assemble_real used GEN_INT to create integers directly from the
longs returned by real_to_target. assemble_integer then went on
to interpret the const_ints as though they had the mode corresponding
to the accompanying size parameter:
imode = mode_for_size (size * BITS_PER_UNIT, mclass, 0).require ();
for (i = 0; i < size; i += subsize)
{
rtx partial = simplify_subreg (omode, x, imode, i);
But in the assemble_real case, X might not be canonical for IMODE.
If the interface to assemble_integer is supposed to allow outputting
(say) the low 4 bytes of a DImode integer, then the simplify_subreg
above is wrong. But if the number of bytes passed to assemble_integer
is supposed to be the number of bytes that the integer actually contains,
assemble_real is wrong.
This patch takes the latter interpretation and makes assemble_real
generate const_ints that are canonical for the number of bytes passed.
The flip_storage_order handling assumes that each long is a full
SImode, which e.g. excludes BITS_PER_UNIT != 8 and float formats
whose memory size is not a multiple of 32 bits (which includes
HFmode at least). The patch therefore leaves that code alone.
If interpreting each integer as SImode is correct, the const_ints
that it generates are also correct.
Tested on aarch64-linux-gnu and x86_64-linux-gnu. Also tested
by making sure that there were no new errors from a range of
cross-built targets. OK to install?
Richard
2019-09-17 Richard Sandiford <richard.sandif...@arm.com>
gcc/
* varasm.c (assemble_real): Generate canonical const_ints.
Index: gcc/varasm.c
===================================================================
--- gcc/varasm.c 2019-09-05 08:49:30.829739618 +0100
+++ gcc/varasm.c 2019-09-17 15:30:10.400740515 +0100
@@ -2873,25 +2873,27 @@ assemble_real (REAL_VALUE_TYPE d, scalar
real_to_target (data, &d, mode);
/* Put out the first word with the specified alignment. */
+ unsigned int chunk_nunits = MIN (nunits, units_per);
if (reverse)
elt = flip_storage_order (SImode, gen_int_mode (data[nelts - 1], SImode));
else
- elt = GEN_INT (data[0]);
- assemble_integer (elt, MIN (nunits, units_per), align, 1);
- nunits -= units_per;
+ elt = GEN_INT (sext_hwi (data[0], chunk_nunits * BITS_PER_UNIT));
+ assemble_integer (elt, chunk_nunits, align, 1);
+ nunits -= chunk_nunits;
/* Subsequent words need only 32-bit alignment. */
align = min_align (align, 32);
for (int i = 1; i < nelts; i++)
{
+ chunk_nunits = MIN (nunits, units_per);
if (reverse)
elt = flip_storage_order (SImode,
gen_int_mode (data[nelts - 1 - i], SImode));
else
- elt = GEN_INT (data[i]);
- assemble_integer (elt, MIN (nunits, units_per), align, 1);
- nunits -= units_per;
+ elt = GEN_INT (sext_hwi (data[i], chunk_nunits * BITS_PER_UNIT));
+ assemble_integer (elt, chunk_nunits, align, 1);
+ nunits -= chunk_nunits;
}
}
