[PATCH] D105169: [Clang/Test]: Rename enable_noundef_analysis to disable-noundef-analysis and turn it off by default

Nathan Chancellor via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Mon Nov 8 14:27:13 PST 2021

nathanchance added a comment.

Prior to the latest revert (fd9b099906c61e46574d1ea2d99b973321fe1d21 <https://reviews.llvm.org/rGfd9b099906c61e46574d1ea2d99b973321fe1d21>), the Linux kernel's binary verifier (`objtool`) points out an issue when building with ThinLTO and `-fsanitize=integer-divide-by-zero`. I have no idea if this is an issue with the tool or this series. A simplified reproducer:

  $ cat ravb_main.i
  int ravb_set_gti_ndev_rate;
  unsigned int ravb_set_gti_ndev_inc;
  void ravb_set_gti_ndev() {
    ravb_set_gti_ndev_inc = 1000000000;
    ravb_set_gti_ndev_inc = ravb_set_gti_ndev_inc / ravb_set_gti_ndev_rate;
    if (ravb_set_gti_ndev_inc)
  $ clang -std=gnu89 -O2 -flto=thin -fsanitize=integer-divide-by-zero -c -o ravb_main.o ravb_main.i
  $ llvm-ar cDPrsT ravb.o ravb_main.o
  $ ld.lld -m elf_x86_64 -r -o ravb.lto.o --whole-archive ravb.o
  $ ./objtool orc generate --no-fp --no-unreachable --retpoline --uaccess --mcount --module ravb.lto.o
  ravb.lto.o: warning: objtool: .text.ravb_set_gti_ndev: unexpected end of section

With LLVM 13.0.0, there is no warning with those commands. The original and reduced `.i` file, interestingness test, and static `objtool` binary are available here <https://github.com/nathanchance/creduce-files/tree/2010d2dc4fd217948a734d8bfb6be5460222b6b4/D105169>.

  rG LLVM Github Monorepo



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