ICE: "unsorted CGUs" #113425

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1. nnethercote

   added

   I-ICEIssue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️

   T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.Relevant to the compiler team, which will review and decide on the PR/issue.

   C-bugCategory: This is a bug.Category: This is a bug.

   on Jul 6, 2023
2. nnethercote

   changed the title [-]unsorted CGUs[/-] [+]ICE: "unsorted CGUs"[/+] on Jul 6, 2023
3. nnethercote commented on Jul 6, 2023

   

   nnethercote

   on Jul 6, 2023

   Last edited by nnethercote

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   [Responding to this comment from the original PR]

   And when I tried switching jemalloc=false on my linux machine, I don't encounter the problem.

   When you have jemalloc=true on linux do you encounter the problem?

   error: internal compiler error: compiler\rustc_monomorphize\src\partitioning.rs:195:9: unsorted CGUs:
                                   - pkg_config.1b83623108ca023c-cgu.0
                                   - pkg_config.1b83623108ca023c-cgu.1
                                   - pkg_config.1b83623108ca023c-cgu.2
                                   - pkg_config.1b83623108ca023c-cgu.3
                                   - pkg_config.1b83623108ca023c-cgu.4
                                   - pkg_config.1b83623108ca023c-cgu.5
                                   - pkg_config.1b83623108ca023c-cgu.6
                                   - pkg_config.1b83623108ca023c-cgu.7
                                   - pkg_config.1b83623108ca023c-cgu.8
                                   - pkg_config.1b83623108ca023c-cgu.9
                                   - pkg_config.1b83623108ca023c-cgu.10
   
   error: internal compiler error: compiler\rustc_monomorphize\src\partitioning.rs:195:9: unsorted CGUs:
                                   - vcpkg.da648edadde02677-cgu.0
                                   - vcpkg.da648edadde02677-cgu.1
                                   - vcpkg.da648edadde02677-cgu.2
                                   - vcpkg.da648edadde02677-cgu.3
                                   - vcpkg.da648edadde02677-cgu.4
                                   - vcpkg.da648edadde02677-cgu.5
                                   - vcpkg.da648edadde02677-cgu.6
                                   - vcpkg.da648edadde02677-cgu.7
                                   - vcpkg.da648edadde02677-cgu.8
                                   - vcpkg.da648edadde02677-cgu.9
                                   - vcpkg.da648edadde02677-cgu.10
                                   - vcpkg.da648edadde02677-cgu.11
                                   - vcpkg.da648edadde02677-cgu.12
                                   - vcpkg.da648edadde02677-cgu.13
                                   - vcpkg.da648edadde02677-cgu.14
                                   - vcpkg.da648edadde02677-cgu.15
   

   Thanks, this is exactly the information I was after. Something weird is going on here -- those numeric suffixes are supposed to be zero-padded, e.g. 00 to 10 for the first examples, and 00 to 15 for the second example. Because then they'd be in name-sorted order. (Without the zero-padding, the one with the 10 suffix is considered lower than the one with the 9 suffix.)

   The code responsible for creating the CGU name is here. It uses let num_digits = codegen_units.len().ilog10() as usize + 1; to compute how many digits the suffix must be, and then creates the suffix with let suffix = format!("{index:0num_digits$}");. Nothing too complicated, except for the use of the magic trailing $ to allow a variable padding amount. And platform independent. The number of CGUs involved in the examples (11 and 16) are completely normal, anything up to 16 is normal, though the code should handle any number. Seems like the kind of code that should not be failing on a single project's CI on a single platform!

   Makes me wonder if there could be a bug on Windows with either ilog10 or the use of 0num_digits$ padding in format!? Though if that was the case every Windows nightly user would be hitting this problem. Hmm.
4. ComputerDruid commented on Jul 7, 2023

   

   ComputerDruid

   on Jul 7, 2023

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   When you have jemalloc=true on linux do you encounter the problem?

   No, I just tried that too and neither way can I reproduce the issue on my linux machine
5. lqd commented on Jul 7, 2023

   

   lqd

   on Jul 7, 2023

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   @ComputerDruid your config uses ThinLTO and LLD: I believe you're hitting #109114.

   Removing lto = "thin" will fix it.

   ❤️React with ❤️1Reacted by Nicholas Nethercote
6. jyn514

   added

   O-windows-msvcToolchain: MSVC, Operating system: WindowsToolchain: MSVC, Operating system: Windows

   on Jul 10, 2023