On 3/24/23 08:11, pan2.li--- via Gcc-patches wrote:
From: Pan Li <pan2...@intel.com>
Fix the bug of the incorrect code generation for the
below code sample.
typedef unsigned short __attribute__((__vector_size__ (32))) V;
typedef unsigned short u16;
void
foo (V m, u16 *ret)
{
V v = 6 > ((V) { 2049, 8 } & m);
*ret = v[0]; // + a + b + c + d;
}
Before this patch.
addi sp,sp,-64
ld a5,0(a0)
li a4,528384
addi a4,a4,-2047
and a5,a5,a4
// slli a5,a5,48 <- eliminated by mistake
// srli a5,a5,48 <- eliminated by mistake
sltiu a5,a5,6
negw a5,a5
sh a5,0(a1)
After this patch.
addi sp,sp,-64
ld a5,0(a0)
li a4,528384
addi a4,a4,-2047
and a5,a5,a4
slli a5,a5,48
srli a5,a5,48
sltiu a5,a5,6
negw a5,a5
sh a5,0(a1)
The simplify_comparation for the AND operation will
try to simplify below RTL code from:
(and:DI (subreg:DI (reg:HI 154) 0) (const_int 0x801))
to:
(subreg:DI (and (reg:HI 154) (const_int 0x801)) 0)
These look equivalent to me -- assuming they're used as rvalues.
If reg:HI 154 is 0x801 and reg:DI 154 is 0x80801, the RTL will
be simplified continuely to:
That statement has no meaning. Each pseudo has one and only one native
mode and you can only refer to it in that mode. ie reg:HI 154. reg:DI
154 has no meaning. You might say that (subreg:DI (reg:HI 154) 0) has
the value 0x80801, but that's OK. The subreg says those bits outside
HImode simply don't matter -- you can not depend on them having any
particular value.
(subreg:DI (reg:HI 154) 0)
I think that's equivalent to (subreg:DI (and:HI (reg:HI 154) (const_int
0x801)) 0) when used as an rvalue.
I suspect your problem is elsewhere.
jeff
