[PATCH] D155176: [BTF] Fix BTFParserTest.cpp for unaligned access after D149058

[Eduard Zingerman via Phabricator via llvm-commits]

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I've tested this patch and it also fixes unit tests for this ARM bot:
https://lab.llvm.org/buildbot/#/builders/245/builds/10973


eddyz87 added a comment.

Hi @luporl,

In D155176#4497053 <https://reviews.llvm.org/D155176#4497053>, @luporl wrote:

> I've tested this patch and it also fixes unit tests for this ARM bot:
> https://lab.llvm.org/buildbot/#/builders/245/builds/10973

Thank you for testing it, the pre-merge build also finished green. May I ask you to be a formal reviewer?
@MaskRay agreed with these changes here <https://reviews.llvm.org/D149058#4496161>.


Test bot reported an issue with unit tests for D149058 <https://reviews.llvm.org/D149058> in [1]:

  [==========] Running 1 test from 1 test suite.
  [----------] Global test environment set-up.
  [----------] 1 test from BTFParserTest
  [ RUN      ] BTFParserTest.simpleCorrectInput
  /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/unittests/DebugInfo/BTF/BTFParserTest.cpp:141:33:
  runtime error: upcast of misaligned address 0x7facce60411f for type 'llvm::SmallString<0>', which requires 8 byte alignment
  0x7facce60411f: note: pointer points here
   64 00 00 00 37  41 60 ce ac 7f 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00
               ^
  SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
  /b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/unittests/DebugInfo/BTF/BTFParserTest.cpp:141:33

The issue is caused by attribute "packed" used for too many things:

  #pragma pack(push, 1)
  struct MockData1 {
    struct B {
      ...
    } BTF;
    struct E {
      ...
    } Ext;
  
    int BTFSectionLen = sizeof(BTF);
    int ExtSectionLen = sizeof(Ext);
  
    SmallString<0> Storage;
    std::unique_ptr<ObjectFile> Obj;
  
  }
  #pragma pack(pop)

Access to unaligned pointers in `Storage`/`Obj` causes unaligned
access errors.

To fix this #pragma directives are pushed invards to apply only to `B`
and `E` definitions.

[1] https://lab.llvm.org/buildbot/#/builders/5/builds/35040


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D155176

Files:
  llvm/unittests/DebugInfo/BTF/BTFParserTest.cpp


Index: llvm/unittests/DebugInfo/BTF/BTFParserTest.cpp
===================================================================
--- llvm/unittests/DebugInfo/BTF/BTFParserTest.cpp
+++ llvm/unittests/DebugInfo/BTF/BTFParserTest.cpp
@@ -45,11 +45,11 @@
 // modified before a call to `makeObj()` to test parser with invalid
 // input, etc.
 
+struct MockData1 {
 // Use "pragma pack" to model .BTF & .BTF.ext sections content using
 // 'struct' objects. This pragma is supported by CLANG, GCC & MSVC,
 // which matters for LLVM CI.
 #pragma pack(push, 1)
-struct MockData1 {
   struct B {
     BTF::Header Header = {};
     // no types
@@ -100,6 +100,7 @@
       Header.LineInfoLen = sizeof(Lines);
     }
   } Ext;
+#pragma pack(pop)
 
   int BTFSectionLen = sizeof(BTF);
   int ExtSectionLen = sizeof(Ext);
@@ -148,7 +149,6 @@
     return *Obj.get();
   }
 };
-#pragma pack(pop)
 
 TEST(BTFParserTest, simpleCorrectInput) {
   BTFParser BTF;


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