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    SubjectRe: [RFC PATCH v3 11/12] powerpc: Remove unreachable() from WARN_ON()
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    Le 24/06/2022 à 20:32, Sathvika Vasireddy a écrit :
    > objtool is throwing *unannotated intra-function call*
    > warnings with a few instructions that are marked
    > unreachable. Remove unreachable() from WARN_ON()
    > to fix these warnings, as the codegen remains same
    > with and without unreachable() in WARN_ON().

    Did you try the two exemples described in commit 1e688dd2a3d6
    ("powerpc/bug: Provide better flexibility to WARN_ON/__WARN_FLAGS() with
    asm goto") ?

    Without your patch:

    00000640 <test>:
    640: 81 23 00 84 lwz r9,132(r3)
    644: 71 29 40 00 andi. r9,r9,16384
    648: 40 82 00 0c bne 654 <test+0x14>
    64c: 80 63 00 0c lwz r3,12(r3)
    650: 4e 80 00 20 blr
    654: 0f e0 00 00 twui r0,0

    00000658 <test9w>:
    658: 2c 04 00 00 cmpwi r4,0
    65c: 41 82 00 0c beq 668 <test9w+0x10>
    660: 7c 63 23 96 divwu r3,r3,r4
    664: 4e 80 00 20 blr
    668: 0f e0 00 00 twui r0,0
    66c: 38 60 00 00 li r3,0
    670: 4e 80 00 20 blr


    With your patch:

    00000640 <test>:
    640: 81 23 00 84 lwz r9,132(r3)
    644: 71 29 40 00 andi. r9,r9,16384
    648: 40 82 00 0c bne 654 <test+0x14>
    64c: 80 63 00 0c lwz r3,12(r3)
    650: 4e 80 00 20 blr
    654: 0f e0 00 00 twui r0,0
    658: 4b ff ff f4 b 64c <test+0xc> <==

    0000065c <test9w>:
    65c: 2c 04 00 00 cmpwi r4,0
    660: 41 82 00 0c beq 66c <test9w+0x10>
    664: 7c 63 23 96 divwu r3,r3,r4
    668: 4e 80 00 20 blr
    66c: 0f e0 00 00 twui r0,0
    670: 38 60 00 00 li r3,0 <==
    674: 4e 80 00 20 blr <==
    678: 38 60 00 00 li r3,0
    67c: 4e 80 00 20 blr


    Christophe

    >
    > Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
    > ---
    > arch/powerpc/include/asm/bug.h | 1 -
    > 1 file changed, 1 deletion(-)
    >
    > diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
    > index ecbae1832de3..df6c11e008b9 100644
    > --- a/arch/powerpc/include/asm/bug.h
    > +++ b/arch/powerpc/include/asm/bug.h
    > @@ -97,7 +97,6 @@
    > __label__ __label_warn_on; \
    > \
    > WARN_ENTRY("twi 31, 0, 0", BUGFLAG_WARNING | (flags), __label_warn_on); \
    > - unreachable(); \
    > \
    > __label_warn_on: \
    > break; \
    \
     
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