https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116444
Bug ID: 116444
Summary: gcc.target/arm/thumb-ifcvt-2.c fails on Cortex-M55 and
misses possible Cortex-M optimization
Product: gcc
Version: 13.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: azoff at gcc dot gnu.org
Target Milestone: ---
Cortex-M55 does not generate optimal code for gcc.target/arm/thumb-ifcvt-2.c.
For Cortex-M3, and other Thumb2 targets, the generated code is:
foo:
cmp r0, r1
ite ne
lslne r0, r0, #1
asreq r0, r1, #1
add r0, r0, r1
bx lr
For Cortex-M55 it's instead:
foo:
lsls r2, r0, #1
cmp r0, r1
asr r3, r1, #1
ite eq
moveq r0, r3
movne r0, r2
add r0, r0, r1
bx lr
The reason why it's different comes from arm_have_conditional_execution()
returning false because "TARGET_COND_ARITH && !reload_completed" is evaluated
to true for Cortex-M55 while Cortex-M3 instead returns true.
