LLVM 18 will soon be relased. This post provides a summary of my contributions in this release cycle to record my learning progress.

• LLVM binary utility maintenance, e.g.
  • adopted llvm-readobj style ObjectFile specific dumpers
  • [llvm-objdump][X86] Add @plt symbols for .plt.got
  • [llvm-readobj] Print <null> for relocation target with an empty name
• compiler-rt maintenance, e.g.
  • changed lsan to work with high-entropy ASLR for x86-64 Linux
  • removed crypt and crypt_r interceptors to work with glibc
  • implemented interceptors for glibc 2.38 __isoc23_strtol and __isoc23_scanf family functions
  • tsan: Respect !nosanitize metadata and remove gcov special case
• -fsanitize=alignment: check memcpy/memmove arguments (#67766)
• LTO maintenance
  • Improve diagnostics handling when parsing module-level inline assembly (#75726)
• MC maintenance
  • [MC,AArch64] Suppress local symbol to STT_SECTION conversion for GOT relocations
  • MC Make .pseudo_probe created sections deterministic after D91878
  • Change .reloc to register used symbols
  • Change SHF_LINK_ORDER and section group parsing order to match GNU assembler
• AArch64
  • Suppress local symbol to STT_SECTION conversion for GOT relocations
  • Restrict MOVZ/MOVK to non-PIC large code model (#70178)
  • clang: Define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16 for AArch64 (#74954)
• RISC-V
  • Clean up code after improved assembler support for linker relaxation
  • Support R_RISCV_SET_ULEB128/R_RISCV_SUB_ULEB128 for .uleb128 directives
  • Parse SHF_LINK_ORDER argument before section group name (#77407)
• x86
  • Support inline assembly constraint "Ws"
  • Change displacement overflow when parsing assembly code (#75747)
  • Fix MSVC-style inline assembly call fptr and jmp fptr (#73207)
  • In 32-bit mode, fix FastISel -fno-pic for intrinsics (#51078)
  • clang: Support arch=x86-64{,-v2,-v3,-v4} for target_clones attribute
  • clang: __builtin_cpu_supports: support x86-64{,-v2,-v3,-v4}
• libunwind
  • Bump to CXX_STANDARD 17 (#75986)

lld

See lld 18 ELF changes

MC

• Removed many obsoleted workarounds from the integrated assembler
• Fixed placement of function entry comments
• Re-architectured a substantial part of the integrated assembler that is used by RISC-V linker relaxation, fixing some longstanding bugs. See The dark side of RISC-V linker relaxation for detail.

Clang

Driver maintenance

• [Driver] -###: exit with code 1 if hasErrorOccurred
• Report errors for target-specific options on unsupported targets
• Remove RequiresPIE and msan's NeedPIE setting (#77689)
• Add -fandroid-pad-segment/-fno-android-pad-segment (#77244)
• Support -mtls-dialect=desc

Others:

• Function multi-versioning: don't set comdat for internal linkage resolvers
• -fsanitize=alignment: check memcpy/memmove arguments (#67766)