diff mbox

[2/5] Tighten condition for converting SUBREG reloads from OP_OUT to OP_INOUT

Message ID 6D39441BF12EF246A7ABCE6654B0235380B5CE85@hhmail02.hh.imgtec.org
State New
Headers show

Commit Message

Matthew Fortune Feb. 7, 2017, 2:08 p.m. UTC 
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(-)

Comments

Matthew Fortune Feb. 20, 2017, 12:09 p.m. UTC | #1 
Matthew Fortune <Matthew.Fortune@imgtec.com> writes:
> 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.

Committed as r245599.

Thanks,
Matthew
diff mbox

Patch

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);