Hi,
This change addresses a comment from Richard Sandiford in:
https://gcc.gnu.org/ml/gcc-patches/2015-01/msg02165.html
where a previous fix was over eager in converting OP_OUT reloads to
OP_INOUT.
No testcase here either but I will try and exercise this code later
with a targeted test using the RTL frontend if possible.
Thanks,
Matthew
gcc/
PR target/78660
* lra-constraints.c (curr_insn_transform): Tighten condition
for converting SUBREG reloads from OP_OUT to OP_INOUT.
---
gcc/lra-constraints.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/gcc/lra-constraints.c b/gcc/lra-constraints.c
index f29308f..66ff2bb 100644
--- a/gcc/lra-constraints.c
+++ b/gcc/lra-constraints.c
@@ -4139,7 +4139,17 @@ curr_insn_transform (bool check_only_p)
|| (GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (reg))
&& WORD_REGISTER_OPERATIONS)))
{
- if (type == OP_OUT)
+ /* An OP_INOUT is required when reloading a subreg of a
+ mode wider than a word to ensure that data beyond the
+ word being reloaded is preserved. Also automatically
+ ensure that strict_low_part reloads are made into
+ OP_INOUT which should already be true from the backend
+ constraints. */
+ if (type == OP_OUT
+ && (curr_static_id->operand[i].strict_low
+ || (GET_MODE_SIZE (GET_MODE (reg)) > UNITS_PER_WORD
+ && GET_MODE_SIZE (mode)
+ < GET_MODE_SIZE (GET_MODE (reg)))))
type = OP_INOUT;
loc = &SUBREG_REG (*loc);
mode = GET_MODE (*loc);
--
2.2.1
