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rs6000: Unaligned stfiwx on older CPUs (PR89746)

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The "classic" PowerPCs (6xx/7xx) are not STRICT_ALIGNMENT, but their
floating point units are.  This is not normally a problem, the ABIs
make everything FP aligned.  The RTL patterns converting FP to integer
however get a potentially unaligned destination, and we do not want to
do an stfiwx on that on such older CPUs.

This fixes it.  It does not change anything for TARGET_MFCRF targets
(POWER4 and later).  It also won't change anything for strict-alignment
targets, or CPUs without hardware FP of course, or CPUs that do not
implement stfiwx (older 4xx/5xx/8xx).

It does not change the corresponding fixuns* pattern, because that can
not be enabled on any CPU that cannot handle unaligned FP well.


	PR target/89746
	* config/rs6000/rs6000.md (fix_trunc<mode>si2_stfiwx): If we have a
	non-TARGET_MFCRF target, and the dest is memory but not 32-bit aligned,
	go via a stack temporary.

From-SVN: r269802
This commit is contained in:
Segher Boessenkool 2019-03-19 17:58:42 +01:00 • committed by Segher Boessenkool
parent bb48c402f4
commit e8926ce09f
2 changed files with 9 additions and 2 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2018-03-19 Segher Boessenkool <segher@kernel.crashing.org>
PR target/89746
* config/rs6000/rs6000.md (fix_trunc<mode>si2_stfiwx): If we have a
non-TARGET_MFCRF target, and the dest is memory but not 32-bit aligned,
go via a stack temporary.
2019-03-19 Jakub Jelinek <jakub@redhat.com>
PR target/89378

4
gcc/config/rs6000/rs6000.md
View file

@ -5639,13 +5639,13 @@
tmp = gen_reg_rtx (DImode);
emit_insn (gen_fctiwz_<mode> (tmp, src));
if (MEM_P (dest))
if (MEM_P (dest) && (TARGET_MFCRF || MEM_ALIGN (dest) >= 32))
{
dest = rs6000_force_indexed_or_indirect_mem (dest);
emit_insn (gen_stfiwx (dest, tmp));
DONE;
}
else if (TARGET_POWERPC64 && (TARGET_MFPGPR || TARGET_DIRECT_MOVE))
else if (TARGET_POWERPC64 && (TARGET_MFPGPR || TARGET_DIRECT_MOVE) && !MEM_P (dest))
{
dest = gen_lowpart (DImode, dest);
emit_move_insn (dest, tmp);