Patchwork [RFA:] fix group-loads of VOIDmode constants, expr.c:emit_group_load_1

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Submitter Hans-Peter Nilsson
Date Dec. 2, 2012, 11:38 a.m.
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Permalink /patch/203201/
State New
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Hans-Peter Nilsson - Dec. 2, 2012, 11:38 a.m.
On Sat, 1 Dec 2012, Eric Botcazou wrote:
> > Of course this matters only to >64bit (i.e. >registersize) values like
> > TImode, alias __int128.  The problem here is that group-loading a
> > constant for a function return-value doesn't work; it's passed to
> > simplify_gen_subreg which horks on the VOIDmode constant.  Thankfully,
> > the code below the context handles this case, twice the register-mode,
> > just fine, so let's just gate the simplify_gen_subreg call with a test
> > for a VOIDmode source.
> IMO that's not as clear a cut as it seems.  simplify_gen_subreg is supposed to
> work on VOIDmode constants, at least to be callable on them, because there is
> the simplify_gen_subreg -> simplify_subreg -> simplify_immed_subreg path.

Oops, that parallel I quoted should've had TImode, not VOIDmode.
The documentation is pretty clear.

Tested as before (but mmix targets only :)

	* config/mmix/mmix.c (mmix_function_value): Set the mode of the
	returned PARALLEL to that of the return-value, not VOIDmode.

brgds, H-P


Index: gcc/config/mmix/mmix.c
--- gcc/config/mmix/mmix.c	(revision 192677)
+++ gcc/config/mmix/mmix.c	(working copy)
@@ -754,7 +754,7 @@  mmix_function_value (const_tree valtype,
 			 gen_rtx_REG (cmode, first_val_regnum + nregs - 1),

-  return gen_rtx_PARALLEL (VOIDmode, gen_rtvec_v (nregs, vec));
+  return gen_rtx_PARALLEL (mode, gen_rtvec_v (nregs, vec));

 /* Implements TARGET_LIBCALL_VALUE.  */