https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112773
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Last reconfirmed| |2023-12-01
--- Comment #10 from Richard Biener <rguenth at gcc dot gnu.org> ---
The issue might be we do not use vec_extract for memory arguments:
/* Use vec_extract patterns for extracting parts of vectors whenever
available. If that fails, see whether the current modes and bitregion
give a natural subreg. */
machine_mode outermode = GET_MODE (op0);
if (VECTOR_MODE_P (outermode) && !MEM_P (op0))
{
and somehow the original reg operand got spilled inbetween. That happens
here, after we could make vec_extract work for this.
/* Make sure we are playing with integral modes. Pun with subregs
if we aren't. */
opt_scalar_int_mode op0_mode = int_mode_for_mode (GET_MODE (op0));
scalar_int_mode imode;
if (!op0_mode.exists (&imode) || imode != GET_MODE (op0))
{
...
else
{
poly_int64 size = GET_MODE_SIZE (GET_MODE (op0));
rtx mem = assign_stack_temp (GET_MODE (op0), size);
emit_move_insn (mem, op0);
op0 = adjust_bitfield_address_size (mem, BLKmode, 0, size);
}
now, if we spilled we can elide the round-down I think (which is for
the fear of accessing invalid memory). Thus like the following?
diff --git a/gcc/expmed.cc b/gcc/expmed.cc
index b294eabb08d..e2b38b87bdf 100644
--- a/gcc/expmed.cc
+++ b/gcc/expmed.cc
@@ -1856,7 +1856,7 @@ extract_bit_field_1 (rtx str_rtx, poly_uint64 bitsize,
poly_uint64 bitnum,
/* If we have a memory source and a non-constant bit offset, restrict
the memory to the referenced bytes. This is a worst-case fallback
but is useful for things like vector booleans. */
- if (MEM_P (op0) && !bitnum.is_constant ())
+ if (MEM_P (str_rtx) && !bitnum.is_constant ())
{
bytenum = bits_to_bytes_round_down (bitnum);
bitnum = num_trailing_bits (bitnum);
but that defers the ICE to
during RTL pass: expand
t.c: In function 'e':
t.c:4:6: internal compiler error: in to_constant, at poly-int.h:588
4 | void e(unsigned f) {
| ^
0x10ea530 poly_int<2u, unsigned long>::to_constant() const
/home/rguenther/src/trunk/gcc/poly-int.h:588
0x13cec67 extract_bit_field_1
/home/rguenther/src/trunk/gcc/expmed.cc:1872
so I guess we really need to match the vec_extract pattern.
So you need to debug why that doesn't match here.
