[PATCH] D28635: [libFuzzer] Portably disassemble and find calls to "sanitizer_cov_trace_pc_guard".

[Marcos Pividori via llvm-commits]

@zturner, yes, it is not well documented. Because of that I propose yo
consider `dumpbin` first, and `link  /dump /disasm` as second option in
case we don't find `dumpbin`.

On Tue, Jan 17, 2017 at 10:00 AM, Zachary Turner <zturner at google.com> wrote:

> By `link`, do you mean the MSVC  linker?  I didn't know it supported /dump
> and /disasm options, and when I run link /help I don't see those options
> listed.
>
> On Fri, Jan 13, 2017 at 1:53 PM Marcos Pividori via Phabricator <
> reviews at reviews.llvm.org> wrote:
>
>> mpividori added inline comments.
>>
>>
>> ================
>> Comment at: lib/Fuzzer/FuzzerTracePC.cpp:162
>> +      size_t PcOffsetEnd = S.find(':');
>> +      if (PcOffsetEnd == std::string::npos) continue;
>> +      S.resize(PcOffsetEnd);
>> ----------------
>> zturner wrote:
>> > Can you put the `continue` on a new line?
>> Ok, I will do that. But, in line 169, the continue is in the same line
>> too. Do you want me to update that too?
>>
>>
>> ================
>> Comment at: lib/Fuzzer/FuzzerUtilWindows.cpp:181
>> +std::string DisassembleCmd(const std::string &FileName) {
>> +  return "dumpbin /disasm " + FileName;
>> +}
>> ----------------
>> zturner wrote:
>> > `dumpbin` is not guaranteed to be in the user's path.  Is this going to
>> cause a problem?  Also I believe `dumpbin` will use Intel syntax for the
>> disassembly.  Does objdump use AT&T syntax by default?  If so, will this
>> cause a problem?
>> @zturner you are right. I didn't realize of that since I was using a
>> terminal with the VS environment.
>> We can use :  `link /dump /disasm` , which is included in PATH, but I
>> couldn't find information if the `/dump` option is a new option or it is
>> also included in old versions.
>> Also, I think we should consider the case when users only using llvm
>> tools, so in that case we could look for: `llvm-objdump`
>>
>> So, I propose to do this:
>> First: See if `dumpbin` is present in PATH,
>> Else: See if `link`  is present in PATH,
>> Else: See if `llvm-objdump` is present in PATH,
>> Else: Fail
>>
>> Would you agree?
>>
>>
>> Repository:
>>   rL LLVM
>>
>> https://reviews.llvm.org/D28635
>>
>>
>>
>>
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