Re: [RFC PATCH v3 11/12] powerpc: Remove unreachable() from WARN_ON()
From: Sathvika Vasireddy <hidden>
Date: 2022-06-27 15:36:35
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On 25/06/22 12:16, Christophe Leroy wrote:
Le 24/06/2022 à 20:32, Sathvika Vasireddy a écrit :quoted
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
The builtin variant of unreachable (__builtin_unreachable()) works. How about using that instead of unreachable() ? - Sathvika