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lower-subreg.c (simplify_gen_subreg_concatn): If we ask for the high part of a paradoxical subreg, return a constant zero.

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* lower-subreg.c (simplify_gen_subreg_concatn): If we ask for the
	high part of a paradoxical subreg, return a constant zero.

From-SVN: r121466
This commit is contained in:
Ian Lance Taylor 2007-02-01 16:43:20 +00:00 committed by Ian Lance Taylor
parent c0d919fa35
commit 0e6c5b5854
2 changed files with 23 additions and 1 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2007-02-01 Ian Lance Taylor <iant@google.com>
* lower-subreg.c (simplify_gen_subreg_concatn): If we ask for the
high part of a paradoxical subreg, return a constant zero.
2007-02-01 Zdenek Dvorak <dvorakz@suse.cz>
* toplev.c (lang_dependent_init): Call init_set_costs.

19
gcc/lower-subreg.c
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@ -372,6 +372,8 @@ static rtx
simplify_gen_subreg_concatn (enum machine_mode outermode, rtx op,
enum machine_mode innermode, unsigned int byte)
{
rtx ret;
/* We have to handle generating a SUBREG of a SUBREG of a CONCATN.
If OP is a SUBREG of a CONCATN, then it must be a simple mode
change with the same size and offset 0, or it must extract a
@ -405,9 +407,24 @@ simplify_gen_subreg_concatn (enum machine_mode outermode, rtx op,
gcc_assert (op != NULL_RTX);
gcc_assert (innermode == GET_MODE (op));
}
if (GET_CODE (op) == CONCATN)
return simplify_subreg_concatn (outermode, op, byte);
return simplify_gen_subreg (outermode, op, innermode, byte);
ret = simplify_gen_subreg (outermode, op, innermode, byte);
/* If we see an insn like (set (reg:DI) (subreg:DI (reg:SI) 0)) then
resolve_simple_move will ask for the high part of the paradoxical
subreg, which does not have a value. Just return a zero. */
if (ret == NULL_RTX
&& GET_CODE (op) == SUBREG
&& SUBREG_BYTE (op) == 0
&& (GET_MODE_SIZE (innermode)
> GET_MODE_SIZE (GET_MODE (SUBREG_REG (op)))))
return CONST0_RTX (outermode);
gcc_assert (ret != NULL_RTX);
return ret;
}
/* Return whether we should resolve X into the registers into which it