1 "register_operand")]
> + "TARGET_64BIT"
> +{
> + loongarch_emit_move (operands[0], operands[1]);
> + emit_insn (gen_abstf_local (operands[0]));
> + DONE;
> +})
> +
> +(define_insn "abstf_local"
> + [(set (match_operand:TF 0 "register_operand" "+r")
> + (abs:TF (match_dup 0)))]
> + "TARGET_64BIT"
> +{
> + operands[0] = gen_rtx_REG (DImode, REGNO (operands[0]) + 1);
> + return "bstrins.d\t%0,$r0,0x3f,0x3f";
> +})
This should be removed because the "generic" expand works fine:
$ cat t.c
_Float128 fabsf128 (_Float128 in)
{
return __builtin_fabsf128 (in);
}
$ cc t.c -S -O2 -o-
fabsf128:
.LFB0 = .
.cfi_startproc
bstrpick.d $r5,$r5,62,0
jr $r1
.cfi_endproc
It does not work with -O0, but -O0 means "not optimized" anyway.
> +;; Implement __builtin_copysignf128 function.
> +
> +(define_insn_and_split "copysigntf3"
> + [(set (match_operand:TF 0 "register_operand" "=&r")
> + (unspec:TF [(match_operand:TF 1 "register_operand" "r")
> + (match_operand:TF 2 "register_operand" "r")]
> + UNSPEC_COPYSIGNF128))]
> + "TARGET_64BIT"
> + "#"
> + "reload_completed"
> + [(const_int 0)]
> +{
> + rtx op0_lo = gen_rtx_REG (DImode,REGNO (operands[0]) + 0);
> + rtx op0_hi = gen_rtx_REG (DImode,REGNO (operands[0]) + 1);
> + rtx op1_lo = gen_rtx_REG (DImode,REGNO (operands[1]) + 0);
> + rtx op1_hi = gen_rtx_REG (DImode,REGNO (operands[1]) + 1);
> + rtx op2_hi = gen_rtx_REG (DImode,REGNO (operands[2]) + 1);
> +
> + if (REGNO (operands[1]) == REGNO (operands[2]))
> + {
> + loongarch_emit_move (operands[0], operands[1]);
> + DONE;
> + }
> + else
> + {
> + loongarch_emit_move (op0_hi, op2_hi);
> + loongarch_emit_move (op0_lo, op1_lo);
> + emit_insn (gen_insvdi (op0_hi, GEN_INT (63), GEN_INT (0), op1_hi));
> + DONE;
> + }
> +})
Hmm... The generic implementation does not work:
copysignf128:
.LFB0 = .
.cfi_startproc
or $r12,$r0,$r0
lu52i.d $r12,$r12,0x8000000000000000>>52
and $r7,$r7,$r12
bstrpick.d $r5,$r5,62,0
or $r5,$r5,$r7
jr $r1
.cfi_endproc
It's sub-optimal. But there seems a general issue about cases like
int test(int a, int b)
{
return (a & ~0x10) | (b & 0x10);
}
It's compiled to:
test:
.LFB0 = .
.cfi_startproc
addi.w $r12,$r0,-17 # 0xffffffffffffffef
and $r12,$r12,$r4
andi $r5,$r5,16
or $r12,$r12,$r5
slli.w $r4,$r12,0
jr $r1
.cfi_endproc
But the optimal implementation should be:
bstrpick.w $r4, $r4, 4, 4
bstrins.w $r5, $r4, 4, 4
or $r5, $r4, $r0
So to me we should fix the general case instead. Please hold this part
(you can commit the remains of the patch w/o the loongarch.md change for
now), and I'll try to fix the general case.
Created https://gcc.gnu.org/PR111252 for tracking the issue.
--
Xi Ruoyao <xry...@xry111.site>
School of Aerospace Science and Technology, Xidian University
