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rtl: directly handle MEM in gen_highpart [PR102125]

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gen_lowpart_general handles forming a lowpart of a MEM by using
adjust_address to rework and validate a new version of the MEM.
Do the same for gen_highpart rather than calling simplify_gen_subreg
for this case.

gcc/ChangeLog:

	PR target/102125
	* emit-rtl.c (gen_highpart): Use adjust_address to handle
	MEM rather than calling simplify_gen_subreg.
This commit is contained in:
Richard Earnshaw 2021-09-09 10:56:01 +01:00
parent c012297c9d
commit 408e8b9066
1 changed files with 13 additions and 10 deletions
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23
gcc/emit-rtl.c
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@ -1625,18 +1625,21 @@ gen_highpart (machine_mode mode, rtx x)
gcc_assert (known_le (msize, (unsigned int) UNITS_PER_WORD)
|| known_eq (msize, GET_MODE_UNIT_SIZE (GET_MODE (x))));
/* gen_lowpart_common handles a lot of special cases due to needing to handle
paradoxical subregs; it only calls simplify_gen_subreg when certain that
it will produce something meaningful. The only case we need to handle
specially here is MEM. */
if (MEM_P (x))
{
poly_int64 offset = subreg_highpart_offset (mode, GET_MODE (x));
return adjust_address (x, mode, offset);
}
result = simplify_gen_subreg (mode, x, GET_MODE (x),
subreg_highpart_offset (mode, GET_MODE (x)));
gcc_assert (result);
/* simplify_gen_subreg is not guaranteed to return a valid operand for
the target if we have a MEM. gen_highpart must return a valid operand,
emitting code if necessary to do so. */
if (MEM_P (result))
{
result = validize_mem (result);
gcc_assert (result);
}
/* Since we handle MEM directly above, we should never get a MEM back
from simplify_gen_subreg. */
gcc_assert (result && !MEM_P (result));
return result;
}