[all-commits] [llvm/llvm-project] 1295aa: [Clang] Add -fwrapv-pointer flag (#122486)

[Nikita Popov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1295aa2e814d1747d69520e34e2c5fb2888e666d
      https://github.com/llvm/llvm-project/commit/1295aa2e814d1747d69520e34e2c5fb2888e666d
  Author: Nikita Popov <npopov at redhat.com>
  Date:   2025-01-28 (Tue, 28 Jan 2025)

  Changed paths:
    M clang/docs/ReleaseNotes.rst
    M clang/include/clang/Basic/LangOptions.def
    M clang/include/clang/Driver/Options.td
    M clang/lib/CodeGen/CGBuiltin.cpp
    M clang/lib/CodeGen/CGExpr.cpp
    M clang/lib/CodeGen/CGExprScalar.cpp
    M clang/lib/Driver/SanitizerArgs.cpp
    M clang/lib/Driver/ToolChains/CommonArgs.cpp
    M clang/lib/Frontend/CompilerInvocation.cpp
    M clang/lib/Sema/SemaExpr.cpp
    M clang/test/CodeGen/integer-overflow.c
    A clang/test/CodeGen/pointer-overflow.c
    M clang/test/Driver/clang_wrapv_opts.c
    M clang/test/Sema/tautological-pointer-comparison.c

  Log Message:
  -----------
  [Clang] Add -fwrapv-pointer flag (#122486)

GCC supports three flags related to overflow behavior:
 * `-fwrapv`: Makes signed integer overflow well-defined.
 * `-fwrapv-pointer`: Makes pointer overflow well-defined.
* `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`, making both
signed integer overflow and pointer overflow well-defined.

Clang currently only supports `-fno-strict-overflow` and `-fwrapv`, but
not `-fwrapv-pointer`.

This PR proposes to introduce `-fwrapv-pointer` and adjust the semantics
of `-fwrapv` to match GCC.

This allows signed integer overflow and pointer overflow to be
controlled independently, while `-fno-strict-overflow` still exists to
control both at the same time (and that option is consistent across GCC
and Clang).



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