[all-commits] [llvm/llvm-project] 55b587: [ubsan][NFCI] Use SanitizerOrdinal instead of Sani...

[Thurston Dang via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 55b587506e5dccb436e5405b7236671112b36244
      https://github.com/llvm/llvm-project/commit/55b587506e5dccb436e5405b7236671112b36244
  Author: Thurston Dang <thurston at google.com>
  Date:   2025-01-10 (Fri, 10 Jan 2025)

  Changed paths:
    M clang/include/clang/Basic/Sanitizers.h
    M clang/lib/CodeGen/CGBuiltin.cpp
    M clang/lib/CodeGen/CGCall.cpp
    M clang/lib/CodeGen/CGClass.cpp
    M clang/lib/CodeGen/CGDecl.cpp
    M clang/lib/CodeGen/CGExpr.cpp
    M clang/lib/CodeGen/CGExprScalar.cpp
    M clang/lib/CodeGen/CGObjC.cpp
    M clang/lib/CodeGen/CodeGenFunction.cpp
    M clang/lib/CodeGen/CodeGenFunction.h
    M clang/lib/CodeGen/ItaniumCXXABI.cpp

  Log Message:
  -----------
  [ubsan][NFCI] Use SanitizerOrdinal instead of SanitizerMask for EmitCheck (exactly one sanitizer is required) (#122511)

The `Checked` parameter of `CodeGenFunction::EmitCheck` is of type
`ArrayRef<std::pair<llvm::Value *, SanitizerMask>>`, which is overly
generalized: SanitizerMask can denote that zero or more sanitizers are
enabled, but `EmitCheck` requires that exactly one sanitizer is
specified in the SanitizerMask (e.g.,
`SanitizeTrap.has(Checked[i].second)` enforces that).

This patch replaces SanitizerMask with SanitizerOrdinal in the `Checked`
parameter of `EmitCheck` and code that transitively relies on it. This
should not affect the behavior of UBSan, but it has the advantages that:
- the code is clearer: it avoids ambiguity in EmitCheck about what to do
if multiple bits are set
- specifying the wrong number of sanitizers in `Checked[i].second` will
be detected as a compile-time error, rather than a runtime assertion
failure

Suggested by Vitaly in https://github.com/llvm/llvm-project/pull/122392
as an alternative to adding an explicit runtime assertion that the
SanitizerMask contains exactly one sanitizer.



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