Hi Jeff,
On Mon, 2024-09-02 at 12:53 -0600, Jeff Law wrote:
> (define_insn_and_split "<optab>_shift_reverse<X:mode>"
> [(set (match_operand:X 0 "register_operand" "=r")
> (any_bitwise:X (ashift:X (match_operand:X 1 "register_operand" "r")
> @@ -2934,9 +2936,9 @@ (define_insn_and_split "<optab>_shift_reverse<X:mode>"
> "(!SMALL_OPERAND (INTVAL (operands[3]))
> && SMALL_OPERAND (INTVAL (operands[3]) >> INTVAL (operands[2]))
> && popcount_hwi (INTVAL (operands[3])) > 1
I'm wondering why we need to check the popcount. With this patch
applied:
long
test1 (long x)
{
return (x & 0x110) << 12;
}
is compiled to:
test1:
andi a0,a0,272
slli a0,a0,12
ret
as we've expected, but:
long
test2 (long x)
{
return (x & 0x100) << 12;
}
is compiled to:
test:
li a5,1048576
slli a0,a0,12
and a0,a0,a5
ret
So why must we spend an instruction to load the single-bit immediate?
--
Xi Ruoyao <xry...@xry111.site>
School of Aerospace Science and Technology, Xidian University
