From: "Jose E. Marchesi" <jose.marchesi@oracle.com>
To: Yonghong Song <yhs@fb.com>
Cc: Lorenz Bauer <oss@lmb.io>,
andrii@kernel.org, bpf@vger.kernel.org, david.faust@oracle.com
Subject: Re: Signedness of char in BTF
Date: Fri, 22 Jul 2022 13:25:33 +0200 [thread overview]
Message-ID: <8735et8k42.fsf@oracle.com> (raw)
In-Reply-To: <d56865b1-30dd-8761-2c12-ae5f66778de1@fb.com> (Yonghong Song's message of "Thu, 21 Jul 2022 15:52:40 -0700")
> The llvm and pahole generate BTF_INT_BOOL when the dwarf type has
> attribute DW_ATE_boolean.
> But BTF_INT_BOOL is actually used in libbpf to differentiate
> configuration values (CONFIG_* = 'y' vs. CONFIG_* = <value>)
>
> In llvm,
> uint8_t BTFEncoding;
> switch (Encoding) {
> case dwarf::DW_ATE_boolean:
> BTFEncoding = BTF::INT_BOOL;
> break;
> case dwarf::DW_ATE_signed:
> case dwarf::DW_ATE_signed_char:
> BTFEncoding = BTF::INT_SIGNED;
> break;
> case dwarf::DW_ATE_unsigned:
> case dwarf::DW_ATE_unsigned_char:
> BTFEncoding = 0;
> break;
> default:
> llvm_unreachable("Unknown BTFTypeInt Encoding");
> }
I just sent a patch to make GCC behave the same way:
https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598702.html
next prev parent reply other threads:[~2022-07-22 11:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-21 14:31 Signedness of char in BTF Lorenz Bauer
2022-07-21 14:54 ` Jose E. Marchesi
2022-07-21 18:44 ` Yonghong Song
2022-07-21 22:21 ` Jose E. Marchesi
2022-07-21 22:52 ` Yonghong Song
2022-07-22 11:25 ` Jose E. Marchesi [this message]
2022-07-22 15:59 ` Yonghong Song
2022-08-02 17:28 ` Jose E. Marchesi
2022-07-21 18:35 ` Yonghong Song
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