https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117191
Bug ID: 117191
Summary: [avr][dse2][lra] wrong dead store elimination
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Keywords: testsuite-fail, wrong-code
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: denisc at gcc dot gnu.org
Target Milestone: ---
Target: avr
Created attachment 59370
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=59370&action=edit
dse2 pass dump file
Failed testcase:
$ make -k check-gcc RUNTESTFLAGS="--target_board=atmega128-sim
--tool_opts='-mlra' avr-torture.exp=lra-pr116550-2.c"
[...]
Running /mnt/d/gcc-avr-lra/gcc/testsuite/gcc.target/avr/torture/avr-torture.exp
...
FAIL: gcc.target/avr/torture/lra-pr116550-2.c -O1 execution test
=== gcc Summary ===
# of expected passes 21
# of unexpected failures 1
/mnt/d/mk-avr-lra/gcc/xgcc version 15.0.0 20241016 (experimental) (GCC)
[...]
This test successfully passed without -mlra option, may be lra related:
$ make -k check-gcc RUNTESTFLAGS="--target_board=atmega128-sim
--tool_opts='-mno-lra' avr-torture.exp=lra-pr116550-2.c"
[...]
Running /mnt/d/gcc-avr-lra/gcc/testsuite/gcc.target/avr/torture/avr-torture.exp
...
=== gcc Summary ===
# of expected passes 22
/mnt/d/mk-avr-lra/gcc/xgcc version 15.0.0 20241016 (experimental) (GCC)
[...]
Testcase
$ avr-gcc -da -O1 -S -dp -fverbose-asm -mmcu=atmega128 lra-pr116550-2.c
dse2 pass made a wrong elimination of insn 554 (%sfp+13)
insn 456 have a use of *(%sfp+13):QI
probably scanning of it have to be like:
**scanning insn=505
mem: (plus:HI (reg/f:HI 28 r28)
(const_int 5 [0x5]))
after canon_rtx address: (plus:HI (reg/f:HI 28 r28)
(const_int 5 [0x5]))
gid=1 offset=5
processing const load gid=1[5..6)
removing from active insn=459 has store
mems_found = 0, cannot_delete = true
but it's
**scanning insn=456
mem: (plus:HI (reg/f:HI 28 r28)
(const_int 13 [0xd]))
after canon_rtx address: (plus:HI (reg/f:HI 28 r28)
(const_int 13 [0xd]))
gid=1 offset=13
processing const load gid=1[13..14)
mems_found = 0, cannot_delete = true
Scanning of insn 456 doesn't have 'removing from active insn=554 has store'
because of that insn 554 was removed but it have a store to *(%sfp+13)
It's wrong because insn 456 have a use of *(%sfp+13)
