Add -Wms-bitfield-padding warning when possible

[ojhunt]

No description provided.

[ojhunt]

This is a draft PR as it might produce a bunch of noise, I've got a PR to fix the cases I can repeat locally: #139825

I suspect issues may occur in other configs and I'd like to hear from others before making this a non-draft PR

[ojhunt]

@mstorsjo @Endilll @IanWood1 given you're doing stage2+ builds would you folk mind seeing if this warning triggers for you? after applying #139825 if possible

[Endilll]

@mstorsjo @Endilll @IanWood1 given you're doing stage2+ builds would you folk mind seeing if this warning triggers for you? after applying #139825 if possible

I applied changes from both PRs, and I'm seeing the following warnings (heavily deduplicated):

/home/user/endill/llvm-project/llvm/include/llvm/CodeGen/MachineInstr.h:152:11: warning: bit-field 'AsmPrinterFlags' of type 'uint8_t' (aka 'unsigned char') has a different storage size than the preceding bit-field (1 vs 4 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
  152 |   uint8_t AsmPrinterFlags : LLVM_MI_ASMPRINTERFLAGS_BITS;
      |           ^
/home/user/endill/llvm-project/llvm/include/llvm/CodeGen/MachineInstr.h:147:12: note: preceding bit-field 'Flags' declared here with type 'uint32_t' (aka 'unsigned int')
  147 |   uint32_t Flags : LLVM_MI_FLAGS_BITS;
      |            ^

In file included from /home/user/endill/llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:14:
/home/user/endill/llvm-project/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h:66:14: warning: bit-field 'IsSubfield' of type 'uint16_t' (aka 'unsigned short') has a different storage size than the preceding bit-field (2 vs 4 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
   66 |     uint16_t IsSubfield : 1;
      |              ^
/home/user/endill/llvm-project/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h:63:9: note: preceding bit-field 'DataOffset' declared here with type 'int'
   63 |     int DataOffset : 31;
      |         ^

/home/user/endill/llvm-project/clang/lib/Basic/DiagnosticIDs.cpp:90:12: warning: bit-field 'OptionGroupIndex' of type 'uint16_t' (aka 'unsigned short') has a different storage size than the preceding bit-field (2 vs 1 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
   90 |   uint16_t OptionGroupIndex : 15;
      |            ^
/home/user/endill/llvm-project/clang/lib/Basic/DiagnosticIDs.cpp:88:11: note: preceding bit-field 'WarnShowInSystemMacro' declared here with type 'uint8_t' (aka 'unsigned char')
   88 |   uint8_t WarnShowInSystemMacro : 1;
      |           ^

/home/user/endill/llvm-project/clang/include/clang/AST/DeclTemplate.h:1862:8: warning: bit-field 'StrictPackMatch' of type 'bool' has a different storage size than the preceding bit-field (1 vs 4 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
 1862 |   bool StrictPackMatch : 1;
      |        ^
/home/user/endill/llvm-project/clang/include/clang/AST/DeclTemplate.h:1855:12: note: preceding bit-field 'SpecializationKind' declared here with type 'unsigned int'
 1855 |   unsigned SpecializationKind : 3;
      |            ^

/home/user/endill/llvm-project/clang/include/clang/Analysis/Analyses/ThreadSafetyTIL.h:1667:8: warning: bit-field 'Visited' of type 'bool' has a different storage size than the preceding bit-field (1 vs 4 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
 1667 |   bool Visited : 1;
      |        ^
/home/user/endill/llvm-project/clang/include/clang/Analysis/Analyses/ThreadSafetyTIL.h:1664:12: note: preceding bit-field 'BlockID' declared here with type 'unsigned int'
 1664 |   unsigned BlockID : 31;
      |            ^

/home/user/endill/llvm-project/clang/include/clang/Sema/ScopeInfo.h:119:8: warning: bit-field 'HasBranchProtectedScope' of type 'bool' has a different storage size than the preceding bit-field (1 vs 4 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
  119 |   bool HasBranchProtectedScope : 1;
      |        ^
/home/user/endill/llvm-project/clang/include/clang/Sema/ScopeInfo.h:115:13: note: preceding bit-field 'Kind' declared here with type 'ScopeKind'
  115 |   ScopeKind Kind : 3;
      |             ^

/home/user/endill/llvm-project/clang/include/clang/Sema/Overload.h:987:14: warning: bit-field 'IsADLCandidate' of type 'unsigned int' has a different storage size than the preceding bit-field (4 vs 1 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
  987 |     unsigned IsADLCandidate : 1;
      |              ^
/home/user/endill/llvm-project/clang/include/clang/Sema/Overload.h:983:10: note: preceding bit-field 'StrictPackMatch' declared here with type 'bool'
  983 |     bool StrictPackMatch : 1;
      |          ^
      
/home/user/endill/llvm-project/clang/include/clang/StaticAnalyzer/Core/AnalyzerOptions.h:272:8: warning: bit-field 'AnalyzerWerror' of type 'bool' has a different storage size than the preceding bit-field (1 vs 4 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
  272 |   bool AnalyzerWerror : 1;
      |        ^
/home/user/endill/llvm-project/clang/include/clang/StaticAnalyzer/Core/AnalyzerOptions.h:269:12: note: preceding bit-field 'NoRetryExhausted' declared here with type 'unsigned int'
  269 |   unsigned NoRetryExhausted : 1;
      |            ^

Most of them are in headers, so you should take care of them before people's build logs are flooded.

P.S. I'm not really doing 2-stage builds. What I do is that I use nightly builds from https://apt.llvm.org, and update 1-2 times per month on average. TIL that the second stage of 2-stage builds is not compatible with distcc, which makes sense, so this was a somewhat painful exercise.

[ojhunt]

@mstorsjo @Endilll @IanWood1 given you're doing stage2+ builds would you folk mind seeing if this warning triggers for you? after applying #139825 if possible

I applied changes from both PRs, and I'm seeing the following warnings (heavily deduplicated):

Thank you very much! I'll try to add the fixes for those ones.

What targets do you have enabled?

[Endilll]

@mstorsjo @Endilll @IanWood1 given you're doing stage2+ builds would you folk mind seeing if this warning triggers for you? after applying #139825 if possible

I applied changes from both PRs, and I'm seeing the following warnings (heavily deduplicated):

Thank you very much! I'll try to add the fixes for those ones.

What targets do you have enabled?

Only X86

[ojhunt]

@mstorsjo @Endilll @IanWood1 given you're doing stage2+ builds would you folk mind seeing if this warning triggers for you? after applying #139825 if possible

I applied changes from both PRs, and I'm seeing the following warnings (heavily deduplicated):

Thank you very much! I'll try to add the fixes for those ones.
What targets do you have enabled?

Only X86

would you mind checking now that #139825 has been merged?

[Endilll]

I'll do a 2-stage build again, now with all the targets enabled. Should I enable any additional diagnostic flags for the second stage?

[ojhunt]

I'll do a 2-stage build again, now with all the targets enabled. Should I enable any additional diagnostic flags for the second stage?

maybe -Werror=ms-bitfield-padding so it dies immediately?

I think I got everything, but I was dealing with some slightly irksome lbc++ linker problems

[Endilll]

In addition to all targets, I also built clang-tools-extra, and there's a warning there:

/home/user/endill/llvm-project/clang-tools-extra/clangd/FuzzyMatch.h:128:12: warning: bit-field 'Prev' of type 'Action' (aka 'bool') has a different storage size than the preceding bit-field (1 vs 4 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
  128 |     Action Prev : 1;
      |            ^
/home/user/endill/llvm-project/clang-tools-extra/clangd/FuzzyMatch.h:127:16: note: preceding bit-field 'Score' declared here with type 'int'
  127 |     signed int Score : 15;
      |                ^

[ojhunt]

In addition to all targets, I also built clang-tools-extra, and there's a warning there:

/home/user/endill/llvm-project/clang-tools-extra/clangd/FuzzyMatch.h:128:12: warning: bit-field 'Prev' of type 'Action' (aka 'bool') has a different storage size than the preceding bit-field (1 vs 4 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
  128 |     Action Prev : 1;
      |            ^
/home/user/endill/llvm-project/clang-tools-extra/clangd/FuzzyMatch.h:127:16: note: preceding bit-field 'Score' declared here with type 'int'
  127 |     signed int Score : 15;
      |                ^

ah ha, thank you!

[Endilll]

I figured out I should compile lld and lldb, too. Here are additional warnings:

/home/user/endill/llvm-project/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.h:192:12: warning: bit-field 'm_sibling_idx' of type 'uint32_t' (aka 'unsigned int') has a different storage size than the preceding bit-field (4 vs 8 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
  192 |   uint32_t m_sibling_idx : 31, m_has_children : 1;
      |            ^
/home/user/endill/llvm-project/lldb/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.h:187:15: note: preceding bit-field 'm_parent_idx' declared here with type 'dw_offset_t' (aka 'unsigned long')
  187 |   dw_offset_t m_parent_idx : 64 - DW_DIE_OFFSET_MAX_BITSIZE;
      |               ^
      
/home/user/endill/llvm-project/lldb/source/Plugins/Language/ObjC/NSArray.cpp:104:16: warning: bit-field '_priv1' of type 'uint64_t' (aka 'unsigned long') has a different storage size than the preceding bit-field (8 vs 4 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
  104 |       uint64_t _priv1 : 4;
      |                ^
/home/user/endill/llvm-project/lldb/source/Plugins/Language/ObjC/NSArray.cpp:103:16: note: preceding bit-field '_size' declared here with type 'uint32_t' (aka 'unsigned int')
  103 |       uint32_t _size : 28;
      |                ^
      
/home/user/endill/llvm-project/lldb/source/Plugins/Language/ObjC/NSSet.cpp:65:14: warning: bit-field '_szidx' of type 'uint32_t' (aka 'unsigned int') has a different storage size than the preceding bit-field (4 vs 8 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
   65 |     uint32_t _szidx : 6;
      |              ^
/home/user/endill/llvm-project/lldb/source/Plugins/Language/ObjC/NSSet.cpp:64:14: note: preceding bit-field '_used' declared here with type 'uint64_t' (aka 'unsigned long')
   64 |     uint64_t _used : 58;
      |              ^
      
/home/user/endill/llvm-project/lldb/source/Plugins/Language/ObjC/NSDictionary.cpp:276:16: warning: bit-field '_kvo' of type 'uint32_t' (aka 'unsigned int') has a different storage size than the preceding bit-field (4 vs 8 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
  276 |       uint32_t _kvo : 1;
      |                ^
/home/user/endill/llvm-project/lldb/source/Plugins/Language/ObjC/NSDictionary.cpp:275:16: note: preceding bit-field '_used' declared here with type 'uint64_t' (aka 'unsigned long')
  275 |       uint64_t _used : 58;
      |                ^
      
/home/user/endill/llvm-project/lld/wasm/InputChunks.h:107:12: warning: bit-field 'live' of type 'unsigned int' has a different storage size than the preceding bit-field (4 vs 1 bytes) and will not be packed under the Microsoft ABI [-Wms-bitfield-padding]
  107 |   unsigned live : 1;
      |            ^
/home/user/endill/llvm-project/lld/wasm/InputChunks.h:102:11: note: preceding bit-field 'sectionKind' declared here with type 'uint8_t' (aka 'unsigned char')
  102 |   uint8_t sectionKind : 3;
      |           ^

[ojhunt]

ah ha, lets see if I can convince my local build to just build all the things