[lldb] SHT_NOBITS sections type

[dlav-sc]

.sbss section was recognized as eSectionTypeOther, but has to be eSectionTypeZeroFill.

Fixed tests for RISCV target:

TestClassLoadingViaMemberTypedef.TestCase
TestClassTemplateNonTypeParameterPack.TestCaseClassTemplateNonTypeParameterPack TestThreadSelectionBug.TestThreadSelectionBug
lldbsuite.test.lldbtest.TestOffsetof
lldbsuite.test.lldbtest.TestOffsetofCpp
TestTargetDumpTypeSystem.TestCase
TestCPP11EnumTypes.CPP11EnumTypesTestCase
TestCppIsTypeComplete.TestCase
TestExprCrash.ExprCrashTestCase
TestDebugIndexCache.DebugIndexCacheTestcase

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[llvmbot]

@llvm/pr-subscribers-lldb

Author: None (dlav-sc)

Changes

.sbss section was recognized as eSectionTypeOther, but has to be eSectionTypeZeroFill.

Fixed tests for RISCV target:

TestClassLoadingViaMemberTypedef.TestCase
TestClassTemplateNonTypeParameterPack.TestCaseClassTemplateNonTypeParameterPack TestThreadSelectionBug.TestThreadSelectionBug
lldbsuite.test.lldbtest.TestOffsetof
lldbsuite.test.lldbtest.TestOffsetofCpp
TestTargetDumpTypeSystem.TestCase
TestCPP11EnumTypes.CPP11EnumTypesTestCase
TestCppIsTypeComplete.TestCase
TestExprCrash.ExprCrashTestCase
TestDebugIndexCache.DebugIndexCacheTestcase

---

Full diff: https://github.com/llvm/llvm-project/pull/99044.diff

1 Files Affected:

• (modified) lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp (+1-1)

diff --git a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
index 51bd34e95c77d..42130e98d5414 100644
--- a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
+++ b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
@@ -1696,7 +1696,7 @@ static SectionType GetSectionTypeFromName(llvm::StringRef Name) {
   return llvm::StringSwitch<SectionType>(Name)
       .Case(".ARM.exidx", eSectionTypeARMexidx)
       .Case(".ARM.extab", eSectionTypeARMextab)
-      .Cases(".bss", ".tbss", eSectionTypeZeroFill)
+      .Cases(".bss", ".tbss", ".sbss", eSectionTypeZeroFill)
       .Case(".ctf", eSectionTypeDebug)
       .Cases(".data", ".tdata", eSectionTypeData)
       .Case(".eh_frame", eSectionTypeEHFrame)

[labath]

I'm wondering if there's a more fundamental fix to be made here. Like perhaps treating treating any allocatable SHT_NOBITS section as ZeroFill.

Basically to add case SHT_NOBITS: if (H.sh_flags & SHF_ALLOC) return eSectionTypeZeroFill; to GetSectionType (line 1716)

[dlav-sc]

I'm wondering if there's a more fundamental fix to be made here. Like perhaps treating treating any allocatable SHT_NOBITS section as ZeroFill.

Basically to add case SHT_NOBITS: if (H.sh_flags & SHF_ALLOC) return eSectionTypeZeroFill; to GetSectionType (line 1716)

Yes, thanks, works fine.

[dlav-sc]

I have also removed .Cases(".bss", ".tbss", eSectionTypeZeroFill).

To be honest, I'm not sure about that. .bss and .tbss have SHT_NOBITS type and SHF_ALLOC flag by Linux Specification, but anyway I have doubts.

[labath]

I have also removed .Cases(".bss", ".tbss", eSectionTypeZeroFill).

To be honest, I'm not sure about that. .bss and .tbss have SHT_NOBITS type and SHF_ALLOC flag by Linux Specification, but anyway I have doubts.

I know what you mean -- you can find very strange elf files out there. However, most elf tools operate on section flags (that's what they're for) and not their names, so I really doubt that e.g. treating a SHT_PROGBITS+SHF_ALLOC section that happens to be called ".bss" as eSectionTypeZeroFill is the right behavior.

So, until proven otherwise, this looks good to me.

[dlav-sc]

I have also removed .Cases(".bss", ".tbss", eSectionTypeZeroFill).
To be honest, I'm not sure about that. .bss and .tbss have SHT_NOBITS type and SHF_ALLOC flag by Linux Specification, but anyway I have doubts.

I know what you mean -- you can find very strange elf files out there. However, most elf tools operate on section flags (that's what they're for) and not their names, so I really doubt that e.g. treating a SHT_PROGBITS+SHF_ALLOC section that happens to be called ".bss" as eSectionTypeZeroFill is the right behavior.

So, until proven otherwise, this looks good to me.

Well, sounds reasonable.
Thanks for the review.

[labath]

You're welcome. BTW, are you able to push the merge button, or do you need someone to do that for you?

[dlav-sc]

BTW, are you able to push the merge button, or do you need someone to do that for you?

No, I don't have permissions. Can you merge it yourself?

[labath]

sure thing.

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