Messages in this thread | | | Date | Mon, 22 May 2017 13:12:48 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 7/7] DWARF: add the config option |
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* Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > How are you handling control flow? > > Control flow of what? > > > > Here's the struct in its current state: > > > > > > #define UNDWARF_REG_UNDEFINED 0 > > > #define UNDWARF_REG_CFA 1 > > > #define UNDWARF_REG_SP 2 > > > #define UNDWARF_REG_FP 3 > > > #define UNDWARF_REG_SP_INDIRECT 4 > > > #define UNDWARF_REG_FP_INDIRECT 5 > > > #define UNDWARF_REG_R10 6 > > > #define UNDWARF_REG_DI 7 > > > #define UNDWARF_REG_DX 8 > > > > > > > Why only those registers? Also, if you have the option I would really > > suggest using the actual x86 register numbers (ax, ex, dx, bx, sp, bp, > > si, di, r8-r15 in that order.) > > Those are the only registers which are ever needed as the base for > finding the previous stack frame. 99% of the time it's sp or bp, the > other registers are needed for aligned stacks and entry code. > > Using the actual register numbers isn't an option because I don't need > them all and they need to fit in a small number of bits. > > This construct might be useful for other arches, which is why I called > it "FP" instead of "BP". But then I ruined that with the last 3 :-)
Please call it BP - 'FP' can easily be read as floating-point, making it all super-confusing. We should use canonical x86 register names and ordering - even if not all registers are used straight away.
Thanks,
Ingo
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