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From: Cary Coutant <ccoutant@gmail.com>
Date: Fri, 29 Jul 2022 13:14:08 -0700
Message-ID: <CAJimCsFaZnnHW9v6i4DgQxf_P7j5SUOJmp5i42AWwMXau5uVKw@mail.gmail.com>
Subject: Re: [PATCH] gold/aarch64: Fix adrp distance check
To: Vladislav Khmelevsky <och95@yandex.ru>
Cc: Binutils <binutils@sourceware.org>
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> The offset between destination and location is a signed number,
> currently the offset is treated as unsigned number, thus mathematical
> shifting of negative value is performed incorrectly.

Do you have a test case to illustrate the problem?

+    int64_t offset
+        = static_cast<int64_t> (Reloc::Page (dest) - Reloc::Page (location));
+    int64_t adrp_imm = offset < 0 ? ~(~offset >> 12) : offset >> 12;

C++ conventions: No space before paren in a function call.

The cast is unnecessary here for assignment to an int64_t. Once the
result is in a signed int, I don't think you need to go to all that
extra trouble to shift it.

I'd suggest this instead:

    int64_t adrp_imm = Reloc::Page(dest) - Reloc::Page(location);
    adrp_imm >>= 12;

-cary