https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43908
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|rtl-optimization |target
Summary|Redundant conditionals [4.5 |Unnecessary mov of a
|only] - unnecessary mov of |constant after unrolling.
|a constant after unrolling. |
Last reconfirmed|2021-07-26 00:00:00 |2024-11-19
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
I can still see the redundant load of #1 with a trunk compiler build in April
2024:
sigh:
@ Function supports interworking.
@ args = 0, pretend = 0, frame = 0
@ frame_needed = 0, uses_anonymous_args = 0
@ link register save eliminated.
mov r3, #1
tst r1, #1
streq r3, [r0, #4]
strne r3, [r0]
mov r3, #1
tst r1, #2
streq r3, [r0, #4]
strne r3, [r0]
mov r3, #1
tst r1, #4
streq r3, [r0, #4]
strne r3, [r0]
mov r3, #1
tst r1, #8
streq r3, [r0, #4]
strne r3, [r0]
mov r3, #1
tst r1, #16
streq r3, [r0, #4]
strne r3, [r0]
mov r3, #1
tst r1, #32
streq r3, [r0, #4]
strne r3, [r0]
mov r3, #1
tst r1, #64
streq r3, [r0, #4]
strne r3, [r0]
mov r3, #1
tst r1, #128
strne r3, [r0]
streq r3, [r0, #4]
bx lr
in particular we also fail to apply conditional store-motion (we refuse
because the access can trap). Enabling that makes somewhat a mess
out of the code though.
I'm quite sure the mov issue is a target issue.
