KDAB / hotspot

The Linux perf GUI for performance analysis.
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Disassembly displays old source (caching issue?) and search is broken #577

Closed GitMensch closed 7 months ago

GitMensch commented 11 months ago

Describe the bug Use of Disassembly shows partially (and not always) the source of a previous disassembly. Furthermore the search function seems to be totally broken.

@lievenhey I guess you can reproduce and want to have a look at this. Search definitely worked in older appimages and "caching atifacts" also seem to be a new thing.

milianw commented 10 months ago

how do you trigger this? can you give more detailed information please?

GitMensch commented 10 months ago

just retested with today's appimage

result: you mostly see the source of source1, instead of source2, but the title is set to and the syntax language is used according to source2 and the number of lines is limited to the lines of the function in source2

lievenhey commented 10 months ago

Just to make sure, you are using the correct version of your executable? Disassembler works with addresses not and dwarf information. In theory a compiler can generate two different binaries for the same source code. Depending if he reorders the binary or not (used in obfuscated code to make leaked debug infos unusable).

I sometimes encounter a similar problem after a compiler change / update.

GitMensch commented 10 months ago

Sometimes the binaries are out of date, often just recompiled. If there are differences then the counters are off by some lines (or plain wrong when the code around it changed).

But this is about totally showing the wrong source, and this is "new" and happens since the last big Disassembly overhaul.

milianw commented 10 months ago

also: for the situation you describe @lievenhey we should ideally catch it and noisily show a warning to the user. we can detect it by comparing buildids.

GitMensch commented 10 months ago

I guess you cannot reproduce that with the appimage? Is that related to QT_QPA_PLATFORM as in #339?

Do we need something like an explicit update call to also change the content of the lines?

lievenhey commented 10 months ago

Ah, found it (actually @milianw but in another context). In HighlightedText::setText the QVector is reset correctly. This causes the weird behaviour you are seeing.

milianw commented 10 months ago

@GitMensch wrote:

At least with the new approach-the problem persists. I can now reproduce: disassembly shown, then showing a different disassembly - the code pane was adjusted to show other code, but the code lines shown mismatches the cycles and the disassembly. If I restart hotspot and show the disassembly of that other function "directly" then there's a perfect match.

I suggest to reopen the originating issue....