The reason for PR116326 is that LRA and reload require different
ELIMINABLE_REGS for a multi-register frame pointer. As ELIMINABLE_REGS
is used to initialize static const objects, it is not possible to make
ELIMINABLE_REGS to depend on options or patch it in some target hook.
It was also concluded that it is not desirable to adjust reload so that
it behaves like LRA, but a hack like #define IN_RELOAD1_CC at the top
of reload1.cc would be fine, see
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116326#c8
This is an according patch that defines IN_RELOAD1_CC and uses it in
avr.h to define ELIMINABLE_REGS.
This is only required for trunk.
PR116326 occurred for some test case in avr-torture.exp, so I didn't
duplicate the test case.
As it appears, this patch also fixes:
https://gcc.gnu.org/PR116324
https://gcc.gnu.org/PR116325
https://gcc.gnu.org/PR116550
Johann
--
AVR: target/116326 - Adjust ELIMINABLE_REGS to reload resp. LRA.
PR target/116326
gcc/
* reload1.cc (IN_RELOAD1_CC): Define prior to all includes.
* config/avr/avr.h (ELIMINABLE_REGS): Depend on IN_RELOAD1_CC. AVR: target/116326 - Adjust ELIMINABLE_REGS to reload resp. LRA.
PR target/116326
gcc/
* reload1.cc (IN_RELOAD1_CC): Define prior to all includes.
* config/avr/avr.h (ELIMINABLE_REGS): Depend on IN_RELOAD1_CC.
diff --git a/gcc/config/avr/avr.h b/gcc/config/avr/avr.h
index 1cf4180e534..d540f2fcb13 100644
--- a/gcc/config/avr/avr.h
+++ b/gcc/config/avr/avr.h
@@ -308,11 +308,20 @@ enum reg_class {
#define STATIC_CHAIN_REGNUM ((AVR_TINY) ? 18 :2)
+#ifndef IN_RELOAD1_CC
+#define ELIMINABLE_REGS \
+ { \
+ { ARG_POINTER_REGNUM, STACK_POINTER_REGNUM }, \
+ { ARG_POINTER_REGNUM, FRAME_POINTER_REGNUM }, \
+ { FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM } \
+ }
+#else
#define ELIMINABLE_REGS { \
{ ARG_POINTER_REGNUM, STACK_POINTER_REGNUM }, \
{ ARG_POINTER_REGNUM, FRAME_POINTER_REGNUM }, \
{ FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM }, \
{ FRAME_POINTER_REGNUM + 1, STACK_POINTER_REGNUM + 1 } }
+#endif /* In reload1.cc ? */
#define INITIAL_ELIMINATION_OFFSET(FROM, TO, OFFSET) \
OFFSET = avr_initial_elimination_offset (FROM, TO)
diff --git a/gcc/reload1.cc b/gcc/reload1.cc
index 2e059b09970..cfa0be24f32 100644
--- a/gcc/reload1.cc
+++ b/gcc/reload1.cc
@@ -17,6 +17,15 @@ You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
+// PR116326: Reload and LRA use different representations of ELIMINABLE_REGS
+// for a multi-register frame-pointer like it is the case for avr. Since
+// ELIMINABLE_REGS is used to initialize a static const object, it is not
+// possible to cater for different ELIMINABLE_REGS by means of a command line
+// option like -m[no-]lra. But with the following macro, we can use #ifdef.
+// This hack was added to reload1.cc because after a complete Reload -> LRA
+// transition, this file will be removed.
+#define IN_RELOAD1_CC
+
#include "config.h"
#include "system.h"
#include "coretypes.h"
