[Lldb-commits] [PATCH] Profile Assembly Until Ret Instruction

[Todd Fiala]

Hey Jason,

Do you have any feedback on this?

Thanks!

-Todd


On Fri, Jul 25, 2014 at 1:42 PM, Tong Shen <endlessroad at google.com> wrote:

> Sorry, wrong version of patch...
>
>
> On Fri, Jul 25, 2014 at 1:41 PM, Tong Shen <endlessroad at google.com> wrote:
>
>> Hi Molenda, lldb-commits,
>>
>> For now, x86 assembly profiler will stop after 10 "non-prologue"
>> instructions. In practice it may not be sufficient. For example, we have a
>> hand-written assembly function, which have hundreds of instruction before
>> actual (stack-adjusting) prologue instructions.
>>
>> One way is to change the limit to 1000; but there will always be
>> functions that break the limit :-) I believe the right thing to do here is
>> parsing all instructions before "ret"/"call" as prologue instructions.
>>
>> Here's what I changed:
>> - For "push %rbx" and "mov %rbx, -8(%rbp)": only add first row for that
>> register. They may appear multiple times in function body. But as long as
>> one of them appears, first appearance should be in prologue(If it's not in
>> prologue, this function will not use %rbx, so these 2 instructions should
>> not appear at all).
>> - Also monitor "add %rsp 0x20".
>> - Remove non prologue instruction count.
>> - Add "call" instruction detection, and stop parsing after it.
>>
>> Thanks.
>>
>> --
>> Best Regards, Tong Shen
>>
>
>
>
> --
> Best Regards, Tong Shen
>
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>


-- 
Todd Fiala | Software Engineer | tfiala at google.com | 650-943-3180
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