Thank you both for the review! Please commit with 'Namhyung Kim <namhyung@google.com>'.

v7 update.

v6 update.

In D131290#3773833, @jhenderson wrote:

I don't think you can rely on the behaviour of what happens to the strings when vectors are resized - I don't believe there's anything in the C++ standard or the existing type's definition that will guarantee the behaviour will remain the same.

In D131290#3771526, @jhenderson wrote:

In D131290#3771470, @MaskRay wrote:

In D131290#3771459, @jhenderson wrote:

In D131290#3771385, @namhyung wrote:

SmallVector<std::string, 0> SecNames; 
...
SecNames.push_back(("PT_LOAD#" + Twine(Idx)).str());

This makes the test failing again.

Please see the second half of my previous comment re. vector resizing (can apply to SmallVector too potentially). I would expect that to be a problem.

I think we should switch to what I originally suggested, drop StringTableBuilder and use a string with \0 terminators:)

I'm actually inclined to agree - the "simplification" is turning out to be more complicated than I expected.

This makes the test failing again.

v5 update. Now it passes the test!

Sorry for the delay. I think I found the reason - it passed a stack-allocate string to the string table builder which keeps the cached string ref. So each section name pointed to the same place in stack and got overwritten. Will add a vector to hold the local strings.

I suspect the StringTableBuilder does something wrong, or my understanding is incorrect. I checked with a debugger that the sh_name offset set correctly, but the first string was "PT_LOAD#3" instead of "PT_LOAD#1". Investigating...

v4 updates. But the test still fails..

v3 updates. But the test still fails.

• remove unnecessary llvm:: prefix
  • convert disassemble-no-section.test to use yaml2obj

If this is available in GNU objdump, could you post the version it was added to, please?

• use StringTableBuilder and SmallString
• fix bug in the p_type check

Not sure what happened with the input data. But at least it worked with my test case and linux perf kcore image.

1. Have you looked into using StringTableBuilder at all?

Hi, I've addressed all the comments from the previous one. Could you please review it again and commit with "Namhyung Kim <namhyung@google.com>"?

Do you need assistance merging this patch into the main branch?

Updates:

• address reviews on test formatting

Updates:

• drop tools/llvm-objdump/no-section-header.test
• fix test failure in Object/objdump-no-sectionheaders.test
• rebase onto main branch
• a few formatting changes

Updated, please take a look!

Updates:

• small formatting issues on the test files

Updates:

• split test cases and improve comments
• remove unnecessary info in the test yaml
• remove const from obj to remove the const_cast

In D128705#3625477, @MaskRay wrote:

perf annotate --stdio --objdump=/path/to/llvm-objdump

This command does not say how perf finds core

Thanks for your detailed review! Really appreciated!

Updates:

• add a test case
• remove a variable to check fake section
• handle llvm-objdump -h use case

Thanks for your review, now I can add a test case for this.

Cool. I didn't know I can use that. With SectionHeaderTable.NoHeaders = true, it'll do all I need. Thanks for the info!

I've changed it to use std::vector and call createFakeSections() in the llvm-objdump. I'm waiting for D128883 to update the test using yaml2obj.

it seems obj2yaml doesn't show size info in the phdr and because of that yaml2obj sets them to 0. So there's no output... I think it should be fixed first.

Also there's no way to specify contents of segment without sections.

Most tests are created from yaml using yaml2obj. Run ninja obj2yaml. You can use obj2yaml bin to get a yaml from a binary, then manually scrub it to have just the needed details.

Consider adding a -h test too just to show the effect.

This needs a test. I suggest llvm/test/tools/llvm-objdump/X86/disassemble-no-section.test.

Thanks for the detailed review! I'll address your comments in the next spin.

I'm new to the project and not familiar with the code base and C++. Please advise me for improvements.