On Thu, Nov 12, 2020 at 5:01 PM Yonghong Song <yhs@xxxxxx> wrote: > > > > On 11/12/20 4:30 PM, Andrii Nakryiko wrote: > > On Thu, Nov 12, 2020 at 4:19 PM Alexei Starovoitov > > <alexei.starovoitov@xxxxxxxxx> wrote: > >> > >> On Thu, Nov 12, 2020 at 4:08 PM Andrii Nakryiko > >> <andrii.nakryiko@xxxxxxxxx> wrote: > >>> > >>> So I looked at your vmlinux image. I think we should just keep > >>> everything mostly as it it right now (without changes in this patch), > >>> but add just two simple checks: > >>> > >>> 1. Skip if fn->declaration (ignore correctly marked func declarations) > >>> 2. Skip if DW_AT_inline: 1 (ignore inlined functions). > >>> > >>> I'd keep the named arguments check as is, I think it's helpful. 1) > >>> will skip stuff that's explicitly marked as declaration. 2) inline > >>> check will partially mitigate dropping of fn->external check (and we > >>> can't really attach to inlined functions). > >> > >> I thought DW_AT_inline is an indication that the function was marked "inline" > >> in C code. That doesn't mean that the function was actually inlined. > >> So I don't think pahole should check that bit. > > > > According to DWARF spec, there are 4 possible values: > > > > DW_INL_not_inlined = 0 Not declared inline nor inlined by > > the compiler > > DW_INL_inlined = 1 Not declared inline but inlined by > > the compiler > > DW_INL_declared_not_inlined = 2 Declared inline but not inlined by > > the compiler > > DW_INL_declared_inlined = 3 Declared inline and inlined by the compiler > > > > So DW_INL_inlined is supposed to be added to functions that are not > > marked inline, but were nevertheless inlined. I saw this for one of > > vfs_getattr entries in DWARF, which clearly is not marked inline. > > I looked at llvm source code, llvm only tries to assign DW_INL_inlined > and also only at certain conditions. Not sure about gcc. Probably > similar. So this field is not reliable, esp. without it does not mean it > is not inlined. Can't say I'm surprised... > > > > > But also that DWARF entry had proper args with names, so it would work > > fine as well. I don't know, with DWARF it's always some guessing game. > > Let's leave DW_AT_inline alone for now. > > > > Important part is skipping declarations (when they are marked as > > such), though I'm not claiming it will solve the problem completely... > > :) > >
