poly_uint64 regsize = REGMODE_NATURAL_SIZE (imode);
- /* ??? This should not be here. Temporarily continue to allow word_mode
- subregs of anything. The most common offender is (subreg:SI (reg:DF)).
- Generally, backends are doing something sketchy but it'll take time to
- fix them all. */
- if (omode == word_mode)
- ;
- /* ??? Similarly, e.g. with (subreg:DF (reg:TI)). Though store_bit_field
- is the culprit here, and not the backends. */
- else if (known_ge (osize, regsize) && known_ge (isize, osize))
- ;
- /* Allow component subregs of complex and vector. Though given the below
- extraction rules, it's not always clear what that means. */
- else if ((COMPLEX_MODE_P (imode) || VECTOR_MODE_P (imode))
- && GET_MODE_INNER (imode) == omode)
- ;
- /* ??? x86 sse code makes heavy use of *paradoxical* vector subregs,
- i.e. (subreg:V4SF (reg:SF) 0) or (subreg:V4SF (reg:V2SF) 0). This
- surely isn't the cleanest way to represent this. It's questionable
- if this ought to be represented at all -- why can't this all be hidden
- in post-reload splitters that make arbitrarily mode changes to the
- registers themselves. */
- else if (VECTOR_MODE_P (omode)
- && GET_MODE_INNER (omode) == GET_MODE_INNER (imode))
- ;
- /* Subregs involving floating point modes are not allowed to
- change size. Therefore (subreg:DI (reg:DF) 0) is fine, but
- (subreg:SI (reg:DF) 0) isn't. */
- else if (FLOAT_MODE_P (imode) || FLOAT_MODE_P (omode))
- {
- if (! (known_eq (isize, osize)
- /* LRA can use subreg to store a floating point value in
- an integer mode. Although the floating point and the
- integer modes need the same number of hard registers,
- the size of floating point mode can be less than the
- integer mode. LRA also uses subregs for a register
- should be used in different mode in on insn. */
- || lra_in_progress))
- return false;
- }
-
/* Paradoxical subregs must have offset zero. */
if (maybe_gt (osize, isize))
return known_eq (offset, 0U);