[all-commits] [llvm/llvm-project] 02b8ee: [llvm] Improve llvm.objectsize computation by comp...

[serge-sans-paille via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 02b8ee281947f6cb39c7eb3c4bbba59322e9015b
      https://github.com/llvm/llvm-project/commit/02b8ee281947f6cb39c7eb3c4bbba59322e9015b
  Author: serge-sans-paille <sguelton at mozilla.com>
  Date:   2024-11-19 (Tue, 19 Nov 2024)

  Changed paths:
    M llvm/include/llvm/IR/Value.h
    M llvm/lib/Analysis/MemoryBuiltins.cpp
    A llvm/test/Transforms/LowerConstantIntrinsics/builtin-object-size-range.ll

  Log Message:
  -----------
  [llvm] Improve llvm.objectsize computation by computing GEP, alloca and malloc parameters bound (#115522)

Using a naive expression walker, it is possible to compute valuable
information for
allocation functions, GEP and alloca, even in the presence of some
dynamic
information.
    
We don't rely on computeConstantRange to avoid taking advantage of
undefined behavior, which would be counter-productive wrt. usual
llvm.objectsize usage.
    
llvm.objectsize plays an important role in _FORTIFY_SOURCE definitions,
so improving its diagnostic in turns improves the security of compiled
application.
    
As a side note, as a result of recent optimization improvements, clang
no
longer passes
https://github.com/serge-sans-paille/builtin_object_size-test-suite
This commit restores the situation and greatly improves the scope of
code handled by the static version of __builtin_object_size.



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